Merge branch 'test/distributed-e2e-hardening' into cursor/e2e-pool-tmpfs-fallback-f29d

test(e2e): prove operations overlap data movement
Merge branch 'main' into test/distributed-e2e-hardening
2026-09-05 19:55:37 +00:00 · 2026-09-05 23:56:21 +08:00 · 2026-09-05 22:50:00 +08:00 · 2026-09-05 22:21:31 +08:00 · 2026-09-05 22:06:30 +08:00 · 2026-09-05 13:47:12 +00:00
233 changed files with 37206 additions and 4859 deletions
@@ -0,0 +1,2 @@
+sha256-linux=9785867929047dfd8c6f768e0d2b1e0a8fdba85216f4a4139093b1619d03ff07
+sha256-darwin=9785867929047dfd8c6f768e0d2b1e0a8fdba85216f4a4139093b1619d03ff07
@@ -1,2 +1,2 @@
 sha256-darwin=a881fd7d3f5cb94654221ca85b8b30cce1b95e608824a55a15339cbc294e6d34
-sha256-linux=e9a8d64e73f627c4d26c236dbbba690c9ee03a9e26d42a4244515b4439365535
+sha256-linux=a2933d83dfe74ffa03410a0959333a1c48288b8469ca9f17273d449d7510c24b
@@ -0,0 +1,72 @@
+{
+  "lane": "ci/test-and-lint",
+  "tests": [
+    {
+      "invariant": "write-quorum",
+      "suite": "rustfs-ecstore",
+      "name": "set_disk::ops::object::inline_put_commit_path_tests::inline_put_direct_commit_accepts_exact_quorum_and_rejects_quorum_minus_one"
+    },
+    {
+      "invariant": "metadata-rollback",
+      "suite": "rustfs-ecstore",
+      "name": "set_disk::core::io_primitives::tests::write_unique_file_info_reverts_metadata_when_write_quorum_fails"
+    },
+    {
+      "invariant": "stale-writer",
+      "suite": "rustfs-ecstore",
+      "name": "set_disk::ops::object::put_object_tmp_cleanup_tests::put_object_no_lock_aborts_after_outer_namespace_lock_loss"
+    },
+    {
+      "invariant": "range-body",
+      "suite": "rustfs-ecstore",
+      "name": "set_disk::ops::object::transition_upload_integrity_tests::transitioned_compressed_object_range_get_returns_plaintext_slice"
+    },
+    {
+      "invariant": "multipart-cancellation",
+      "suite": "rustfs-ecstore",
+      "name": "set_disk::ops::multipart::tests::cancelled_complete_keeps_upload_lock_through_tail_cleanup"
+    },
+    {
+      "invariant": "list-uncommitted-version",
+      "suite": "rustfs-filemeta",
+      "name": "metacache::tests::resolve_with_write_quorum_slack_keeps_partial_latest_hidden_during_merge"
+    },
+    {
+      "invariant": "minio-object-fixture",
+      "suite": "rustfs-filemeta",
+      "name": "filemeta::test::parses_real_minio_object_xlmeta"
+    },
+    {
+      "invariant": "corrupt-part-arrays",
+      "suite": "rustfs-filemeta",
+      "name": "filemeta::test::crc_valid_but_part_arrays_corrupt_into_fileinfo_errors_not_panics"
+    }
+  ],
+  "fixtures": [
+    {
+      "path": "crates/filemeta/tests/fixtures/minio/object_large_bin.xlmeta.hex",
+      "sha256": "e8093767806d701e639b48d023190e858fbc4cde69bcfd83c22af8cba8452ce5",
+      "source": "MinIO RELEASE.2025-07-23T15-54-02Z; crates/ecstore/tests/fixtures/minio/README.md"
+    },
+    {
+      "path": "crates/filemeta/tests/fixtures/minio/object_small_txt.xlmeta.hex",
+      "sha256": "2a415ad3a3be5a9440035d4026ff880e0e8c1ec1701be9f4e077734e8dce03da",
+      "source": "MinIO RELEASE.2025-07-23T15-54-02Z; crates/ecstore/tests/fixtures/minio/README.md"
+    },
+    {
+      "path": "crates/filemeta/tests/fixtures/minio/object_versioned_txt.xlmeta.hex",
+      "sha256": "7f21f50c326dd8b0228deb6dbdb7052b3d0a3f8ee6c85d43486f0e6bb7a97261",
+      "source": "MinIO RELEASE.2025-07-23T15-54-02Z; crates/ecstore/tests/fixtures/minio/README.md"
+    },
+    {
+      "path": "crates/ecstore/tests/fixtures/minio/bucket_metadata.blob.hex",
+      "sha256": "f2b6e260aff106adf6039feb1c645686e84e75404ff725491fb18668be5db203",
+      "source": "MinIO RELEASE.2025-07-23T15-54-02Z; crates/ecstore/tests/fixtures/minio/README.md"
+    },
+    {
+      "path": "crates/ecstore/tests/fixtures/minio/bucket_metadata_full.xlmeta.hex",
+      "sha256": "3b6de589519c08a1614c8bd409bb8199c17d42043861b07bce513075e6fbfc12",
+      "source": "MinIO RELEASE.2025-07-23T15-54-02Z; crates/ecstore/tests/fixtures/minio/README.md"
+    }
+  ]
+}
@@ -3,9 +3,10 @@
 .NOTPARALLEL: pre-commit pre-pr dev-check

 .PHONY: setup-hooks
-setup-hooks: ## Set up git hooks
+setup-hooks: ## Install the configured pre-commit hooks
 	@echo "🔧 Setting up git hooks..."
-	chmod +x .git/hooks/pre-commit
+	pre-commit validate-config
+	pre-commit install
 	@echo "✅ Git hooks setup complete!"

 .PHONY: doc-paths-check
@@ -40,6 +40,7 @@ script-tests: ## Run shell script tests
 	$(RUSTFS_PYTHON_BIN) ./scripts/check_test_wiring.py --self-test
 	$(RUSTFS_PYTHON_BIN) ./scripts/check_security_coverage.py --self-test
 	$(RUSTFS_PYTHON_BIN) ./scripts/check_scheduled_validation_freshness.py --self-test
+	$(RUSTFS_PYTHON_BIN) ./scripts/test_security_workflow.py
 	$(RUSTFS_PYTHON_BIN) ./scripts/s3-tests/test_report_compat.py
 	bash -n ./scripts/validate_object_data_cache_cold_stampede.sh
 	$(RUSTFS_PYTHON_BIN) ./scripts/check_object_data_cache_follower_samples.py --self-test
@@ -69,7 +69,7 @@ filter = 'package(rustfs-ecstore) & test(/^(bucket::lifecycle::bucket_lifecycle_
 setup = 'ecstore-large-stack'

 [[profile.default.scripts]]
-filter = 'package(rustfs-ecstore) | package(rustfs-s3select-api) | package(rustfs-scanner) | (package(rustfs) & test(/^(app::multipart_usecase::tests::concurrent_completions_share_durable_bucket_quota_reservations|app::object::delete::tests::compressed_delete_requests_update_observed_usage_without_releasing_quota_floor|app::object::internal_put::tests::internal_multipart_roundtrip_completes_and_abort_leaves_nothing|storage::access::tests::(delete_object_access_captures_authorized_bucket_incarnation|copy_operations_reject_recreated_source_bucket_after_authorization|request_slot_keeps_bucket_policy_bound_to_its_store))$/))'
+filter = 'package(rustfs-ecstore) | package(rustfs-s3select-api) | package(rustfs-scanner) | (package(rustfs) & test(/^(app::multipart_usecase::tests::concurrent_completions_share_durable_bucket_quota_reservations|app::object::delete::tests::compressed_delete_requests_update_observed_usage_without_releasing_quota_floor|app::object::internal_put::tests::internal_multipart_roundtrip_completes_and_abort_leaves_nothing|app::object::restore::tests::execute_restore_object_maps_failures_to_typed_s3_errors|storage::access::tests::(delete_object_access_captures_authorized_bucket_incarnation|copy_operations_reject_recreated_source_bucket_after_authorization|request_slot_keeps_bucket_policy_bound_to_its_store))$/))'
 setup = 'ecstore-base-stack'

 [[profile.default.scripts]]
@@ -183,6 +183,13 @@ test-group = 'e2e-reliability'
 filter = 'package(e2e_test) & test(/^inline_fast_path_cluster_test::/)'
 test-group = 'e2e-inline-boundaries'

+# 4-node 4-drive distributed Actions suite: each case starts four rustfs
+# processes and up to sixteen data directories. Serialize across nextest's
+# process boundary so several 4x4 clusters never overlap.
+[[profile.default.overrides]]
+filter = 'package(e2e_test) & test(/^distributed::/)'
+test-group = 'e2e-cluster-nightly'
+
 # Vault KMS tests share the fixed dev-server port 8200. serial_test's #[serial]
 # does not cross nextest process boundaries, so keep every Vault-backed test in
 # one group.
@@ -210,7 +217,7 @@ filter = 'package(rustfs-ecstore) & test(/^(bucket::lifecycle::bucket_lifecycle_
 setup = 'ecstore-large-stack'

 [[profile.ci.scripts]]
-filter = 'package(rustfs-ecstore) | package(rustfs-s3select-api) | package(rustfs-scanner) | (package(rustfs) & test(/^(app::multipart_usecase::tests::concurrent_completions_share_durable_bucket_quota_reservations|app::object::delete::tests::compressed_delete_requests_update_observed_usage_without_releasing_quota_floor|app::object::internal_put::tests::internal_multipart_roundtrip_completes_and_abort_leaves_nothing|storage::access::tests::(delete_object_access_captures_authorized_bucket_incarnation|copy_operations_reject_recreated_source_bucket_after_authorization|request_slot_keeps_bucket_policy_bound_to_its_store))$/))'
+filter = 'package(rustfs-ecstore) | package(rustfs-s3select-api) | package(rustfs-scanner) | (package(rustfs) & test(/^(app::multipart_usecase::tests::concurrent_completions_share_durable_bucket_quota_reservations|app::object::delete::tests::compressed_delete_requests_update_observed_usage_without_releasing_quota_floor|app::object::internal_put::tests::internal_multipart_roundtrip_completes_and_abort_leaves_nothing|app::object::restore::tests::execute_restore_object_maps_failures_to_typed_s3_errors|storage::access::tests::(delete_object_access_captures_authorized_bucket_incarnation|copy_operations_reject_recreated_source_bucket_after_authorization|request_slot_keeps_bucket_policy_bound_to_its_store))$/))'
 setup = 'ecstore-base-stack'

 [[profile.ci.scripts]]
@@ -526,6 +533,27 @@ path = "junit.xml"
 filter = 'package(e2e_test)'
 test-group = 'e2e-cluster-nightly'

+# ---------------------------------------------------------------------------
+# e2e-distributed profile — 4-node 4-disk Actions suite
+# ---------------------------------------------------------------------------
+# Storage-sensitive PR / nightly / dispatch lane owned by
+# .github/workflows/e2e-distributed.yml.
+# Each case starts four rustfs processes (and for site replication, two
+# clusters). Upgrade cases also require RUSTFS_UPGRADE_SOURCE_BINARY.
+# Serialized via e2e-cluster-nightly with no retries.
+[profile.e2e-distributed]
+default-filter = 'package(e2e_test) & test(/^distributed::/)'
+fail-fast = false
+# Decommission / rebalance cases poll for up to 180s with little stdout.
+slow-timeout = { period = "120s", terminate-after = 6 }
+
+[profile.e2e-distributed.junit]
+path = "junit.xml"
+
+[[profile.e2e-distributed.overrides]]
+filter = 'package(e2e_test)'
+test-group = 'e2e-cluster-nightly'
+
 # ---------------------------------------------------------------------------
 # e2e-odm-interop profile — on-demand migration provider interop lane (ODM-20)
 # ---------------------------------------------------------------------------
@@ -586,6 +614,10 @@ path = "junit.xml"
 #     cluster-fault lane. heal_erasure_disk_rebuild is intentionally not
 #     excluded here because backlog#2213 promotes core heal rebuild coverage to
 #     this merge/main lane while retaining nightly coverage.
+#   * distributed:: — 4-node 4-disk Actions suite (S3, lock, versioning,
+#     replication, quota, observability, expand/decommission/rebalance, site
+#     replication, chaos, upgrade history/IAM). Owns [profile.e2e-distributed] and
+#     .github/workflows/e2e-distributed.yml.
 #   * on_demand_migration::interop_test — the ODM-20 provider interoperability
 #     cases, which are meaningless without a source: they run in the dedicated
 #     [profile.e2e-odm-interop] lane below, where the workflow points them at a
@@ -607,6 +639,7 @@ default-filter = """
    package(e2e_test)
    & !test(/^protocols::/)
    & !test(/^(admin_timeout_regression_test|cluster_concurrency_test|cluster_multidrive_pool_test|degraded_listing_availability_test|namespace_lock_quorum_test|object_lambda_test|stale_multipart_cleanup_cluster_test)::/)
+    & !test(/^distributed::/)
    & !test(/^replication_extension_test::/)
    & !test(/^replication_target_matrix_test::/)
    & !test(/^on_demand_migration::(concurrency_test|fault_test|interop_test|real_source_test)::/)
@@ -0,0 +1,115 @@
+# Copyright 2024 RustFS Team
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+name: Quick Checks
+description: Run the shared compile-free RustFS quality checks.
+
+runs:
+  using: composite
+  steps:
+    - name: Install quality tools
+      uses: taiki-e/install-action@bffeee26d4db9be238a4ea78d8826604ebcb594d # v2
+      with:
+        tool: |
+          ripgrep@15.2.0
+          shellcheck@0.11.0
+
+    - name: Install actionlint
+      shell: bash
+      run: |
+        actionlint_dir="$(mktemp -d "${RUNNER_TEMP}/actionlint.XXXXXX")"
+        curl --fail --location --silent --show-error \
+          --output "$actionlint_dir/actionlint.tar.gz" \
+          https://github.com/rhysd/actionlint/releases/download/v1.7.12/actionlint_1.7.12_linux_amd64.tar.gz
+        echo "8aca8db96f1b94770f1b0d72b6dddcb1ebb8123cb3712530b08cc387b349a3d8  $actionlint_dir/actionlint.tar.gz" | sha256sum --check --status
+        tar -xzf "$actionlint_dir/actionlint.tar.gz" -C "$actionlint_dir" actionlint
+        rm "$actionlint_dir/actionlint.tar.gz"
+        echo "$actionlint_dir" >> "$GITHUB_PATH"
+
+    - name: Install Rust toolchain
+      uses: dtolnay/rust-toolchain@29eef336d9b2848a0b548edc03f92a220660cdb8 # stable
+      with:
+        components: rustfmt
+
+    - name: Check workflow syntax and shell scripts
+      shell: bash
+      run: shellcheck --version && actionlint
+
+    - name: Check code formatting
+      shell: bash
+      run: cargo fmt --all --check
+
+    - name: Check unsafe code allowances
+      shell: bash
+      run: ./scripts/check_unsafe_code_allowances.sh
+
+    - name: Check layered dependencies
+      shell: bash
+      run: ./scripts/check_layer_dependencies.sh
+
+    - name: Check architecture migration rules
+      shell: bash
+      run: ./scripts/check_architecture_migration_rules.sh
+
+    - name: Check logging guardrails
+      shell: bash
+      run: ./scripts/check_logging_guardrails.sh
+
+    - name: Check error other(format!) ratchet
+      shell: bash
+      run: ./scripts/check_error_other_format_ratchet.sh
+
+    - name: Check tokio io-uring feature guard
+      shell: bash
+      run: ./scripts/check_no_tokio_io_uring.sh
+
+    - name: Check extension schema boundaries
+      shell: bash
+      run: ./scripts/check_extension_schema_boundaries.sh
+
+    - name: Check body-cache whitelist guard
+      shell: bash
+      run: ./scripts/check_body_cache_whitelist.sh
+
+    - name: Check s3s footprint ratchet
+      shell: bash
+      run: ./scripts/check_s3s_footprint.sh
+
+    - name: Check cryptographic capability wording
+      shell: bash
+      run: ./scripts/check_fips_wording.sh
+
+    - name: Check no embedded secret material
+      shell: bash
+      run: ./scripts/check_embedded_secrets.sh
+
+    - name: Check test wiring
+      shell: bash
+      run: |
+        python3 ./scripts/check_test_wiring.py --self-test
+        python3 ./scripts/check_scheduled_validation_freshness.py --self-test
+        python3 ./scripts/test_security_workflow.py
+        python3 ./scripts/check_test_wiring.py
+
+    - name: Check no planning docs committed
+      shell: bash
+      run: ./scripts/check_no_planning_docs.sh
+
+    - name: Check CI paths stay in sync
+      shell: bash
+      run: ./scripts/check_ci_paths_sync.sh
+
+    - name: Check io_uring lane --lib precondition
+      shell: bash
+      run: ./scripts/check_uring_lane_lib_only.sh
@@ -10,16 +10,16 @@ Use N/A when there is no related issue.

 ## Summary of Changes
 <!--
-Briefly explain what changed and why reviewers should accept it.
-Focus on behavior, compatibility, and review-relevant context.
+Describe the concrete problem and resulting behavior. For a behavior change, name the input or state that triggers it and the expected outcome. Explain any new dependency or abstraction that the change needs.
 -->

 ## Verification
 <!--
-List the commands or checks you ran, for example:
- `make pre-commit`
+Give 1–3 concrete pieces of evidence for the changed behavior: the test or command, its observed result, and the regression it catches. For a bug fix, record a failing-before/passing-after check or explain why it was unavailable.

-Use N/A only when verification is not applicable.
+Identify the tested commit and any local changes. When testing a prebuilt binary or external service, include its source/version and artifact identity; a successful run against a different build is not evidence for this change.
+
+List relevant checks not run and the remaining risk. Use the validation tier in AGENTS.md; do not run broader checks solely to fill this section. For documentation-only changes, list the applicable documentation checks. Use N/A only when verification is not applicable.
 -->

 ## Impact
@@ -4,6 +4,11 @@
  { "workflow": ".github/workflows/ci.yml", "max_age_hours": 192 },
  { "workflow": ".github/workflows/coverage.yml", "max_age_hours": 192 },
  { "workflow": ".github/workflows/e2e-replication-nightly.yml", "max_age_hours": 36 },
+  {
+    "workflow": ".github/workflows/e2e-distributed.yml",
+    "max_age_hours": 36,
+    "never_ran_grace_until": "2026-09-18T00:00:00Z"
+  },
  { "workflow": ".github/workflows/e2e-s3tests.yml", "max_age_hours": 192 },
  { "workflow": ".github/workflows/fuzz.yml", "max_age_hours": 36 },
  { "workflow": ".github/workflows/mint.yml", "max_age_hours": 192 },
@@ -12,24 +12,10 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.

-# Companion to ci.yml for required status checks.
-#
-# ci.yml skips docs-only pull requests via paths-ignore, but the branch ruleset
-# requires a check named "Test and Lint" — without this workflow a docs-only PR
-# would wait on it forever. This workflow triggers on exactly the paths ci.yml
-# ignores and reports success under the same job name. Mixed PRs trigger both
-# workflows and the real check still gates: a required check with any failing
-# run blocks the merge.
-# https://docs.github.com/en/repositories/configuring-branches-and-merges-in-your-repository/defining-the-mergeability-of-pull-requests/troubleshooting-required-status-checks#handling-skipped-but-required-checks
-#
-# "Quick Checks" is mirrored here ahead of the ruleset change that will make it
-# required too (rustfs/backlog#1599). Until that change lands this job is
-# inert; mirroring it first is what lets the ruleset change happen without
-# stranding docs-only PRs on a check nobody reports.
-#
-# Keep the paths list below in sync with the pull_request paths-ignore list
-# in ci.yml, and keep the quick-checks steps below byte-identical to the
-# quick-checks job in ci.yml.
+# Reports the existing required checks for paths excluded by ci.yml.
+# Mixed PRs can trigger both workflows; their Quick Checks jobs use one shared
+# action to keep validation coverage aligned. Keep this paths list in sync with
+# ci.yml's pull_request.paths-ignore via scripts/check_ci_paths_sync.sh.

 name: Continuous Integration (docs only)

@@ -59,19 +45,6 @@ permissions:
  contents: read

 jobs:
-  # Deliberately NOT a bare `echo`. Once "Quick Checks" becomes a required
-  # check, ci.yml gates every expensive job behind it, so a mixed PR reports
-  # two check runs with this name: the real one (45-51s) and this companion.
-  # GitHub has no written contract for how it picks between same-named
-  # required check runs ("latest wins" vs "any failure blocks"), so instead of
-  # relying on ordering we make both runs execute the same commands against
-  # the same merge ref — their conclusions are then necessarily identical and
-  # the choice does not matter. Keep these steps byte-identical to the
-  # quick-checks job in ci.yml (a guard script that asserts this, and the paths
-  # sync below, is tracked in rustfs/backlog#1603).
-  #
-  # For a genuinely docs-only PR this adds no strictness (no code changed, so
-  # fmt and the guards always pass) and costs ~50s of ubuntu-latest.
  quick-checks:
    name: Quick Checks
    runs-on: ubuntu-latest
@@ -82,63 +55,8 @@ jobs:
        with:
          persist-credentials: false

-      - name: Install ripgrep
-        uses: taiki-e/install-action@bffeee26d4db9be238a4ea78d8826604ebcb594d # v2
-        with:
-          tool: ripgrep@15.2.0
-
-      - name: Install Rust toolchain
-        uses: dtolnay/rust-toolchain@29eef336d9b2848a0b548edc03f92a220660cdb8 # stable
-        with:
-          components: rustfmt
-
-      - name: Check code formatting
-        run: cargo fmt --all --check
-
-      - name: Check unsafe code allowances
-        run: ./scripts/check_unsafe_code_allowances.sh
-
-      - name: Check layered dependencies
-        run: ./scripts/check_layer_dependencies.sh
-
-      - name: Check architecture migration rules
-        run: ./scripts/check_architecture_migration_rules.sh
-
-      - name: Check logging guardrails
-        run: ./scripts/check_logging_guardrails.sh
-
-      - name: Check tokio io-uring feature guard
-        run: ./scripts/check_no_tokio_io_uring.sh
-
-      - name: Check extension schema boundaries
-        run: ./scripts/check_extension_schema_boundaries.sh
-
-      - name: Check body-cache whitelist guard
-        run: ./scripts/check_body_cache_whitelist.sh
-
-      - name: Check s3s footprint ratchet
-        run: ./scripts/check_s3s_footprint.sh
-
-      - name: Check cryptographic capability wording
-        run: ./scripts/check_fips_wording.sh
-
-      - name: Check no embedded secret material
-        run: ./scripts/check_embedded_secrets.sh
-
-      - name: Check test wiring
-        run: |
-          python3 ./scripts/check_test_wiring.py --self-test
-          python3 ./scripts/check_scheduled_validation_freshness.py --self-test
-          python3 ./scripts/check_test_wiring.py
-
-      - name: Check no planning docs committed
-        run: ./scripts/check_no_planning_docs.sh
-
-      - name: Check CI paths stay in sync
-        run: ./scripts/check_ci_paths_sync.sh
-
-      - name: Check io_uring lane --lib precondition
-        run: ./scripts/check_uring_lane_lib_only.sh
+      - name: Run shared quick checks
+        uses: ./.github/actions/quick-checks

  test-and-lint:
    name: Test and Lint
@@ -100,12 +100,7 @@ jobs:
      - name: Typos check with custom config file
        uses: crate-ci/typos@37bb98842b0d8c4ffebdb75301a13db0267cef89 # master

-  # Fast, compile-free checks that fail early so contributors get feedback in
-  # ~1 minute instead of waiting for the full test job.
-  #
-  # These steps are mirrored byte-for-byte in ci-docs-only.yml so that a mixed
-  # PR, which reports two check runs named "Quick Checks", cannot get one red
-  # and one green. Edit both jobs together.
+  # Fail early with compile-free checks shared with docs-only CI.
  quick-checks:
    name: Quick Checks
    if: github.event_name != 'pull_request' || github.event.action != 'closed'
@@ -117,66 +112,8 @@ jobs:
        with:
          persist-credentials: false

-      - name: Install ripgrep
-        uses: taiki-e/install-action@bffeee26d4db9be238a4ea78d8826604ebcb594d # v2
-        with:
-          tool: ripgrep@15.2.0
-
-      - name: Install Rust toolchain
-        uses: dtolnay/rust-toolchain@29eef336d9b2848a0b548edc03f92a220660cdb8 # stable
-        with:
-          components: rustfmt
-
-      - name: Check code formatting
-        run: cargo fmt --all --check
-
-      - name: Check unsafe code allowances
-        run: ./scripts/check_unsafe_code_allowances.sh
-
-      - name: Check layered dependencies
-        run: ./scripts/check_layer_dependencies.sh
-
-      - name: Check architecture migration rules
-        run: ./scripts/check_architecture_migration_rules.sh
-
-      - name: Check logging guardrails
-        run: ./scripts/check_logging_guardrails.sh
-
-      - name: Check error other(format!) ratchet
-        run: ./scripts/check_error_other_format_ratchet.sh
-
-      - name: Check tokio io-uring feature guard
-        run: ./scripts/check_no_tokio_io_uring.sh
-
-      - name: Check extension schema boundaries
-        run: ./scripts/check_extension_schema_boundaries.sh
-
-      - name: Check body-cache whitelist guard
-        run: ./scripts/check_body_cache_whitelist.sh
-
-      - name: Check s3s footprint ratchet
-        run: ./scripts/check_s3s_footprint.sh
-
-      - name: Check cryptographic capability wording
-        run: ./scripts/check_fips_wording.sh
-
-      - name: Check no embedded secret material
-        run: ./scripts/check_embedded_secrets.sh
-
-      - name: Check test wiring
-        run: |
-          python3 ./scripts/check_test_wiring.py --self-test
-          python3 ./scripts/check_scheduled_validation_freshness.py --self-test
-          python3 ./scripts/check_test_wiring.py
-
-      - name: Check no planning docs committed
-        run: ./scripts/check_no_planning_docs.sh
-
-      - name: Check CI paths stay in sync
-        run: ./scripts/check_ci_paths_sync.sh
-
-      - name: Check io_uring lane --lib precondition
-        run: ./scripts/check_uring_lane_lib_only.sh
+      - name: Run shared quick checks
+        uses: ./.github/actions/quick-checks

  test-and-lint:
    name: Test and Lint
@@ -269,6 +206,7 @@ jobs:
          CARGO_BUILD_JOBS: ${{ (github.event_name == 'push' || github.event_name == 'workflow_dispatch') && '3' || '2' }}
        run: |
          mkdir -p artifacts/test-and-lint
+          rm -f target/nextest/ci/junit.xml
          ./scripts/ci/resource_sampler.sh start nextest
          trap './scripts/ci/resource_sampler.sh stop' EXIT
          set +e
@@ -277,6 +215,12 @@ jobs:
            --status-level all --final-status-level all \
            2>&1 | tee artifacts/test-and-lint/nextest.log
          status=${PIPESTATUS[0]}
+          if [[ "${status}" -eq 0 ]]; then
+            cargo nextest list --profile ci --all --exclude e2e_test --message-format json \
+              > artifacts/test-and-lint/core-test-listing.json \
+              && python3 scripts/check_test_wiring.py --check-core artifacts/test-and-lint/core-test-listing.json \
+              && test -s target/nextest/ci/junit.xml || status=$?
+          fi
          {
            echo "command=cargo nextest run --profile ci --all --exclude e2e_test"
            echo "exit_status=${status}"
@@ -0,0 +1,206 @@
+# Copyright 2024 RustFS Team
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# 4-node 4-disk distributed e2e lane.
+#
+# Each selected test starts a real localhost cluster via
+# `RustFSTestClusterEnvironment` (4 processes; 4 drives per node unless the
+# case is a two-site 4-node 1-drive pair or a 4-node upgrade). Membership is
+# `[profile.e2e-distributed]` in `.config/nextest.toml`. Storage-sensitive PRs,
+# nightly runs, and manual dispatches all execute the same fail-closed suite.
+# Upgrade cases download the same pinned previous release as e2e-upgrade.yml.
+#
+# Isolated pool filesystems: expand/decommission/rebalance cases require
+# independent `statfs` capacity. `sm-standard-4` is an ARC pod
+# (`scripts/ci/check_runner_ephemerality.sh`) and usually has no
+# `/dev/loop-control`, so `mount -o loop` fails with ENOENT ("mount failed:
+# No such file or directory"). The prepare step therefore mounts four 1 GiB
+# tmpfs instances and exports them as `RUSTFS_E2E_POOL_ROOTS`.
+
+name: e2e-distributed
+
+on:
+  pull_request:
+    paths:
+      - "Cargo.lock"
+      - "Cargo.toml"
+      - ".config/nextest.toml"
+      - ".github/workflows/e2e-distributed.yml"
+      - "crates/audit/**"
+      - "crates/common/**"
+      - "crates/config/**"
+      - "crates/e2e_test/**"
+      - "crates/ecstore/**"
+      - "crates/filemeta/**"
+      - "crates/heal/**"
+      - "crates/iam/**"
+      - "crates/lock/**"
+      - "crates/madmin/**"
+      - "crates/notify/**"
+      - "crates/replication/**"
+      - "crates/s3-client/**"
+      - "crates/s3-ops/**"
+      - "crates/s3-types/**"
+      - "crates/scanner/**"
+      - "crates/storage-api/**"
+      - "crates/utils/**"
+      - "rustfs/**"
+  workflow_dispatch:
+    inputs:
+      filter:
+        description: "Optional nextest -E filter (default: the whole e2e-distributed profile)"
+        required: false
+        default: ""
+  schedule:
+    # 05:53 UTC nightly — clear of e2e-nightly (04:29) and ODM interop (05:23).
+    - cron: "53 5 * * *"
+
+permissions:
+  contents: read
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: ${{ github.event_name != 'schedule' }}
+
+jobs:
+  distributed:
+    name: Distributed 4-node 4-disk e2e
+    runs-on: sm-standard-4
+    timeout-minutes: 180
+    env:
+      FORCE_JAVASCRIPT_ACTIONS_TO_NODE24: "true"
+      NO_PROXY: 127.0.0.1,localhost
+      HTTP_PROXY: ""
+      HTTPS_PROXY: ""
+      # Pinned previous release used by distributed::upgrade_test (same pin as e2e-upgrade.yml).
+      UPGRADE_SOURCE_VERSION: 1.0.0-rc.2
+      UPGRADE_SOURCE_ASSET: rustfs-linux-x86_64-gnu-v1.0.0-rc.2.zip
+      UPGRADE_SOURCE_SHA256: 7c789386bf85278f865b8e0d359bf4edb84d5aa408cc3fa54a18c25ca74cd6e7
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0 # v7
+        with:
+          persist-credentials: false
+
+      - name: Setup Rust environment
+        uses: ./.github/actions/setup
+        with:
+          rust-version: stable
+          cache-shared-key: ci-e2e-distributed
+          cache-save-if: ${{ github.ref == 'refs/heads/main' }}
+          install-build-packaging-tools: 'false'
+
+      - name: Prepare isolated filesystems for pool movement
+        run: |
+          set -euo pipefail
+          mount_base="${RUNNER_TEMP}/rustfs-e2e-pools"
+          mkdir -p "${mount_base}"
+          roots=()
+          for pool in 0 1 2 3; do
+            mountpoint="${mount_base}/pool-${pool}"
+            mkdir -p "${mountpoint}"
+            # sm-standard-4 is an ARC pod without usable loop devices, so
+            # `mount -o loop` fails with ENOENT. Sized tmpfs still reports a
+            # distinct st_dev and independent 1G statfs capacity.
+            sudo mount -t tmpfs -o size=1G,nosuid,nodev,mode=1777 tmpfs "${mountpoint}"
+            sudo chmod 1777 "${mountpoint}"
+            roots+=("${mountpoint}")
+          done
+          printf -v joined_roots '%s:' "${roots[@]}"
+          echo "RUSTFS_E2E_POOL_ROOTS=${joined_roots%:}" >> "${GITHUB_ENV}"
+          findmnt --noheadings --output TARGET,SOURCE,FSTYPE,SIZE --target "${roots[0]}"
+          findmnt --noheadings --output TARGET,SOURCE,FSTYPE,SIZE --target "${roots[1]}"
+          findmnt --noheadings --output TARGET,SOURCE,FSTYPE,SIZE --target "${roots[2]}"
+          findmnt --noheadings --output TARGET,SOURCE,FSTYPE,SIZE --target "${roots[3]}"
+
+      - name: Download pinned previous release
+        env:
+          SOURCE_DIR: ${{ runner.temp }}/rustfs-upgrade-source
+        run: |
+          set -euo pipefail
+          mkdir -p "$SOURCE_DIR"
+          archive="$SOURCE_DIR/$UPGRADE_SOURCE_ASSET"
+          curl --fail --location --retry 3 --output "$archive" \
+            "https://github.com/${GITHUB_REPOSITORY}/releases/download/${UPGRADE_SOURCE_VERSION}/${UPGRADE_SOURCE_ASSET}"
+          echo "$UPGRADE_SOURCE_SHA256  $archive" | sha256sum --check --strict
+          unzip -q "$archive" -d "$SOURCE_DIR"
+          chmod +x "$SOURCE_DIR/rustfs"
+          test -x "$SOURCE_DIR/rustfs"
+          echo "RUSTFS_UPGRADE_SOURCE_BINARY=$SOURCE_DIR/rustfs" >> "$GITHUB_ENV"
+
+      - name: Build rustfs binary
+        run: |
+          cargo build -p rustfs --bins
+          : > target/debug/rustfs.features
+
+      - name: Verify distributed e2e membership
+        env:
+          NEXTEST_LISTING: ${{ runner.temp }}/rustfs-e2e-distributed-list.json
+        run: |
+          cargo nextest list --profile e2e-distributed -p e2e_test --message-format json > "${NEXTEST_LISTING}"
+          python3 ./scripts/check_test_wiring.py --check-profile e2e-distributed "${NEXTEST_LISTING}"
+
+      - name: Run distributed 4-node e2e suite
+        env:
+          RUSTFS_E2E_LOG_DIR: ${{ runner.temp }}/rustfs-e2e-distributed-logs
+          FILTER: ${{ inputs.filter }}
+        run: |
+          set -euo pipefail
+          if [ -n "${FILTER}" ]; then
+            cargo nextest run --profile e2e-distributed -p e2e_test -E "${FILTER}"
+          else
+            cargo nextest run --profile e2e-distributed -p e2e_test --no-tests=fail
+          fi
+
+      - name: Upload distributed e2e diagnostics
+        if: always()
+        uses: actions/upload-artifact@b7c566a772e6b6bfb58ed0dc250532a479d7789f # v6
+        with:
+          name: e2e-distributed-${{ github.run_number }}
+          path: |
+            target/nextest/e2e-distributed/junit.xml
+            ${{ runner.temp }}/rustfs-e2e-distributed-list.json
+            ${{ runner.temp }}/rustfs-e2e-distributed-logs/
+          retention-days: 7
+          if-no-files-found: warn
+
+      - name: Unmount isolated pool filesystems
+        if: always()
+        run: |
+          set -euo pipefail
+          mount_base="${RUNNER_TEMP}/rustfs-e2e-pools"
+          for pool in 0 1 2 3; do
+            mountpoint="${mount_base}/pool-${pool}"
+            if mountpoint --quiet "${mountpoint}"; then
+              sudo umount "${mountpoint}"
+            fi
+          done
+
+  alert-on-failure:
+    name: Alert on scheduled failure
+    needs: [distributed]
+    if: always() && github.event_name == 'schedule' && contains(needs.*.result, 'failure')
+    runs-on: ubuntu-latest
+    timeout-minutes: 10
+    permissions:
+      contents: read
+      issues: write
+    steps:
+      - uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0 # v7
+        with:
+          persist-credentials: false
+      - name: Open or update failure-tracking issue
+        uses: ./.github/actions/schedule-failure-issue
+        with:
+          github-token: ${{ secrets.GITHUB_TOKEN }}
@@ -54,9 +54,6 @@ env:
 jobs:
  heal-test:
    runs-on: smoke-testing
-    # Requirement: a failing suite must not fail the workflow; failures
-    # are filed to rustfs/backlog and the chain continues.
-    continue-on-error: true
    timeout-minutes: 480
    # Standalone manual run, or one link of the nightly functional chain
    # (storage -> heal -> pool). Pool expansion no longer re-runs heal.
@@ -152,6 +149,60 @@ jobs:
          else
            PACKAGE_SOURCE="${RUSTFS_NIGHTLY_PACKAGE_URL}"
          fi
+          STEPS_TABLE="/tmp/rustfs-heal-steps.md"
+          python3 - "${LOG_FILE}" "${STEPS_TABLE}" <<'PY'
+          import re
+          import sys
+
+          log_file, out_file = sys.argv[1], sys.argv[2]
+          ansi = re.compile(r'\x1b\[[0-9;]*m')
+          step_re = re.compile(r'^\[HEAL-STEP\]\s+(\d+)\s+(.+?)\s+(PASS|FAIL|SKIP)\s*$')
+          ver_re = re.compile(r'^\[HEAL-VERSION\]\s+(\S+)(?:\s+\(node\s+(\S+)\))?\s*$')
+          result_re = re.compile(r'^\[HEAL-RESULT\]\s+(PASS|FAIL)\s+(.*)$')
+
+          steps = {}
+          order = []
+          version = None
+          version_node = None
+          verdict = None
+          verdict_detail = ''
+          try:
+              with open(log_file, 'r', encoding='utf-8', errors='replace') as fh:
+                  for raw in fh:
+                      line = ansi.sub('', raw).strip()
+                      m = step_re.match(line)
+                      if m:
+                          n, desc, status = m.group(1), m.group(2), m.group(3)
+                          if n not in steps:
+                              order.append(n)
+                          steps[n] = (desc, status)  # later lines win (fail after pass)
+                          continue
+                      m = ver_re.match(line)
+                      if m:
+                          version, version_node = m.group(1), m.group(2)
+                          continue
+                      m = result_re.match(line)
+                      if m:
+                          verdict, verdict_detail = m.group(1), m.group(2)
+          except FileNotFoundError:
+              pass
+
+          with open(out_file, 'w', encoding='utf-8') as out:
+              out.write('## Step Results\n\n')
+              if version:
+                  node_note = f' (captured via `rustfs --version` on {version_node})' if version_node else ''
+                  out.write(f'- Version under test: **{version}**{node_note}\n')
+              if verdict:
+                  out.write(f'- Overall result: **{verdict}** — {verdict_detail}\n')
+              out.write('\n')
+              out.write('| Step | Description | Result |\n')
+              out.write('| --- | --- | --- |\n')
+              for n in sorted(order, key=int):
+                  desc, status = steps[n]
+                  out.write(f'| {n} | {desc} | {status} |\n')
+              if not order:
+                  out.write('| - | - | NOT RUN (no step result lines found) |\n')
+          PY
          {
            echo "# RustFS heal test report"
            echo ""
@@ -160,6 +211,8 @@ jobs:
            echo "- Package: ${PACKAGE_SOURCE}"
            echo "- Test Step Outcome: ${{ steps.test.outcome }}"
            echo ""
+            cat "${STEPS_TABLE}" || true
+            echo ""
            echo "## Log tail"
            echo '```text'
            tail -n 200 "${LOG_FILE}" || true
@@ -49,7 +49,6 @@ env:
 jobs:
  kms-test:
    runs-on: smoke-testing
-    continue-on-error: true
    timeout-minutes: 420
    if: ${{ github.event_name == 'workflow_dispatch' || github.event_name == 'repository_dispatch' }}
    steps:
@@ -109,7 +108,6 @@ jobs:

      - name: Run KMS suite
        id: test
-        continue-on-error: true
        env:
          LOG_FILE: /tmp/rustfs-kms.log
        run: |
@@ -84,9 +84,6 @@ env:
 jobs:
  performance-test:
    runs-on: pf-testing
-    # Requirement: a failing benchmark must not fail the workflow;
-    # failures are filed to rustfs/backlog.
-    continue-on-error: true
    timeout-minutes: 900
    # Run on manual dispatch, or when the nightly build completed successfully.
    # Skipped when nightly failed.
@@ -76,9 +76,6 @@ jobs:
  pool-expansion-test:
    name: Pool expansion / decommission test
    runs-on: smoke-testing
-    # Requirement: a failing suite must not fail the workflow; failures
-    # are filed to rustfs/backlog and the chain continues.
-    continue-on-error: true
    timeout-minutes: 360
    if: ${{ github.event_name == 'workflow_dispatch' || github.event_name == 'repository_dispatch' }}
    env:
@@ -380,6 +377,60 @@ jobs:
          else
            PACKAGE_SOURCE="${RUSTFS_NIGHTLY_PACKAGE_URL}"
          fi
+          STEPS_TABLE="${POOL_ARTIFACT_DIR}/pool-steps.md"
+          python3 - "${LOG_FILE}" "${STEPS_TABLE}" <<'PY'
+          import re
+          import sys
+
+          log_file, out_file = sys.argv[1], sys.argv[2]
+          ansi = re.compile(r'\x1b\[[0-9;]*m')
+          step_re = re.compile(r'^\[POOL-STEP\]\s+(\d+)\s+(.+?)\s+(PASS|FAIL|SKIP)\s*$')
+          ver_re = re.compile(r'^\[POOL-VERSION\]\s+(\S+)(?:\s+\(node\s+(\S+)\))?\s*$')
+          result_re = re.compile(r'^\[POOL-RESULT\]\s+(PASS|FAIL)\s+(.*)$')
+
+          steps = {}
+          order = []
+          version = None
+          version_node = None
+          verdict = None
+          verdict_detail = ''
+          try:
+              with open(log_file, 'r', encoding='utf-8', errors='replace') as fh:
+                  for raw in fh:
+                      line = ansi.sub('', raw).strip()
+                      m = step_re.match(line)
+                      if m:
+                          n, desc, status = m.group(1), m.group(2), m.group(3)
+                          if n not in steps:
+                              order.append(n)
+                          steps[n] = (desc, status)  # later lines win (fail after pass)
+                          continue
+                      m = ver_re.match(line)
+                      if m:
+                          version, version_node = m.group(1), m.group(2)
+                          continue
+                      m = result_re.match(line)
+                      if m:
+                          verdict, verdict_detail = m.group(1), m.group(2)
+          except FileNotFoundError:
+              pass
+
+          with open(out_file, 'w', encoding='utf-8') as out:
+              out.write('## Step Results\n\n')
+              if version:
+                  node_note = f' (captured via `rustfs --version` on {version_node})' if version_node else ''
+                  out.write(f'- Version under test: **{version}**{node_note}\n')
+              if verdict:
+                  out.write(f'- Overall result: **{verdict}** — {verdict_detail}\n')
+              out.write('\n')
+              out.write('| Step | Description | Result |\n')
+              out.write('| --- | --- | --- |\n')
+              for n in sorted(order, key=int):
+                  desc, status = steps[n]
+                  out.write(f'| {n} | {desc} | {status} |\n')
+              if not order:
+                  out.write('| - | - | NOT RUN (no step result lines found) |\n')
+          PY
          {
            echo "# RustFS pool expansion test report"
            echo ""
@@ -389,6 +440,8 @@ jobs:
            echo "- Warp concurrent: ${{ inputs.warp_concurrent || '32' }}"
            echo "- Test Step Outcome: ${{ steps.pool_test.outcome }}"
            echo ""
+            cat "${STEPS_TABLE}" || true
+            echo ""
            echo "## Log tail"
            echo '```text'
            tail -n 200 "${LOG_FILE}" || true
@@ -62,9 +62,6 @@ env:
 jobs:
  replication-test:
    runs-on: smoke-testing
-    # A failed replication run must not break the chain or the workflow: the
-    # failure is reported to rustfs/backlog instead (see the issue step).
-    continue-on-error: true
    timeout-minutes: 360
    if: ${{ github.event_name == 'workflow_dispatch' || github.event_name == 'repository_dispatch' }}
    steps:
@@ -116,7 +113,6 @@ jobs:

      - name: Run replication suite
        id: test
-        continue-on-error: true
        env:
          LOG_FILE: /tmp/rustfs-replication.log
        run: |
@@ -37,7 +37,6 @@ env:
 jobs:
  s3-compat-test:
    runs-on: smoke-testing
-    continue-on-error: true
    timeout-minutes: 360
    if: ${{ github.event_name == 'workflow_dispatch' || github.event_name == 'repository_dispatch' }}
    steps:
@@ -88,7 +87,6 @@ jobs:

      - name: Run S3 compatibility suite
        id: test
-        continue-on-error: true
        env:
          LOG_FILE: /tmp/rustfs-s3-compat.log
        run: |
@@ -74,10 +74,23 @@ env:
 jobs:
  security-test:
    runs-on: smoke-testing
-    continue-on-error: true
    timeout-minutes: 360
    if: ${{ github.event_name == 'workflow_dispatch' || github.event_name == 'repository_dispatch' }}
    steps:
+      - name: Checkout repository (for the OIDC live gate script)
+        uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0 # v7
+        with:
+          persist-credentials: false
+
+      - name: Initialize security evidence
+        id: evidence
+        run: |
+          set -euo pipefail
+          umask 077
+          SECURITY_ARTIFACTS_DIR="${RUNNER_TEMP}/rustfs-security-${GITHUB_RUN_ID}-${GITHUB_RUN_ATTEMPT}"
+          mkdir -- "${SECURITY_ARTIFACTS_DIR}"
+          printf 'SECURITY_ARTIFACTS_DIR=%s\n' "${SECURITY_ARTIFACTS_DIR}" >> "${GITHUB_ENV}"
+
      # auto-testing is private: clone it with the dedicated PF token (not
      # GITHUB_TOKEN) and retry transient GitHub/network failures.
      - name: Checkout auto-testing scripts (with retry)
@@ -98,11 +111,6 @@ jobs:
          echo "ERROR: unable to clone rustfs/auto-testing after 5 attempts" >&2
          exit 1

-      - name: Checkout repository (for the OIDC live gate script)
-        uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0 # v7
-        with:
-          persist-credentials: false
-
      - name: Show environment
        run: |
          uname -a
@@ -135,7 +143,8 @@ jobs:
        id: test
        continue-on-error: true
        env:
-          REPORT_FILE: /tmp/rustfs-security-report.md
+          REPORT_FILE: ${{ env.SECURITY_ARTIFACTS_DIR }}/suite-report.md
+          TMPDIR: ${{ env.SECURITY_ARTIFACTS_DIR }}
          RUSTFS_SECURITY_OIDC_LIVE_SCRIPT: ${{ github.workspace }}/scripts/test/oidc_keycloak_live.sh
        run: |
          set -euo pipefail
@@ -159,29 +168,48 @@ jobs:
          else
            ARGS+=(--package-url "${RUSTFS_NIGHTLY_PACKAGE_URL}")
          fi
-          ./auto-testing/rustfs-security-test.sh "${ARGS[@]}"
+          GITHUB_STEP_SUMMARY=/dev/null ./auto-testing/rustfs-security-test.sh "${ARGS[@]}"

      - name: Generate report
-        if: always()
+        id: report
+        if: ${{ always() && steps.evidence.outcome == 'success' }}
+        env:
+          TEST_OUTCOME: ${{ steps.test.outcome }}
        run: |
          set -euo pipefail
-          if [ ! -f /tmp/rustfs-security-report.md ]; then
-            {
-              echo "# RustFS security test report"
-              echo ""
-              echo "- Run: ${{ github.server_url }}/${{ github.repository }}/actions/runs/${{ github.run_id }}"
-              echo "- Trigger: ${{ github.event_name }}"
-              echo "- Test Step Outcome: failure (suite did not produce a report)"
-            } > /tmp/rustfs-security-report.md
+          RESULT=failure
+          if [ "${TEST_OUTCOME}" = "success" ] && [ -s "${SECURITY_ARTIFACTS_DIR}/suite-report.md" ]; then
+            RESULT=success
          fi
-          cat /tmp/rustfs-security-report.md >> "${GITHUB_STEP_SUMMARY}"
+          {
+            echo "# RustFS security test report"
+            echo ""
+            echo "- Run: ${GITHUB_SERVER_URL}/${GITHUB_REPOSITORY}/actions/runs/${GITHUB_RUN_ID}"
+            echo "- Attempt: ${GITHUB_RUN_ATTEMPT}"
+            echo "- Workflow Commit: ${GITHUB_SHA}"
+            echo "- Trigger: ${GITHUB_EVENT_NAME}"
+            echo "- Test Step Outcome: ${RESULT}"
+            echo "- Suite Step Outcome: ${TEST_OUTCOME}"
+            echo ""
+            # The dashboard prioritizes case rows over the step outcome.
+            # Keep partial case results in the artifact when the suite fails.
+            if [ "${RESULT}" = "success" ]; then
+              cat "${SECURITY_ARTIFACTS_DIR}/suite-report.md"
+            elif [ -s "${SECURITY_ARTIFACTS_DIR}/suite-report.md" ]; then
+              echo "The suite did not complete successfully. See suite-report.md in this run's artifact for diagnostics."
+            else
+              echo "The suite did not produce a non-empty report."
+            fi
+          } > "${SECURITY_ARTIFACTS_DIR}/report.md"
+          cat "${SECURITY_ARTIFACTS_DIR}/report.md" >> "${GITHUB_STEP_SUMMARY}"
+          [ "${RESULT}" = "success" ]

      - name: Upload functional report to dashboard
-        if: always()
+        if: ${{ always() && steps.evidence.outcome == 'success' }}
        continue-on-error: true
        env:
          GH_TOKEN: ${{ env.PF_TESTING_GH_TOKEN }}
-          REPORT_FILE: /tmp/rustfs-security-report.md
+          REPORT_FILE: ${{ env.SECURITY_ARTIFACTS_DIR }}/report.md
          SUITE: security
        run: |
          set -euo pipefail
@@ -210,8 +238,9 @@ jobs:
          GH_TOKEN: ${{ secrets.PF_TESTING_GH_TOKEN }}
          SUITE: 'security'
          SUITE_LABEL: 'Security'
+          EVIDENCE_OUTCOME: ${{ steps.evidence.outcome }}
          RUN_URL: ${{ github.server_url }}/${{ github.repository }}/actions/runs/${{ github.run_id }}
-          REPORT_FILE: '/tmp/rustfs-security-report.md'
+          REPORT_FILE: ${{ env.SECURITY_ARTIFACTS_DIR }}/report.md
          LOG_FILE: ''
        run: |
          set -euo pipefail
@@ -245,7 +274,7 @@ jobs:
            echo ""
            echo "## Report (errors and symptoms)"
            echo ""
-            if [ -s "${REPORT_FILE}" ]; then
+            if [ "${EVIDENCE_OUTCOME}" = "success" ] && [ -s "${REPORT_FILE}" ]; then
              redact < "${REPORT_FILE}"
            elif [ -s "${LOG_FILE:-}" ]; then
              echo "(report file missing; log tail below)"
@@ -263,14 +292,12 @@ jobs:
          echo "filed backlog issue for suite ${SUITE}"

      - name: Upload report and logs
-        if: always()
+        if: ${{ always() && steps.evidence.outcome == 'success' }}
        uses: actions/upload-artifact@b7c566a772e6b6bfb58ed0dc250532a479d7789f # v6
        with:
-          name: rustfs-security-test-${{ github.run_id }}
-          path: |
-            /tmp/rustfs-security-report.md
-            /tmp/rustfs-security.*/*
-          if-no-files-found: ignore
+          name: rustfs-security-test-${{ github.run_id }}-${{ github.run_attempt }}
+          path: ${{ env.SECURITY_ARTIFACTS_DIR }}/
+          if-no-files-found: error
          retention-days: 3

      - name: Cleanup environment (after)
@@ -46,7 +46,6 @@ env:
 jobs:
  storage-test:
    runs-on: smoke-testing
-    continue-on-error: true
    timeout-minutes: 360
    if: ${{ github.event_name == 'workflow_dispatch' || github.event_name == 'repository_dispatch' }}
    steps:
@@ -97,7 +96,6 @@ jobs:

      - name: Run storage engine suite
        id: test
-        continue-on-error: true
        env:
          LOG_FILE: /tmp/rustfs-storage.log
        run: |
@@ -61,9 +61,6 @@ env:
 jobs:
  tier-test:
    runs-on: smoke-testing
-    # Requirement: a failing suite must not fail the workflow; failures
-    # are filed to rustfs/backlog and the chain continues.
-    continue-on-error: true
    timeout-minutes: 420
    if: ${{ github.event_name == 'workflow_dispatch' || github.event_name == 'repository_dispatch' }}
    steps:
@@ -18,15 +18,15 @@ on:
  workflow_dispatch:
    inputs:
      from_version:
-        description: 'OLD RustFS release tag (e.g. 1.0.0-rc.4-preview.1)'
+        description: 'OLD RustFS release tag, e.g. 1.0.0-rc.3 (its release must ship a .deb asset). Leave empty for the default.'
        required: false
-        default: '1.0.0-rc.4-preview.1'
+        default: '1.0.0-rc.3'
      from_url:
        description: 'OLD .deb URL. Overrides from_version.'
        required: false
        type: string
      to_version:
-        description: 'NEW RustFS release tag (leave empty for latest nightly)'
+        description: 'NEW RustFS release tag, e.g. 1.0.0-rc.5 (any version with a .deb asset). Leave empty for latest nightly.'
        required: false
      to_url:
        description: 'NEW .deb URL. Overrides to_version / nightly default.'
@@ -79,7 +79,6 @@ env:
 jobs:
  upgrade-test:
    runs-on: smoke-testing
-    continue-on-error: true
    timeout-minutes: 420
    if: ${{ github.event_name == 'workflow_dispatch' || github.event_name == 'repository_dispatch' }}
    steps:
@@ -142,9 +141,9 @@ jobs:

      - name: Run upgrade compatibility suite
        id: test
-        continue-on-error: true
        env:
          LOG_FILE: /tmp/rustfs-upgrade.log
+          GH_TOKEN: ${{ secrets.PF_TESTING_GH_TOKEN }}
        run: |
          set -euo pipefail
          chmod +x auto-testing/rustfs-upgrade-test.sh
@@ -175,6 +174,29 @@ jobs:
          else
            ARGS+=(--to-url "${RUSTFS_NIGHTLY_PACKAGE_URL}")
          fi
+          # Fail fast with a clear message when a requested release tag has
+          # no .deb asset (e.g. 1.0.0-rc.4 ships only zips), instead of
+          # letting the suite die mid-run on a 404.
+          check_release_asset() {
+            local version="$1" tag asset url
+            [ -n "${version}" ] && [ "${version}" != "null" ] || return 0
+            tag="${version#v}"
+            asset="rustfs_${tag//-/.}_amd64.deb"
+            url="https://github.com/rustfs/rustfs/releases/download/${tag}/${asset}"
+            if ! gh api "repos/rustfs/rustfs/releases/tags/${tag}" --jq '.assets[].name' 2>/dev/null | grep -qxF "${asset}"; then
+              echo "ERROR: release ${tag} has no downloadable asset ${asset}:" >&2
+              echo "       ${url}" >&2
+              echo "Pick a tag whose release ships a .deb (check its release assets)." >&2
+              exit 1
+            fi
+            echo "resolved ${tag} -> ${url}"
+          }
+          if [ -z "${FROM_URL}" ]; then
+            check_release_asset "${FROM_VERSION}"
+          fi
+          if [ -z "${TO_URL}" ]; then
+            check_release_asset "${TO_VERSION}"
+          fi
          ./auto-testing/rustfs-upgrade-test.sh "${ARGS[@]}"

      - name: Generate report
@@ -203,54 +225,75 @@ jobs:
            TO_SOURCE="${RUSTFS_NIGHTLY_PACKAGE_URL}"
          fi
          CASE_TABLE="/tmp/rustfs-upgrade-cases.md"
-          python3 - "${LOG_FILE}" "${CASE_TABLE}" <<'PY'
+          MATRIX_TABLE="/tmp/rustfs-upgrade-matrix.md"
+          python3 - "${LOG_FILE}" "${CASE_TABLE}" "${MATRIX_TABLE}" <<'PY'
          import re
          import sys

-          log_file, out_file = sys.argv[1], sys.argv[2]
+          log_file, out_file, matrix_file = sys.argv[1], sys.argv[2], sys.argv[3]
          ansi = re.compile(r'\x1b\[[0-9;]*m')
          start_re = re.compile(r'^---\s+([A-Z]+-[0-9]+)\s+(.+?)\s+---$')
          done_re = re.compile(r'^\[(PASS|FAIL|UNSUPPORTED)\]\s+([A-Z]+-[0-9]+)\b')
+          topo_re = re.compile(
+              r'^\[UPG-TOPO\]\s+(\S+)\s+(\S+)\s+(\S+)\s+(\S+)\s+PASS=(\d+)\s+FAIL=(\d+)\s*$')

          rows = []
          index = {}
+          topo_rows = []
          try:
-            with open(log_file, 'r', encoding='utf-8', errors='replace') as fh:
-              for raw in fh:
-                line = ansi.sub('', raw).strip()
-                m = start_re.match(line)
-                if m:
-                  case_id, name = m.group(1), m.group(2)
-                  if case_id not in index:
-                    index[case_id] = len(rows)
-                    rows.append([case_id, name, 'RUNNING'])
-                  continue
-                m = done_re.match(line)
-                if m:
-                  status, case_id = m.group(1), m.group(2)
-                  if case_id in index:
-                    rows[index[case_id]][2] = status
-                  else:
-                    rows.append([case_id, case_id, status])
-                    index[case_id] = len(rows) - 1
+              with open(log_file, 'r', encoding='utf-8', errors='replace') as fh:
+                  for raw in fh:
+                      line = ansi.sub('', raw).strip()
+                      m = topo_re.match(line)
+                      if m:
+                          topo_rows.append(m.groups())
+                          continue
+                      m = start_re.match(line)
+                      if m:
+                          case_id, name = m.group(1), m.group(2)
+                          if case_id not in index:
+                              index[case_id] = len(rows)
+                              rows.append([case_id, name, 'RUNNING'])
+                          continue
+                      m = done_re.match(line)
+                      if m:
+                          status, case_id = m.group(1), m.group(2)
+                          if case_id in index:
+                              rows[index[case_id]][2] = status
+                          else:
+                              rows.append([case_id, case_id, status])
+                              index[case_id] = len(rows) - 1
          except FileNotFoundError:
-            rows = []
+              rows = []

          counts = {'PASS': 0, 'FAIL': 0, 'UNSUPPORTED': 0, 'RUNNING': 0}
          for _, _, status in rows:
-            counts[status] = counts.get(status, 0) + 1
+              counts[status] = counts.get(status, 0) + 1

          with open(out_file, 'w', encoding='utf-8') as out:
-            out.write('## Case Summary\n\n')
-            out.write(f"- Total: {len(rows)}\\n")
-            out.write(f"- PASS: {counts.get('PASS', 0)}\\n")
-            out.write(f"- FAIL: {counts.get('FAIL', 0)}\\n")
-            out.write(f"- UNSUPPORTED: {counts.get('UNSUPPORTED', 0)}\\n")
-            out.write('\\n')
-            out.write('| Case | Name | Status |\\n')
-            out.write('| --- | --- | --- |\\n')
-            for case_id, name, status in rows:
-              out.write(f'| {case_id} | {name} | {status} |\\n')
+              out.write('## Case Summary\n\n')
+              out.write(f"- Total: {len(rows)}\\n")
+              out.write(f"- PASS: {counts.get('PASS', 0)}\\n")
+              out.write(f"- FAIL: {counts.get('FAIL', 0)}\\n")
+              out.write(f"- UNSUPPORTED: {counts.get('UNSUPPORTED', 0)}\\n")
+              out.write('\\n')
+              out.write('| Case | Name | Status |\\n')
+              out.write('| --- | --- | --- |\\n')
+              for case_id, name, status in rows:
+                  out.write(f'| {case_id} | {name} | {status} |\\n')
+
+          # Upgrade matrix: one row per topology/backend with the versions
+          # captured on the nodes (rustfs --version) and the aggregated
+          # result. The dashboard renders this table directly.
+          with open(matrix_file, 'w', encoding='utf-8') as out:
+              out.write('## Upgrade Matrix\n\n')
+              out.write('| Topology | KMS Backend | From Version | To Version | Result |\n')
+              out.write('| --- | --- | --- | --- | --- |\n')
+              for topo, backend, old_v, new_v, npass, nfail in topo_rows:
+                  result = 'PASS' if nfail == '0' else 'FAIL'
+                  out.write(f'| {topo} | {backend} | {old_v} | {new_v} | {result} (PASS={npass} FAIL={nfail}) |\n')
+              if not topo_rows:
+                  out.write('| - | - | - | - | NOT RUN (suite failed before upgrade) |\n')
          PY
          {
            echo "# RustFS upgrade compatibility report"
@@ -261,6 +304,8 @@ jobs:
            echo "- To: ${TO_SOURCE}"
            echo "- Test Step Outcome: ${{ steps.test.outcome }}"
            echo ""
+            cat "${MATRIX_TABLE}" || true
+            echo ""
            cat "${CASE_TABLE}" || true
            echo ""
            echo "## Log tail"
@@ -42,6 +42,7 @@ jobs:
      - name: Check latest scheduled runs
        env:
          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+          RUSTFS_DEFAULT_BRANCH: ${{ github.event.repository.default_branch }}
        run: |
          set +e
          python3 scripts/check_scheduled_validation_freshness.py \
@@ -22,6 +22,7 @@ on:
      - "Continuous Integration"
      - "coverage"
      - "e2e-nightly"
+      - "e2e-distributed"
      - "e2e-s3tests"
      - "Fuzz"
      - "mint"
@@ -33,6 +33,7 @@ profile.json
 *.zst
 .secrets
 *.go
+!crates/zip/tests/fixtures/snowball/**/generate/*.go
 *.pb
 *.svg
 deploy/logs/*.log.*
@@ -3,9 +3,9 @@
 repos:
  - repo: local
    hooks:
-      - id: rustfs-dev-check
-        name: rustfs dev-check
-        entry: make dev-check
+      - id: rustfs-fmt-check
+        name: Rust formatting
+        entry: cargo fmt --all --check
        language: system
        types: [rust]
        pass_filenames: false
@@ -109,24 +109,17 @@ affected boundaries and risks. CI still runs its configured repository gates.

 ### 🔒 Git Pre-commit Hooks (optional)

-Git hooks are **not** versioned in this repository, so a fresh clone has no
-active pre-commit hook. If you add your own `.git/hooks/pre-commit` (a good
-choice is a one-liner that runs `make pre-commit`), you can mark it executable
-with:
+The optional hook uses the checked-in `.pre-commit-config.yaml`. Install [pre-commit](https://pre-commit.com/#installation), then run this from the checkout or a linked worktree:

 ```bash
 make setup-hooks
 ```

-Or manually:
+The hook runs `cargo fmt --all --check` when staged files include Rust source. It does not compile the workspace or run tests. Fix formatting with `cargo fmt --all`, inspect and stage the result, then commit again.

-```bash
-chmod +x .git/hooks/pre-commit
-```
+`pre-commit install` resolves Git's hook directory for linked worktrees and preserves an existing hook in migration mode. If you use `core.hooksPath`, keep that hook manager and integrate `pre-commit run` there; the installer refuses to silently replace that configuration.

-With or without a hook, follow the verification tiers in `AGENTS.md`. Run the
-applicable scoped checks, and reserve `make pre-pr` for broad cross-module
-changes whose impact cannot be bounded by those checks.
+A local hook provides early formatting feedback. With or without it, follow the verification tiers in `AGENTS.md`, run relevant behavioral tests, and satisfy the CI merge gates. `make pre-commit` and `make dev-check` remain explicit broader commands.

 ### 📝 Formatting Configuration

@@ -138,31 +131,11 @@ fn_call_width = 90
 single_line_let_else_max_width = 100
 ```

-### 🚫 Commit Prevention
-
-If you set up a pre-commit hook and your code doesn't meet the formatting requirements, the hook will:
-
-1. **Block the commit** and show clear error messages
-2. **Provide exact commands** to fix the issues
-3. **Guide you through** the resolution process
-
-Example output when formatting fails:
-
-```
-❌ Code formatting check failed!
-💡 Please run 'cargo fmt --all' to format your code before committing.
-
-🔧 Quick fix:
-   cargo fmt --all
-   git add .
-   git commit
-```
-
 ### 🔄 Development Workflow

 1. **Make your changes**
 2. **Format your code**: `make fmt` or `cargo fmt --all`
-3. **Run the fast gate**: `make pre-commit` (no clippy, no tests)
+3. **Select relevant checks** using the validation tier in `AGENTS.md`; use `make pre-commit` when its broader fast gate adds useful coverage
 4. **Commit your changes**: `git commit -m "your message"`
 5. **Complete the applicable multi-role adversarial review** for non-exempt changes (see `AGENTS.md`)
 6. **Run applicable scoped checks before opening/updating a PR**; consider
@@ -206,11 +179,12 @@ Configure your IDE to:
 #### Pre-commit hook not running?

 ```bash
-# Check if hook is executable
-ls -la .git/hooks/pre-commit
-
-# Make it executable if needed
-chmod +x .git/hooks/pre-commit
+pre-commit validate-config
+pre-commit run --all-files
+# Inspect any configured hook manager; do not overwrite it.
+git config --get core.hooksPath
+# Install if no separate hook manager is configured.
+make setup-hooks
 ```

 #### Formatting issues?
@@ -165,10 +165,10 @@ http-body = "1.1.0"
 http-body-util = "0.1.5"
 minlz = "1.2.3"
 reqwest = "0.13.4"
-rustfs-kafka-async = { version = "1.2.0" }
+rustfs-kafka-async = { version = "1.3.1" }
 socket2 = { version = "0.6.5" }
 tokio = { version = "1.53.1" }
-tokio-rustls = { default-features = false, version = "0.26.4" }
+tokio-rustls = { default-features = false, version = "0.26.5" }
 tokio-stream = { version = "0.1.19" }
 tokio-test = "0.4.5"
 tokio-util = { version = "0.7.19" }
@@ -199,10 +199,10 @@ serde_urlencoded = "0.7.1"
 # matching stable releases are not available yet, while previous stable lines
 # have incompatible APIs. Keep them exact-pinned and monitor upstream for stable
 # releases.
-aes-gcm = { version = "=0.11.1" }
-argon2 = { version = "=0.6.0" }
-blake2 = "=0.11.0"
-chacha20poly1305 = { version = "=0.11.0" }
+aes-gcm = { version = "0.11.1" }
+argon2 = { version = "0.6.0" }
+blake2 = "0.11.0"
+chacha20poly1305 = { version = "0.11.0" }
 crc-fast = "1.10.0"
 hmac = { version = "0.13.0" }
 jsonwebtoken = { version = "11.0.0" }
@@ -234,18 +234,22 @@ tokio-postgres-rustls = "0.14.0"
 # Utilities and Tools
 anyhow = "1.0.104"
 arc-swap = "1.9.2"
-# RUSTFS_COMPAT_TODO(tokio-tar-extension-limits): keep the fork pin until every parser hardening used by Snowball is released upstream. Remove after astral-sh/tokio-tar#118 is merged and a published release includes extension, physical-entry, and sparse limits, cancellation-safe sparse parsing, and error-fused entry streams.
+# RUSTFS_COMPAT_TODO(tokio-tar-extension-limits): keep the fork pin while Snowball and Swift still depend on it. Remove after Snowball uses a released tar-codec/tar-framing API that exposes precedence-resolved MinIO vendor records, RustFS preserves cancellation-safe ownership of large streamed members, footerless minio-go input is accepted only at an authenticated complete request boundary, the existing resource-limit, cancellation, and error-fuse regressions pass, and Swift no longer needs this fork.
 astral-tokio-tar = { git = "https://github.com/cxymds/tokio-tar.git", rev = "603756478b7668436e464519c77ccac22a99ba96" }
+# Candidate Snowball parser versions exercised by rustfs-zip compatibility fixtures.
+tar-codec = "0.0.14"
+tar-framing = "0.0.14"
 atoi = "3.1.0"
 atomic_enum = "0.3.0"
-aws-config = { version = "1.11.0" }
+aws-config = { version = "1.12.0" }
 aws-credential-types = { version = "1.3.0" }
-aws-sdk-kms = { default-features = false, version = "1.117.0" }
-aws-sdk-s3 = { default-features = false, version = "1.144.0" }
-aws-sdk-sts = { default-features = false, version = "1.113.0" }
+aws-sdk-kms = { default-features = false, version = "1.118.0" }
+aws-sdk-s3 = { default-features = false, version = "1.145.0" }
+aws-sdk-sts = { default-features = false, version = "1.114.0" }
+aws-smithy-async = { version = "1.3.0" }
 aws-smithy-http-client = { default-features = false, version = "1.4.0" }
-aws-smithy-runtime-api = { version = "1.15.0" }
-aws-smithy-types = { version = "1.6.2" }
+aws-smithy-runtime-api = { version = "1.16.0" }
+aws-smithy-types = { version = "1.6.3" }
 base64-simd = "0.8.0"
 brotli = "9.0.0"
 clap = { version = "4.6.6" }
@@ -339,7 +343,7 @@ windows = { version = "0.62.2" }
 windows-sys = "0.61.2"
 xxhash-rust = { version = "0.8.18" }
 zip = "8.6.0"
-zstd = "0.13.3"
+zstd = "0.14.0"

 # Observability and Metrics
 metrics = "0.24.6"
@@ -359,15 +363,15 @@ libunftp = { version = "0.23.0" }
 unftp-core = "0.1.0"
 suppaftp = { version = "11.0.0" }
 rcgen = { version = "0.14.10", default-features = false, features = ["aws_lc_rs", "crypto", "pem"] }
-russh = { version = "0.63.1" }
+russh = { version = "0.63.2" }
 russh-sftp = "2.4.0"

 # WebDAV
 dav-server = "0.11.0"

 # Performance Analysis and Memory Profiling
-rustfs-mimalloc = { version = "0.5.2" }
-hotpath = { version = "0.24.0", default-features = false }
+rustfs-mimalloc = { version = "0.5.3" }
+hotpath = { version = "0.25.0", default-features = false }
 # Snapshot testing for output format regression detection
 insta = { version = "1.48" }

@@ -130,6 +130,21 @@ Scanner cycle budget controls:
  - timeout returns S3 `SlowDown`, so clients should use normal SDK retry handling.
  - this is not a fdatasync or group-commit switch. Track fdatasync batching separately with `rustfs_s3_put_object_rename_fdatasync_batch_files`.

+## Remote tier timeout environment variables
+
+- `RUSTFS_TIER_REMOTE_CONNECT_TIMEOUT_SECS`
+  - remote tier TCP connect timeout.
+  - default is `10`.
+  - must be positive; zero fails tier client initialization, while an invalid integer is logged and falls back to the default.
+- `RUSTFS_TIER_REMOTE_REQUEST_TIMEOUT_SECS`
+  - remote tier request timeout through response headers.
+  - default is `86400` so large transition uploads keep a production-safe budget.
+  - must be positive; zero fails tier client initialization, while an invalid integer is logged and falls back to the default. Very large values are accepted and act as a correspondingly long budget.
+- `RUSTFS_TIER_REMOTE_RESPONSE_BODY_IDLE_TIMEOUT_SECS`
+  - maximum idle time between remote tier response-body chunks.
+  - default is `60`; the timer resets only when non-empty body data keeps progressing.
+  - must be positive; zero fails tier client initialization, while an invalid integer is logged and falls back to the default.
+
 ## Drive timeout environment variables

 - `RUSTFS_DRIVE_METADATA_TIMEOUT_SECS`
@@ -137,6 +137,28 @@ pub const DEFAULT_TIER_REMOTE_VERSION_STATE_FLEET_CONFIRMED: bool = false;
 const _: () = assert!(!DEFAULT_TIER_REMOTE_VERSION_STATE_WRITE);
 const _: () = assert!(!DEFAULT_TIER_REMOTE_VERSION_STATE_FLEET_CONFIRMED);

+/// Environment variable for remote tier TCP connect timeout in seconds.
+pub const ENV_TIER_REMOTE_CONNECT_TIMEOUT_SECS: &str = "RUSTFS_TIER_REMOTE_CONNECT_TIMEOUT_SECS";
+/// Default remote tier TCP connect timeout in seconds.
+pub const DEFAULT_TIER_REMOTE_CONNECT_TIMEOUT_SECS: u64 = 10;
+
+/// Environment variable for the remote tier request timeout in seconds.
+///
+/// This bounds upload/download request progress through response headers. The
+/// default is intentionally large so multi-TiB transition uploads keep their
+/// previous production budget while black-hole remotes no longer wait forever.
+pub const ENV_TIER_REMOTE_REQUEST_TIMEOUT_SECS: &str = "RUSTFS_TIER_REMOTE_REQUEST_TIMEOUT_SECS";
+/// Default remote tier request timeout in seconds.
+pub const DEFAULT_TIER_REMOTE_REQUEST_TIMEOUT_SECS: u64 = 24 * 60 * 60;
+
+/// Environment variable for remote tier response-body idle timeout in seconds.
+///
+/// The timer is re-armed on every non-empty response-body chunk, so slow but
+/// progressing remotes can continue while silent response bodies are cancelled.
+pub const ENV_TIER_REMOTE_RESPONSE_BODY_IDLE_TIMEOUT_SECS: &str = "RUSTFS_TIER_REMOTE_RESPONSE_BODY_IDLE_TIMEOUT_SECS";
+/// Default remote tier response-body idle timeout in seconds.
+pub const DEFAULT_TIER_REMOTE_RESPONSE_BODY_IDLE_TIMEOUT_SECS: u64 = 60;
+
 /// Request the object-transaction fencing contract used by storage-owned
 /// cleanup receipts and lock-window optimizations.
 ///
@@ -812,6 +834,16 @@ mod remote_version_state_tests {
        );
    }

+    #[test]
+    fn remote_tier_timeout_env_names_are_stable() {
+        assert_eq!(super::ENV_TIER_REMOTE_CONNECT_TIMEOUT_SECS, "RUSTFS_TIER_REMOTE_CONNECT_TIMEOUT_SECS");
+        assert_eq!(super::ENV_TIER_REMOTE_REQUEST_TIMEOUT_SECS, "RUSTFS_TIER_REMOTE_REQUEST_TIMEOUT_SECS");
+        assert_eq!(
+            super::ENV_TIER_REMOTE_RESPONSE_BODY_IDLE_TIMEOUT_SECS,
+            "RUSTFS_TIER_REMOTE_RESPONSE_BODY_IDLE_TIMEOUT_SECS"
+        );
+    }
+
    #[test]
    fn data_movement_part_checksum_gate_uses_stable_environment_names() {
        assert_eq!(super::ENV_DATA_MOVEMENT_PART_CHECKSUMS_WRITE, "RUSTFS_DATA_MOVEMENT_PART_CHECKSUMS_WRITE");
@@ -26,6 +26,7 @@ Registered in [`src/lib.rs`](src/lib.rs). Grouped by concern:
 | **protocols** | [`src/protocols/`](src/protocols) | FTPS, WebDAV, SFTP compliance. Fixed ports, own guide: [`src/protocols/README.md`](src/protocols/README.md) |
 | **reliant** | [`src/reliant/`](src/reliant) | Tests that reuse an **externally started** server (SQL/select, conditional writes, lifecycle, deleted-object reads, node-interact). Run via [`scripts/run_e2e_tests.sh`](../../scripts/run_e2e_tests.sh); see [`src/reliant/README.md`](src/reliant/README.md) |
 | **cluster** | `cluster_concurrency_test`, `stale_multipart_cleanup_cluster_test`, `namespace_lock_quorum_test`, `admin_timeout_regression_test`, `object_lambda_test`, `replication_extension_test`, `tier_stats_cluster_test` | Multi-node scenarios via `RustFSTestClusterEnvironment` |
+| **distributed 4×4** | [`src/distributed/`](src/distributed) | Storage-sensitive PR and nightly `e2e-distributed` lane: S3, object lock/WORM, versioning, bucket/site replication, quota, expand/decommission/rebalance, concurrency, chaos, 4-node upgrade of historical data and IAM AK/SK. Map: [`docs/testing/distributed-e2e.md`](../../docs/testing/distributed-e2e.md) |
 | **chaos / reliability** | [`src/chaos.rs`](src/chaos.rs), `reliability_disk_fault_test`, `heal_erasure_disk_rebuild_test`, `server_startup_failfast_test` | Disk offline/replace/corrupt, EC rebuild, heal, fail-fast startup |
 | **upgrade compatibility** | `upgrade_compatibility_test` | Pinned previous-release writes followed by current-build reads on the same data directory |

@@ -171,6 +172,7 @@ the same profile for membership and execution with one nightly worker.
 | KMS suite | `e2e-full` job, merge queue + main | **Active** |
 | Direct and mixed-version rolling upgrades from pinned previous release | `e2e-upgrade.yml`, storage-sensitive PRs + release tags + weekly | **Active** |
 | Cluster faults (`e2e-nightly` profile) | consolidated nightly workflow | **Active** (backlog#1149 ci-7) |
+| Distributed 4-node 4-disk (`e2e-distributed` profile) | `.github/workflows/e2e-distributed.yml` | **Active** (storage-sensitive PR / nightly / dispatch) |
 | Protocols (FTPS/WebDAV/SFTP) | consolidated nightly workflow, serial | **Active** (backlog#1149 ci-7) |
 | Replication (fast subset) | `e2e-smoke` profile, `e2e-tests` job, every PR | **Active** (backlog#1147 repl-1) |
 | Replication (slow + multi-node) | `e2e-repl-nightly` profile, consolidated nightly workflow | **Active** (backlog#1147 repl-1) |
@@ -191,6 +193,9 @@ cargo nextest run --profile e2e-smoke -p e2e_test
 cargo nextest run --profile e2e-full -p e2e_test
 # Cluster fault nightly lane
 cargo nextest run --profile e2e-nightly -p e2e_test
+# 4-node 4-disk distributed lane (S3 / lock / versioning / replication / decommission / chaos / upgrade)
+# Upgrade cases need RUSTFS_UPGRADE_SOURCE_BINARY; without it they fail closed.
+cargo nextest run --profile e2e-distributed -p e2e_test
 # Replication nightly lane; awscurl is required for STS paths
 cargo nextest run --profile e2e-repl-nightly -p e2e_test
 # Fixed-port protocol nightly lane
@@ -1700,6 +1700,69 @@ impl RustFSTestClusterEnvironment {
        Ok(())
    }

+    /// Append a new single-node erasure pool to a stopped multi-pool cluster.
+    ///
+    /// Used to simulate pool expansion on localhost: every pool already owns
+    /// exactly one node with `drives_per_node >= 2` (the only multi-pool layout
+    /// the single-host `RUSTFS_VOLUMES` syntax can express). The new node is
+    /// allocated a fresh port and empty drive directories; callers must
+    /// [`Self::start`] afterwards so every process picks up the extended
+    /// volumes argument. Existing data directories are left untouched.
+    pub async fn append_single_node_pool(&mut self) -> Result<usize, Box<dyn std::error::Error + Send + Sync>> {
+        if self.nodes.iter().any(|node| node.process.is_some()) {
+            return Err("stop the cluster before appending a pool".into());
+        }
+        if self.topology.drives_per_node < 2 {
+            return Err(
+                "append_single_node_pool requires drives_per_node >= 2 (the server parser rejects a single-drive ellipses pool)"
+                    .into(),
+            );
+        }
+
+        let mut pools = self.topology.normalized_pools();
+        for (pool_idx, nodes) in pools.iter().enumerate() {
+            if nodes.len() != 1 {
+                return Err(format!(
+                    "pool {pool_idx} spans {} nodes; append_single_node_pool requires one node per pool",
+                    nodes.len()
+                )
+                .into());
+            }
+        }
+
+        let new_idx = self.nodes.len();
+        let port = RustFSTestEnvironment::find_available_port().await?;
+        let address = format!("127.0.0.1:{port}");
+        let data_dirs: Vec<String> = (0..self.topology.drives_per_node)
+            .map(|drive| format!("{}/node{}/drive{}", self.temp_dir, new_idx, drive))
+            .collect();
+        for dir in &data_dirs {
+            fs::create_dir_all(dir).await?;
+        }
+
+        self.nodes.push(ClusterNode {
+            url: format!("http://{address}"),
+            address,
+            data_dir: data_dirs[0].clone(),
+            data_dirs,
+            pool_idx: pools.len(),
+            process: None,
+        });
+        pools.push(vec![new_idx]);
+        self.topology.node_count = self.nodes.len();
+        self.topology.pools = pools;
+        self.node_extra_env.push(Vec::new());
+        self.node_capture_log_paths.push(None);
+        self.volume_proxy_addresses.push(None);
+
+        if !self.extra_env.iter().any(|(key, _)| key == "RUSTFS_UNSAFE_BYPASS_DISK_CHECK") {
+            self.extra_env
+                .push(("RUSTFS_UNSAFE_BYPASS_DISK_CHECK".to_string(), "true".to_string()));
+        }
+
+        Ok(new_idx)
+    }
+
    /// Gracefully stop one cluster node and wait for its process to exit.
    ///
    /// This is intentionally separate from [`Self::stop_node`]: the latter is
@@ -0,0 +1,222 @@
+// Copyright 2026 RustFS Team
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+use super::harness::{
+    DistCluster, DistLayout, TestResult, assert_object_bytes, payload_for, put_object, retrying_get_equals, unique_bucket,
+    wait_for_ready, wait_until,
+};
+use crate::chaos::{census_object_version_on_disk, signed_admin_post};
+use crate::common::{build_test_s3_config, init_logging};
+use crate::fault_proxy::FaultMode;
+use aws_sdk_s3::Client;
+use std::path::PathBuf;
+use std::sync::Arc;
+use std::time::Duration;
+use tokio::sync::{Barrier, mpsc};
+use tokio::time::timeout;
+
+#[tokio::test]
+async fn kill_and_restart_node_preserves_objects() -> TestResult {
+    init_logging();
+    let mut dist = DistCluster::start(DistLayout::FourByFour).await?;
+    let bucket = unique_bucket("killnode");
+    dist.create_bucket(&bucket).await?;
+    let body = vec![0x11u8; 128 * 1024];
+    put_object(&dist.client(0)?, &bucket, "keep.bin", body.clone()).await?;
+
+    dist.cluster.stop_node(3)?;
+    retrying_get_equals(&dist.client(0)?, &bucket, "keep.bin", &body, Duration::from_secs(20)).await?;
+
+    dist.cluster.start_node(3).await?;
+    wait_for_ready(&dist.cluster).await?;
+    assert_object_bytes(&dist.client(3)?, &bucket, "keep.bin", &body).await?;
+    Ok(())
+}
+
+#[tokio::test]
+async fn full_cluster_restart_preserves_objects() -> TestResult {
+    init_logging();
+    let mut dist = DistCluster::start(DistLayout::FourByFour).await?;
+    let bucket = unique_bucket("pwr");
+    dist.create_bucket(&bucket).await?;
+    let body = vec![0x44u8; 64 * 1024];
+    put_object(&dist.client(1)?, &bucket, "survive.bin", body.clone()).await?;
+
+    dist.cluster.stop();
+    dist.cluster.start().await?;
+    wait_for_ready(&dist.cluster).await?;
+    for node_idx in 0..dist.cluster.nodes.len() {
+        assert_object_bytes(&dist.client(node_idx)?, &bucket, "survive.bin", &body).await?;
+    }
+    Ok(())
+}
+
+#[tokio::test]
+async fn fresh_drive_replacement_is_physically_healed_without_data_change() -> TestResult {
+    init_logging();
+    let mut dist = DistCluster::start_with_env(DistLayout::FourByFour, &[("RUSTFS_HEAL_ENABLED", "true")]).await?;
+    let bucket = unique_bucket("baddrive");
+    dist.create_bucket(&bucket).await?;
+    let body = payload_for("fresh-drive/durable.bin", 8 * 1024 * 1024);
+    put_object(&dist.client(1)?, &bucket, "durable.bin", body.clone()).await?;
+
+    let replaced_drive = PathBuf::from(&dist.cluster.nodes[0].data_dirs[0]);
+    let baseline = census_object_version_on_disk(&replaced_drive, &bucket, "durable.bin", None)?;
+    assert!(
+        baseline.is_complete(),
+        "replacement target did not hold a complete baseline shard: {baseline:?}"
+    );
+    assert!(
+        !baseline.expected_part_numbers.is_empty(),
+        "replacement witness must use physical part shards: {baseline:?}"
+    );
+
+    dist.cluster.stop_node(0)?;
+    let format_path = replaced_drive.join(".rustfs.sys/format.json");
+    let format = std::fs::read(&format_path)?;
+    let retired_drive = PathBuf::from(format!("{}.retired", replaced_drive.display()));
+    std::fs::rename(&replaced_drive, &retired_drive)?;
+    std::fs::create_dir_all(format_path.parent().ok_or("replacement format path omitted parent")?)?;
+    std::fs::write(&format_path, format)?;
+    let empty = census_object_version_on_disk(&replaced_drive, &bucket, "durable.bin", None)?;
+    assert!(!empty.has_xl_meta, "fresh replacement unexpectedly retained object metadata: {empty:?}");
+
+    dist.cluster.start_node(0).await?;
+    wait_for_ready(&dist.cluster).await?;
+    let heal_body =
+        r#"{"recursive":true,"dryRun":false,"remove":false,"recreate":true,"scanMode":2,"updateParity":false,"nolock":false}"#;
+    let heal_url = format!("{}/rustfs/admin/v3/heal/{bucket}?forceStart=true", dist.cluster.nodes[1].url);
+    signed_admin_post(&heal_url, Some(heal_body), &dist.cluster.access_key, &dist.cluster.secret_key).await?;
+    wait_until(
+        Duration::from_secs(90),
+        || async {
+            let healed = census_object_version_on_disk(&replaced_drive, &bucket, "durable.bin", None)?;
+            Ok(healed.matches_manifest(&baseline))
+        },
+        "fresh replacement contains the original complete shard manifest",
+    )
+    .await?;
+
+    for node_idx in 0..dist.cluster.nodes.len() {
+        assert_object_bytes(&dist.client(node_idx)?, &bucket, "durable.bin", &body).await?;
+    }
+    Ok(())
+}
+
+#[tokio::test]
+async fn concurrent_gets_survive_peer_node_kill() -> TestResult {
+    init_logging();
+    let mut dist = DistCluster::start(DistLayout::FourByFour).await?;
+    let bucket = unique_bucket("getkill");
+    dist.create_bucket(&bucket).await?;
+    let body = payload_for("inflight/steady.bin", 8 * 1024 * 1024);
+    put_object(&dist.client(0)?, &bucket, "steady.bin", body.clone()).await?;
+
+    let live: Vec<_> = (0..3).map(|idx| dist.client(idx)).collect::<Result<Vec<_>, _>>()?;
+    let worker_count = 12;
+    let release = Arc::new(Barrier::new(worker_count + 1));
+    let (started_tx, mut started_rx) = mpsc::unbounded_channel();
+    let mut handles = Vec::new();
+    for idx in 0..worker_count {
+        let client = live[idx % live.len()].clone();
+        let bucket = bucket.clone();
+        let body = body.clone();
+        let release = release.clone();
+        let started_tx = started_tx.clone();
+        handles.push(tokio::spawn(async move {
+            let response = client.get_object().bucket(&bucket).key("steady.bin").send().await?;
+            if response.content_length() != Some(body.len() as i64) {
+                return Err::<(), Box<dyn std::error::Error + Send + Sync>>(
+                    format!("worker {idx} received a wrong content length").into(),
+                );
+            }
+            started_tx.send(idx)?;
+            release.wait().await;
+            let actual = response.body.collect().await?.into_bytes();
+            if actual.as_ref() != body.as_slice() {
+                return Err(format!("worker {idx} received corrupted bytes after peer kill").into());
+            }
+            Ok(())
+        }));
+    }
+    drop(started_tx);
+    for _ in 0..worker_count {
+        timeout(Duration::from_secs(30), started_rx.recv())
+            .await?
+            .ok_or("a streaming GET exited before reaching the kill barrier")?;
+    }
+
+    dist.cluster.stop_node(3)?;
+    release.wait().await;
+    for handle in handles {
+        handle.await??;
+    }
+
+    dist.cluster.start_node(3).await?;
+    wait_for_ready(&dist.cluster).await?;
+    assert_object_bytes(&dist.client(3)?, &bucket, "steady.bin", &body).await?;
+    Ok(())
+}
+
+#[tokio::test]
+async fn blackholed_node_client_network_preserves_cluster_availability_and_recovers() -> TestResult {
+    init_logging();
+    let dist = DistCluster::start(DistLayout::FourByFour).await?;
+    let proxy = crate::fault_proxy::FaultProxy::start(dist.cluster.nodes[3].address.parse()?).await?;
+    let proxied_url = format!("http://{}", proxy.local_addr());
+    let proxied_client = Client::from_conf(build_test_s3_config(
+        &proxied_url,
+        &dist.cluster.access_key,
+        &dist.cluster.secret_key,
+        None,
+        "distributed-network-chaos",
+    ));
+
+    let result: TestResult = async {
+        let bucket = unique_bucket("netfault");
+        dist.create_bucket(&bucket).await?;
+        let baseline = payload_for("network/baseline.bin", 1024 * 1024);
+        put_object(&dist.client(0)?, &bucket, "baseline.bin", baseline.clone()).await?;
+        assert_object_bytes(&proxied_client, &bucket, "baseline.bin", &baseline).await?;
+
+        proxy.set_mode(FaultMode::Blackhole);
+        assert_eq!(proxy.mode(), FaultMode::Blackhole);
+        if let Ok(Ok(_)) = timeout(
+            Duration::from_secs(5),
+            proxied_client.get_object().bucket(&bucket).key("baseline.bin").send(),
+        )
+        .await
+        {
+            return Err("blackholed node endpoint unexpectedly completed a GET".into());
+        }
+
+        let during = payload_for("network/during.bin", 1024 * 1024);
+        timeout(Duration::from_secs(30), async {
+            put_object(&dist.client(1)?, &bucket, "during-blackhole.bin", during.clone()).await?;
+            assert_object_bytes(&dist.client(2)?, &bucket, "baseline.bin", &baseline).await?;
+            assert_object_bytes(&dist.client(0)?, &bucket, "during-blackhole.bin", &during).await?;
+            Ok::<_, Box<dyn std::error::Error + Send + Sync>>(())
+        })
+        .await??;
+
+        proxy.set_mode(FaultMode::Pass);
+        retrying_get_equals(&proxied_client, &bucket, "during-blackhole.bin", &during, Duration::from_secs(30)).await?;
+        Ok(())
+    }
+    .await;
+
+    proxy.set_mode(FaultMode::Pass);
+    proxy.shutdown().await;
+    result
+}
@@ -0,0 +1,98 @@
+// Copyright 2026 RustFS Team
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+use super::harness::{DistCluster, DistLayout, TestResult, assert_object_bytes, payload_for, put_object, unique_bucket};
+use crate::common::init_logging;
+use std::collections::BTreeSet;
+use std::sync::Arc;
+use tokio::sync::Barrier;
+
+#[tokio::test]
+async fn four_node_high_concurrency_mixed_workload_is_consistent_on_every_node() -> TestResult {
+    init_logging();
+    let dist = DistCluster::start(DistLayout::FourByFour).await?;
+    let bucket = unique_bucket("conc");
+    dist.create_bucket(&bucket).await?;
+    let clients = Arc::new(dist.clients()?);
+    let worker_count = 24;
+    let rounds = 4;
+    let barrier = Arc::new(Barrier::new(worker_count));
+
+    let mut handles = Vec::new();
+    for idx in 0..worker_count {
+        let clients = clients.clone();
+        let barrier = barrier.clone();
+        let bucket = bucket.clone();
+        handles.push(tokio::spawn(async move {
+            barrier.wait().await;
+            let writer = &clients[idx % clients.len()];
+            let reader = &clients[(idx + 1) % clients.len()];
+            let copier = &clients[(idx + 2) % clients.len()];
+            let mut retained = Vec::with_capacity(rounds);
+            for round in 0..rounds {
+                let key = format!("source/worker-{idx:02}-round-{round}.bin");
+                let copy_key = format!("retained/worker-{idx:02}-round-{round}.bin");
+                let body = payload_for(&key, 64 * 1024);
+                put_object(writer, &bucket, &key, body.clone()).await?;
+
+                let head = reader.head_object().bucket(&bucket).key(&key).send().await?;
+                if head.content_length() != Some(body.len() as i64) {
+                    return Err(format!("HEAD returned the wrong size for {key}: {head:?}").into());
+                }
+                assert_object_bytes(reader, &bucket, &key, &body).await?;
+
+                copier
+                    .copy_object()
+                    .bucket(&bucket)
+                    .key(&copy_key)
+                    .copy_source(format!("{bucket}/{key}"))
+                    .send()
+                    .await?;
+                assert_object_bytes(writer, &bucket, &copy_key, &body).await?;
+
+                writer.delete_object().bucket(&bucket).key(&key).send().await?;
+                let missing = reader
+                    .head_object()
+                    .bucket(&bucket)
+                    .key(&key)
+                    .send()
+                    .await
+                    .expect_err("deleted source key must not remain visible");
+                if missing.raw_response().map(|response| response.status().as_u16()) != Some(404) {
+                    return Err(format!("deleted source {key} returned an unexpected result: {missing:?}").into());
+                }
+                retained.push((copy_key, body));
+            }
+            Ok::<_, Box<dyn std::error::Error + Send + Sync>>(retained)
+        }));
+    }
+
+    let mut inventory = Vec::new();
+    for handle in handles {
+        inventory.extend(handle.await??);
+    }
+
+    let expected_keys: BTreeSet<_> = inventory.iter().map(|(key, _)| key.as_str()).collect();
+    for (node_idx, client) in clients.iter().enumerate() {
+        let listed = client.list_objects_v2().bucket(&bucket).prefix("retained/").send().await?;
+        let listed_keys: BTreeSet<_> = listed.contents().iter().filter_map(|object| object.key()).collect();
+        assert_eq!(listed_keys, expected_keys, "node {node_idx} returned a divergent retained-key listing");
+        for (key, body) in &inventory {
+            assert_object_bytes(client, &bucket, key, body)
+                .await
+                .map_err(|error| format!("node {node_idx} failed to read {key}: {error}"))?;
+        }
+    }
+    Ok(())
+}
@@ -0,0 +1,74 @@
+// Copyright 2026 RustFS Team
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+use super::harness::{
+    DECOMMISSION_POOL_ID, DistCluster, DistLayout, TestResult, assert_inventory, decommission_running_with_progress,
+    decommission_status_json, payload_for, put_inventory_retrying, retrying_get_equals, retrying_put, start_decommission,
+    unique_bucket, wait_for_decommission_complete, wait_for_decommission_running_with_progress,
+};
+use crate::common::init_logging;
+use std::sync::Arc;
+use std::time::Duration;
+use tokio::sync::Barrier;
+
+#[tokio::test]
+async fn concurrent_puts_during_decommission_do_not_lose_baseline_or_new_objects() -> TestResult {
+    init_logging();
+    let mut dist = DistCluster::start(DistLayout::SingleNodeFourDrive).await?;
+    let bucket = unique_bucket("concdecom");
+    dist.create_bucket(&bucket).await?;
+    let baseline_client = dist.client(0)?;
+    let inventory = put_inventory_retrying(&baseline_client, &bucket, 96, 256 * 1024, Duration::from_secs(30)).await?;
+    dist.expand_to_four_pools().await?;
+
+    start_decommission(&dist.cluster, DECOMMISSION_POOL_ID).await?;
+
+    let clients = Arc::new(dist.clients()?);
+    let barrier = Arc::new(Barrier::new(17));
+    let mut handles = Vec::new();
+    for idx in 0..16 {
+        let clients = clients.clone();
+        let barrier = barrier.clone();
+        let bucket = bucket.clone();
+        handles.push(tokio::spawn(async move {
+            barrier.wait().await;
+            let client = &clients[idx % clients.len()];
+            let key = format!("live/{idx:02}.bin");
+            let body = payload_for(&key, 8 * 1024);
+            retrying_put(client, &bucket, &key, body.clone(), Duration::from_secs(45)).await?;
+            Ok::<_, Box<dyn std::error::Error + Send + Sync>>((key, body))
+        }));
+    }
+
+    wait_for_decommission_running_with_progress(&dist.cluster, DECOMMISSION_POOL_ID, Duration::from_secs(30)).await?;
+    barrier.wait().await;
+
+    let mut live_objects = Vec::new();
+    for handle in handles {
+        live_objects.push(handle.await??);
+    }
+    let status = decommission_status_json(&dist.cluster).await?;
+    if !decommission_running_with_progress(&status, DECOMMISSION_POOL_ID)? {
+        return Err(format!("decommission did not remain active across concurrent PUTs: {status}").into());
+    }
+
+    wait_for_decommission_complete(&dist.cluster, DECOMMISSION_POOL_ID, Duration::from_secs(180)).await?;
+
+    let checker = dist.client(2)?;
+    assert_inventory(&checker, &bucket, &inventory).await?;
+    for (key, body) in live_objects {
+        retrying_get_equals(&checker, &bucket, &key, &body, Duration::from_secs(30)).await?;
+    }
+    Ok(())
+}
@@ -0,0 +1,156 @@
+// Copyright 2026 RustFS Team
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+use super::harness::{
+    DECOMMISSION_POOL_ID, DistCluster, DistLayout, TestResult, assert_inventory, enable_versioning, put_inventory_retrying,
+    sha256_hex, start_decommission, unique_bucket, wait_for_decommission_active, wait_for_decommission_complete,
+};
+use crate::common::init_logging;
+use aws_sdk_s3::primitives::ByteStream;
+use aws_sdk_s3::types::{CompletedMultipartUpload, CompletedPart};
+use std::time::Duration;
+
+#[tokio::test]
+async fn decommission_does_not_alter_object_sha256_across_pools() -> TestResult {
+    init_logging();
+    let mut dist = DistCluster::start(DistLayout::SingleNodeFourDrive).await?;
+    let bucket = unique_bucket("integrity");
+    dist.create_bucket(&bucket).await?;
+    let client = dist.client(0)?;
+    enable_versioning(&client, &bucket).await?;
+    let inventory = put_inventory_retrying(&client, &bucket, 96, 256 * 1024, Duration::from_secs(30)).await?;
+    let before: Vec<(String, String)> = inventory.iter().map(|(key, body)| (key.clone(), sha256_hex(body))).collect();
+
+    let versioned_key = "history/versioned.bin";
+    let version_one = b"historical bytes before data movement".to_vec();
+    let version_two = b"current bytes before data movement".to_vec();
+    let version_one_id = client
+        .put_object()
+        .bucket(&bucket)
+        .key(versioned_key)
+        .body(ByteStream::from(version_one.clone()))
+        .send()
+        .await?
+        .version_id()
+        .ok_or("historical PUT omitted version ID")?
+        .to_string();
+    let version_two_id = client
+        .put_object()
+        .bucket(&bucket)
+        .key(versioned_key)
+        .body(ByteStream::from(version_two.clone()))
+        .send()
+        .await?
+        .version_id()
+        .ok_or("current PUT omitted version ID")?
+        .to_string();
+
+    let multipart_key = "multipart/moved.bin";
+    let first_part = vec![0x31; 5 * 1024 * 1024];
+    let second_part = vec![0x72; 1024 * 1024];
+    let upload = client
+        .create_multipart_upload()
+        .bucket(&bucket)
+        .key(multipart_key)
+        .send()
+        .await?;
+    let upload_id = upload.upload_id().ok_or("movement multipart upload omitted upload ID")?;
+    let uploaded_one = client
+        .upload_part()
+        .bucket(&bucket)
+        .key(multipart_key)
+        .upload_id(upload_id)
+        .part_number(1)
+        .body(ByteStream::from(first_part.clone()))
+        .send()
+        .await?;
+    let uploaded_two = client
+        .upload_part()
+        .bucket(&bucket)
+        .key(multipart_key)
+        .upload_id(upload_id)
+        .part_number(2)
+        .body(ByteStream::from(second_part.clone()))
+        .send()
+        .await?;
+    client
+        .complete_multipart_upload()
+        .bucket(&bucket)
+        .key(multipart_key)
+        .upload_id(upload_id)
+        .multipart_upload(
+            CompletedMultipartUpload::builder()
+                .parts(
+                    CompletedPart::builder()
+                        .part_number(1)
+                        .e_tag(uploaded_one.e_tag().ok_or("movement part 1 omitted ETag")?)
+                        .build(),
+                )
+                .parts(
+                    CompletedPart::builder()
+                        .part_number(2)
+                        .e_tag(uploaded_two.e_tag().ok_or("movement part 2 omitted ETag")?)
+                        .build(),
+                )
+                .build(),
+        )
+        .send()
+        .await?;
+
+    dist.expand_to_four_pools().await?;
+
+    start_decommission(&dist.cluster, DECOMMISSION_POOL_ID).await?;
+    wait_for_decommission_active(&dist.cluster, DECOMMISSION_POOL_ID, Duration::from_secs(30)).await?;
+    wait_for_decommission_complete(&dist.cluster, DECOMMISSION_POOL_ID, Duration::from_secs(180)).await?;
+
+    let after_client = dist.client(2)?;
+    assert_inventory(&after_client, &bucket, &inventory).await?;
+    for (key, expected_hash) in before {
+        let got = after_client.get_object().bucket(&bucket).key(&key).send().await?;
+        let body = got.body.collect().await?.into_bytes();
+        assert_eq!(sha256_hex(body.as_ref()), expected_hash, "checksum changed for {key} after decommission");
+    }
+    for (version_id, expected) in [(&version_one_id, &version_one), (&version_two_id, &version_two)] {
+        let got = after_client
+            .get_object()
+            .bucket(&bucket)
+            .key(versioned_key)
+            .version_id(version_id)
+            .send()
+            .await?
+            .body
+            .collect()
+            .await?
+            .into_bytes();
+        assert_eq!(got.as_ref(), expected.as_slice(), "version {version_id} changed after decommission");
+    }
+    let mut expected_multipart = first_part;
+    expected_multipart.extend_from_slice(&second_part);
+    let got_multipart = after_client
+        .get_object()
+        .bucket(&bucket)
+        .key(multipart_key)
+        .send()
+        .await?
+        .body
+        .collect()
+        .await?
+        .into_bytes();
+    assert_eq!(
+        sha256_hex(got_multipart.as_ref()),
+        sha256_hex(&expected_multipart),
+        "multipart checksum changed after decommission"
+    );
+    Ok(())
+}
@@ -0,0 +1,81 @@
+// Copyright 2026 RustFS Team
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+use super::harness::{
+    DECOMMISSION_POOL_ID, DistCluster, DistLayout, TestResult, assert_inventory, list_pools_json, put_inventory,
+    put_inventory_retrying, start_decommission, start_rebalance, unique_bucket, wait_for_decommission_active,
+    wait_for_decommission_complete, wait_for_rebalance_active, wait_for_rebalance_complete,
+};
+use crate::common::init_logging;
+use std::time::Duration;
+
+#[tokio::test]
+async fn four_node_pool_expand_preserves_objects_then_rebalance() -> TestResult {
+    init_logging();
+    let mut dist = DistCluster::start(DistLayout::SingleNodeFourDrive).await?;
+    let bucket = unique_bucket("expand");
+    dist.create_bucket(&bucket).await?;
+    let client = dist.client(0)?;
+    let inventory = put_inventory(&client, &bucket, 64, 256 * 1024).await?;
+    assert_inventory(&client, &bucket, &inventory).await?;
+
+    for expected_nodes in 2..=4 {
+        let new_node = dist.append_pool_and_restart().await?;
+        assert_eq!(new_node + 1, expected_nodes);
+        assert_inventory(&dist.client(new_node)?, &bucket, &inventory).await?;
+    }
+    assert_eq!(dist.cluster.nodes.len(), 4);
+
+    // Prove that the expanded pool map is durable, and clear any recovery
+    // latch raised while the newly-added pool replicas converged.
+    dist.restart_current_binary_gracefully().await?;
+
+    let after_expand = dist.client(0)?;
+    assert_inventory(&after_expand, &bucket, &inventory).await?;
+    let peer = dist.client(3)?;
+    assert_inventory(&peer, &bucket, &inventory).await?;
+
+    let rebalance_id = start_rebalance(&dist.cluster).await?;
+    wait_for_rebalance_active(&dist.cluster, &rebalance_id, Duration::from_secs(30)).await?;
+    wait_for_rebalance_complete(&dist.cluster, &rebalance_id, Duration::from_secs(180)).await?;
+    assert_inventory(&peer, &bucket, &inventory).await?;
+    Ok(())
+}
+
+#[tokio::test]
+async fn four_pool_decommission_moves_objects_without_loss() -> TestResult {
+    init_logging();
+    let mut dist = DistCluster::start(DistLayout::SingleNodeFourDrive).await?;
+    let bucket = unique_bucket("decom");
+    dist.create_bucket(&bucket).await?;
+    let client = dist.client(0)?;
+    let inventory = put_inventory_retrying(&client, &bucket, 96, 128 * 1024, Duration::from_secs(30)).await?;
+    dist.expand_to_four_pools().await?;
+
+    let pools_before = list_pools_json(&dist.cluster).await?;
+    let pool_count = pools_before
+        .as_array()
+        .map(Vec::len)
+        .or_else(|| pools_before.get("pools").and_then(serde_json::Value::as_array).map(Vec::len))
+        .ok_or_else(|| format!("pool list omitted an array: {pools_before}"))?;
+    assert_eq!(pool_count, 4, "expected exactly four pools before decommission: {pools_before}");
+
+    start_decommission(&dist.cluster, DECOMMISSION_POOL_ID).await?;
+    wait_for_decommission_active(&dist.cluster, DECOMMISSION_POOL_ID, Duration::from_secs(30)).await?;
+    wait_for_decommission_complete(&dist.cluster, DECOMMISSION_POOL_ID, Duration::from_secs(180)).await?;
+
+    let after = dist.client(2)?;
+    assert_inventory(&after, &bucket, &inventory).await?;
+    Ok(())
+}
@@ -0,0 +1,149 @@
+// Copyright 2026 RustFS Team
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+use super::harness::{
+    DistCluster, DistLayout, TestResult, assert_object_bytes, get_object_bytes, put_object, unique_bucket, wait_until,
+};
+use crate::common::init_logging;
+use aws_sdk_s3::primitives::ByteStream;
+use aws_sdk_s3::types::{CompletedMultipartUpload, CompletedPart};
+use std::time::Duration;
+
+#[tokio::test]
+async fn four_node_four_drive_multipart_and_cross_node_listing_agree() -> TestResult {
+    init_logging();
+    let dist = DistCluster::start(DistLayout::FourByFour).await?;
+    let bucket = unique_bucket("extra");
+    dist.create_bucket(&bucket).await?;
+    let client = dist.client(0)?;
+
+    let key = "multipart.bin";
+    let part1 = vec![0x41u8; 5 * 1024 * 1024];
+    let part2 = vec![0x42u8; 5 * 1024 * 1024];
+    let upload = client.create_multipart_upload().bucket(&bucket).key(key).send().await?;
+    let upload_id = upload.upload_id().ok_or("missing upload id")?.to_string();
+
+    let uploaded1 = client
+        .upload_part()
+        .bucket(&bucket)
+        .key(key)
+        .upload_id(&upload_id)
+        .part_number(1)
+        .body(ByteStream::from(part1.clone()))
+        .send()
+        .await?;
+    let uploaded2 = client
+        .upload_part()
+        .bucket(&bucket)
+        .key(key)
+        .upload_id(&upload_id)
+        .part_number(2)
+        .body(ByteStream::from(part2.clone()))
+        .send()
+        .await?;
+
+    client
+        .complete_multipart_upload()
+        .bucket(&bucket)
+        .key(key)
+        .upload_id(&upload_id)
+        .multipart_upload(
+            CompletedMultipartUpload::builder()
+                .parts(
+                    CompletedPart::builder()
+                        .part_number(1)
+                        .e_tag(uploaded1.e_tag().unwrap_or_default())
+                        .build(),
+                )
+                .parts(
+                    CompletedPart::builder()
+                        .part_number(2)
+                        .e_tag(uploaded2.e_tag().unwrap_or_default())
+                        .build(),
+                )
+                .build(),
+        )
+        .send()
+        .await?;
+
+    let mut expected = part1;
+    expected.extend_from_slice(&part2);
+    for node_idx in 0..dist.cluster.nodes.len() {
+        assert_object_bytes(&dist.client(node_idx)?, &bucket, key, &expected).await?;
+    }
+
+    put_object(&client, &bucket, "list/a", b"a".to_vec()).await?;
+    put_object(&dist.client(2)?, &bucket, "list/b", b"b".to_vec()).await?;
+    let mut seen = Vec::new();
+    for node_idx in 0..dist.cluster.nodes.len() {
+        let listed = dist
+            .client(node_idx)?
+            .list_objects_v2()
+            .bucket(&bucket)
+            .prefix("list/")
+            .send()
+            .await?;
+        let keys: Vec<String> = listed
+            .contents()
+            .iter()
+            .filter_map(|object| object.key().map(str::to_string))
+            .collect();
+        seen.push(keys);
+    }
+    for keys in &seen[1..] {
+        assert_eq!(&seen[0], keys, "list results diverged across nodes: {seen:?}");
+    }
+
+    let got = get_object_bytes(&dist.client(3)?, &bucket, "list/a").await?;
+    assert_eq!(got, b"a");
+    Ok(())
+}
+
+#[tokio::test]
+async fn four_node_list_buckets_agree_across_all_nodes() -> TestResult {
+    init_logging();
+    let dist = DistCluster::start(DistLayout::FourByFour).await?;
+    let bucket = unique_bucket("listed");
+    dist.create_bucket(&bucket).await?;
+    put_object(&dist.client(0)?, &bucket, "seed.bin", b"seed".to_vec()).await?;
+
+    for node_idx in 0..dist.cluster.nodes.len() {
+        let client = dist.client(node_idx)?;
+        let name = bucket.clone();
+        wait_until(
+            Duration::from_secs(20),
+            || {
+                let client = client.clone();
+                let name = name.clone();
+                async move {
+                    let listed = client.list_buckets().send().await?;
+                    Ok(listed.buckets().iter().any(|entry| entry.name() == Some(name.as_str())))
+                }
+            },
+            &format!("node {node_idx} lists {bucket}"),
+        )
+        .await?;
+        wait_until(
+            Duration::from_secs(20),
+            || {
+                let client = dist.client(node_idx).expect("client");
+                let name = bucket.clone();
+                async move { Ok(get_object_bytes(&client, &name, "seed.bin").await.ok() == Some(b"seed".to_vec())) }
+            },
+            &format!("node {node_idx} reads seed.bin"),
+        )
+        .await?;
+    }
+    Ok(())
+}
@@ -0,0 +1,35 @@
+// Copyright 2026 RustFS Team
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//! 4-node 4-drive distributed e2e coverage.
+//!
+//! Selected by `[profile.e2e-distributed]` and run from
+//! `.github/workflows/e2e-distributed.yml`. Excluded from `e2e-full` because
+//! each case starts four real `rustfs` processes.
+
+mod chaos_test;
+mod concurrency_stability_test;
+mod concurrent_data_movement_test;
+mod data_integrity_movement_test;
+mod expand_decommission_rebalance_test;
+mod extra_test;
+mod harness;
+mod object_lock_test;
+mod observability_test;
+mod replication_quota_test;
+mod s3_basic_test;
+mod s3_during_data_movement_test;
+mod site_replication_test;
+mod upgrade_test;
+mod versioning_test;
@@ -0,0 +1,219 @@
+// Copyright 2026 RustFS Team
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+use super::harness::{DistCluster, DistLayout, TestResult, unique_bucket};
+use crate::common::init_logging;
+use crate::object_lock::common::{
+    delete_object_with_bypass, put_object_lock_configuration, put_object_with_legal_hold, put_object_with_retention,
+};
+use aws_sdk_s3::Client;
+use aws_sdk_s3::error::ProvideErrorMetadata;
+use aws_sdk_s3::error::SdkError;
+use aws_sdk_s3::operation::delete_object::DeleteObjectError;
+use aws_sdk_s3::primitives::ByteStream;
+use aws_sdk_s3::types::{
+    DefaultRetention, ObjectLockConfiguration, ObjectLockEnabled, ObjectLockLegalHoldStatus, ObjectLockRetentionMode,
+    ObjectLockRule,
+};
+use chrono::{Duration as ChronoDuration, Utc};
+
+fn delete_denied(error: &SdkError<DeleteObjectError>, context: &str) -> TestResult {
+    let code = error.as_service_error().and_then(ProvideErrorMetadata::code);
+    if code == Some("AccessDenied") {
+        Ok(())
+    } else {
+        Err(format!("{context}: expected AccessDenied, got {error:?}").into())
+    }
+}
+
+async fn expect_versioned_delete_denied(
+    client: &Client,
+    bucket: &str,
+    key: &str,
+    version_id: &str,
+    bypass: bool,
+    context: &str,
+) -> TestResult {
+    match delete_object_with_bypass(client, bucket, key, Some(version_id), bypass).await {
+        Ok(_) => Err(format!("{context}: DeleteObject of retained version must be denied").into()),
+        Err(error) => delete_denied(error.as_ref(), context),
+    }
+}
+
+#[tokio::test]
+async fn four_node_four_drive_object_lock_worm_blocks_delete() -> TestResult {
+    init_logging();
+    let dist = DistCluster::start(DistLayout::FourByFour).await?;
+    let client = dist.client(0)?;
+    let peer = dist.client(2)?;
+    let bucket = unique_bucket("objlock");
+
+    client
+        .create_bucket()
+        .bucket(&bucket)
+        .object_lock_enabled_for_bucket(true)
+        .send()
+        .await?;
+
+    let retain_until = Utc::now() + ChronoDuration::days(1);
+
+    let compliance_key = "compliance.bin";
+    let compliance_version = put_object_with_retention(
+        &client,
+        &bucket,
+        compliance_key,
+        b"locked-compliance",
+        ObjectLockRetentionMode::Compliance,
+        retain_until,
+    )
+    .await?;
+
+    // Unversioned DELETE is allowed: it only creates a delete marker. WORM
+    // applies to a specific version id.
+    let marker = peer.delete_object().bucket(&bucket).key(compliance_key).send().await?;
+    assert_eq!(
+        marker.delete_marker(),
+        Some(true),
+        "unversioned DELETE on a locked object must create a delete marker"
+    );
+
+    expect_versioned_delete_denied(&peer, &bucket, compliance_key, &compliance_version, false, "COMPLIANCE without bypass")
+        .await?;
+    expect_versioned_delete_denied(&peer, &bucket, compliance_key, &compliance_version, true, "COMPLIANCE with bypass").await?;
+
+    let governance_key = "governance.bin";
+    let governance_version = put_object_with_retention(
+        &client,
+        &bucket,
+        governance_key,
+        b"locked-governance",
+        ObjectLockRetentionMode::Governance,
+        retain_until,
+    )
+    .await?;
+
+    expect_versioned_delete_denied(&peer, &bucket, governance_key, &governance_version, false, "GOVERNANCE without bypass")
+        .await?;
+    delete_object_with_bypass(&peer, &bucket, governance_key, Some(&governance_version), true).await?;
+    let deleted_governance = peer
+        .head_object()
+        .bucket(&bucket)
+        .key(governance_key)
+        .version_id(&governance_version)
+        .send()
+        .await
+        .expect_err("GOVERNANCE bypass must remove the retained version");
+    assert_eq!(
+        deleted_governance.raw_response().map(|response| response.status().as_u16()),
+        Some(404),
+        "deleted GOVERNANCE version returned an unexpected HEAD result: {deleted_governance:?}"
+    );
+
+    let hold_key = "legal-hold.bin";
+    let hold_version =
+        put_object_with_legal_hold(&client, &bucket, hold_key, b"legal-hold", ObjectLockLegalHoldStatus::On).await?;
+    expect_versioned_delete_denied(&peer, &bucket, hold_key, &hold_version, false, "legal hold without bypass").await?;
+    expect_versioned_delete_denied(&peer, &bucket, hold_key, &hold_version, true, "legal hold with bypass").await?;
+
+    Ok(())
+}
+
+#[tokio::test]
+async fn four_node_default_retention_is_visible_and_non_lock_bucket_rejects_configuration() -> TestResult {
+    init_logging();
+    let dist = DistCluster::start(DistLayout::FourByFour).await?;
+    let writer = dist.client(0)?;
+    let reader = dist.client(3)?;
+    let bucket = unique_bucket("default-lock");
+
+    writer
+        .create_bucket()
+        .bucket(&bucket)
+        .object_lock_enabled_for_bucket(true)
+        .send()
+        .await?;
+    put_object_lock_configuration(&writer, &bucket, ObjectLockRetentionMode::Governance, Some(1), None).await?;
+
+    let key = "default-governance.bin";
+    let put = writer
+        .put_object()
+        .bucket(&bucket)
+        .key(key)
+        .body(ByteStream::from_static(b"default retention payload"))
+        .send()
+        .await?;
+    let version_id = put.version_id().ok_or("default-retained PUT omitted version ID")?;
+
+    let config = reader.get_object_lock_configuration().bucket(&bucket).send().await?;
+    let default_retention = config
+        .object_lock_configuration()
+        .and_then(|configuration| configuration.rule())
+        .and_then(|rule| rule.default_retention())
+        .ok_or("GetObjectLockConfiguration omitted default retention")?;
+    assert_eq!(default_retention.mode().map(|mode| mode.as_str()), Some("GOVERNANCE"));
+    assert_eq!(default_retention.days(), Some(1));
+
+    let retention = reader
+        .get_object_retention()
+        .bucket(&bucket)
+        .key(key)
+        .version_id(version_id)
+        .send()
+        .await?;
+    let retention = retention.retention().ok_or("GetObjectRetention omitted applied retention")?;
+    assert_eq!(retention.mode().map(|mode| mode.as_str()), Some("GOVERNANCE"));
+    let retain_until = retention
+        .retain_until_date()
+        .ok_or("default retention omitted retain-until date")?;
+    assert!(retain_until.secs() > Utc::now().timestamp(), "default retention is not in the future");
+
+    let versioning = reader.get_bucket_versioning().bucket(&bucket).send().await?;
+    assert_eq!(versioning.status().map(|status| status.as_str()), Some("Enabled"));
+    expect_versioned_delete_denied(&reader, &bucket, key, version_id, false, "default GOVERNANCE retention without bypass")
+        .await?;
+
+    let plain_bucket = unique_bucket("no-lock");
+    dist.create_bucket(&plain_bucket).await?;
+    let configuration = ObjectLockConfiguration::builder()
+        .object_lock_enabled(ObjectLockEnabled::Enabled)
+        .rule(
+            ObjectLockRule::builder()
+                .default_retention(
+                    DefaultRetention::builder()
+                        .mode(ObjectLockRetentionMode::Governance)
+                        .days(1)
+                        .build(),
+                )
+                .build(),
+        )
+        .build();
+    let error = writer
+        .put_object_lock_configuration()
+        .bucket(&plain_bucket)
+        .object_lock_configuration(configuration)
+        .send()
+        .await
+        .expect_err("an unversioned bucket must reject Object Lock enablement");
+    let service_error = error
+        .as_service_error()
+        .ok_or("non-lock bucket rejection was not an S3 service error")?;
+    assert_eq!(service_error.code(), Some("InvalidBucketState"), "unexpected error: {error:?}");
+    assert_eq!(
+        service_error.message(),
+        Some("Object Lock configuration cannot be enabled on existing buckets"),
+        "unexpected error: {error:?}"
+    );
+
+    Ok(())
+}
@@ -0,0 +1,236 @@
+// Copyright 2026 RustFS Team
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+use super::harness::{DistCluster, DistLayout, TestResult, cluster_admin_ok, unique_bucket, wait_for_ready};
+use crate::common::{admin_request, init_logging, local_http_client};
+use aws_sdk_s3::operation::RequestId;
+use aws_sdk_s3::primitives::ByteStream;
+use bytes::Bytes;
+use http::Method;
+use http_body_util::{BodyExt, Empty};
+use hyper::body::Incoming;
+use hyper::service::service_fn;
+use hyper::{Request, Response};
+use hyper_util::rt::TokioIo;
+use local_ip_address::local_ip;
+use rustfs_madmin::metrics::RealtimeMetrics;
+use rustfs_utils::egress::ENV_OUTBOUND_ALLOW_ORIGINS;
+use serde_json::Value;
+use std::convert::Infallible;
+use std::time::Duration;
+use tokio::net::TcpListener;
+use tokio::sync::mpsc;
+use tokio::task::JoinHandle;
+use tokio::time::{Instant, timeout};
+
+async fn spawn_audit_collector() -> TestResult<(String, mpsc::UnboundedReceiver<Value>, JoinHandle<()>)> {
+    let listener = TcpListener::bind("0.0.0.0:0").await?;
+    let endpoint = format!("http://{}/audit", std::net::SocketAddr::new(local_ip()?, listener.local_addr()?.port()));
+    let (tx, rx) = mpsc::unbounded_channel();
+    let handle = tokio::spawn(async move {
+        loop {
+            let Ok((stream, _)) = listener.accept().await else {
+                return;
+            };
+            let tx = tx.clone();
+            tokio::spawn(async move {
+                let service = service_fn(move |request: Request<Incoming>| {
+                    let tx = tx.clone();
+                    async move {
+                        let method = request.method().clone();
+                        if let Ok(body) = request.into_body().collect().await
+                            && method == Method::POST
+                            && let Ok(payload) = serde_json::from_slice::<Value>(&body.to_bytes())
+                        {
+                            if let Some(records) = payload["Records"].as_array() {
+                                for entry in records {
+                                    let _ = tx.send(entry.clone());
+                                }
+                            } else {
+                                let _ = tx.send(payload);
+                            }
+                        }
+                        Ok::<_, Infallible>(Response::new(Empty::<Bytes>::new()))
+                    }
+                });
+                let _ = hyper::server::conn::http1::Builder::new()
+                    .serve_connection(TokioIo::new(stream), service)
+                    .await;
+            });
+        }
+    });
+    Ok((endpoint, rx, handle))
+}
+
+async fn wait_for_audit_entry(
+    rx: &mut mpsc::UnboundedReceiver<Value>,
+    bucket: &str,
+    key: &str,
+    request_id: &str,
+) -> TestResult<Value> {
+    let deadline = Instant::now() + Duration::from_secs(30);
+    let mut seen = Vec::new();
+    loop {
+        let remaining = deadline.saturating_duration_since(Instant::now());
+        if remaining.is_zero() {
+            return Err(format!(
+                "audit webhook did not receive PutObject for {bucket}/{key}; received {} other records: {seen:?}",
+                seen.len()
+            )
+            .into());
+        }
+        let entry = match timeout(remaining, rx.recv()).await {
+            Ok(Some(entry)) => entry,
+            Ok(None) => return Err("audit collector stopped before the expected entry arrived".into()),
+            Err(_) => {
+                return Err(format!(
+                    "audit webhook did not receive PutObject for {bucket}/{key}; received {} other records: {seen:?}",
+                    seen.len()
+                )
+                .into());
+            }
+        };
+        if entry["api"]["name"].as_str() == Some("s3:PutObject")
+            && entry["api"]["bucket"].as_str() == Some(bucket)
+            && entry["api"]["object"].as_str() == Some(key)
+            && entry["requestID"].as_str() == Some(request_id)
+        {
+            return Ok(entry);
+        }
+        if seen.len() < 8 {
+            seen.push(format!(
+                "api={:?} bucket={:?} object={:?} requestID={:?}",
+                entry["api"]["name"].as_str(),
+                entry["api"]["bucket"].as_str(),
+                entry["api"]["object"].as_str(),
+                entry["requestID"].as_str()
+            ));
+        }
+    }
+}
+
+#[tokio::test]
+async fn four_node_health_inventory_metrics_and_audit_delivery_are_consistent() -> TestResult {
+    init_logging();
+    let (audit_endpoint, mut audit_entries, collector) = spawn_audit_collector().await?;
+    let audit_origin = reqwest::Url::parse(&audit_endpoint)?.origin().ascii_serialization();
+    let audit_env = [
+        ("RUSTFS_AUDIT_ENABLE", "true"),
+        ("RUSTFS_AUDIT_WEBHOOK_ENABLE_DISTRIBUTED", "on"),
+        ("RUSTFS_AUDIT_WEBHOOK_ENDPOINT_DISTRIBUTED", audit_endpoint.as_str()),
+        (ENV_OUTBOUND_ALLOW_ORIGINS, audit_origin.as_str()),
+    ];
+    let mut dist = DistCluster::new_stopped_with_env(DistLayout::FourByFour, &audit_env).await?;
+    for node_idx in 0..dist.cluster.nodes.len() {
+        let queue_dir = format!("{}/audit-queue-node-{node_idx}", dist.cluster.temp_dir);
+        tokio::fs::create_dir_all(&queue_dir).await?;
+        dist.cluster
+            .set_node_env(node_idx, "RUSTFS_AUDIT_WEBHOOK_QUEUE_DIR_DISTRIBUTED", queue_dir)?;
+    }
+    dist.cluster.start().await?;
+    wait_for_ready(&dist.cluster).await?;
+
+    let http = local_http_client();
+    for node in &dist.cluster.nodes {
+        for probe in ["ready", "live"] {
+            let response = http.get(format!("{}/health/{probe}", node.url)).send().await?;
+            assert!(
+                response.status().is_success(),
+                "node {} {probe} probe failed: {}",
+                node.address,
+                response.status()
+            );
+        }
+    }
+
+    let info_body = cluster_admin_ok(&dist.cluster, Method::GET, "/rustfs/admin/v3/info", None).await?;
+    let info: Value = serde_json::from_str(&info_body)?;
+    let servers = info["info"]["servers"]
+        .as_array()
+        .ok_or_else(|| format!("admin info omitted servers: {info}"))?;
+    assert_eq!(servers.len(), 4, "admin info did not report all four nodes: {info}");
+
+    let storage_body = cluster_admin_ok(&dist.cluster, Method::GET, "/rustfs/admin/v3/storageinfo", None).await?;
+    let storage: Value = serde_json::from_str(&storage_body)?;
+    let disks = storage["info"]["disks"]
+        .as_array()
+        .ok_or_else(|| format!("storageinfo omitted disks: {storage}"))?;
+    assert_eq!(disks.len(), 16, "storageinfo did not report all sixteen drives: {storage}");
+    assert!(
+        disks.iter().all(|disk| {
+            disk["state"].as_str().is_some_and(|state| state.eq_ignore_ascii_case("ok"))
+                && disk["runtimeState"]
+                    .as_str()
+                    .is_some_and(|state| state.eq_ignore_ascii_case("online"))
+        }),
+        "storageinfo reported a drive that was not healthy and online: {storage}"
+    );
+
+    for (node_idx, node) in dist.cluster.nodes.iter().enumerate() {
+        let (status, metrics_body) = admin_request(
+            &node.url,
+            Method::GET,
+            "/rustfs/admin/v3/metrics?n=1&by-host=true&by-disk=true",
+            None,
+            &dist.cluster.access_key,
+            &dist.cluster.secret_key,
+        )
+        .await?;
+        assert!(status.is_success(), "node {node_idx} metrics failed: {status} {metrics_body}");
+        let sample: RealtimeMetrics = serde_json::from_str(
+            metrics_body
+                .lines()
+                .next()
+                .ok_or_else(|| format!("node {node_idx} returned empty metrics"))?,
+        )?;
+        assert!(sample.finally, "node {node_idx} metrics sample was not terminal");
+        assert!(sample.errors.is_empty(), "node {node_idx} metrics reported errors: {:?}", sample.errors);
+        assert!(!sample.hosts.is_empty(), "node {node_idx} metrics omitted hosts");
+    }
+
+    let targets_body = cluster_admin_ok(&dist.cluster, Method::GET, "/rustfs/admin/v3/audit/target/list", None).await?;
+    let targets: Value = serde_json::from_str(&targets_body)?;
+    let configured = targets["audit_endpoints"]
+        .as_array()
+        .ok_or_else(|| format!("audit target list omitted audit_endpoints: {targets}"))?
+        .iter()
+        .any(|target| target["account_id"].as_str() == Some("distributed") && target["service"].as_str() == Some("webhook"));
+    assert!(configured, "configured audit webhook was missing: {targets}");
+
+    let bucket = unique_bucket("audit");
+    dist.create_bucket(&bucket).await?;
+    let key = "correlated/audit-object.bin";
+    let put = dist
+        .client(2)?
+        .put_object()
+        .bucket(&bucket)
+        .key(key)
+        .body(ByteStream::from_static(b"distributed audit payload"))
+        .send()
+        .await?;
+    let request_id = put.request_id().ok_or("PutObject response omitted request ID")?;
+    let audit = wait_for_audit_entry(&mut audit_entries, &bucket, key, request_id).await?;
+    assert_eq!(
+        audit["api"]["status_code"].as_i64(),
+        Some(200),
+        "audit entry did not report success: {audit}"
+    );
+    assert!(
+        !audit.to_string().contains(&dist.cluster.secret_key),
+        "audit entry leaked the root secret key"
+    );
+
+    collector.abort();
+    Ok(())
+}
@@ -0,0 +1,191 @@
+// Copyright 2026 RustFS Team
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+use super::harness::{
+    DistCluster, DistLayout, TestResult, enable_versioning, put_bucket_replication, put_object, retrying_put, set_bucket_quota,
+    set_remote_target, unique_bucket, wait_for_ready, wait_for_replicated_bytes, wait_until,
+};
+use crate::common::{FAST_DATA_USAGE_SCANNER_ENV, init_logging};
+use aws_sdk_s3::error::ProvideErrorMetadata;
+use aws_sdk_s3::primitives::ByteStream;
+use http::Method;
+use std::time::Duration;
+
+async fn wait_for_replication_status(
+    client: &aws_sdk_s3::Client,
+    bucket: &str,
+    key: &str,
+    expected: &[&str],
+    timeout: Duration,
+) -> TestResult {
+    wait_until(
+        timeout,
+        || async {
+            let head = client.head_object().bucket(bucket).key(key).send().await?;
+            Ok(head
+                .replication_status()
+                .is_some_and(|status| expected.contains(&status.as_str())))
+        },
+        &format!("replication status for {bucket}/{key} in {expected:?}"),
+    )
+    .await
+}
+
+#[tokio::test]
+async fn four_node_bucket_replication_converges_to_peer_cluster() -> TestResult {
+    init_logging();
+    let (source, mut target) = DistCluster::start_replication_pair().await?;
+    let source_bucket = unique_bucket("replsrc");
+    let target_bucket = unique_bucket("repldst");
+    source.create_bucket(&source_bucket).await?;
+    target.create_bucket(&target_bucket).await?;
+
+    let source_client = source.client(0)?;
+    let target_client = target.client(0)?;
+    enable_versioning(&source_client, &source_bucket).await?;
+    enable_versioning(&target_client, &target_bucket).await?;
+
+    let arn = set_remote_target(&source.cluster, &source_bucket, &target.cluster, &target_bucket).await?;
+    put_bucket_replication(&source.cluster, &source_bucket, &arn).await?;
+
+    let key = "replicated/metadata-and-tags.bin";
+    let body = b"distributed-bucket-replication".to_vec();
+    source_client
+        .put_object()
+        .bucket(&source_bucket)
+        .key(key)
+        .metadata("origin", "four-node-source")
+        .tagging("suite=distributed&shape=metadata")
+        .body(ByteStream::from(body.clone()))
+        .send()
+        .await?;
+    wait_for_replicated_bytes(&target_client, &target_bucket, key, &body, Duration::from_secs(45)).await?;
+    wait_for_replication_status(&source_client, &source_bucket, key, &["COMPLETED"], Duration::from_secs(30)).await?;
+
+    let peer_read = target.client(3)?;
+    wait_for_replicated_bytes(&peer_read, &target_bucket, key, &body, Duration::from_secs(15)).await?;
+    let replica_head = peer_read.head_object().bucket(&target_bucket).key(key).send().await?;
+    assert_eq!(
+        replica_head
+            .metadata()
+            .and_then(|metadata| metadata.get("origin"))
+            .map(String::as_str),
+        Some("four-node-source")
+    );
+    assert_eq!(replica_head.replication_status().map(|status| status.as_str()), Some("REPLICA"));
+    let replica_tags = peer_read.get_object_tagging().bucket(&target_bucket).key(key).send().await?;
+    let tags: std::collections::BTreeMap<_, _> = replica_tags.tag_set().iter().map(|tag| (tag.key(), tag.value())).collect();
+    assert_eq!(tags.get("suite"), Some(&"distributed"));
+    assert_eq!(tags.get("shape"), Some(&"metadata"));
+
+    target.cluster.stop();
+    let outage_key = "replicated/queued-during-target-outage.bin";
+    let outage_body = b"retry-after-target-restart".to_vec();
+    put_object(&source_client, &source_bucket, outage_key, outage_body.clone()).await?;
+    wait_for_replication_status(
+        &source_client,
+        &source_bucket,
+        outage_key,
+        &["PENDING", "FAILED"],
+        Duration::from_secs(30),
+    )
+    .await?;
+
+    target.cluster.start().await?;
+    wait_for_ready(&target.cluster).await?;
+    wait_for_replicated_bytes(&target.client(2)?, &target_bucket, outage_key, &outage_body, Duration::from_secs(90)).await?;
+    wait_for_replication_status(&source_client, &source_bucket, outage_key, &["COMPLETED"], Duration::from_secs(45)).await?;
+    Ok(())
+}
+
+#[tokio::test]
+async fn four_node_four_drive_hard_quota_rejects_over_limit_put() -> TestResult {
+    init_logging();
+    let dist = DistCluster::start_with_env(DistLayout::FourByFour, FAST_DATA_USAGE_SCANNER_ENV).await?;
+    let bucket = unique_bucket("quota");
+    dist.create_bucket(&bucket).await?;
+    set_bucket_quota(&dist.cluster, &bucket, 8 * 1024).await?;
+
+    let client = dist.client(1)?;
+    retrying_put(&client, &bucket, "small.bin", vec![0u8; 1024], Duration::from_secs(30)).await?;
+    wait_until(
+        Duration::from_secs(30),
+        || async {
+            let (status, body) = super::harness::cluster_admin(
+                &dist.cluster,
+                Method::GET,
+                &format!("/rustfs/admin/v3/quota-stats/{bucket}"),
+                None,
+            )
+            .await?;
+            if !status.is_success() {
+                return Ok(false);
+            }
+            let stats: serde_json::Value =
+                serde_json::from_str(&body).map_err(|error| format!("quota stats returned invalid JSON: {error}: {body}"))?;
+            let usage = stats
+                .get("current_usage")
+                .and_then(serde_json::Value::as_u64)
+                .ok_or_else(|| format!("quota stats omitted current_usage: {stats}"))?;
+            Ok(usage >= 1024)
+        },
+        "quota stats observe small object",
+    )
+    .await?;
+
+    let oversized_key = "too-big.bin";
+    let error = client
+        .put_object()
+        .bucket(&bucket)
+        .key(oversized_key)
+        .body(vec![0u8; 16 * 1024].into())
+        .send()
+        .await
+        .expect_err("hard quota must reject the oversized PUT");
+    let service_error = error
+        .as_service_error()
+        .ok_or("quota rejection was not an S3 service error")?;
+    assert_eq!(
+        error.raw_response().map(|response| response.status().as_u16()),
+        Some(400),
+        "quota rejection must be HTTP 400: {error:?}"
+    );
+    assert_eq!(service_error.code(), Some("InvalidRequest"), "unexpected quota error: {error:?}");
+    assert!(
+        service_error
+            .message()
+            .is_some_and(|message| message.starts_with("Bucket quota exceeded")),
+        "PUT must fail specifically at quota admission: {error:?}"
+    );
+
+    let missing = client
+        .head_object()
+        .bucket(&bucket)
+        .key(oversized_key)
+        .send()
+        .await
+        .expect_err("an object rejected by quota must not become visible");
+    assert_eq!(
+        missing.raw_response().map(|response| response.status().as_u16()),
+        Some(404),
+        "quota-rejected object returned an unexpected HEAD result: {missing:?}"
+    );
+
+    let listed = client.list_objects_v2().bucket(&bucket).send().await?;
+    assert!(
+        listed.contents().iter().all(|object| object.key() != Some(oversized_key)),
+        "quota-rejected key leaked into ListObjectsV2"
+    );
+    Ok(())
+}
@@ -0,0 +1,258 @@
+// Copyright 2026 RustFS Team
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+use super::harness::{DistCluster, DistLayout, TestResult, assert_object_bytes, get_object_bytes, put_object, unique_bucket};
+use crate::common::{init_logging, local_http_client};
+use aws_sdk_s3::error::ProvideErrorMetadata;
+use aws_sdk_s3::presigning::PresigningConfig;
+use aws_sdk_s3::primitives::ByteStream;
+use aws_sdk_s3::types::{Delete, MetadataDirective, ObjectIdentifier};
+use std::time::Duration;
+
+#[tokio::test]
+async fn four_node_four_drive_s3_put_get_head_list_copy_rename_delete_and_presign() -> TestResult {
+    init_logging();
+    let dist = DistCluster::start(DistLayout::FourByFour).await?;
+    let bucket = unique_bucket("s3basic");
+    dist.create_bucket(&bucket).await?;
+
+    let writer = dist.client(0)?;
+    let reader = dist.client(3)?;
+    let key = "dir/object.bin";
+    let body = vec![0xA5u8; 256 * 1024];
+    put_object(&writer, &bucket, key, body.clone()).await?;
+
+    let head = reader.head_object().bucket(&bucket).key(key).send().await?;
+    assert_eq!(head.content_length(), Some(body.len() as i64));
+    assert_object_bytes(&reader, &bucket, key, &body).await?;
+
+    let ranged = reader
+        .get_object()
+        .bucket(&bucket)
+        .key(key)
+        .range("bytes=0-15")
+        .send()
+        .await?;
+    let ranged_body = ranged.body.collect().await?.into_bytes();
+    assert_eq!(ranged_body.as_ref(), &body[..16]);
+
+    let listed = reader.list_objects_v2().bucket(&bucket).prefix("dir/").send().await?;
+    let keys: Vec<_> = listed.contents().iter().filter_map(|object| object.key()).collect();
+    assert_eq!(keys, vec![key]);
+
+    let copy_key = "dir/object-copy.bin";
+    reader
+        .copy_object()
+        .bucket(&bucket)
+        .key(copy_key)
+        .copy_source(format!("{bucket}/{key}"))
+        .metadata_directive(MetadataDirective::Copy)
+        .send()
+        .await?;
+    assert_object_bytes(&writer, &bucket, copy_key, &body).await?;
+
+    let moved_key = "dir/object-moved.bin";
+    writer
+        .copy_object()
+        .bucket(&bucket)
+        .key(moved_key)
+        .copy_source(format!("{bucket}/{copy_key}"))
+        .send()
+        .await?;
+    writer.delete_object().bucket(&bucket).key(copy_key).send().await?;
+    match writer.head_object().bucket(&bucket).key(copy_key).send().await {
+        Ok(_) => return Err("copied source still present after rename delete".into()),
+        Err(error) if error.as_service_error().is_some_and(|err| err.is_not_found()) => {}
+        Err(error) => return Err(error.into()),
+    }
+    assert_object_bytes(&reader, &bucket, moved_key, &body).await?;
+
+    let presigned = writer
+        .get_object()
+        .bucket(&bucket)
+        .key(key)
+        .presigned(PresigningConfig::expires_in(Duration::from_secs(120))?)
+        .await?;
+    let response = local_http_client().get(presigned.uri().to_string()).send().await?;
+    assert!(response.status().is_success(), "presigned GET failed: {}", response.status());
+    let presigned_body = response.bytes().await?;
+    assert_eq!(presigned_body.as_ref(), body.as_slice());
+
+    let empty_key = "empty";
+    put_object(&writer, &bucket, empty_key, Vec::new()).await?;
+    let empty = get_object_bytes(&reader, &bucket, empty_key).await?;
+    assert!(empty.is_empty());
+
+    let deleted = writer
+        .delete_objects()
+        .bucket(&bucket)
+        .delete(
+            Delete::builder()
+                .objects(ObjectIdentifier::builder().key(key).build()?)
+                .objects(ObjectIdentifier::builder().key(moved_key).build()?)
+                .objects(ObjectIdentifier::builder().key(empty_key).build()?)
+                .build()?,
+        )
+        .send()
+        .await?;
+    assert!(deleted.errors().is_empty(), "DeleteObjects reported failures: {deleted:?}");
+    assert_eq!(deleted.deleted().len(), 3, "DeleteObjects did not acknowledge every key");
+
+    let remaining = reader.list_objects_v2().bucket(&bucket).send().await?;
+    assert!(remaining.contents().is_empty(), "bucket still has objects after delete");
+    Ok(())
+}
+
+#[tokio::test]
+async fn four_node_s3_metadata_tags_special_keys_pagination_and_multipart_abort() -> TestResult {
+    init_logging();
+    let dist = DistCluster::start(DistLayout::FourByFour).await?;
+    let bucket = unique_bucket("s3matrix");
+    dist.create_bucket(&bucket).await?;
+    let writer = dist.client(0)?;
+    let reader = dist.client(3)?;
+
+    let special_key = "unicode/测试 space+percent%25.txt";
+    let special_body = b"metadata and tagging survive distributed routing".to_vec();
+    let put = writer
+        .put_object()
+        .bucket(&bucket)
+        .key(special_key)
+        .metadata("test-meta", "distributed")
+        .tagging("purpose=compatibility&scope=four-by-four")
+        .body(ByteStream::from(special_body.clone()))
+        .send()
+        .await?;
+    let etag = put.e_tag().ok_or("PutObject omitted ETag")?.to_string();
+
+    let head = reader.head_object().bucket(&bucket).key(special_key).send().await?;
+    assert_eq!(
+        head.metadata()
+            .and_then(|metadata| metadata.get("test-meta"))
+            .map(String::as_str),
+        Some("distributed")
+    );
+    assert_eq!(head.e_tag(), Some(etag.as_str()));
+    let tags = reader.get_object_tagging().bucket(&bucket).key(special_key).send().await?;
+    let actual_tags: std::collections::BTreeMap<_, _> = tags
+        .tag_set()
+        .iter()
+        .map(|tag| (tag.key().to_string(), tag.value().to_string()))
+        .collect();
+    assert_eq!(actual_tags.get("purpose").map(String::as_str), Some("compatibility"));
+    assert_eq!(actual_tags.get("scope").map(String::as_str), Some("four-by-four"));
+
+    let conditional = reader
+        .get_object()
+        .bucket(&bucket)
+        .key(special_key)
+        .if_match(&etag)
+        .send()
+        .await?;
+    assert_eq!(conditional.body.collect().await?.into_bytes().as_ref(), special_body.as_slice());
+    let invalid_range = reader
+        .get_object()
+        .bucket(&bucket)
+        .key(special_key)
+        .range("bytes=999999-1000000")
+        .send()
+        .await
+        .expect_err("an unsatisfiable range must fail");
+    assert_eq!(
+        invalid_range.as_service_error().and_then(ProvideErrorMetadata::code),
+        Some("InvalidRange"),
+        "unexpected invalid-range error: {invalid_range:?}"
+    );
+
+    let upload_key = "multipart/aborted.bin";
+    let upload = writer
+        .create_multipart_upload()
+        .bucket(&bucket)
+        .key(upload_key)
+        .send()
+        .await?;
+    let upload_id = upload.upload_id().ok_or("CreateMultipartUpload omitted upload ID")?;
+    writer
+        .upload_part()
+        .bucket(&bucket)
+        .key(upload_key)
+        .upload_id(upload_id)
+        .part_number(1)
+        .body(ByteStream::from(vec![0x5Au8; 5 * 1024 * 1024]))
+        .send()
+        .await?;
+    let pending = reader
+        .list_multipart_uploads()
+        .bucket(&bucket)
+        .prefix("multipart/")
+        .send()
+        .await?;
+    assert!(pending.uploads().iter().any(|entry| entry.upload_id() == Some(upload_id)));
+    writer
+        .abort_multipart_upload()
+        .bucket(&bucket)
+        .key(upload_key)
+        .upload_id(upload_id)
+        .send()
+        .await?;
+    let after_abort = reader
+        .list_multipart_uploads()
+        .bucket(&bucket)
+        .prefix("multipart/")
+        .send()
+        .await?;
+    assert!(after_abort.uploads().iter().all(|entry| entry.upload_id() != Some(upload_id)));
+    let aborted_head = reader
+        .head_object()
+        .bucket(&bucket)
+        .key(upload_key)
+        .send()
+        .await
+        .expect_err("aborted multipart upload must not create an object");
+    assert_eq!(
+        aborted_head.raw_response().map(|response| response.status().as_u16()),
+        Some(404),
+        "aborted multipart object returned an unexpected HEAD result: {aborted_head:?}"
+    );
+
+    for index in 0..113 {
+        let key = format!("page/{index:04}.txt");
+        put_object(&writer, &bucket, &key, format!("page-{index}").into_bytes()).await?;
+    }
+    let mut token = None;
+    let mut paged_keys = Vec::new();
+    loop {
+        let page = reader
+            .list_objects_v2()
+            .bucket(&bucket)
+            .prefix("page/")
+            .max_keys(37)
+            .set_continuation_token(token.take())
+            .send()
+            .await?;
+        paged_keys.extend(page.contents().iter().filter_map(|object| object.key().map(str::to_string)));
+        if page.is_truncated() != Some(true) {
+            break;
+        }
+        token = Some(
+            page.next_continuation_token()
+                .ok_or("truncated ListObjectsV2 page omitted next continuation token")?
+                .to_string(),
+        );
+    }
+    assert_eq!(paged_keys.len(), 113);
+    let expected: Vec<_> = (0..113).map(|index| format!("page/{index:04}.txt")).collect();
+    assert_eq!(paged_keys, expected, "pagination lost, duplicated, or reordered keys");
+    Ok(())
+}
@@ -0,0 +1,94 @@
+// Copyright 2026 RustFS Team
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+use super::harness::{
+    DECOMMISSION_POOL_ID, DistCluster, DistLayout, TestResult, assert_inventory, decommission_running_with_progress,
+    decommission_status_json, put_inventory_retrying, rebalance_running_with_progress, rebalance_status_json,
+    retrying_get_equals, retrying_put, start_decommission, start_rebalance, unique_bucket, wait_for_decommission_complete,
+    wait_for_decommission_running_with_progress, wait_for_rebalance_complete, wait_for_rebalance_running_with_progress,
+};
+use crate::common::init_logging;
+use std::time::Duration;
+
+#[tokio::test]
+async fn s3_put_get_list_succeed_during_decommission_and_rebalance() -> TestResult {
+    init_logging();
+    let mut dist = DistCluster::start(DistLayout::SingleNodeFourDrive).await?;
+    let bucket = unique_bucket("s3move");
+    dist.create_bucket(&bucket).await?;
+    let client = dist.client(0)?;
+    let inventory = put_inventory_retrying(&client, &bucket, 96, 256 * 1024, Duration::from_secs(30)).await?;
+    dist.expand_to_four_pools().await?;
+
+    start_decommission(&dist.cluster, DECOMMISSION_POOL_ID).await?;
+    wait_for_decommission_running_with_progress(&dist.cluster, DECOMMISSION_POOL_ID, Duration::from_secs(30)).await?;
+    let live = dist.client(2)?;
+    retrying_put(
+        &live,
+        &bucket,
+        "during-decommission.bin",
+        b"written-while-decommissioning".to_vec(),
+        Duration::from_secs(30),
+    )
+    .await?;
+    retrying_get_equals(
+        &live,
+        &bucket,
+        "during-decommission.bin",
+        b"written-while-decommissioning",
+        Duration::from_secs(30),
+    )
+    .await?;
+    let listed = live.list_objects_v2().bucket(&bucket).send().await?;
+    assert!(
+        listed
+            .contents()
+            .iter()
+            .any(|object| object.key() == Some("during-decommission.bin")),
+        "list during decommission missed the newly written key"
+    );
+    let status = decommission_status_json(&dist.cluster).await?;
+    if !decommission_running_with_progress(&status, DECOMMISSION_POOL_ID)? {
+        return Err(format!("decommission did not remain active across the S3 operations: {status}").into());
+    }
+
+    wait_for_decommission_complete(&dist.cluster, DECOMMISSION_POOL_ID, Duration::from_secs(180)).await?;
+    assert_inventory(&live, &bucket, &inventory).await?;
+
+    let rebalance_id = start_rebalance(&dist.cluster).await?;
+    wait_for_rebalance_running_with_progress(&dist.cluster, &rebalance_id, Duration::from_secs(30)).await?;
+    retrying_put(
+        &live,
+        &bucket,
+        "during-rebalance.bin",
+        b"written-while-rebalancing".to_vec(),
+        Duration::from_secs(30),
+    )
+    .await?;
+    retrying_get_equals(
+        &live,
+        &bucket,
+        "during-rebalance.bin",
+        b"written-while-rebalancing",
+        Duration::from_secs(30),
+    )
+    .await?;
+    let status = rebalance_status_json(&dist.cluster).await?;
+    if !rebalance_running_with_progress(&status, &rebalance_id)? {
+        return Err(format!("rebalance did not remain active across the S3 operations: {status}").into());
+    }
+    wait_for_rebalance_complete(&dist.cluster, &rebalance_id, Duration::from_secs(180)).await?;
+    assert_inventory(&dist.client(1)?, &bucket, &inventory).await?;
+    Ok(())
+}
@@ -0,0 +1,128 @@
+// Copyright 2026 RustFS Team
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+use super::harness::{
+    DistCluster, TestResult, cluster_admin_ok, enable_versioning, put_object, unique_bucket, wait_for_replicated_bytes,
+    wait_until,
+};
+use crate::common::{init_logging, signed_request};
+use http::{Method, StatusCode};
+use rustfs_madmin::{PeerSite, ReplicateAddStatus, SiteReplicationInfo, SyncStatus};
+use std::time::Duration;
+
+async fn site_replication_add(
+    cluster: &crate::common::RustFSTestClusterEnvironment,
+    sites: &[PeerSite],
+) -> TestResult<ReplicateAddStatus> {
+    let url = format!("{}/rustfs/admin/v3/site-replication/add?replicateILMExpiry=false", cluster.nodes[0].url);
+    let response = signed_request(
+        Method::PUT,
+        &url,
+        &cluster.access_key,
+        &cluster.secret_key,
+        Some(serde_json::to_vec(sites)?),
+        Some("application/json"),
+    )
+    .await?;
+    if response.status() != StatusCode::OK {
+        let status = response.status();
+        let body = response.text().await.unwrap_or_default();
+        return Err(format!("site replication add failed: {status} {body}").into());
+    }
+    Ok(serde_json::from_slice(&response.bytes().await?)?)
+}
+
+async fn site_replication_info(cluster: &crate::common::RustFSTestClusterEnvironment) -> TestResult<SiteReplicationInfo> {
+    let body = cluster_admin_ok(cluster, Method::GET, "/rustfs/admin/v3/site-replication/info", None).await?;
+    Ok(serde_json::from_str(&body)?)
+}
+
+async fn wait_for_site_replication_enabled(cluster: &crate::common::RustFSTestClusterEnvironment) -> TestResult {
+    wait_until(
+        Duration::from_secs(30),
+        || async {
+            let info = site_replication_info(cluster).await?;
+            Ok(info.enabled && info.sites.len() == 2 && info.sites.iter().all(|site| site.sync_state == SyncStatus::Enable))
+        },
+        "site replication enabled with two synchronized sites",
+    )
+    .await
+}
+
+#[tokio::test]
+async fn four_node_site_replication_replicates_object_to_peer_site() -> TestResult {
+    init_logging();
+    let (site_a, site_b) = DistCluster::start_replication_pair().await?;
+    let bucket = unique_bucket("siterepl");
+    site_a.create_bucket(&bucket).await?;
+    site_b.create_bucket(&bucket).await?;
+
+    let client_a = site_a.client(0)?;
+    let client_b = site_b.client(0)?;
+    enable_versioning(&client_a, &bucket).await?;
+    enable_versioning(&client_b, &bucket).await?;
+
+    let sites = vec![
+        PeerSite {
+            name: "site-a".to_string(),
+            endpoint: site_a.cluster.nodes[0].url.clone(),
+            access_key: site_a.cluster.access_key.clone(),
+            secret_key: site_a.cluster.secret_key.clone(),
+            ..Default::default()
+        },
+        PeerSite {
+            name: "site-b".to_string(),
+            endpoint: site_b.cluster.nodes[0].url.clone(),
+            access_key: site_b.cluster.access_key.clone(),
+            secret_key: site_b.cluster.secret_key.clone(),
+            ..Default::default()
+        },
+    ];
+    let add_status = site_replication_add(&site_a.cluster, &sites).await?;
+    assert!(
+        add_status.success && add_status.err_detail.is_empty() && add_status.initial_sync_error_message.is_empty(),
+        "site replication add reported failure: {add_status:?}"
+    );
+    wait_for_site_replication_enabled(&site_a.cluster).await?;
+    wait_for_site_replication_enabled(&site_b.cluster).await?;
+
+    let info_a = site_replication_info(&site_a.cluster).await?;
+    let remote = info_a
+        .sites
+        .iter()
+        .find(|site| site.name == "site-b")
+        .ok_or_else(|| format!("site A info omitted the configured site-b peer: {info_a:?}"))?;
+    assert_eq!(remote.endpoint, site_b.cluster.nodes[0].url);
+    let deployment_ids: std::collections::BTreeSet<_> = info_a.sites.iter().map(|site| site.deployment_id.as_str()).collect();
+    assert!(
+        deployment_ids.iter().all(|deployment_id| !deployment_id.is_empty()) && deployment_ids.len() == 2,
+        "site peers must have two distinct non-empty deployment IDs: {info_a:?}"
+    );
+    assert!(info_a.retry_stats.is_none(), "site A has pending replication retries: {info_a:?}");
+    assert!(info_a.pending_operation.is_none(), "site A has a pending operation: {info_a:?}");
+
+    let key = "site-object.bin";
+    let body = b"four-node-site-replication".to_vec();
+    put_object(&client_a, &bucket, key, body.clone()).await?;
+    wait_for_replicated_bytes(&client_b, &bucket, key, &body, Duration::from_secs(60)).await?;
+
+    let peer_b = site_b.client(3)?;
+    wait_for_replicated_bytes(&peer_b, &bucket, key, &body, Duration::from_secs(20)).await?;
+
+    let reverse_key = "reverse/site-object.bin";
+    let reverse_body = b"site-b-to-site-a".to_vec();
+    put_object(&site_b.client(2)?, &bucket, reverse_key, reverse_body.clone()).await?;
+    wait_for_replicated_bytes(&site_a.client(3)?, &bucket, reverse_key, &reverse_body, Duration::from_secs(60)).await?;
+    Ok(())
+}
@@ -0,0 +1,345 @@
+// Copyright 2026 RustFS Team
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//! 4-node upgrade coverage for historical objects and IAM AK/SK.
+//!
+//! Complements `upgrade_compatibility_test` (single-node SSE/multipart and
+//! mixed-version listing). This module pins the distributed contract the
+//! hardware upgrade chain is meant to catch: after a 4-node upgrade, objects
+//! written on the previous release still read back, and IAM user credentials
+//! created before the upgrade still authenticate.
+//!
+//! Requires `RUSTFS_UPGRADE_SOURCE_BINARY` pointing at the pinned previous
+//! release. The `e2e-distributed` workflow downloads that binary; a local run
+//! without it fails closed rather than skipping.
+
+use super::harness::{
+    DistCluster, DistLayout, TestResult, assert_object_bytes, cluster_admin_ok, enable_versioning, get_object_bytes, put_object,
+    unique_bucket, wait_until,
+};
+use crate::common::{
+    AdminTransport, admin_add_canned_policy_via, admin_attach_user_policy_via, admin_create_user_via, init_logging,
+};
+use aws_sdk_s3::Client;
+use aws_sdk_s3::error::ProvideErrorMetadata;
+use std::path::{Path, PathBuf};
+use std::time::Duration;
+use uuid::Uuid;
+
+const SOURCE_BINARY_ENV: &str = "RUSTFS_UPGRADE_SOURCE_BINARY";
+const IAM_SECRET: &str = "UpgradeTestSecretKey1";
+const WRONG_SECRET: &str = "WrongSecretKey000000";
+const CREDENTIAL_TIMEOUT: Duration = Duration::from_secs(30);
+
+struct UpgradeSeed {
+    history_bucket: String,
+    history_key: &'static str,
+    history_body: Vec<u8>,
+    versioned_bucket: String,
+    versioned_key: &'static str,
+    version1: String,
+    version1_body: Vec<u8>,
+    version2: String,
+    version2_body: Vec<u8>,
+    iam_bucket: String,
+    iam_key: &'static str,
+    iam_body: Vec<u8>,
+    iam_user: String,
+    iam_secret: &'static str,
+}
+
+fn source_binary() -> TestResult<PathBuf> {
+    let path = std::env::var_os(SOURCE_BINARY_ENV).map(PathBuf::from).ok_or_else(|| {
+        format!(
+            "{SOURCE_BINARY_ENV} must point to the pinned previous release binary (the e2e-distributed workflow downloads it)"
+        )
+    })?;
+    if !path.is_file() {
+        return Err(format!("upgrade source binary does not exist: {}", path.display()).into());
+    }
+    Ok(path)
+}
+
+fn capture_upgrade_logs(cluster: &mut DistCluster, label: &str) -> TestResult {
+    let Some(log_dir) = std::env::var_os("RUSTFS_E2E_LOG_DIR") else {
+        return Ok(());
+    };
+    std::fs::create_dir_all(&log_dir)?;
+    for node_idx in 0..cluster.cluster.nodes.len() {
+        let path = Path::new(&log_dir).join(format!("{label}-node-{node_idx}.log"));
+        cluster
+            .cluster
+            .set_node_capture_log_path(node_idx, path.to_string_lossy().into_owned())?;
+    }
+    Ok(())
+}
+
+fn iam_rw_policy(bucket: &str) -> String {
+    serde_json::json!({
+        "Version": "2012-10-17",
+        "Statement": [{
+            "Effect": "Allow",
+            "Action": ["s3:*"],
+            "Resource": [
+                format!("arn:aws:s3:::{bucket}"),
+                format!("arn:aws:s3:::{bucket}/*")
+            ]
+        }]
+    })
+    .to_string()
+}
+
+async fn create_iam_user(dist: &DistCluster, user: &str, secret: &str, policy_name: &str, bucket: &str) -> TestResult {
+    let url = &dist.cluster.nodes[0].url;
+    let access = &dist.cluster.access_key;
+    let admin_secret = &dist.cluster.secret_key;
+    admin_create_user_via(AdminTransport::Signed, url, access, admin_secret, user, secret).await?;
+    admin_add_canned_policy_via(AdminTransport::Signed, url, access, admin_secret, policy_name, &iam_rw_policy(bucket)).await?;
+    admin_attach_user_policy_via(AdminTransport::Signed, url, access, admin_secret, policy_name, user).await?;
+    Ok(())
+}
+
+async fn wait_for_put(client: &Client, bucket: &str, key: &str, body: Vec<u8>, label: &str) -> TestResult {
+    wait_until(
+        CREDENTIAL_TIMEOUT,
+        || {
+            let client = client.clone();
+            let bucket = bucket.to_string();
+            let key = key.to_string();
+            let body = body.clone();
+            async move {
+                put_object(&client, &bucket, &key, body).await?;
+                Ok(true)
+            }
+        },
+        label,
+    )
+    .await
+}
+
+async fn wait_for_bytes(client: &Client, bucket: &str, key: &str, expected: &[u8], label: &str) -> TestResult {
+    wait_until(
+        CREDENTIAL_TIMEOUT,
+        || {
+            let client = client.clone();
+            let bucket = bucket.to_string();
+            let key = key.to_string();
+            let expected = expected.to_vec();
+            async move {
+                let got = get_object_bytes(&client, &bucket, &key).await?;
+                Ok(got == expected)
+            }
+        },
+        label,
+    )
+    .await
+}
+
+async fn seed_history_and_iam(dist: &DistCluster) -> TestResult<UpgradeSeed> {
+    let history_bucket = unique_bucket("upg-hist");
+    let versioned_bucket = unique_bucket("upg-ver");
+    let iam_bucket = unique_bucket("upg-iam");
+    dist.create_bucket(&history_bucket).await?;
+    dist.create_bucket(&versioned_bucket).await?;
+    dist.create_bucket(&iam_bucket).await?;
+
+    let root = dist.client(0)?;
+    enable_versioning(&root, &versioned_bucket).await?;
+
+    let history_key = "plain-history.bin";
+    let history_body = b"written by the previous 4-node release".to_vec();
+    put_object(&root, &history_bucket, history_key, history_body.clone()).await?;
+
+    let versioned_key = "versioned-history.txt";
+    let version1_body = b"version-one-before-upgrade".to_vec();
+    let version1 = root
+        .put_object()
+        .bucket(&versioned_bucket)
+        .key(versioned_key)
+        .body(aws_sdk_s3::primitives::ByteStream::from(version1_body.clone()))
+        .send()
+        .await?
+        .version_id()
+        .ok_or("first versioned PUT omitted version ID")?
+        .to_string();
+    let version2_body = b"version-two-before-upgrade".to_vec();
+    let version2 = root
+        .put_object()
+        .bucket(&versioned_bucket)
+        .key(versioned_key)
+        .body(aws_sdk_s3::primitives::ByteStream::from(version2_body.clone()))
+        .send()
+        .await?
+        .version_id()
+        .ok_or("second versioned PUT omitted version ID")?
+        .to_string();
+
+    let iam_user = format!("upg{}", &Uuid::new_v4().simple().to_string()[..8]);
+    let policy_name = format!("upgpol{}", &Uuid::new_v4().simple().to_string()[..8]);
+    create_iam_user(dist, &iam_user, IAM_SECRET, &policy_name, &iam_bucket).await?;
+
+    let iam_key = "iam-history.bin";
+    let iam_body = b"written with pre-upgrade IAM AK/SK".to_vec();
+    let iam_client = dist.client_with_credentials(1, &iam_user, IAM_SECRET)?;
+    wait_for_put(&iam_client, &iam_bucket, iam_key, iam_body.clone(), "IAM user PUT before upgrade").await?;
+
+    Ok(UpgradeSeed {
+        history_bucket,
+        history_key,
+        history_body,
+        versioned_bucket,
+        versioned_key,
+        version1,
+        version1_body,
+        version2,
+        version2_body,
+        iam_bucket,
+        iam_key,
+        iam_body,
+        iam_user,
+        iam_secret: IAM_SECRET,
+    })
+}
+
+async fn assert_history_and_iam(dist: &DistCluster, seed: &UpgradeSeed, context: &str) -> TestResult {
+    let root_a = dist.client(0)?;
+    let root_b = dist.client(3)?;
+    wait_for_bytes(
+        &root_b,
+        &seed.history_bucket,
+        seed.history_key,
+        &seed.history_body,
+        &format!("{context}: root GET historical object"),
+    )
+    .await?;
+    assert_object_bytes(&root_a, &seed.history_bucket, seed.history_key, &seed.history_body).await?;
+
+    let v1 = root_b
+        .get_object()
+        .bucket(&seed.versioned_bucket)
+        .key(seed.versioned_key)
+        .version_id(&seed.version1)
+        .send()
+        .await?;
+    let v1_body = v1.body.collect().await?.into_bytes();
+    if v1_body.as_ref() != seed.version1_body.as_slice() {
+        return Err(format!("{context}: version 1 bytes changed after upgrade").into());
+    }
+    let v2 = root_a
+        .get_object()
+        .bucket(&seed.versioned_bucket)
+        .key(seed.versioned_key)
+        .version_id(&seed.version2)
+        .send()
+        .await?;
+    let v2_body = v2.body.collect().await?.into_bytes();
+    if v2_body.as_ref() != seed.version2_body.as_slice() {
+        return Err(format!("{context}: version 2 bytes changed after upgrade").into());
+    }
+
+    let users = cluster_admin_ok(&dist.cluster, http::Method::GET, "/rustfs/admin/v3/list-users", None).await?;
+    if !users.contains(&seed.iam_user) {
+        return Err(format!("{context}: list-users lost IAM user {}: {users}", seed.iam_user).into());
+    }
+
+    let iam_on_upgraded = dist.client_with_credentials(0, &seed.iam_user, seed.iam_secret)?;
+    let iam_on_peer = dist.client_with_credentials(3, &seed.iam_user, seed.iam_secret)?;
+    wait_for_bytes(
+        &iam_on_upgraded,
+        &seed.iam_bucket,
+        seed.iam_key,
+        &seed.iam_body,
+        &format!("{context}: IAM GET historical object on node 0"),
+    )
+    .await?;
+    wait_for_bytes(
+        &iam_on_peer,
+        &seed.iam_bucket,
+        seed.iam_key,
+        &seed.iam_body,
+        &format!("{context}: IAM GET historical object on node 3"),
+    )
+    .await?;
+
+    let post_key = format!("after-upgrade-{context}.txt");
+    let post_body = format!("{context}: written with the same IAM AK/SK after upgrade").into_bytes();
+    wait_for_put(
+        &iam_on_peer,
+        &seed.iam_bucket,
+        &post_key,
+        post_body.clone(),
+        &format!("{context}: IAM PUT after upgrade"),
+    )
+    .await?;
+    assert_object_bytes(&iam_on_upgraded, &seed.iam_bucket, &post_key, &post_body).await?;
+
+    let bad = dist.client_with_credentials(1, &seed.iam_user, WRONG_SECRET)?;
+    match bad.get_object().bucket(&seed.iam_bucket).key(seed.iam_key).send().await {
+        Ok(_) => return Err(format!("{context}: wrong secret must not read the IAM object").into()),
+        Err(error) => {
+            let code = error.as_service_error().and_then(ProvideErrorMetadata::code);
+            let rejected = code == Some("SignatureDoesNotMatch")
+                || code == Some("InvalidAccessKeyId")
+                || code == Some("AccessDenied")
+                || code == Some("InvalidArgument")
+                || error.raw_response().is_some_and(|response| response.status().as_u16() == 403);
+            if !rejected {
+                return Err(format!("{context}: wrong secret failed with unexpected error {error:?}").into());
+            }
+        }
+    }
+
+    let post_root_key = format!("root-after-{context}.bin");
+    let post_root_body = format!("{context}: root write after upgrade").into_bytes();
+    put_object(&root_a, &seed.history_bucket, &post_root_key, post_root_body.clone()).await?;
+    assert_object_bytes(&root_b, &seed.history_bucket, &post_root_key, &post_root_body).await?;
+    Ok(())
+}
+
+#[tokio::test]
+async fn four_node_direct_upgrade_preserves_history_and_iam_credentials() -> TestResult {
+    init_logging();
+    let previous = source_binary()?;
+    let mut dist = DistCluster::new_stopped(DistLayout::FourNodeFourDisk).await?;
+    capture_upgrade_logs(&mut dist, "direct-upgrade")?;
+    dist.start_from_binary(&previous).await?;
+
+    let seed = seed_history_and_iam(&dist).await?;
+    dist.restart_with_current_binary().await?;
+    assert_history_and_iam(&dist, &seed, "direct").await?;
+    Ok(())
+}
+
+#[tokio::test]
+async fn four_node_rolling_upgrade_preserves_history_and_iam_credentials() -> TestResult {
+    init_logging();
+    let previous = source_binary()?;
+    let mut dist = DistCluster::new_stopped(DistLayout::FourNodeFourDisk).await?;
+    capture_upgrade_logs(&mut dist, "rolling-upgrade")?;
+    dist.start_from_binary(&previous).await?;
+
+    let seed = seed_history_and_iam(&dist).await?;
+
+    dist.replace_node_with_current_binary(0).await?;
+    assert_history_and_iam(&dist, &seed, "one-current-node").await?;
+
+    for node_idx in [1, 2] {
+        dist.replace_node_with_current_binary(node_idx).await?;
+    }
+    assert_history_and_iam(&dist, &seed, "one-previous-node").await?;
+
+    dist.replace_node_with_current_binary(3).await?;
+    assert_history_and_iam(&dist, &seed, "homogeneous-current").await?;
+    Ok(())
+}
@@ -0,0 +1,188 @@
+// Copyright 2026 RustFS Team
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+use super::harness::{DistCluster, DistLayout, TestResult, enable_versioning, get_object_bytes, put_object, unique_bucket};
+use crate::common::init_logging;
+use aws_sdk_s3::error::ProvideErrorMetadata;
+use aws_sdk_s3::types::{BucketVersioningStatus, VersioningConfiguration};
+
+#[tokio::test]
+async fn four_node_four_drive_versioning_put_list_get_delete_marker() -> TestResult {
+    init_logging();
+    let dist = DistCluster::start(DistLayout::FourByFour).await?;
+    let bucket = unique_bucket("version");
+    dist.create_bucket(&bucket).await?;
+    let writer = dist.client(0)?;
+    let reader = dist.client(3)?;
+    enable_versioning(&writer, &bucket).await?;
+
+    let key = "versioned.txt";
+    let v1_id = writer
+        .put_object()
+        .bucket(&bucket)
+        .key(key)
+        .body(b"v1".to_vec().into())
+        .send()
+        .await?
+        .version_id()
+        .ok_or("v1 PUT omitted version ID")?
+        .to_string();
+    let v2_id = writer
+        .put_object()
+        .bucket(&bucket)
+        .key(key)
+        .body(b"v2".to_vec().into())
+        .send()
+        .await?
+        .version_id()
+        .ok_or("v2 PUT omitted version ID")?
+        .to_string();
+
+    let versions = reader.list_object_versions().bucket(&bucket).prefix(key).send().await?;
+    let matching_versions: Vec<_> = versions
+        .versions()
+        .iter()
+        .filter(|version| version.key() == Some(key))
+        .collect();
+    assert_eq!(matching_versions.len(), 2, "fresh key must have exactly two versions: {versions:?}");
+    assert!(versions.delete_markers().is_empty(), "fresh key unexpectedly has a delete marker");
+    assert!(
+        matching_versions
+            .iter()
+            .any(|version| version.version_id() == Some(v1_id.as_str()) && version.is_latest() != Some(true)),
+        "v1 was not the historical version: {versions:?}"
+    );
+    assert!(
+        matching_versions
+            .iter()
+            .any(|version| version.version_id() == Some(v2_id.as_str()) && version.is_latest() == Some(true)),
+        "v2 was not the latest version: {versions:?}"
+    );
+
+    let latest = get_object_bytes(&reader, &bucket, key).await?;
+    assert_eq!(latest, b"v2");
+
+    let older = reader.get_object().bucket(&bucket).key(key).version_id(&v1_id).send().await?;
+    let older_body = older.body.collect().await?.into_bytes();
+    assert_eq!(older_body.as_ref(), b"v1");
+
+    let deleted = writer.delete_object().bucket(&bucket).key(key).send().await?;
+    assert_eq!(deleted.delete_marker(), Some(true));
+    let marker_id = deleted.version_id().ok_or("DeleteObject omitted delete-marker version ID")?;
+    let after_delete = reader.list_object_versions().bucket(&bucket).prefix(key).send().await?;
+    let matching_markers: Vec<_> = after_delete
+        .delete_markers()
+        .iter()
+        .filter(|marker| marker.key() == Some(key))
+        .collect();
+    assert_eq!(
+        matching_markers.len(),
+        1,
+        "delete marker missing or duplicated after current-version delete: {after_delete:?}"
+    );
+    assert!(
+        matching_markers[0].version_id() == Some(marker_id) && matching_markers[0].is_latest() == Some(true),
+        "DeleteObject response and ListObjectVersions disagree about the marker: {after_delete:?}"
+    );
+
+    let latest_after_delete = reader.get_object().bucket(&bucket).key(key).send().await;
+    match latest_after_delete {
+        Ok(_) => return Err("current version should be a delete marker".into()),
+        Err(error)
+            if error
+                .as_service_error()
+                .and_then(ProvideErrorMetadata::code)
+                .is_some_and(|code| code == "NoSuchKey" || code == "NotFound") => {}
+        Err(error) => return Err(error.into()),
+    }
+
+    let restored = reader.get_object().bucket(&bucket).key(key).version_id(&v1_id).send().await?;
+    let restored_body = restored.body.collect().await?.into_bytes();
+    assert_eq!(restored_body.as_ref(), b"v1");
+
+    writer
+        .delete_object()
+        .bucket(&bucket)
+        .key(key)
+        .version_id(marker_id)
+        .send()
+        .await?;
+    assert_eq!(get_object_bytes(&reader, &bucket, key).await?, b"v2");
+    Ok(())
+}
+
+#[tokio::test]
+async fn four_node_versioning_suspension_keeps_one_null_version_and_history() -> TestResult {
+    init_logging();
+    let dist = DistCluster::start(DistLayout::FourByFour).await?;
+    let bucket = unique_bucket("suspend");
+    dist.create_bucket(&bucket).await?;
+    let writer = dist.client(0)?;
+    let reader = dist.client(3)?;
+    enable_versioning(&writer, &bucket).await?;
+
+    let key = "suspended.txt";
+    let original = writer
+        .put_object()
+        .bucket(&bucket)
+        .key(key)
+        .body(b"enabled-history".to_vec().into())
+        .send()
+        .await?
+        .version_id()
+        .ok_or("enabled PUT omitted version ID")?
+        .to_string();
+    writer
+        .put_bucket_versioning()
+        .bucket(&bucket)
+        .versioning_configuration(
+            VersioningConfiguration::builder()
+                .status(BucketVersioningStatus::Suspended)
+                .build(),
+        )
+        .send()
+        .await?;
+
+    put_object(&writer, &bucket, key, b"null-one".to_vec()).await?;
+    put_object(&writer, &bucket, key, b"null-two".to_vec()).await?;
+    assert_eq!(get_object_bytes(&reader, &bucket, key).await?, b"null-two");
+
+    let versions = reader.list_object_versions().bucket(&bucket).prefix(key).send().await?;
+    let matching: Vec<_> = versions
+        .versions()
+        .iter()
+        .filter(|version| version.key() == Some(key))
+        .collect();
+    assert!(matching.iter().any(|version| version.version_id() == Some(original.as_str())));
+    let null_version_count = matching
+        .iter()
+        .filter(|version| {
+            matches!(
+                version.version_id(),
+                None | Some("") | Some("null") | Some("00000000-0000-0000-0000-000000000000")
+            )
+        })
+        .count();
+    assert_eq!(null_version_count, 1, "suspended overwrites must keep one null version: {versions:?}");
+
+    let historical = reader
+        .get_object()
+        .bucket(&bucket)
+        .key(key)
+        .version_id(&original)
+        .send()
+        .await?;
+    assert_eq!(historical.body.collect().await?.into_bytes().as_ref(), b"enabled-history");
+    Ok(())
+}
@@ -378,6 +378,11 @@ mod bucket_stats_regression_test;
 #[cfg(test)]
 mod distributed_startup_regression_test;

+// 4-node / 4-disk distributed Actions suite (S3, lock, versioning, replication,
+// quota, observability, expand/decommission/rebalance, site replication, chaos).
+#[cfg(test)]
+mod distributed;
+
 // P1 regression: tier/ILM transition (rustfs#5218, #5130, #5011, #4826, #5024)
 #[cfg(test)]
 mod tier_transition_regression_test;
@@ -6743,6 +6743,99 @@ async fn test_site_replication_replicates_object_with_bucket_versioning_real_dua
    Ok(())
 }

+#[tokio::test]
+async fn test_site_replication_replays_bucket_created_during_peer_outage_real_dual_node() -> TestResult {
+    init_logging();
+
+    // Keep compilation outside the scenario timeout. Recovery itself waits
+    // for the production 30-second lightweight retry tick.
+    let _rustfs_binary = rustfs_binary_path();
+
+    match timeout(Duration::from_secs(150), async {
+        let mut site_env = replication_fast_env();
+        site_env.extend_from_slice(LOOPBACK_REPLICATION_TARGET_ENV);
+
+        let mut site_a_env = RustFSTestEnvironment::new().await?;
+        site_a_env.start_rustfs_server_with_env(vec![], &site_env).await?;
+
+        let mut site_b_env = RustFSTestEnvironment::new().await?;
+        site_b_env.start_rustfs_server_without_cleanup_with_env(&site_env).await?;
+
+        let site_a_client = site_a_env.create_s3_client();
+        let site_b_client = site_b_env.create_s3_client();
+        let bucket = "site-repl-peer-outage";
+        let key = "after-recovery.txt";
+        let payload = b"site replication recovered the missed bucket".to_vec();
+
+        let add_status = site_replication_add(
+            &site_a_env,
+            &[
+                PeerSite {
+                    name: "outage-site-a".to_string(),
+                    endpoint: site_a_env.url.clone(),
+                    access_key: site_a_env.access_key.clone(),
+                    secret_key: site_a_env.secret_key.clone(),
+                    ..Default::default()
+                },
+                PeerSite {
+                    name: "outage-site-b".to_string(),
+                    endpoint: site_b_env.url.clone(),
+                    access_key: site_b_env.access_key.clone(),
+                    secret_key: site_b_env.secret_key.clone(),
+                    ..Default::default()
+                },
+            ],
+        )
+        .await?;
+        assert!(add_status.success, "unexpected site add result: {add_status:?}");
+        wait_for_site_replication_enabled(&site_a_env, 2).await?;
+        wait_for_site_replication_enabled(&site_b_env, 2).await?;
+
+        site_b_env.stop_server();
+        site_a_client.create_bucket().bucket(bucket).send().await?;
+        site_a_client.head_bucket().bucket(bucket).send().await?;
+
+        let queued = site_replication_info(&site_a_env)
+            .await?
+            .retry_stats
+            .ok_or("peer outage did not persist a site replication retry event")?;
+        assert!(queued.pending + queued.failed > 0, "peer outage retry queue was unexpectedly empty");
+
+        site_b_env.restart_server_preserving_data(vec![], &site_env).await?;
+        let recovery_deadline = tokio::time::Instant::now() + Duration::from_secs(75);
+        loop {
+            let bucket_recovered = site_b_client.head_bucket().bucket(bucket).send().await.is_ok();
+            let queue_empty = site_replication_info(&site_a_env).await?.retry_stats.is_none();
+            if bucket_recovered && queue_empty {
+                break;
+            }
+            if tokio::time::Instant::now() >= recovery_deadline {
+                return Err(format!(
+                    "site replication retry did not settle after peer recovery; bucket_recovered={bucket_recovered}, queue_empty={queue_empty}"
+                )
+                .into());
+            }
+            sleep(Duration::from_millis(250)).await;
+        }
+
+        site_a_client
+            .put_object()
+            .bucket(bucket)
+            .key(key)
+            .body(ByteStream::from(payload.clone()))
+            .send()
+            .await?;
+        assert_eq!(wait_for_object_on_target(&site_b_client, bucket, key).await?, payload);
+
+        Ok(())
+    })
+    .await
+    {
+        Ok(result) => result,
+        Err(_) => Err("site replication peer-outage recovery timed out after 150 seconds".into()),
+    }
+}
+
 /// Re-applying a site's own replication config must not disable the peer's reverse direction.
 ///
 /// `PutBucketReplication` broadcasts the config to every peer — the console's replication
@@ -215,6 +215,7 @@ serde_urlencoded.workspace = true
 google-cloud-storage = { workspace = true }
 google-cloud-auth = { workspace = true }
 faster-hex = { workspace = true }
+quick-xml = { workspace = true }
 ratelimit = { workspace = true }
 aws-smithy-http-client = { workspace = true, default-features = false, features = ["rustls-aws-lc"] }

@@ -244,6 +245,7 @@ windows-sys = { workspace = true, features = [
 windows-sys = { workspace = true, features = ["Win32_System_Ioctl"] }

 [dev-dependencies]
+aws-smithy-async.workspace = true
 tokio = { workspace = true, features = ["rt-multi-thread", "macros", "test-util", "fs"] }
 criterion = { workspace = true, features = ["html_reports"] }
 temp-env = { workspace = true, features = ["async_closure"] }
@@ -153,12 +153,13 @@ pub mod bucket {
            LastSourceError, LatencyBucketSnapshot, NEGATIVE_CACHE_MAX_ENTRIES, NegativeCache, OdmBucketSnapshot, OdmLookup,
            OdmOp, OdmOutcome, OdmStateError, OdmStats, OdmStatsSnapshot, OnDemandMigrationSys, PullError, PullFailureReason,
            PullFollower, PullLeader, PullOutcome, PullPath, PullResult, PullSlot, SOURCE_LATENCY_BUCKET_BOUNDS_MS,
-            SourceLatencySnapshot, source_client_spec,
+            SourceLatencySnapshot, source_backend_spec, source_client_spec,
        };
        pub use crate::bucket::on_demand_migration::{
-            ConfigPublishHook, FilterConfig, HeadPolicy, ON_DEMAND_MIGRATION_CONFIG_HOOK, ON_DEMAND_MIGRATION_CONFIG_VERSION,
-            OnDemandMigrationConfig, OnDemandMigrationConfigError, PathStyle, PolicyConfig, Provider, RangeGetPolicy,
-            SourceConfig, SourceCredentials, SourceErrorPolicy, SourceTimeout, TlsConfig, ValidationContext,
+            AzureSourceConfig, ConfigPublishHook, FilterConfig, GcsSourceConfig, HeadPolicy, ON_DEMAND_MIGRATION_CONFIG_HOOK,
+            ON_DEMAND_MIGRATION_CONFIG_VERSION, OnDemandMigrationConfig, OnDemandMigrationConfigError, PathStyle, PolicyConfig,
+            Provider, RangeGetPolicy, SourceConfig, SourceCredentials, SourceErrorPolicy, SourceTimeout, TlsConfig,
+            ValidationContext,
        };
        pub use crate::bucket::on_demand_migration::{
            EnqueueOutcome, LocalObject, MAX_MULTIPART_PARTS, OdmWriteBack, PULL_MAX_RETRIES, PULL_RETRY_BASE_DELAYS,
@@ -167,9 +168,10 @@ pub mod bucket {
            idle_guarded_body,
        };
        pub use crate::bucket::on_demand_migration::{
-            FetchRequest, LIST_THROUGH_TOKEN_VERSION, ListEntryKey, ListThroughCursor, ListThroughMerger, ListThroughToken,
-            ListThroughTokenError, MAX_LIST_FETCHES_PER_SIDE, MergeOutcome, MergePick, MergeSide, SOURCE_LIST_MAX_RATE_WAIT,
-            SOURCE_LIST_RATE_PER_SEC, SourceListPlan, SourceListRateLimiter, decode_continuation_token, source_list_plan,
+            FetchRequest, LIST_THROUGH_TOKEN_VERSION, ListEntryKey, ListPageError, ListThroughCursor, ListThroughMerger,
+            ListThroughToken, ListThroughTokenError, MAX_LIST_FETCHES_PER_SIDE, MAX_LIST_NO_PROGRESS_PAGES, MergeOutcome,
+            MergePick, MergeSide, SOURCE_LIST_MAX_RATE_WAIT, SOURCE_LIST_RATE_PER_SEC, SourceListPlan, SourceListRateLimiter,
+            decode_continuation_token, source_list_plan,
        };
        pub mod backfill {
            pub use crate::bucket::on_demand_migration::backfill::{
@@ -184,9 +186,9 @@ pub mod bucket {
        }
        pub mod source_client {
            pub use crate::bucket::on_demand_migration::source_client::{
-                SourceClient, SourceClientSpec, SourceError, SourceGet, SourceHead, SourceListRequest, SourceObject, SourcePage,
-                SourceProbe, SourceProvider, SourceSse, SourceTimeouts, USER_AGENT_SUFFIX, is_multipart_etag, range_header_value,
-                resolve_path_style,
+                AzureAuth, AzureSourceSpec, GcsSourceSpec, SourceBackendSpec, SourceClient, SourceClientSpec, SourceError,
+                SourceGet, SourceHead, SourceListRequest, SourceObject, SourcePage, SourceProbe, SourceProvider, SourceSse,
+                SourceTimeouts, USER_AGENT_SUFFIX, is_multipart_etag, range_header_value, resolve_path_style,
            };
        }
    }
@@ -196,15 +198,16 @@ pub mod bucket {
        pub use crate::bucket::metadata_sys::ConfigWriteLockProbe;
        pub use crate::bucket::metadata_sys::{
            BucketMetadataMutationGuard, BucketMetadataSys, ObjectLockConfigState, acquire_bucket_metadata_transaction_lock,
-            acquire_bucket_metadata_transaction_lock_for_incarnation, capture_bucket_metadata_incarnation, delete,
-            delete_if_incarnation, delete_under_transaction_lock, get, get_accelerate_config, get_bucket_policy,
-            get_bucket_policy_raw, get_bucket_targets_config, get_config_from_disk, get_cors_config, get_durability_config,
-            get_global_bucket_metadata_sys, get_lifecycle_config, get_logging_config, get_notification_config,
-            get_object_lock_config, get_object_lock_config_state, get_on_demand_migration_config, get_public_access_block_config,
-            get_quota_config, get_replication_config, get_request_payment_config, get_sse_config, get_tagging_config,
-            get_versioning_config, get_website_config, init_bucket_metadata_sys, list_bucket_targets, reload_bucket_metadata,
-            remove_bucket_metadata, set_bucket_metadata, update, update_bucket_targets_under_transaction_lock,
-            update_config_with, update_if_incarnation, update_quota_if_incarnation, update_under_transaction_lock,
+            acquire_bucket_metadata_transaction_lock_for_incarnation, acquire_scanner_bucket_incarnation_fence,
+            capture_bucket_metadata_incarnation, delete, delete_if_incarnation, delete_under_transaction_lock, get,
+            get_accelerate_config, get_bucket_policy, get_bucket_policy_raw, get_bucket_targets_config, get_config_from_disk,
+            get_cors_config, get_durability_config, get_global_bucket_metadata_sys, get_lifecycle_config, get_logging_config,
+            get_notification_config, get_object_lock_config, get_object_lock_config_state, get_on_demand_migration_config,
+            get_public_access_block_config, get_quota_config, get_replication_config, get_request_payment_config, get_sse_config,
+            get_tagging_config, get_versioning_config, get_website_config, init_bucket_metadata_sys, list_bucket_targets,
+            reload_bucket_metadata, remove_bucket_metadata, set_bucket_metadata, update,
+            update_bucket_targets_under_transaction_lock, update_config_with, update_if_incarnation, update_quota_if_incarnation,
+            update_under_transaction_lock,
        };
    }

@@ -252,6 +255,13 @@ pub mod bucket {
        };
    }

+    pub mod sealed_credentials {
+        pub use crate::bucket::sealed_credentials::{
+            CredentialSealer, SEALED_CREDENTIAL_VERSION, SealScope, SealedCredential, SealedCredentialError,
+            SealedCredentialStore, credential_sealer, install_credential_sealer, seal_secret, unseal_secret,
+        };
+    }
+
    pub mod replication {
        pub use crate::bucket::replication::replication_pool::{
            DurableMrfBacklogSummary, DurableMrfBucketBacklog, DurableMrfTargetBacklog, MrfBacklogObservabilitySummary,
@@ -472,9 +482,11 @@ pub mod notification {
    #[cfg(any(test, feature = "test-util"))]
    pub use crate::services::notification_sys::rotate_cross_pool_fence_fleet_proof_for_test;
    pub use crate::services::notification_sys::{
-        ClusterTierDailyStats, CrossPoolFenceFleetProofToken, NotificationPeerErr, NotificationSys, ScannerPublicationLeaseGrant,
-        acquire_cross_pool_fence_fleet_proof, cross_pool_fence_fleet_proof_matches, get_global_notification_sys,
-        new_global_notification_sys, scanner_peer_transport_error_message_is_retryable, start_remote_version_state_fleet_probe,
+        ClusterTierDailyStats, CrossPoolFenceFleetProofToken, LegacyTransitionStateReconcileFleetProofToken, NotificationPeerErr,
+        NotificationSys, ScannerPublicationLeaseGrant, acquire_cross_pool_fence_fleet_proof,
+        acquire_legacy_transition_state_reconcile_fleet_proof, cross_pool_fence_fleet_proof_matches, get_global_notification_sys,
+        legacy_transition_state_reconcile_fleet_proof_matches, new_global_notification_sys,
+        scanner_peer_transport_error_message_is_retryable, start_remote_version_state_fleet_probe,
    };
 }

@@ -551,6 +563,12 @@ pub mod set_disk {
    pub mod test_util {
        pub use crate::bucket::quota::reservation::fail_next_quota_ledger_save_for_test;
        pub use crate::set_disk::{MultipartCommitBarrier, MultipartCommitPause, PutObjectCommitBarrier, PutObjectCommitPause};
+
+        /// Keep a namespace commit pending until the returned owner is dropped.
+        #[must_use]
+        pub fn hold_namespace_commit(store: &crate::store::ECStore) -> impl Send + Sync {
+            store.ctx.begin_namespace_commit()
+        }
    }
 }

@@ -59,7 +59,7 @@ use rustfs_utils::http::{
    insert_header,
 };
 use serde::{Deserialize, Serialize};
-use std::collections::HashMap;
+use std::collections::{HashMap, HashSet};
 use std::error::Error;
 use std::fmt;
 use std::str::FromStr as _;
@@ -376,6 +376,11 @@ pub struct BucketTargetSys {
    /// [`SsecPassthroughCapability`]; reset alongside `arn_remotes_map`.
    ssec_passthrough_map: Arc<RwLock<HashMap<String, SsecPassthroughRecord>>>,
    pub targets_map: Arc<RwLock<HashMap<String, Vec<BucketTarget>>>>,
+    /// Buckets whose persisted `bucket-targets.json` exists but cannot be
+    /// decoded (rustfs/backlog#2282). Written under the bucket's update mutex
+    /// alongside `targets_map`, and read before it so an unreadable
+    /// configuration surfaces as a typed error instead of an empty target set.
+    unreadable_targets: Arc<RwLock<HashSet<String>>>,
    pub h_mutex: Arc<RwLock<HashMap<String, EpHealth>>>,
    target_h_mutex: Arc<RwLock<HashMap<String, EpHealth>>>,
    pub hc_client: Arc<HttpClient>,
@@ -419,6 +424,7 @@ impl BucketTargetSys {
            arn_remotes_map: Arc::new(RwLock::new(HashMap::new())),
            ssec_passthrough_map: Arc::new(RwLock::new(HashMap::new())),
            targets_map: Arc::new(RwLock::new(HashMap::new())),
+            unreadable_targets: Arc::new(RwLock::new(HashSet::new())),
            h_mutex: Arc::new(RwLock::new(HashMap::new())),
            target_h_mutex: Arc::new(RwLock::new(HashMap::new())),
            hc_client: Arc::new(build_health_check_client()),
@@ -628,30 +634,40 @@ impl BucketTargetSys {
        health_map.clone()
    }

-    pub async fn list_targets(&self, bucket: &str, arn_type: &str) -> Vec<BucketTarget> {
+    /// Targets of one bucket, or of every bucket when `bucket` is empty.
+    ///
+    /// A bucket that simply has no targets yields an empty list; a bucket
+    /// whose persisted configuration cannot be decoded is an error, so an
+    /// admin listing reports the fault instead of an empty list that reads as
+    /// "replication is not configured" (rustfs/backlog#2282).
+    pub async fn list_targets(&self, bucket: &str, arn_type: &str) -> Result<Vec<BucketTarget>, BucketTargetError> {
        let health_stats = self.target_health_stats().await;
        let mut targets = Vec::new();

        if !bucket.is_empty() {
-            if let Ok(bucket_targets) = self.list_bucket_targets(bucket).await {
-                for mut target in bucket_targets.targets {
-                    if arn_type.is_empty() || target.target_type.to_string() == arn_type {
-                        if let Some(health) = health_stats.get(&target.arn) {
-                            target.total_downtime = health.offline_duration;
-                            target.online = health.online;
-                            target.last_online = health.last_online;
-                            target.latency = target::LatencyStat {
-                                curr: health.latency.curr,
-                                avg: health.latency.avg,
-                                max: health.latency.peak,
-                            };
-                            target.offline_count = health.offline_count;
+            match self.list_bucket_targets(bucket).await {
+                Ok(bucket_targets) => {
+                    for mut target in bucket_targets.targets {
+                        if arn_type.is_empty() || target.target_type.to_string() == arn_type {
+                            if let Some(health) = health_stats.get(&target.arn) {
+                                target.total_downtime = health.offline_duration;
+                                target.online = health.online;
+                                target.last_online = health.last_online;
+                                target.latency = target::LatencyStat {
+                                    curr: health.latency.curr,
+                                    avg: health.latency.avg,
+                                    max: health.latency.peak,
+                                };
+                                target.offline_count = health.offline_count;
+                            }
+                            targets.push(target);
                        }
-                        targets.push(target);
                    }
                }
+                Err(BucketTargetError::BucketRemoteTargetNotFound { .. }) => {}
+                Err(err) => return Err(err),
            }
-            return targets;
+            return Ok(targets);
        }

        let targets_map = self.targets_map.read().await;
@@ -674,10 +690,16 @@ impl BucketTargetSys {
            }
        }

-        targets
+        Ok(targets)
    }

    pub async fn list_bucket_targets(&self, bucket: &str) -> Result<BucketTargets, BucketTargetError> {
+        if self.unreadable_targets.read().await.contains(bucket) {
+            return Err(BucketTargetError::BucketRemoteTargetsUnreadable {
+                bucket: bucket.to_string(),
+            });
+        }
+
        let targets_map = self.targets_map.read().await;
        if let Some(targets) = targets_map.get(bucket) {
            Ok(BucketTargets {
@@ -690,13 +712,30 @@ impl BucketTargetSys {
        }
    }

+    /// Record that this bucket's persisted targets configuration exists but
+    /// cannot be decoded (rustfs/backlog#2282).
+    ///
+    /// Any snapshot published from an earlier readable load is deliberately
+    /// left in place: withdrawing it would produce exactly the silent "no
+    /// targets configured" state this marker exists to prevent. The marker is
+    /// cleared by the next successful publish, which is what makes a repaired
+    /// configuration take effect without a restart.
+    pub async fn mark_targets_unreadable(&self, bucket: &str) {
+        let update_mutex = self.target_update_mutex(bucket).await;
+        let _update_guard = update_mutex.lock().await;
+
+        self.unreadable_targets.write().await.insert(bucket.to_string());
+    }
+
    pub async fn delete(&self, bucket: &str) {
        let update_mutex = self.target_update_mutex(bucket).await;
        let _update_guard = update_mutex.lock().await;

-        // Lock order: targets_map, then arn_remotes_map, then target_h_mutex,
-        // then ssec_passthrough_map (always last; also taken standalone by the
-        // capability accessors).
+        // Lock order: unreadable_targets, then targets_map, then
+        // arn_remotes_map, then target_h_mutex, then ssec_passthrough_map
+        // (always last; also taken standalone by the capability accessors).
+        self.unreadable_targets.write().await.remove(bucket);
+
        let mut targets_map = self.targets_map.write().await;
        let mut arn_remotes_map = self.arn_remotes_map.write().await;
        let mut health_map = self.target_h_mutex.write().await;
@@ -1093,6 +1132,11 @@ impl BucketTargetSys {
    /// Keeping persisted-config reads under the same mutex prevents a stale
    /// reload from overwriting a concurrent credential rotation.
    async fn update_all_targets_locked(&self, bucket: &str, targets: Option<&BucketTargets>) {
+        // Reaching here means the persisted configuration decoded, so the
+        // unreadable marker (if any) is stale. Cleared before the maps below
+        // so `unreadable_targets` stays the outermost of this module's locks.
+        self.unreadable_targets.write().await.remove(bucket);
+
        let mut clients = Vec::new();
        if let Some(new_targets) = targets {
            for target in &new_targets.targets {
@@ -1100,9 +1144,9 @@ impl BucketTargetSys {
            }
        }

-        // Lock order: targets_map, then arn_remotes_map, then target_h_mutex,
-        // then ssec_passthrough_map (always last; also taken standalone by the
-        // capability accessors).
+        // Lock order: unreadable_targets (above), then targets_map, then
+        // arn_remotes_map, then target_h_mutex, then ssec_passthrough_map
+        // (always last; also taken standalone by the capability accessors).
        let mut targets_map = self.targets_map.write().await;
        let mut arn_remotes_map = self.arn_remotes_map.write().await;
        let mut health_map = self.target_h_mutex.write().await;
@@ -1161,6 +1205,11 @@ impl BucketTargetSys {
    }

    pub async fn set(&self, bucket: &str, meta: &BucketMetadata) {
+        if meta.bucket_targets_unreadable() {
+            self.mark_targets_unreadable(bucket).await;
+            return;
+        }
+
        let Some(config) = &meta.bucket_target_config else {
            return;
        };
@@ -2276,6 +2325,13 @@ pub enum BucketTargetError {
    BucketRemoteTargetNotFound {
        bucket: String,
    },
+    /// The bucket's persisted targets configuration exists but cannot be
+    /// decoded. Distinct from `BucketRemoteTargetNotFound`, which means the
+    /// bucket genuinely has no targets: callers must not degrade this one to
+    /// an empty target set (rustfs/backlog#2282).
+    BucketRemoteTargetsUnreadable {
+        bucket: String,
+    },
    BucketRemoteArnTypeInvalid {
        bucket: String,
    },
@@ -2309,6 +2365,9 @@ impl fmt::Display for BucketTargetError {
            BucketTargetError::BucketRemoteTargetNotFound { bucket } => {
                write!(f, "Remote target not found for bucket: {bucket}")
            }
+            BucketTargetError::BucketRemoteTargetsUnreadable { bucket } => {
+                write!(f, "Persisted replication target configuration is unreadable for bucket: {bucket}")
+            }
            BucketTargetError::BucketRemoteArnTypeInvalid { bucket } => {
                write!(f, "Invalid ARN type for bucket: {bucket}")
            }
@@ -3256,7 +3315,7 @@ mod tests {
            }],
        );

-        let targets = sys.list_targets("", "").await;
+        let targets = sys.list_targets("", "").await.expect("listing every bucket's targets");

        assert_eq!(targets.len(), 1);
        assert!(!targets[0].online);
@@ -25,6 +25,7 @@ use super::{
    manual_transition_job, tier_delete_journal, transition_transaction,
 };
 use crate::error::{Error, Result};
+use crate::services::tier::tier_probe_intent;

 pub(crate) const ILM_META_PREFIX: &str = "ilm";
 const ILM_META_OBJECT_PREFIX: &str = "ilm/";
@@ -35,6 +36,7 @@ pub(crate) enum DurableIlmRecordKind {
    TierDeleteJournal,
    TierDeleteDispatchManifest,
    TransitionTransaction,
+    TierProbeIntent,
    ManualTransitionJob,
    ManualTransitionScope,
    ManualTransitionTask,
@@ -73,6 +75,12 @@ pub(crate) const TRANSITION_TRANSACTION_NAMESPACE: DurableIlmNamespace = Durable
    max_record_size: transition_transaction::MAX_TRANSITION_TRANSACTION_SIZE,
    kind: DurableIlmRecordKind::TransitionTransaction,
 };
+pub(crate) const TIER_PROBE_INTENT_NAMESPACE: DurableIlmNamespace = DurableIlmNamespace {
+    name: "tier-probe-intent",
+    prefix: tier_probe_intent::TIER_PROBE_INTENT_RECORD_PREFIX,
+    max_record_size: tier_probe_intent::MAX_TIER_PROBE_INTENT_SIZE,
+    kind: DurableIlmRecordKind::TierProbeIntent,
+};
 pub(crate) const MANUAL_TRANSITION_JOB_NAMESPACE: DurableIlmNamespace = DurableIlmNamespace {
    name: "manual-transition-job",
    prefix: "ilm/manual-transition/jobs",
@@ -98,11 +106,12 @@ pub(crate) const MANUAL_TRANSITION_WORKER_RESULT_NAMESPACE: DurableIlmNamespace
    kind: DurableIlmRecordKind::ManualTransitionWorkerResult,
 };

-pub(crate) const DURABLE_ILM_NAMESPACES: [DurableIlmNamespace; 8] = [
+pub(crate) const DURABLE_ILM_NAMESPACES: [DurableIlmNamespace; 9] = [
    TIER_DELETE_JOURNAL_NAMESPACE,
    TIER_DELETE_JOURNAL_V6_NAMESPACE,
    TIER_DELETE_DISPATCH_MANIFEST_NAMESPACE,
    TRANSITION_TRANSACTION_NAMESPACE,
+    TIER_PROBE_INTENT_NAMESPACE,
    MANUAL_TRANSITION_JOB_NAMESPACE,
    MANUAL_TRANSITION_SCOPE_NAMESPACE,
    MANUAL_TRANSITION_TASK_NAMESPACE,
@@ -200,6 +209,15 @@ pub(crate) enum DurableIlmRecordCheckpoint {
        revision: u64,
        state: transition_transaction::TransitionTransactionState,
    },
+    TierProbeIntent {
+        content_sha256: String,
+        identity_sha256: String,
+        remote_version_sha256: String,
+        remote_version_known: bool,
+        owner_fence_sha256: String,
+        revision: u64,
+        state: tier_probe_intent::TierProbeIntentState,
+    },
    ManualTransitionJob {
        content_sha256: String,
        identity_sha256: String,
@@ -232,6 +250,7 @@ impl DurableIlmRecordCheckpoint {
            | Self::TierDeleteDispatchManifest { content_sha256, .. }
            | Self::TierDeleteDispatchParent { content_sha256, .. }
            | Self::TransitionTransaction { content_sha256, .. }
+            | Self::TierProbeIntent { content_sha256, .. }
            | Self::ManualTransitionJob { content_sha256, .. }
            | Self::ManualTransitionScope { content_sha256, .. }
            | Self::ManualTransitionTask { content_sha256 }
@@ -421,6 +440,32 @@ impl DurableIlmRecordCheckpoint {
                        .is_some_and(|expected_revision| *next_revision == expected_revision)
                    && (!previous_remote_version_known || previous_remote_version == next_remote_version)
            }
+            (
+                Self::TierProbeIntent {
+                    identity_sha256: previous_identity,
+                    remote_version_sha256: previous_remote_version,
+                    remote_version_known: previous_remote_version_known,
+                    owner_fence_sha256: previous_owner_fence,
+                    revision: previous_revision,
+                    state: previous_state,
+                    ..
+                },
+                Self::TierProbeIntent {
+                    identity_sha256: next_identity,
+                    remote_version_sha256: next_remote_version,
+                    owner_fence_sha256: next_owner_fence,
+                    revision: next_revision,
+                    state: next_state,
+                    ..
+                },
+            ) => {
+                previous_identity == next_identity
+                    && previous_owner_fence == next_owner_fence
+                    && next_revision
+                        .checked_sub(*previous_revision)
+                        .is_some_and(|distance| distance == 1 && tier_probe_state_reaches(*previous_state, *next_state, distance))
+                    && (!previous_remote_version_known || previous_remote_version == next_remote_version)
+            }
            (
                Self::ManualTransitionJob {
                    content_sha256: previous_content,
@@ -500,6 +545,14 @@ impl DurableIlmRecordCheckpoint {
    /// after the exact terminal ETag and terminal receipt were committed, to
    /// purge older object versions exposed by that deletion.
    pub(crate) fn is_predecessor_of_terminal(&self, terminal: &Self) -> bool {
+        if let Self::TierProbeIntent { state, .. } = terminal
+            && !matches!(
+                state,
+                tier_probe_intent::TierProbeIntentState::AbortedNoRemote | tier_probe_intent::TierProbeIntentState::Completed
+            )
+        {
+            return false;
+        }
        if self == terminal || self.validate_successor(terminal).is_ok() {
            return true;
        }
@@ -568,6 +621,37 @@ impl DurableIlmRecordCheckpoint {
                        }
                    })
            }
+            (
+                Self::TierProbeIntent {
+                    identity_sha256: previous_identity,
+                    remote_version_sha256: previous_remote_version,
+                    remote_version_known: previous_remote_version_known,
+                    owner_fence_sha256: previous_owner_fence,
+                    revision: previous_revision,
+                    state: previous_state,
+                    ..
+                },
+                Self::TierProbeIntent {
+                    identity_sha256: terminal_identity,
+                    remote_version_sha256: terminal_remote_version,
+                    owner_fence_sha256: terminal_owner_fence,
+                    revision: terminal_revision,
+                    state: terminal_state,
+                    ..
+                },
+            ) => {
+                previous_identity == terminal_identity
+                    && previous_owner_fence == terminal_owner_fence
+                    && matches!(
+                        terminal_state,
+                        tier_probe_intent::TierProbeIntentState::AbortedNoRemote
+                            | tier_probe_intent::TierProbeIntentState::Completed
+                    )
+                    && terminal_revision
+                        .checked_sub(*previous_revision)
+                        .is_some_and(|distance| tier_probe_state_reaches(*previous_state, *terminal_state, distance))
+                    && (!previous_remote_version_known || previous_remote_version == terminal_remote_version)
+            }
            _ => false,
        }
    }
@@ -606,6 +690,23 @@ fn transition_state_distance(
    }
 }

+fn tier_probe_state_reaches(
+    from: tier_probe_intent::TierProbeIntentState,
+    to: tier_probe_intent::TierProbeIntentState,
+    revision_distance: u64,
+) -> bool {
+    use tier_probe_intent::TierProbeIntentState::{AbortedNoRemote, CleanupPending, Completed, UploadOutcomeUnknown, Uploaded};
+
+    match (from, to) {
+        (UploadOutcomeUnknown, Uploaded | CleanupPending | AbortedNoRemote) => revision_distance == 1,
+        (UploadOutcomeUnknown, Completed) => matches!(revision_distance, 2 | 3),
+        (Uploaded, CleanupPending) => revision_distance == 1,
+        (Uploaded, Completed) => revision_distance == 2,
+        (CleanupPending, Completed) => revision_distance == 1,
+        _ => false,
+    }
+}
+
 fn manual_job_state_reaches(
    from: manual_transition_job::ManualTransitionJobState,
    to: manual_transition_job::ManualTransitionJobState,
@@ -1082,6 +1183,42 @@ pub(crate) fn validate_durable_ilm_record(path: &str, data: &[u8]) -> Result<Val
                },
            )
        }
+        DurableIlmRecordKind::TierProbeIntent => {
+            let probe_id = tier_probe_intent::tier_probe_intent_id_from_record_object_name(path)
+                .map_err(|err| Error::other(err.to_string()))?;
+            let intent =
+                tier_probe_intent::TierProbeIntent::decode(probe_id, data).map_err(|err| Error::other(err.to_string()))?;
+            let canonical =
+                tier_probe_intent::tier_probe_intent_record_object_name(probe_id).map_err(|err| Error::other(err.to_string()))?;
+            if canonical != path {
+                return Err(Error::other("tier probe intent path is not canonical"));
+            }
+            let identity_sha256 = checkpoint_hash(&(
+                intent.probe_id,
+                &intent.operation,
+                &intent.tier_name,
+                intent.destination_id,
+                &intent.probe_object,
+                &intent.creator_id,
+                intent.creator_epoch,
+                intent.created_at_unix_nanos,
+            ))?;
+            let remote_version_sha256 = checkpoint_hash(&intent.remote_version)?;
+            let owner_fence_sha256 = checkpoint_hash(&intent.owner)?;
+            (
+                "probe_id",
+                probe_id.to_string(),
+                DurableIlmRecordCheckpoint::TierProbeIntent {
+                    content_sha256,
+                    identity_sha256,
+                    remote_version_sha256,
+                    remote_version_known: !intent.remote_version.is_unknown(),
+                    owner_fence_sha256,
+                    revision: intent.revision,
+                    state: intent.state,
+                },
+            )
+        }
        DurableIlmRecordKind::ManualTransitionJob => {
            let job_id = manual_transition_job::manual_transition_job_id_from_record_object_name(path)
                .map_err(|err| Error::other(err.to_string()))?;
@@ -1237,6 +1374,102 @@ mod tests {
        }
    }

+    fn tier_probe_intent_fixture() -> tier_probe_intent::TierProbeIntent {
+        let probe_id = Uuid::parse_str("36e2220e-9ad2-495b-b3bc-c4d2caf70a31").expect("fixture uuid should parse");
+        tier_probe_intent::TierProbeIntent {
+            probe_id,
+            revision: 1,
+            state: tier_probe_intent::TierProbeIntentState::UploadOutcomeUnknown,
+            operation: tier_probe_intent::TierProbeOperationIdentity::Verify {
+                config_etag: "config-etag".to_string(),
+                backend_identity: [1; 32],
+            },
+            tier_name: "COLD-A".to_string(),
+            destination_id: [1; 32],
+            probe_object: tier_probe_intent::tier_probe_object_name(probe_id),
+            creator_id: "node-a".to_string(),
+            creator_epoch: Uuid::parse_str("76746062-c05a-40b7-9e38-d2722d7e0332").expect("fixture creator epoch should parse"),
+            created_at_unix_nanos: 1_780_000_000_000_000_000,
+            owner: tier_probe_intent::TierProbeOwnerFence {
+                owner_id: "node-a".to_string(),
+                owner_epoch: Uuid::parse_str("76746062-c05a-40b7-9e38-d2722d7e0332").expect("fixture owner epoch should parse"),
+                not_after_unix_nanos: 1_780_000_900_000_000_000,
+            },
+            remote_version: tier_probe_intent::TierProbeRemoteVersion::default(),
+        }
+    }
+
+    fn tier_probe_checkpoint(intent: &tier_probe_intent::TierProbeIntent) -> DurableIlmRecordCheckpoint {
+        let path =
+            tier_probe_intent::tier_probe_intent_record_object_name(intent.probe_id).expect("tier probe path should build");
+        let encoded = intent.encode().expect("tier probe intent should encode");
+        let namespace = classify_durable_ilm_record(&path)
+            .expect("tier probe namespace should classify")
+            .expect("tier probe intent should be durable");
+        assert_eq!(namespace, &TIER_PROBE_INTENT_NAMESPACE);
+        validate_durable_ilm_record(&path, &encoded)
+            .expect("tier probe intent should validate")
+            .checkpoint
+    }
+
+    #[test]
+    fn tier_probe_intent_checkpoint_tracks_exact_monotonic_generations() {
+        let initial_intent = tier_probe_intent_fixture();
+        let initial = tier_probe_checkpoint(&initial_intent);
+
+        let mut uploaded_intent = initial_intent;
+        uploaded_intent
+            .advance(
+                tier_probe_intent::TierProbeIntentState::Uploaded,
+                tier_probe_intent::TierProbeRemoteVersion::versioned("opaque-v1"),
+            )
+            .expect("uploaded state should advance");
+        let uploaded = tier_probe_checkpoint(&uploaded_intent);
+        initial
+            .validate_successor(&uploaded)
+            .expect("durable receipt may adopt the exact uploaded generation");
+
+        let mut cleanup_intent = uploaded_intent.clone();
+        cleanup_intent
+            .advance(
+                tier_probe_intent::TierProbeIntentState::CleanupPending,
+                uploaded_intent.remote_version.clone(),
+            )
+            .expect("cleanup state should advance");
+        let cleanup = tier_probe_checkpoint(&cleanup_intent);
+        uploaded
+            .validate_successor(&cleanup)
+            .expect("durable receipt may adopt the exact cleanup generation");
+
+        let mut completed_intent = cleanup_intent.clone();
+        completed_intent
+            .advance(tier_probe_intent::TierProbeIntentState::Completed, cleanup_intent.remote_version.clone())
+            .expect("completed state should advance");
+        let completed = tier_probe_checkpoint(&completed_intent);
+        cleanup
+            .validate_successor(&completed)
+            .expect("durable receipt may adopt the exact terminal generation");
+        assert!(
+            initial.is_predecessor_of_terminal(&completed),
+            "terminal cleanup must recognize the full acknowledged-PUT path"
+        );
+        assert!(
+            initial.validate_successor(&completed).is_err(),
+            "ordinary receipt advancement must not skip intermediate generations"
+        );
+        assert!(
+            !initial.is_predecessor_of_terminal(&uploaded),
+            "a nonterminal generation must not be accepted as terminal proof"
+        );
+
+        let mut rebound = uploaded_intent;
+        rebound.owner.owner_epoch = Uuid::new_v4();
+        assert!(
+            rebound.encode().is_err(),
+            "dormant v1 must reject owner takeover before producing a checkpoint"
+        );
+    }
+
    #[test]
    fn tier_delete_dispatch_manifest_namespace_validates_monotonic_branches() {
        use tier_delete_journal::TierDeleteDispatchManifestState::{Aborted, Aborting, Completed, DispatchAuthorized, Preparing};
@@ -1170,6 +1170,7 @@ pub async fn save_manual_transition_job_record_if_current(
        data.clone(),
        &ObjectOptions {
            max_parity: true,
+            write_completion: crate::object_api::WriteCompletion::TailDrained,
            http_preconditions: Some(HTTPPreconditions {
                if_match: Some(current_etag.to_string()),
                ..Default::default()
@@ -1242,6 +1243,7 @@ pub(crate) async fn save_manual_transition_worker_result_if_absent(
        data,
        &ObjectOptions {
            max_parity: true,
+            write_completion: crate::object_api::WriteCompletion::TailDrained,
            http_preconditions: Some(HTTPPreconditions {
                if_none_match: Some("*".to_string()),
                ..Default::default()
@@ -1270,6 +1272,7 @@ pub(crate) async fn save_manual_transition_task_if_absent(
        data,
        &ObjectOptions {
            max_parity: true,
+            write_completion: crate::object_api::WriteCompletion::TailDrained,
            http_preconditions: Some(HTTPPreconditions {
                if_none_match: Some("*".to_string()),
                ..Default::default()
@@ -1621,6 +1624,7 @@ pub async fn save_manual_transition_scope_admission_if_absent(
        data.clone(),
        &ObjectOptions {
            max_parity: true,
+            write_completion: crate::object_api::WriteCompletion::TailDrained,
            http_preconditions: Some(HTTPPreconditions {
                if_none_match: Some("*".to_string()),
                ..Default::default()
@@ -1672,6 +1676,7 @@ pub async fn save_manual_transition_scope_admission_if_current(
        data.clone(),
        &ObjectOptions {
            max_parity: true,
+            write_completion: crate::object_api::WriteCompletion::TailDrained,
            http_preconditions: Some(HTTPPreconditions {
                if_match: Some(current_etag.to_string()),
                ..Default::default()
@@ -1733,6 +1733,7 @@ async fn save_config_if_none_fenced(
        data.clone(),
        &ObjectOptions {
            max_parity: true,
+            write_completion: crate::object_api::WriteCompletion::TailDrained,
            http_preconditions: Some(HTTPPreconditions {
                if_none_match: Some("*".to_string()),
                ..Default::default()
@@ -1832,6 +1833,7 @@ async fn save_decommission_manifest_checkpoint_if_match(

        let mut opts = ObjectOptions {
            max_parity: true,
+            write_completion: crate::object_api::WriteCompletion::TailDrained,
            no_lock: true,
            http_preconditions: Some(HTTPPreconditions {
                if_match: Some(observed_etag),
@@ -1960,6 +1962,7 @@ async fn save_config_if_match_fenced(
        data.clone(),
        &ObjectOptions {
            max_parity: true,
+            write_completion: crate::object_api::WriteCompletion::TailDrained,
            http_preconditions: Some(HTTPPreconditions {
                if_match: Some(etag.to_string()),
                ..Default::default()
@@ -3780,6 +3783,7 @@ where
                data.clone(),
                &ObjectOptions {
                    max_parity: true,
+                    write_completion: crate::object_api::WriteCompletion::TailDrained,
                    http_preconditions: Some(HTTPPreconditions {
                        if_none_match: Some("*".to_string()),
                        ..Default::default()
@@ -3869,6 +3873,7 @@ where
                data.clone(),
                &ObjectOptions {
                    max_parity: true,
+                    write_completion: crate::object_api::WriteCompletion::TailDrained,
                    http_preconditions: Some(HTTPPreconditions {
                        if_match: Some(etag),
                        ..Default::default()
@@ -3893,6 +3898,7 @@ where
                data.clone(),
                &ObjectOptions {
                    max_parity: true,
+                    write_completion: crate::object_api::WriteCompletion::TailDrained,
                    http_preconditions: Some(HTTPPreconditions {
                        if_none_match: Some("*".to_string()),
                        ..Default::default()
@@ -15,8 +15,6 @@
 #![allow(unused_variables)]
 #![allow(unused_mut)]
 #![allow(unused_assignments)]
-#![allow(unused_must_use)]
-#![allow(clippy::all)]

 use super::runtime_boundary as runtime_sources;
 use crate::bucket::lifecycle::bucket_lifecycle_ops::ExpiryOp;
@@ -72,9 +70,11 @@ static REMOTE_DELETE_BREAKER: LazyLock<Mutex<RemoteDeleteBreaker>> = LazyLock::n
 });

 #[cfg(test)]
-static REMOTE_TIER_DELETE_TEST_HOOK: std::sync::LazyLock<
-    std::sync::Mutex<Option<Box<dyn Fn(&str, &str, &str) -> std::io::Result<()> + Send + Sync>>>,
-> = std::sync::LazyLock::new(|| std::sync::Mutex::new(None));
+type RemoteTierDeleteTestHook = Box<dyn Fn(&str, &str, &str) -> std::io::Result<()> + Send + Sync>;
+
+#[cfg(test)]
+static REMOTE_TIER_DELETE_TEST_HOOK: std::sync::LazyLock<std::sync::Mutex<Option<RemoteTierDeleteTestHook>>> =
+    std::sync::LazyLock::new(|| std::sync::Mutex::new(None));

 #[derive(Debug)]
 struct RemoteDeleteBreaker {
@@ -107,7 +107,7 @@ impl RemoteDeleteBreaker {
    fn prune(&mut self, now: Instant) {
        while let Some(ts) = self.failures.front().copied() {
            if now.duration_since(ts) > self.window {
-                self.failures.pop_front();
+                let _ = self.failures.pop_front();
            } else {
                break;
            }
@@ -137,10 +137,10 @@ fn is_signer_header_error(err: &std::io::Error) -> bool {
        return false;
    }

-    if let Some(source) = err.get_ref() {
-        if error_chain_contains_signer_header_marker(source) {
-            return true;
-        }
+    if let Some(source) = err.get_ref()
+        && error_chain_contains_signer_header_marker(source)
+    {
+        return true;
    }

    let message = err.to_string().to_ascii_lowercase();
@@ -205,7 +205,7 @@ impl ObjSweeper {

    #[allow(dead_code, reason = "MinIO-parity surface with no caller in this port (backlog#1823)")]
    pub fn with_version(&mut self, vid: Option<Uuid>) -> &Self {
-        self.version_id = vid.clone();
+        self.version_id = vid;
        self
    }

@@ -219,7 +219,7 @@ impl ObjSweeper {
    #[allow(dead_code, reason = "MinIO-parity surface with no caller in this port (backlog#1823)")]
    pub fn get_opts(&self) -> lifecycle::ObjectOpts {
        let mut opts = ObjectOpts {
-            version_id: self.version_id.clone(),
+            version_id: self.version_id,
            versioned: self.versioned,
            version_suspended: self.suspended,
            ..Default::default()
@@ -388,8 +388,8 @@ impl Jentry {
 impl ExpiryOp for Jentry {
    fn op_hash(&self) -> u64 {
        let mut hasher = Sha256::new();
-        hasher.update(format!("{}", self.tier_name).as_bytes());
-        hasher.update(format!("{}", self.obj_name).as_bytes());
+        hasher.update(self.tier_name.as_bytes());
+        hasher.update(self.obj_name.as_bytes());
        xxh64::xxh64(hasher.finalize().as_slice(), XXHASH_SEED)
    }

@@ -436,7 +436,7 @@ async fn delete_object_from_remote_tier_raw_with_manager(
    tier_name: &str,
    tier_config_mgr: &Arc<tokio::sync::RwLock<TierConfigMgr>>,
 ) -> Result<(), std::io::Error> {
-    let lease = TierConfigMgr::acquire_operation_lease(&tier_config_mgr, tier_name)
+    let lease = TierConfigMgr::acquire_operation_lease(tier_config_mgr, tier_name)
        .await
        .map_err(std::io::Error::other)?;
    delete_object_from_remote_tier_raw_with_lease(obj_name, rv_id, &lease, false, true).await
@@ -612,6 +612,7 @@ pub(crate) async fn save_transition_transaction_record(
        data.clone(),
        &ObjectOptions {
            max_parity: true,
+            write_completion: crate::object_api::WriteCompletion::TailDrained,
            http_preconditions: Some(HTTPPreconditions {
                if_none_match: Some("*".to_string()),
                ..Default::default()
@@ -658,6 +659,7 @@ pub(crate) async fn save_transition_transaction_record_if_current(
        data.clone(),
        &ObjectOptions {
            max_parity: true,
+            write_completion: crate::object_api::WriteCompletion::TailDrained,
            http_preconditions: Some(HTTPPreconditions {
                if_match: Some(etag),
                ..Default::default()
@@ -477,6 +477,18 @@ impl BucketMetadata {
        !self.table_bucket_config_json.is_empty()
    }

+    /// `bucket-targets.json` is stored for this bucket but this build cannot
+    /// decode it.
+    ///
+    /// Keeps "no replication targets configured" and "the target
+    /// configuration cannot be read" apart, the same distinction the
+    /// `fabricated` marker draws for the bucket metadata as a whole. Only
+    /// meaningful after [`Self::parse_all_configs`] has run; readers must fail
+    /// closed on `true` instead of serving an empty target set.
+    pub fn bucket_targets_unreadable(&self) -> bool {
+        !self.bucket_targets_config_json.is_empty() && self.bucket_target_config.is_none()
+    }
+
    /// Parsed per-bucket durability override, if a valid one is stored.
    ///
    /// Absent/empty/unparsable payloads all mean "no override" (the bucket
@@ -964,7 +976,32 @@ impl BucketMetadata {
        Ok(())
    }

-    fn parse_all_configs(&mut self) -> Result<()> {
+    /// Decode every stored sub-configuration into its typed field.
+    ///
+    /// A decode failure never fails the whole load: this runs on every bucket
+    /// metadata read, including startup and peer reload, so one bucket's
+    /// corrupt sub-configuration must not make the bucket — or the node —
+    /// unloadable. Instead the failure is *retained*: the raw bytes stay
+    /// untouched and the typed field stays `None`, so `!raw.is_empty() &&
+    /// typed.is_none()` is the durable "exists but cannot be read" signal that
+    /// each accessor keys off. Which accessors must fail closed on it:
+    ///
+    /// | Config | Verdict |
+    /// |---|---|
+    /// | policy | Fails closed: `get_bucket_policy` re-parses the raw JSON and propagates the error; `get_bucket_policy_raw` returns the stored bytes. |
+    /// | object lock | Fails closed in `object_lock_config_state_from_authoritative_metadata`; a retention decision may never be taken on a guess. |
+    /// | versioning | Fails closed in `get_versioning_config`; guessing Unversioned would make delete markers and version ids diverge from what is on disk. |
+    /// | replication | Fails closed in `get_replication_config`. |
+    /// | bucket targets | Fails closed in `get_bucket_targets_config`, and `sync_bucket_target_sys` marks the bucket unreadable in `BucketTargetSys` instead of publishing an empty target set (rustfs/backlog#2282). |
+    /// | encryption | Fails closed in `get_sse_config`: degrading to "no default encryption" stores plaintext objects the operator required to be encrypted. |
+    /// | public access block | Fails closed in `get_public_access_block_config`: degrading grants the anonymous access the operator asked to block. |
+    /// | quota | Fails closed in `get_quota_config`; the enforcement path in `quota::checker` already re-parses the raw JSON and refuses on error. |
+    /// | lifecycle | Safe to degrade: no rules means no expiration and no transition, so nothing is deleted or moved on the strength of an unreadable rule set. The bucket keeps serving reads and writes. |
+    /// | notification | Safe to degrade: events are an outbound side channel; no consumer draws a durability or authorization conclusion from their absence. |
+    /// | tagging | Safe to degrade: bucket tags are cost-allocation labels here; object-level tag conditions come from object metadata, not this blob. |
+    /// | CORS | Safe to degrade: an absent CORS configuration rejects cross-origin browser requests, which is already the restrictive direction. |
+    /// | logging, website, accelerate, request payment, bucket ACL | Safe to degrade: each only shapes an optional response or an optional side channel, and none of them authorizes an action or decides whether data is retained. |
+    pub(super) fn parse_all_configs(&mut self) -> Result<()> {
        if let Err(e) = self.parse_policy_config() {
            tracing::warn!(
                event = "bucket_metadata_parse_failed",
@@ -1088,20 +1125,26 @@ impl BucketMetadata {
                "Failed to parse bucket metadata config"
            );
        }
+        // A stored targets blob that cannot be decoded must not collapse into
+        // the empty target set: that is indistinguishable from "no replication
+        // configured", so replication stops and no caller ever sees an error
+        // (rustfs/backlog#2282). Leaving the typed field `None` while the raw
+        // bytes stay non-empty is the retained parse failure every targets
+        // reader keys off; the bytes are preserved so the configuration is
+        // still recoverable.
+        self.bucket_target_config = None;
        if !self.bucket_targets_config_json.is_empty() {
-            if let Err(e) = serde_json::from_slice::<BucketTargets>(&self.bucket_targets_config_json)
-                .map(|t| self.bucket_target_config = Some(t))
-            {
-                tracing::warn!(
+            match serde_json::from_slice::<BucketTargets>(&self.bucket_targets_config_json) {
+                Ok(targets) => self.bucket_target_config = Some(targets),
+                Err(e) => tracing::error!(
                    event = "bucket_metadata_parse_failed",
                    component = "ecstore",
                    subsystem = "bucket_metadata",
                    bucket = %self.name,
                    config = "bucket_targets",
                    error = %e,
-                    "Failed to parse bucket metadata config"
-                );
-                self.bucket_target_config = Some(BucketTargets::default());
+                    "Bucket replication targets are unreadable; replication for this bucket fails closed"
+                ),
            }
        } else {
            self.bucket_target_config = Some(BucketTargets::default());
@@ -1535,6 +1578,117 @@ mod test {
        assert_eq!(bucket_targets.targets[0].target_bucket, "target-bucket");
    }

+    /// rustfs/backlog#2282: a stored targets blob this build cannot decode
+    /// must not become the empty target set, and must stay distinguishable
+    /// from a bucket that never configured a target.
+    #[test]
+    fn unreadable_bucket_targets_never_degrade_to_an_empty_target_set() {
+        let truncated = br#"{"targets":[{"endpoint":"s3.example.com","#.to_vec();
+        let mut corrupt = BucketMetadata::new("corrupt-targets");
+        corrupt.bucket_targets_config_json = truncated.clone();
+
+        corrupt
+            .parse_all_configs()
+            .expect("one unreadable sub-config must not fail the whole metadata load");
+
+        assert!(
+            corrupt.bucket_target_config.is_none(),
+            "an undecodable targets blob must not produce a target set at all"
+        );
+        assert!(corrupt.bucket_targets_unreadable());
+        assert_eq!(
+            corrupt.bucket_targets_config_json, truncated,
+            "the raw bytes must survive so the configuration stays recoverable"
+        );
+
+        // The genuinely-absent case is unchanged, and the two now diverge.
+        let mut absent = BucketMetadata::new("no-targets");
+        absent.parse_all_configs().expect("absent targets parse");
+        assert!(
+            absent.bucket_target_config.as_ref().is_some_and(BucketTargets::is_empty),
+            "a bucket that configured no target still reads as an empty target set"
+        );
+        assert!(!absent.bucket_targets_unreadable());
+    }
+
+    /// `Credentials` carries no struct-level `serde(default)`, so one target
+    /// missing `secretKey` is a hard parse error for the whole document. That
+    /// must surface as "unreadable", never as "no targets configured".
+    #[test]
+    fn bucket_targets_missing_secret_key_are_unreadable_not_empty() {
+        let mut bm = BucketMetadata::new("missing-secret-key");
+        bm.bucket_targets_config_json = br#"{"targets":[{"endpoint":"s3.example.com","targetbucket":"remote","arn":"arn:rustfs:replication:us-east-1:src:1","credentials":{"accessKey":"AKIAEXAMPLE"}}]}"#.to_vec();
+
+        bm.parse_all_configs()
+            .expect("a rejected targets document must not fail the whole metadata load");
+
+        assert!(
+            bm.bucket_targets_unreadable(),
+            "a targets document rejected for a missing secretKey is unreadable, not empty"
+        );
+        assert!(bm.bucket_target_config.is_none());
+    }
+
+    /// The invariant every branch of `parse_all_configs` shares: a stored but
+    /// undecodable payload keeps its raw bytes and leaves the typed field
+    /// `None`, so no branch fabricates a value. What a reader may then do with
+    /// that state is decided per config; see the table on `parse_all_configs`.
+    #[test]
+    fn every_config_branch_retains_its_parse_failure_instead_of_defaulting() {
+        let malformed_xml = b"<not-a-valid-document".to_vec();
+        let malformed_json = b"{not-json".to_vec();
+
+        let mut bm = BucketMetadata::new("all-configs-malformed");
+        bm.policy_config_json = malformed_json.clone();
+        bm.quota_config_json = malformed_json.clone();
+        bm.bucket_targets_config_json = malformed_json.clone();
+        bm.notification_config_xml = malformed_xml.clone();
+        bm.lifecycle_config_xml = malformed_xml.clone();
+        bm.object_lock_config_xml = malformed_xml.clone();
+        bm.versioning_config_xml = malformed_xml.clone();
+        bm.encryption_config_xml = malformed_xml.clone();
+        bm.tagging_config_xml = malformed_xml.clone();
+        bm.replication_config_xml = malformed_xml.clone();
+        bm.cors_config_xml = malformed_xml.clone();
+        bm.logging_config_xml = malformed_xml.clone();
+        bm.website_config_xml = malformed_xml.clone();
+        bm.accelerate_config_xml = malformed_xml.clone();
+        bm.request_payment_config_xml = malformed_xml.clone();
+        bm.public_access_block_config_xml = malformed_xml.clone();
+        // `bucket_acl_config_json` is only checked for UTF-8, so only invalid
+        // UTF-8 exercises its failure branch.
+        bm.bucket_acl_config_json = vec![0xff, 0xfe];
+
+        bm.parse_all_configs()
+            .expect("a bucket whose every config is corrupt must still load its metadata");
+
+        let cleared: [(&str, bool); 17] = [
+            ("policy", bm.policy_config.is_none()),
+            ("quota", bm.quota_config.is_none()),
+            ("bucket_targets", bm.bucket_target_config.is_none()),
+            ("notification", bm.notification_config.is_none()),
+            ("lifecycle", bm.lifecycle_config.is_none()),
+            ("object_lock", bm.object_lock_config.is_none()),
+            ("versioning", bm.versioning_config.is_none()),
+            ("encryption", bm.sse_config.is_none()),
+            ("tagging", bm.tagging_config.is_none()),
+            ("replication", bm.replication_config.is_none()),
+            ("cors", bm.cors_config.is_none()),
+            ("logging", bm.logging_config.is_none()),
+            ("website", bm.website_config.is_none()),
+            ("accelerate", bm.accelerate_config.is_none()),
+            ("request_payment", bm.request_payment_config.is_none()),
+            ("public_access_block", bm.public_access_block_config.is_none()),
+            ("bucket_acl", bm.bucket_acl_config.is_none()),
+        ];
+        for (config, is_cleared) in cleared {
+            assert!(is_cleared, "{config}: a corrupt payload must not be replaced by a default");
+        }
+
+        assert_eq!(bm.bucket_targets_config_json, malformed_json, "raw bytes are retained");
+        assert_eq!(bm.lifecycle_config_xml, malformed_xml, "raw bytes are retained");
+    }
+
    #[test]
    fn lifecycle_update_config_clears_parsed_config_on_delete() {
        let mut bm = BucketMetadata::new("test-bucket");
@@ -360,6 +360,16 @@ async fn refresh_buckets_metadata_once(sys: Arc<RwLock<BucketMetadataSys>>) {
 }

 async fn sync_bucket_target_sys(bucket: &str, bm: &BucketMetadata) {
+    if bm.bucket_targets_unreadable() {
+        // "The configuration cannot be read" is not "no targets configured".
+        // Publishing an empty snapshot here is what silently stopped
+        // replication (rustfs/backlog#2282): mark the bucket instead, so every
+        // targets reader gets a typed error, and leave any snapshot from an
+        // earlier readable load in place rather than withdrawing it.
+        BucketTargetSys::get().mark_targets_unreadable(bucket).await;
+        return;
+    }
+
    BucketTargetSys::get()
        .update_all_targets(bucket, bm.bucket_target_config.as_ref())
        .await;
@@ -645,6 +655,12 @@ pub struct BucketMetadataMutationGuard {
 }

 impl BucketMetadataMutationGuard {
+    /// Returns the storage-verified identity while both incarnation fences remain valid.
+    pub fn checked_bucket_incarnation(&self) -> Result<(&str, Uuid)> {
+        self.ensure_valid(&self.bucket)?;
+        Ok((&self.bucket, self.incarnation_id))
+    }
+
    fn ensure_valid(&self, bucket: &str) -> Result<()> {
        if self.bucket != bucket {
            return Err(Error::other("bucket metadata mutation guard does not match bucket"));
@@ -664,6 +680,29 @@ async fn acquire_config_write_guard_for_incarnation(
    sys: Arc<RwLock<BucketMetadataSys>>,
    bucket: &str,
    expected_incarnation_id: Option<Uuid>,
+) -> Result<BucketMetadataMutationGuard> {
+    acquire_config_write_guard_with_migration(sys, bucket, expected_incarnation_id, true).await
+}
+
+/// Scanner probes must not create an incarnation to make a capability available.
+pub async fn acquire_scanner_bucket_incarnation_fence(
+    bucket: &str,
+    expected_incarnation_id: Uuid,
+    expected_owner_id: Uuid,
+) -> Result<BucketMetadataMutationGuard> {
+    super::utils::check_valid_bucket_name(bucket)?;
+    let sys = get_bucket_metadata_sys()?;
+    if expected_owner_id.is_nil() || sys.read().await.api.id != expected_owner_id || expected_incarnation_id.is_nil() {
+        return Err(Error::other("scanner bucket incarnation owner does not match"));
+    }
+    acquire_config_write_guard_with_migration(sys, bucket, Some(expected_incarnation_id), false).await
+}
+
+async fn acquire_config_write_guard_with_migration(
+    sys: Arc<RwLock<BucketMetadataSys>>,
+    bucket: &str,
+    expected_incarnation_id: Option<Uuid>,
+    migrate: bool,
 ) -> Result<BucketMetadataMutationGuard> {
    let metadata_sys = sys.read().await.clone();
    let lifecycle_guard = metadata_sys.api.acquire_bucket_lifecycle_read_lock(bucket).await?;
@@ -671,13 +710,15 @@ async fn acquire_config_write_guard_for_incarnation(
    // Legacy buckets are migrated while the lifecycle fence prevents a
    // same-name replacement. The second read under the write transaction is
    // the CAS source of truth for the actual rewrite.
-    await_bucket_namespace_operation(
-        Some(&lifecycle_guard),
-        bucket,
-        "bucket config incarnation migration",
-        metadata_sys.get_bucket_incarnation_id(bucket),
-    )
-    .await?;
+    if migrate {
+        await_bucket_namespace_operation(
+            Some(&lifecycle_guard),
+            bucket,
+            "bucket config incarnation migration",
+            metadata_sys.get_bucket_incarnation_id(bucket),
+        )
+        .await?;
+    }
    let transaction_guard = await_bucket_namespace_operation(
        Some(&lifecycle_guard),
        bucket,
@@ -2118,7 +2159,9 @@ impl BucketMetadataSys {
    pub async fn get_public_access_block_config(&self, bucket: &str) -> Result<(PublicAccessBlockConfiguration, OffsetDateTime)> {
        let (bm, _) = self.get_config(bucket).await?;

-        if let Some(config) = &bm.public_access_block_config {
+        if !bm.public_access_block_config_xml.is_empty() && bm.public_access_block_config.is_none() {
+            Err(Error::other("persisted bucket public access block configuration is invalid"))
+        } else if let Some(config) = &bm.public_access_block_config {
            Ok((config.clone(), bm.public_access_block_config_updated_at))
        } else {
            Err(Error::ConfigNotFound)
@@ -2429,7 +2472,9 @@ impl BucketMetadataSys {
    pub async fn get_sse_config(&self, bucket: &str) -> Result<(ServerSideEncryptionConfiguration, OffsetDateTime)> {
        let (bm, _) = self.get_config(bucket).await?;

-        if let Some(config) = &bm.sse_config {
+        if !bm.encryption_config_xml.is_empty() && bm.sse_config.is_none() {
+            Err(Error::other("persisted bucket encryption configuration is invalid"))
+        } else if let Some(config) = &bm.sse_config {
            Ok((config.clone(), bm.encryption_config_updated_at))
        } else {
            Err(Error::ConfigNotFound)
@@ -2500,7 +2545,9 @@ impl BucketMetadataSys {
    pub async fn get_quota_config(&self, bucket: &str) -> Result<(BucketQuota, OffsetDateTime)> {
        let (bm, _) = self.get_config(bucket).await?;

-        if let Some(config) = &bm.quota_config {
+        if !bm.quota_config_json.is_empty() && bm.quota_config.is_none() {
+            Err(Error::other("persisted bucket quota configuration is invalid"))
+        } else if let Some(config) = &bm.quota_config {
            Ok((config.clone(), bm.quota_config_updated_at))
        } else {
            Err(Error::ConfigNotFound)
@@ -2522,7 +2569,9 @@ impl BucketMetadataSys {
    pub async fn get_bucket_targets_config(&self, bucket: &str) -> Result<BucketTargets> {
        let (bm, _) = self.get_config(bucket).await?;

-        if let Some(config) = &bm.bucket_target_config {
+        if bm.bucket_targets_unreadable() {
+            Err(Error::other("persisted bucket replication target configuration is invalid"))
+        } else if let Some(config) = &bm.bucket_target_config {
            Ok(config.clone())
        } else {
            Err(Error::ConfigNotFound)
@@ -2593,6 +2642,7 @@ pub(crate) mod test_support {
 mod tests {
    use super::test_support::isolated_store_over_temp_disks;
    use super::*;
+    use crate::bucket::bucket_target_sys::BucketTargetError;
    use crate::bucket::metadata::{
        BUCKET_ACCELERATE_CONFIG, BUCKET_CORS_CONFIG, BUCKET_LIFECYCLE_CONFIG, BUCKET_LOGGING_CONFIG, BUCKET_NOTIFICATION_CONFIG,
        BUCKET_POLICY_CONFIG, BUCKET_PUBLIC_ACCESS_BLOCK_CONFIG, BUCKET_REPLICATION_CONFIG, BUCKET_REQUEST_PAYMENT_CONFIG,
@@ -2788,6 +2838,36 @@ mod tests {
        );
    }

+    /// The `parse_all_configs` audit (rustfs/backlog#2282): every accessor
+    /// whose configuration grants something — plaintext storage, anonymous
+    /// access, capacity, replication targets — reports a corrupt payload as
+    /// invalid rather than as absent, because "absent" is what grants it.
+    #[tokio::test]
+    async fn malformed_permissive_configs_are_not_reported_as_absent() {
+        let (_dirs, ecstore) = isolated_store_over_temp_disks().await;
+        let sys = BucketMetadataSys::new(ecstore);
+        let bucket = "malformed-permissive-config";
+        let mut metadata = BucketMetadata::new(bucket);
+        metadata.encryption_config_xml = b"<ServerSideEncryptionConfiguration".to_vec();
+        metadata.public_access_block_config_xml = b"<PublicAccessBlockConfiguration".to_vec();
+        metadata.quota_config_json = b"{not-json".to_vec();
+        metadata.bucket_targets_config_json = b"{not-json".to_vec();
+        metadata
+            .parse_all_configs()
+            .expect("a corrupt sub-config must not fail the load");
+        sys.set(bucket.to_string(), Arc::new(metadata)).await;
+
+        for (config, result) in [
+            ("encryption", sys.get_sse_config(bucket).await.err()),
+            ("public access block", sys.get_public_access_block_config(bucket).await.err()),
+            ("quota", sys.get_quota_config(bucket).await.err()),
+            ("bucket targets", sys.get_bucket_targets_config(bucket).await.err()),
+        ] {
+            let err = result.unwrap_or_else(|| panic!("malformed {config} metadata must not read as a value"));
+            assert_ne!(err, Error::ConfigNotFound, "malformed {config} metadata must not be reported as absent");
+        }
+    }
+
    #[tokio::test]
    async fn config_states_distinguish_authoritative_absence_from_fabricated_metadata() {
        use std::sync::atomic::Ordering;
@@ -3127,6 +3207,82 @@ mod tests {
        );
    }

+    #[tokio::test]
+    async fn scoped_dirty_usage_incarnation_probe_does_not_migrate_legacy_metadata() {
+        let (dirs, store) = isolated_store_over_temp_disks().await;
+        let sys = Arc::new(RwLock::new(BucketMetadataSys::new(store.clone())));
+        let bucket = "scoped-ack-legacy";
+        for dir in &dirs {
+            std::fs::create_dir_all(dir.path().join(bucket)).expect("create legacy bucket");
+        }
+        let mut metadata = BucketMetadata::new(bucket);
+        metadata.bucket_incarnation_id = Uuid::nil();
+        sys.read()
+            .await
+            .persist_and_set(metadata)
+            .await
+            .expect("persist legacy metadata");
+        assert!(
+            acquire_config_write_guard_with_migration(sys.clone(), bucket, Some(Uuid::new_v4()), false)
+                .await
+                .is_err()
+        );
+        assert!(load_bucket_incarnation(store, bucket).await.expect("read sidecar").is_none());
+        assert!(
+            sys.read()
+                .await
+                .get_config_from_disk(bucket)
+                .await
+                .expect("read metadata")
+                .bucket_incarnation_id
+                .is_nil()
+        );
+    }
+
+    #[tokio::test(flavor = "multi_thread", worker_threads = 4)]
+    #[serial]
+    async fn scoped_dirty_usage_incarnation_rejects_deleted_and_recreated_bucket() {
+        let (_dirs, store) = isolated_store_over_temp_disks().await;
+        init_bucket_metadata_sys(store.clone(), Vec::new()).await;
+        let sys = bucket_metadata_sys_of(&store.ctx).expect("metadata owner");
+        let bucket = "scoped-ack-recreated";
+        store
+            .make_bucket(bucket, &MakeBucketOptions::default())
+            .await
+            .expect("create bucket");
+        let old = store.bucket_incarnation_id_from_disk(bucket).await.expect("old incarnation");
+        let guard = acquire_config_write_guard_with_migration(sys.clone(), bucket, Some(old), false)
+            .await
+            .expect("trusted incarnation fence");
+        assert_eq!(guard.checked_bucket_incarnation().expect("valid fences"), (bucket, old));
+        drop(guard);
+        store
+            .delete_bucket(bucket, &DeleteBucketOptions::default())
+            .await
+            .expect("delete bucket");
+        assert!(
+            acquire_config_write_guard_with_migration(sys.clone(), bucket, Some(old), false)
+                .await
+                .is_err()
+        );
+        store
+            .make_bucket(bucket, &MakeBucketOptions::default())
+            .await
+            .expect("recreate bucket");
+        let new = store.bucket_incarnation_id_from_disk(bucket).await.expect("new incarnation");
+        assert_ne!(old, new);
+        assert!(
+            acquire_config_write_guard_with_migration(sys.clone(), bucket, Some(old), false)
+                .await
+                .is_err()
+        );
+        assert!(
+            acquire_config_write_guard_with_migration(sys, bucket, Some(new), false)
+                .await
+                .is_ok()
+        );
+    }
+
    #[tokio::test]
    async fn old_node_metadata_rewrite_cannot_replace_bucket_incarnation_sidecar() {
        let (dirs, ecstore) = isolated_store_over_temp_disks().await;
@@ -4066,6 +4222,114 @@ mod tests {
        target_sys.delete(bucket).await;
    }

+    /// rustfs/backlog#2282: an unreadable `bucket-targets.json` reaches every
+    /// targets reader as a typed error; it neither withdraws a snapshot a
+    /// previous readable load published, nor collapses into the "no targets
+    /// configured" state that a bucket with an absent configuration reports.
+    #[tokio::test]
+    #[serial]
+    async fn unreadable_bucket_targets_fail_closed_and_stay_distinct_from_absent() {
+        let (_dirs, ecstore) = isolated_store_over_temp_disks().await;
+        let sys = BucketMetadataSys::new(ecstore);
+        let target_sys = BucketTargetSys::get();
+        let unreadable = "targets-unreadable";
+        let absent = "targets-absent";
+        target_sys.delete(unreadable).await;
+        target_sys.delete(absent).await;
+
+        // A readable load publishes this bucket's targets.
+        let mut readable = BucketMetadata::new(unreadable);
+        readable.bucket_target_config = Some(BucketTargets {
+            targets: vec![target(unreadable, "live")],
+        });
+        sync_bucket_target_sys(unreadable, &readable).await;
+        assert_eq!(
+            target_sys
+                .list_bucket_targets(unreadable)
+                .await
+                .expect("readable targets publish")
+                .targets
+                .len(),
+            1
+        );
+
+        // The same bucket reloaded with a blob that cannot be decoded.
+        let mut corrupt = BucketMetadata::new(unreadable);
+        corrupt.bucket_targets_config_json = br#"{"targets":[{"endpoint":"#.to_vec();
+        corrupt
+            .parse_all_configs()
+            .expect("an unreadable targets blob must not fail the metadata load");
+        sys.set(unreadable.to_string(), Arc::new(corrupt)).await;
+
+        assert!(
+            matches!(
+                target_sys.list_bucket_targets(unreadable).await,
+                Err(BucketTargetError::BucketRemoteTargetsUnreadable { .. })
+            ),
+            "an unreadable configuration must not read as an empty or a missing target set"
+        );
+        assert!(
+            target_sys.list_targets(unreadable, "").await.is_err(),
+            "the admin listing must surface the fault instead of an empty list"
+        );
+        let err = sys
+            .get_bucket_targets_config(unreadable)
+            .await
+            .expect_err("an unreadable targets configuration must not read as a value");
+        assert_ne!(err, Error::ConfigNotFound, "unreadable must not be reported as absent");
+
+        // A bucket that never configured a target keeps its previous behavior.
+        let mut no_targets = BucketMetadata::new(absent);
+        no_targets.parse_all_configs().expect("absent targets parse");
+        sys.set(absent.to_string(), Arc::new(no_targets)).await;
+        assert!(
+            matches!(
+                target_sys.list_bucket_targets(absent).await,
+                Err(BucketTargetError::BucketRemoteTargetNotFound { .. })
+            ),
+            "an absent configuration must still report as a missing target set"
+        );
+        assert!(
+            target_sys
+                .list_targets(absent, "")
+                .await
+                .expect("an absent configuration lists no targets")
+                .is_empty()
+        );
+        assert!(
+            sys.get_bucket_targets_config(absent)
+                .await
+                .expect("an absent targets configuration still reads as an empty set")
+                .is_empty(),
+            "the absent path must keep returning an empty target set, exactly as before"
+        );
+
+        // One bucket's unreadable configuration does not reach another bucket.
+        assert!(!matches!(
+            target_sys.list_bucket_targets(absent).await,
+            Err(BucketTargetError::BucketRemoteTargetsUnreadable { .. })
+        ));
+
+        // A repaired configuration takes effect on the next load, no restart.
+        let mut repaired = BucketMetadata::new(unreadable);
+        repaired.bucket_target_config = Some(BucketTargets {
+            targets: vec![target(unreadable, "repaired")],
+        });
+        sync_bucket_target_sys(unreadable, &repaired).await;
+        assert_eq!(
+            target_sys
+                .list_bucket_targets(unreadable)
+                .await
+                .expect("a repaired configuration clears the unreadable marker")
+                .targets
+                .len(),
+            1
+        );
+
+        target_sys.delete(unreadable).await;
+        target_sys.delete(absent).await;
+    }
+
    #[tokio::test]
    #[serial]
    async fn metadata_reload_clears_stale_bucket_targets_when_config_is_removed() {
@@ -31,6 +31,7 @@ pub mod policy_sys;
 pub mod quota;
 pub mod remote_s3_client;
 pub mod replication;
+pub mod sealed_credentials;
 pub mod tagging;
 pub mod target;
 pub mod utils;
@@ -0,0 +1,172 @@
+// Copyright 2024 RustFS Team
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//! One contract every [`SourceBackend`] implementation must satisfy.
+//!
+//! The migration pipeline talks to a source only through the trait, so a new
+//! provider is correct exactly when it answers the same questions the same way:
+//! the same head fields, the same range semantics, the same page shape, the
+//! same error classes. Each backend supplies a fixture that answers this fixed
+//! corpus in its own dialect and then runs [`assert_backend_contract`], so a
+//! provider-specific mapping bug shows up as a contract failure rather than as
+//! a surprise in the pull pipeline.
+//!
+//! Backends differ in two documented ways, declared through
+//! [`BackendCapabilities`]: whether the provider's ETag is a content digest,
+//! and whether the provider can resume a listing from a key.
+
+use super::source_client::{SourceBackend, SourceError, SourceListRequest};
+use crate::storage_api_contracts::range::HTTPRangeSpec;
+use std::collections::HashMap;
+
+/// The single object every fixture serves.
+pub(super) const OBJECT_KEY: &str = "dir/a.txt";
+pub(super) const OBJECT_BODY: &[u8] = b"hello";
+/// MD5 of [`OBJECT_BODY`]; the ETag of the object on a digest provider.
+pub(super) const OBJECT_MD5: &str = "5d41402abc4b2a76b9719d911017c592";
+/// The second key the fixture's listing returns, on its second page.
+pub(super) const SECOND_KEY: &str = "dir/b.txt";
+pub(super) const COMMON_PREFIX: &str = "dir/sub/";
+pub(super) const LIST_CURSOR: &str = "cursor-1";
+/// A key the fixture answers with the provider's "no such object".
+pub(super) const MISSING_KEY: &str = "missing";
+/// A key the fixture answers with the provider's "not authorized".
+pub(super) const FORBIDDEN_KEY: &str = "secret";
+
+/// Where backends are allowed to differ.
+#[derive(Clone, Copy, Debug)]
+pub(super) struct BackendCapabilities {
+    /// The provider's ETag is an opaque token, not a digest of the bytes.
+    pub(super) etag_is_opaque: bool,
+    /// The provider can resume a listing from a key rather than only from an
+    /// opaque cursor.
+    pub(super) supports_start_after: bool,
+    /// The provider has an object-tagging concept at all. GCS does not, and
+    /// answers with an empty map instead of failing a pull.
+    pub(super) supports_tagging: bool,
+}
+
+/// Drives `backend` through the shared corpus. Fixtures are scripted in
+/// request order, so the call order here is part of the contract.
+pub(super) async fn assert_backend_contract(backend: &dyn SourceBackend, caps: BackendCapabilities) {
+    // 1. HEAD maps the object's shared fields.
+    let head = backend.head(OBJECT_KEY).await.expect("HEAD of the fixture object");
+    assert_eq!(head.size, OBJECT_BODY.len() as u64, "HEAD reports the object size");
+    assert_eq!(head.content_type.as_deref(), Some("text/plain"));
+    assert_eq!(
+        head.user_metadata,
+        HashMap::from([("owner".to_string(), "alice".to_string())]),
+        "user metadata is keyed without the provider prefix"
+    );
+    assert!(head.storage_class.is_some(), "the provider's tier is recorded");
+    assert!(head.last_modified.is_some(), "the provider's timestamp is parsed");
+    assert!(head.sse.is_none(), "the fixture object is not server-side encrypted");
+    assert!(!head.is_multipart_etag);
+    assert_eq!(head.etag_is_opaque, caps.etag_is_opaque);
+    match caps.etag_is_opaque {
+        false => assert_eq!(head.etag.as_deref(), Some(OBJECT_MD5), "a digest ETag is mapped verbatim"),
+        true => assert!(head.etag.is_some(), "an opaque ETag is still recorded"),
+    }
+
+    // 2. An unranged GET streams the whole object and reports no range.
+    let got = backend.get(OBJECT_KEY, None).await.expect("unranged GET");
+    assert_eq!(got.head.size, OBJECT_BODY.len() as u64);
+    assert!(got.content_range.is_none(), "an unranged GET has no content-range");
+    assert_eq!(got.head.etag_is_opaque, caps.etag_is_opaque, "GET and HEAD agree about the ETag");
+    let body = got.body.collect().await.expect("body streams").into_bytes();
+    assert_eq!(body.as_ref(), OBJECT_BODY);
+
+    // 3. A ranged GET returns exactly the requested interval, and `size` is
+    //    the length of the returned bytes rather than of the object.
+    let range = HTTPRangeSpec {
+        is_suffix_length: false,
+        start: 1,
+        end: 3,
+    };
+    let got = backend.get(OBJECT_KEY, Some(&range)).await.expect("ranged GET");
+    assert_eq!(got.head.size, 3, "a ranged GET reports the range length");
+    assert_eq!(got.content_range.as_deref(), Some("bytes 1-3/5"));
+    let body = got.body.collect().await.expect("body streams").into_bytes();
+    assert_eq!(body.as_ref(), &OBJECT_BODY[1..=3]);
+
+    // 4. A delimiter listing rolls prefixes up and hands back a cursor.
+    let page = backend
+        .list(&SourceListRequest {
+            prefix: Some("dir/"),
+            delimiter: Some("/"),
+            max_keys: 2,
+            ..Default::default()
+        })
+        .await
+        .expect("first listing page");
+    assert_eq!(page.objects.len(), 1, "the first page holds one object");
+    assert_eq!(page.objects[0].key, OBJECT_KEY, "listing keys are in the source namespace");
+    assert_eq!(page.objects[0].size, OBJECT_BODY.len() as u64);
+    assert!(page.objects[0].last_modified.is_some());
+    assert_eq!(page.common_prefixes, vec![COMMON_PREFIX.to_string()]);
+    assert!(page.is_truncated);
+    assert_eq!(page.next_continuation_token.as_deref(), Some(LIST_CURSOR));
+
+    // 5. The cursor is passed back verbatim and the last page ends the walk.
+    let page = backend
+        .list(&SourceListRequest {
+            prefix: Some("dir/"),
+            delimiter: Some("/"),
+            continuation_token: Some(LIST_CURSOR),
+            max_keys: 2,
+            ..Default::default()
+        })
+        .await
+        .expect("second listing page");
+    assert_eq!(page.objects.len(), 1);
+    assert_eq!(page.objects[0].key, SECOND_KEY);
+    assert!(!page.is_truncated);
+    assert!(page.next_continuation_token.is_none(), "a complete listing carries no cursor");
+
+    // 6. Tags come back as a flat map, empty on a provider without tags.
+    let tags = backend.tagging(OBJECT_KEY).await.expect("object tags");
+    match caps.supports_tagging {
+        true => assert_eq!(tags, HashMap::from([("env".to_string(), "prod".to_string())])),
+        false => assert!(tags.is_empty(), "a provider without tags reports none: {tags:?}"),
+    }
+
+    // 7. The probe confirms the bucket or container answers.
+    backend.probe().await.expect("probe of the fixture bucket");
+
+    // 8. A missing object is `NotFound`, and never retried.
+    let err = backend.head(MISSING_KEY).await.expect_err("a missing object must fail");
+    assert!(matches!(err, SourceError::NotFound), "{err:?}");
+    assert_eq!(err.class_label(), "not_found");
+    assert!(!err.is_retryable());
+
+    // 9. A denied object is `AccessDenied`, and never retried.
+    let err = backend.head(FORBIDDEN_KEY).await.expect_err("a denied object must fail");
+    assert!(matches!(err, SourceError::AccessDenied), "{err:?}");
+    assert_eq!(err.class_label(), "access_denied");
+    assert!(!err.is_retryable());
+
+    // 10. A provider without a key cursor must refuse one instead of listing
+    //     from the wrong position. This issues no request either way.
+    if !caps.supports_start_after {
+        let err = backend
+            .list(&SourceListRequest {
+                start_after: Some(OBJECT_KEY),
+                max_keys: 1,
+                ..Default::default()
+            })
+            .await
+            .expect_err("a backend without a key cursor must refuse start_after");
+        assert!(matches!(err, SourceError::Unsupported(_)), "{err:?}");
+    }
+}
@@ -25,8 +25,8 @@
 //!   [`BACKFILL_SAVE_INTERVAL`], and at every page end, with an `If-Match`
 //!   compare-and-set so a concurrent cancel or takeover is never overwritten.
 //! - The `continuation_token` only advances once every pull queued from the
-//!   page before it has reported back, so a crash re-lists at most one page
-//!   (already-present keys are then skipped, never re-pulled).
+//!   page before it has succeeded. After a failure it stays at that page,
+//!   so crash recovery cannot skip failed pulls (existing keys are skipped).
 //! - The owner holds a lease of [`BACKFILL_LEASE`] renewed by every save. The
 //!   recovery loop ([`run_backfill_recovery_loop`]) scans the buckets this
 //!   node has an ODM state for every [`BACKFILL_RECOVERY_INTERVAL`] and takes
@@ -367,9 +367,8 @@ pub struct LocalBackfillObject {
    pub source_etag: Option<String>,
 }

-/// Receiver of one queued pull's report; `None` when the pull was coalesced
-/// into one already running.
-pub type PullReport = Option<oneshot::Receiver<QueuedPullOutcome>>;
+/// Shared report of a new or coalesced pull; absent only when not admitted.
+pub type PullReport = Option<super::pull::QueuedPullReport>;

 /// Everything the job needs from its bucket, so the loop can run against a
 /// mock in unit tests. Production: [`BucketBackfillContext`].
@@ -684,6 +683,7 @@ async fn write_checkpoint(
    };
    let opts = ObjectOptions {
        max_parity: true,
+        write_completion: crate::object_api::WriteCompletion::TailDrained,
        http_preconditions: Some(preconditions),
        ..Default::default()
    };
@@ -1190,9 +1190,11 @@ impl Job {
    }

    async fn main_loop(&mut self) -> Result<(), Stop> {
+        let mut cursor = self.checkpoint.continuation_token.clone();
+        let failed_at_resume = self.checkpoint.failed;
        loop {
            self.check_cancel()?;
-            let page = self.list_page().await?;
+            let page = self.list_page(cursor.as_deref()).await?;
            for object in &page.objects {
                self.check_cancel()?;
                self.checkpoint.listed += 1;
@@ -1204,10 +1206,13 @@ impl Job {
                self.drain_ready();
                self.tick(false).await?;
            }
-            // Only advance the cursor once every pull of this page reported
-            // back, so a takeover re-lists at most this page.
+            // A persisted cursor certifies successful work, not just listing
+            // progress. Keep it at the first failed page for crash recovery.
            self.drain_all().await?;
-            self.checkpoint.continuation_token = page.next_continuation_token.clone();
+            cursor = page.next_continuation_token;
+            if self.checkpoint.failed == failed_at_resume {
+                self.checkpoint.continuation_token = cursor.clone();
+            }
            self.tick(true).await?;
            if !page.is_truncated {
                return Ok(());
@@ -1222,7 +1227,7 @@ impl Job {
        }
    }

-    async fn list_page(&mut self) -> Result<SourcePage, Stop> {
+    async fn list_page(&mut self, cursor: Option<&str>) -> Result<SourcePage, Stop> {
        let mut attempt = 0;
        loop {
            while !self.context.source_available() {
@@ -1230,7 +1235,7 @@ impl Job {
                self.tick(false).await?;
            }
            let prefix = self.checkpoint.prefix.clone();
-            let token = self.checkpoint.continuation_token.clone();
+            let token = cursor.map(str::to_string);
            match self
                .context
                .list_page(prefix.as_deref(), token.as_deref(), BACKFILL_LIST_PAGE_SIZE)
@@ -1304,9 +1309,10 @@ impl Job {
        }
        loop {
            match self.context.enqueue(key) {
-                (EnqueueOutcome::Enqueued, report) => {
+                (EnqueueOutcome::Enqueued | EnqueueOutcome::Coalesced, report) => {
                    self.checkpoint.enqueued += 1;
-                    if let Some(rx) = report {
+                    let rx = report.ok_or(Stop::Unavailable)?;
+                    {
                        let key = key.to_string();
                        self.outstanding.push(Box::pin(async move { (key, rx.await) }));
                    }
@@ -1321,11 +1327,6 @@ impl Job {
                    );
                    return Ok(());
                }
-                (EnqueueOutcome::Coalesced, _) => {
-                    // Someone else pulls it; its result is not ours to count.
-                    self.checkpoint.enqueued += 1;
-                    return Ok(());
-                }
                (EnqueueOutcome::QueueFull, _) => {
                    // Wait, never drop: one completion frees a slot.
                    if self.outstanding.is_empty() {
@@ -1639,6 +1640,7 @@ mod tests {
        queue_capacity: usize,
        pending: Mutex<Vec<(String, oneshot::Sender<QueuedPullOutcome>)>>,
        fail_keys: HashSet<String>,
+        coalesced: bool,
        auto_complete: AtomicBool,
        cancel: CancellationToken,
        config_updated_at: Mutex<Option<OffsetDateTime>>,
@@ -1666,6 +1668,7 @@ mod tests {
                queue_capacity: usize::MAX,
                pending: Mutex::new(Vec::new()),
                fail_keys: HashSet::new(),
+                coalesced: false,
                auto_complete: AtomicBool::new(true),
                cancel: CancellationToken::new(),
                config_updated_at: Mutex::new(Some(ts(1_700_000_000))),
@@ -1745,7 +1748,12 @@ mod tests {
            } else {
                self.pending.lock().push((key.to_string(), tx));
            }
-            (EnqueueOutcome::Enqueued, Some(rx))
+            let outcome = if self.coalesced {
+                EnqueueOutcome::Coalesced
+            } else {
+                EnqueueOutcome::Enqueued
+            };
+            (outcome, Some(futures::FutureExt::shared(rx)))
        }

        fn cancel_token(&self) -> CancellationToken {
@@ -1911,7 +1919,7 @@ mod tests {
    #[tokio::test]
    async fn failed_pulls_are_counted_hashed_and_finish_with_failures() {
        let bucket = "backfill-failed";
-        let mut context = MockContext::new(5, 1000);
+        let mut context = MockContext::new(5, 2);
        Arc::get_mut(&mut context)
            .expect("unshared")
            .fail_keys
@@ -1926,12 +1934,52 @@ mod tests {
            .checkpoint;
        assert_eq!(cp.state, BackfillState::CompletedWithFailures);
        assert_eq!((cp.pulled, cp.failed), (4, 1));
+        assert_eq!(cp.continuation_token.as_deref(), Some("2"), "retain the first failed page for recovery");
        assert_eq!(cp.failed_keys, vec![key_hash("k/00002")]);
        let last = cp.last_error.expect("last error");
        assert_eq!(last.class, "local_write");
        assert_eq!(last.key_hash.as_deref(), Some(key_hash("k/00002").as_str()));
    }

+    #[tokio::test]
+    async fn coalesced_pulls_block_the_checkpoint_and_report_failures() {
+        let bucket = "backfill-coalesced";
+        let mut context = MockContext::new(1, 1);
+        {
+            let ctx = Arc::get_mut(&mut context).expect("unshared");
+            ctx.coalesced = true;
+            ctx.auto_complete = AtomicBool::new(false);
+            ctx.fail_keys.insert("k/00000".to_string());
+        }
+        let (_dirs, store, runner) = runner_with("node-a", bucket, Arc::clone(&context)).await;
+        runner.start(bucket, BackfillRequest::default()).await.expect("start");
+        tokio::time::timeout(Duration::from_secs(10), async {
+            while context.pending.lock().is_empty() {
+                tokio::task::yield_now().await;
+            }
+        })
+        .await
+        .expect("job enqueued");
+        assert!(runner.is_running_locally(bucket), "coalescing is not completion");
+        let cp = read_checkpoint(&store, bucket)
+            .await
+            .expect("read")
+            .expect("checkpoint")
+            .checkpoint;
+        assert!(cp.state.is_active());
+        assert!(cp.continuation_token.is_none());
+        context.complete_pending();
+        runner.wait_until_idle(bucket).await;
+        let cp = read_checkpoint(&store, bucket)
+            .await
+            .expect("read")
+            .expect("checkpoint")
+            .checkpoint;
+        assert_eq!(cp.state, BackfillState::CompletedWithFailures);
+        assert_eq!((cp.enqueued, cp.pulled, cp.failed), (1, 0, 1));
+        assert_eq!(cp.failed_keys, vec![key_hash("k/00000")]);
+    }
+
    #[tokio::test]
    async fn listing_failure_marks_the_job_failed_with_the_error_class() {
        let bucket = "backfill-list-error";
@@ -2144,6 +2192,68 @@ mod tests {
        assert_eq!(runner.recover_once().await.taken_over, 0, "a finished job is not recovered");
    }

+    #[tokio::test]
+    async fn recovery_advances_past_historical_failures_but_pins_new_failures() {
+        let bucket = "backfill-takeover-failed";
+        let mut context = MockContext::new(8, 2);
+        {
+            let ctx = Arc::get_mut(&mut context).expect("unshared");
+            ctx.auto_complete = AtomicBool::new(false);
+            ctx.fail_keys.insert("k/00004".to_string());
+        }
+        let (_dirs, store, runner) = runner_with("node-b", bucket, Arc::clone(&context)).await;
+        let crashed_at = OffsetDateTime::now_utc() - Duration::from_secs(300);
+        let mut crashed = BackfillCheckpoint::new(&BackfillRequest::default(), ts(1_700_000_000), "node-a", crashed_at);
+        crashed.continuation_token = Some("2".to_string());
+        crashed.failed = 1;
+        crashed.record_failure("local_write", Some("k/00002"), crashed_at);
+        write_checkpoint(&store, bucket, &crashed, None)
+            .await
+            .expect("seed failed page with an expired lease");
+
+        assert_eq!(runner.recover_once().await.taken_over, 1);
+        for (page_start, durable_token, failures) in [(2, "2", 1), (4, "4", 1), (6, "4", 2)] {
+            tokio::time::timeout(Duration::from_secs(10), async {
+                loop {
+                    if context.pending.lock().len() == 2 {
+                        break;
+                    }
+                    tokio::task::yield_now().await;
+                }
+            })
+            .await
+            .expect("resumed page enqueued before its reports complete");
+            assert_eq!(
+                context.pending.lock().iter().map(|(key, _)| key.clone()).collect::<Vec<_>>(),
+                vec![format!("k/{page_start:05}"), format!("k/{:05}", page_start + 1)]
+            );
+            let cp = read_checkpoint(&store, bucket)
+                .await
+                .expect("read persisted page boundary")
+                .expect("checkpoint")
+                .checkpoint;
+            assert_eq!(cp.job_id, crashed.job_id);
+            assert_eq!(cp.owner.as_ref().map(|owner| owner.node.as_str()), Some("node-b"));
+            assert_eq!(cp.continuation_token.as_deref(), Some(durable_token));
+            assert_eq!(cp.failed, failures);
+            context.complete_pending();
+        }
+        runner.wait_until_idle(bucket).await;
+        let cp = read_checkpoint(&store, bucket)
+            .await
+            .expect("read completed checkpoint")
+            .expect("checkpoint")
+            .checkpoint;
+        assert_eq!(cp.state, BackfillState::CompletedWithFailures);
+        assert_eq!((cp.pulled, cp.failed), (5, 2));
+        assert_eq!(cp.continuation_token.as_deref(), Some("4"));
+        assert_eq!(cp.failed_keys, vec![key_hash("k/00002"), key_hash("k/00004")]);
+        assert_eq!(
+            context.list_requests.lock().as_slice(),
+            &[Some("2".to_string()), Some("4".to_string()), Some("6".to_string())]
+        );
+    }
+
    #[tokio::test]
    async fn recovery_cancels_a_job_whose_config_changed_and_reclaims_own_node_jobs() {
        let bucket = "backfill-recovery-config";
@@ -86,7 +86,12 @@ impl BreakerVerdict {
            Some(SourceError::Throttled | SourceError::Timeout | SourceError::Connect(_) | SourceError::ServerError(_)) => {
                BreakerVerdict::Failure
            }
-            Some(SourceError::AccessDenied | SourceError::Unsupported(_) | SourceError::Other(_)) => BreakerVerdict::Neutral,
+            Some(
+                SourceError::AccessDenied
+                | SourceError::Unsupported(_)
+                | SourceError::InvalidPagination(_)
+                | SourceError::Other(_),
+            ) => BreakerVerdict::Neutral,
        }
    }
 }
@@ -30,6 +30,10 @@ pub const ON_DEMAND_MIGRATION_CONFIG_VERSION: u32 = 1;
 const REDACTED: &str = "REDACTED";
 const AUTO_REGION: &str = "auto";
 const AUTO_REGION_FALLBACK: &str = "us-east-1";
+/// Public Azure Blob host suffix; the account name is the first label.
+pub const AZURE_BLOB_SUFFIX: &str = "blob.core.windows.net";
+/// Public Google Cloud Storage endpoint for the native provider.
+pub const GCS_DEFAULT_ENDPOINT: &str = "https://storage.googleapis.com";

 const KIB: u64 = 1024;
 const MIB: u64 = 1024 * KIB;
@@ -75,14 +79,25 @@ pub struct SourceConfig {
    pub bucket: String,
    #[serde(default)]
    pub path_style: PathStyle,
-    /// `None` means anonymous access to a public source bucket.
+    /// `None` means anonymous access to a public source bucket. Only the
+    /// SigV4 providers read it; `azure` and `gcs_native` carry their own
+    /// credentials in `azure` / `gcs`.
    #[serde(default)]
    pub credentials: Option<SourceCredentials>,
    #[serde(default)]
    pub tls: TlsConfig,
+    /// Required for [`Provider::Azure`] and rejected for every other
+    /// provider.
+    #[serde(default)]
+    pub azure: Option<AzureSourceConfig>,
+    /// Required for [`Provider::GcsNative`] and rejected for every other
+    /// provider. [`Provider::Gcs`] keeps using `credentials` because it
+    /// speaks the S3 interoperability API.
+    #[serde(default)]
+    pub gcs: Option<GcsSourceConfig>,
 }

-/// Source vendor family. `azure` is deliberately absent from this version.
+/// Source vendor family.
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
 #[serde(rename_all = "lowercase")]
 pub enum Provider {
@@ -94,6 +109,12 @@ pub enum Provider {
    R2,
    /// GCS XML interoperability API with HMAC keys.
    Gcs,
+    /// Native Azure Blob service; parameters in `source.azure`.
+    Azure,
+    /// Native GCS JSON API with a service-account key; parameters in
+    /// `source.gcs`.
+    #[serde(rename = "gcs_native")]
+    GcsNative,
 }

 impl Provider {
@@ -105,13 +126,22 @@ impl Provider {
            Provider::Rustfs => "rustfs",
            Provider::R2 => "r2",
            Provider::Gcs => "gcs",
+            Provider::Azure => "azure",
+            Provider::GcsNative => "gcs_native",
        }
    }

+    /// Providers that do not speak S3 and therefore ignore `region`,
+    /// `path_style` and `credentials`.
+    pub fn is_native(&self) -> bool {
+        matches!(self, Provider::Azure | Provider::GcsNative)
+    }
+
    /// Providers whose SDKs accept `region = "auto"`; RustFS maps it to
-    /// `us-east-1` for signing.
+    /// `us-east-1` for signing. The native providers never sign with a
+    /// region, so they accept it as well.
    fn accepts_auto_region(&self) -> bool {
-        matches!(self, Provider::R2 | Provider::Minio | Provider::Rustfs)
+        matches!(self, Provider::R2 | Provider::Minio | Provider::Rustfs) || self.is_native()
    }
 }

@@ -164,6 +194,73 @@ impl fmt::Debug for SourceCredentials {
    }
 }

+/// Native Azure Blob source parameters. The container is `source.bucket`,
+/// so a config never carries two names for the same container. Exactly one
+/// of `account_key` and `sas_token` must be set: the account key signs with
+/// Shared Key, the SAS token is appended to every request URL.
+#[derive(Clone, PartialEq, Eq, Serialize, Deserialize)]
+#[serde(deny_unknown_fields)]
+pub struct AzureSourceConfig {
+    /// Storage account name; also derives the default `blob.core.windows.net`
+    /// endpoint when `source.endpoint` is absent.
+    pub account: String,
+    /// Base64 shared key of the storage account.
+    #[serde(default)]
+    pub account_key: Option<String>,
+    /// SAS query string without the leading `?`.
+    #[serde(default)]
+    pub sas_token: Option<String>,
+}
+
+impl AzureSourceConfig {
+    /// A copy safe to return to admin clients or log: both secrets are
+    /// replaced by `REDACTED`, and whether each is set stays visible.
+    pub fn redacted(&self) -> Self {
+        Self {
+            account: self.account.clone(),
+            account_key: self.account_key.as_ref().map(|_| REDACTED.to_string()),
+            sas_token: self.sas_token.as_ref().map(|_| REDACTED.to_string()),
+        }
+    }
+}
+
+impl fmt::Debug for AzureSourceConfig {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_struct("AzureSourceConfig")
+            .field("account", &self.account)
+            .field("account_key", &self.account_key.as_ref().map(|_| REDACTED))
+            .field("sas_token", &self.sas_token.as_ref().map(|_| REDACTED))
+            .finish()
+    }
+}
+
+/// Native Google Cloud Storage source parameters. The bucket is
+/// `source.bucket`; only the service-account key lives here.
+#[derive(Clone, PartialEq, Eq, Serialize, Deserialize)]
+#[serde(deny_unknown_fields)]
+pub struct GcsSourceConfig {
+    /// Service-account key JSON, verbatim as downloaded from Google Cloud.
+    pub service_account_json: String,
+}
+
+impl GcsSourceConfig {
+    /// A copy safe to return to admin clients or log: the whole key JSON is
+    /// a secret (it embeds the private key), so it is replaced wholesale.
+    pub fn redacted(&self) -> Self {
+        Self {
+            service_account_json: REDACTED.to_string(),
+        }
+    }
+}
+
+impl fmt::Debug for GcsSourceConfig {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_struct("GcsSourceConfig")
+            .field("service_account_json", &REDACTED)
+            .finish()
+    }
+}
+
 #[derive(Debug, Clone, PartialEq, Eq, Default, Serialize, Deserialize)]
 #[serde(deny_unknown_fields)]
 pub struct TlsConfig {
@@ -354,6 +451,14 @@ pub enum OnDemandMigrationConfigError {
    InvalidBucket(&'static str),
    #[error("source credentials field {0} must not be empty")]
    EmptyCredential(&'static str),
+    #[error("source.{0} is required for provider {1}")]
+    MissingProviderBlock(&'static str, Provider),
+    #[error("source.{0} is not valid for provider {1}")]
+    UnexpectedProviderBlock(&'static str, Provider),
+    /// Carries only the reason: the block holds account keys, SAS tokens and
+    /// service-account JSON, so no value of it is ever echoed.
+    #[error("source.{0} is invalid: {1}")]
+    InvalidProviderBlock(&'static str, &'static str),
    #[error("source tls.ca_cert_pem is not a PEM certificate")]
    InvalidCaCert,
    #[error("filter.{0} must be null or a non-empty string")]
@@ -388,6 +493,8 @@ impl OnDemandMigrationConfig {
    pub fn redacted(&self) -> Self {
        let mut copy = self.clone();
        copy.source.credentials = self.source.credentials.as_ref().map(SourceCredentials::redacted);
+        copy.source.azure = self.source.azure.as_ref().map(AzureSourceConfig::redacted);
+        copy.source.gcs = self.source.gcs.as_ref().map(GcsSourceConfig::redacted);
        copy
    }

@@ -433,6 +540,12 @@ impl SourceConfig {
        match (&self.endpoint, self.provider) {
            (Some(endpoint), _) => endpoint.clone(),
            (None, Provider::Aws) => format!("https://s3.{}.amazonaws.com", self.region),
+            (None, Provider::Azure) => self
+                .azure
+                .as_ref()
+                .map(|azure| format!("https://{}.{AZURE_BLOB_SUFFIX}", azure.account))
+                .unwrap_or_default(),
+            (None, Provider::GcsNative) => GCS_DEFAULT_ENDPOINT.to_string(),
            (None, _) => String::new(),
        }
    }
@@ -448,6 +561,8 @@ impl SourceConfig {
    }

    fn validate(&self) -> Result<(), OnDemandMigrationConfigError> {
+        self.validate_provider_block()?;
+
        if self.region.is_empty() {
            return Err(OnDemandMigrationConfigError::EmptyRegion);
        }
@@ -466,6 +581,9 @@ impl SourceConfig {
                    ));
                }
            }
+            // Both native providers derive a fixed endpoint; Azure's is built
+            // from the account name, already checked by `validate_provider_block`.
+            None if self.provider.is_native() => {}
            None => return Err(OnDemandMigrationConfigError::MissingEndpoint(self.provider)),
        }

@@ -496,6 +614,84 @@ impl SourceConfig {

        Ok(())
    }
+
+    /// The provider-specific block must be present for exactly its own
+    /// provider: a stray `azure` block on an `s3` source would otherwise be
+    /// accepted, stored, and silently ignored by the client builder.
+    fn validate_provider_block(&self) -> Result<(), OnDemandMigrationConfigError> {
+        let missing = OnDemandMigrationConfigError::MissingProviderBlock;
+        let unexpected = OnDemandMigrationConfigError::UnexpectedProviderBlock;
+        let invalid = OnDemandMigrationConfigError::InvalidProviderBlock;
+
+        if self.provider != Provider::Azure && self.azure.is_some() {
+            return Err(unexpected("azure", self.provider));
+        }
+        if self.provider != Provider::GcsNative && self.gcs.is_some() {
+            return Err(unexpected("gcs", self.provider));
+        }
+
+        match self.provider {
+            Provider::Azure => {
+                let azure = self.azure.as_ref().ok_or(missing("azure", self.provider))?;
+                if azure.account.is_empty() {
+                    return Err(invalid("azure", "account must not be empty"));
+                }
+                // The account feeds a hostname when the endpoint is derived:
+                // keep it to label characters so it cannot rewrite the host.
+                if !azure.account.bytes().all(|b| b.is_ascii_alphanumeric() || b == b'-') {
+                    return Err(invalid("azure", "account contains characters outside [A-Za-z0-9-]"));
+                }
+                match (azure.account_key.as_deref(), azure.sas_token.as_deref()) {
+                    (Some(_), Some(_)) => return Err(invalid("azure", "account_key and sas_token are mutually exclusive")),
+                    (None, None) => return Err(invalid("azure", "one of account_key and sas_token is required")),
+                    (Some(key), None) => {
+                        if key.is_empty() {
+                            return Err(invalid("azure", "account_key must not be empty"));
+                        }
+                        // Decoded here so a mistyped key fails at the admin
+                        // boundary instead of on the first source request.
+                        if base64_simd::STANDARD.decode_to_vec(key.as_bytes()).is_err() {
+                            return Err(invalid("azure", "account_key is not base64"));
+                        }
+                    }
+                    (None, Some(sas)) => {
+                        if sas.is_empty() {
+                            return Err(invalid("azure", "sas_token must not be empty"));
+                        }
+                        if sas.starts_with('?') {
+                            return Err(invalid("azure", "sas_token must not start with '?'"));
+                        }
+                        if sas.chars().any(char::is_whitespace) {
+                            return Err(invalid("azure", "sas_token must not contain whitespace"));
+                        }
+                    }
+                }
+            }
+            Provider::GcsNative => {
+                let gcs = self.gcs.as_ref().ok_or(missing("gcs", self.provider))?;
+                let key: serde_json::Value = serde_json::from_str(&gcs.service_account_json)
+                    .map_err(|_| invalid("gcs", "service_account_json is not valid JSON"))?;
+                let Some(object) = key.as_object() else {
+                    return Err(invalid("gcs", "service_account_json is not a JSON object"));
+                };
+                if object.get("type").and_then(serde_json::Value::as_str) != Some("service_account") {
+                    return Err(invalid("gcs", "service_account_json is not a service_account key"));
+                }
+                for field in ["client_email", "private_key"] {
+                    if object
+                        .get(field)
+                        .and_then(serde_json::Value::as_str)
+                        .is_none_or(str::is_empty)
+                    {
+                        return Err(invalid("gcs", "service_account_json is missing client_email or private_key"));
+                    }
+                }
+            }
+            Provider::S3 | Provider::Aws | Provider::Minio | Provider::Rustfs | Provider::R2 | Provider::Gcs => {}
+        }
+
+        Ok(())
+    }
 }

 fn validate_endpoint(endpoint: &str) -> Result<(), OnDemandMigrationConfigError> {
@@ -699,7 +895,15 @@ mod tests {
            ),
            (
                "provider enum",
-                r#"{"source":{"provider":"azure","endpoint":"https://h","region":"r","bucket":"b"}}"#,
+                r#"{"source":{"provider":"swift","endpoint":"https://h","region":"r","bucket":"b"}}"#,
+            ),
+            (
+                "azure block",
+                r#"{"source":{"provider":"azure","region":"auto","bucket":"b","azure":{"account":"acct","account_key":"a2V5","extra":1}}}"#,
+            ),
+            (
+                "gcs block",
+                r#"{"source":{"provider":"gcs_native","region":"auto","bucket":"b","gcs":{"service_account_json":"{}","extra":1}}}"#,
            ),
        ] {
            let err = OnDemandMigrationConfig::from_json(json.as_bytes()).expect_err(label);
@@ -820,9 +1024,201 @@ mod tests {
                "{provider}"
            );
        }
+        // The native providers never sign with a region, so "auto" is the
+        // honest value to write for them.
+        for cfg in [azure_cfg(), gcs_native_cfg()] {
+            assert_eq!(cfg.source.region, "auto");
+            cfg.validate(empty_ctx())
+                .unwrap_or_else(|err| panic!("{}: {err}", cfg.source.provider));
+        }
        assert_eq!(sample().source.effective_region(), "us-west-1");
    }

+    const SERVICE_ACCOUNT_JSON: &str = r#"{"type":"service_account","project_id":"p","client_email":"a@b.iam.gserviceaccount.com","private_key":"-----BEGIN PRIVATE KEY-----\nsecret\n-----END PRIVATE KEY-----"}"#;
+
+    fn azure_cfg() -> OnDemandMigrationConfig {
+        let mut cfg = sample();
+        cfg.source.provider = Provider::Azure;
+        cfg.source.endpoint = None;
+        cfg.source.region = "auto".to_string();
+        cfg.source.credentials = None;
+        cfg.source.azure = Some(AzureSourceConfig {
+            account: "legacyaccount".to_string(),
+            account_key: Some("c2VjcmV0LWtleQ==".to_string()),
+            sas_token: None,
+        });
+        cfg
+    }
+
+    fn gcs_native_cfg() -> OnDemandMigrationConfig {
+        let mut cfg = sample();
+        cfg.source.provider = Provider::GcsNative;
+        cfg.source.endpoint = None;
+        cfg.source.region = "auto".to_string();
+        cfg.source.credentials = None;
+        cfg.source.gcs = Some(GcsSourceConfig {
+            service_account_json: SERVICE_ACCOUNT_JSON.to_string(),
+        });
+        cfg
+    }
+
+    #[test]
+    fn native_providers_derive_their_endpoint_and_round_trip_on_the_wire() {
+        let azure = azure_cfg();
+        assert_eq!(azure.source.effective_endpoint(), "https://legacyaccount.blob.core.windows.net");
+        let gcs = gcs_native_cfg();
+        assert_eq!(gcs.source.effective_endpoint(), "https://storage.googleapis.com");
+
+        for cfg in [azure_cfg(), gcs_native_cfg()] {
+            let json = cfg.to_json().expect("config must serialize");
+            assert_eq!(OnDemandMigrationConfig::from_json(&json).expect("config must parse"), cfg);
+        }
+        // The wire labels are part of the admin contract.
+        assert!(
+            String::from_utf8(azure_cfg().to_json().expect("json"))
+                .expect("utf8")
+                .contains(r#""provider":"azure""#)
+        );
+        assert!(
+            String::from_utf8(gcs_native_cfg().to_json().expect("json"))
+                .expect("utf8")
+                .contains(r#""provider":"gcs_native""#)
+        );
+    }
+
+    #[test]
+    fn an_explicit_endpoint_overrides_the_derived_native_one() {
+        // Azurite and fake-gcs-server are addressed this way.
+        let mut cfg = azure_cfg();
+        cfg.source.endpoint = Some("http://azurite.example.com:10000".to_string());
+        cfg.validate(empty_ctx()).expect("an explicit native endpoint is allowed");
+        assert_eq!(cfg.source.effective_endpoint(), "http://azurite.example.com:10000");
+
+        cfg.source.endpoint = Some("http://azurite.example.com:10000/devstoreaccount1".to_string());
+        assert!(
+            matches!(cfg.validate(empty_ctx()), Err(OnDemandMigrationConfigError::InvalidEndpoint(_))),
+            "a native endpoint is still an origin"
+        );
+    }
+
+    #[test]
+    fn a_provider_block_belongs_to_exactly_its_own_provider() {
+        let mut cfg = sample();
+        cfg.source.azure = azure_cfg().source.azure;
+        assert_eq!(
+            cfg.validate(empty_ctx()),
+            Err(OnDemandMigrationConfigError::UnexpectedProviderBlock("azure", Provider::S3))
+        );
+
+        let mut cfg = sample();
+        cfg.source.gcs = gcs_native_cfg().source.gcs;
+        assert_eq!(
+            cfg.validate(empty_ctx()),
+            Err(OnDemandMigrationConfigError::UnexpectedProviderBlock("gcs", Provider::S3))
+        );
+
+        let mut cfg = azure_cfg();
+        cfg.source.azure = None;
+        assert_eq!(
+            cfg.validate(empty_ctx()),
+            Err(OnDemandMigrationConfigError::MissingProviderBlock("azure", Provider::Azure))
+        );
+
+        let mut cfg = gcs_native_cfg();
+        cfg.source.gcs = None;
+        assert_eq!(
+            cfg.validate(empty_ctx()),
+            Err(OnDemandMigrationConfigError::MissingProviderBlock("gcs", Provider::GcsNative))
+        );
+    }
+
+    #[test]
+    fn azure_block_rules() {
+        let with = |account: &str, key: Option<&str>, sas: Option<&str>| {
+            let mut cfg = azure_cfg();
+            cfg.source.azure = Some(AzureSourceConfig {
+                account: account.to_string(),
+                account_key: key.map(str::to_string),
+                sas_token: sas.map(str::to_string),
+            });
+            cfg.validate(empty_ctx())
+        };
+
+        with("legacyaccount", None, Some("sv=2021-08-06&sig=abc%3D")).expect("a SAS token is a complete credential");
+        with("legacyaccount", Some("c2VjcmV0LWtleQ=="), None).expect("an account key is a complete credential");
+
+        for (label, result) in [
+            ("empty account", with("", Some("c2VjcmV0LWtleQ=="), None)),
+            // The account becomes the first label of the derived hostname.
+            ("account with a dot", with("legacy.account", Some("c2VjcmV0LWtleQ=="), None)),
+            ("account with a slash", with("legacy/account", Some("c2VjcmV0LWtleQ=="), None)),
+            ("no credential", with("legacyaccount", None, None)),
+            ("both credentials", with("legacyaccount", Some("c2VjcmV0LWtleQ=="), Some("sv=1"))),
+            ("empty key", with("legacyaccount", Some(""), None)),
+            ("key that is not base64", with("legacyaccount", Some("not base64!"), None)),
+            ("empty sas", with("legacyaccount", None, Some(""))),
+            ("sas with a leading question mark", with("legacyaccount", None, Some("?sv=1"))),
+            ("sas with whitespace", with("legacyaccount", None, Some("sv=1 &sig=a"))),
+        ] {
+            assert!(
+                matches!(result, Err(OnDemandMigrationConfigError::InvalidProviderBlock("azure", _))),
+                "{label}: {result:?}"
+            );
+        }
+    }
+
+    #[test]
+    fn gcs_native_block_requires_a_usable_service_account_key() {
+        let with = |json: &str| {
+            let mut cfg = gcs_native_cfg();
+            cfg.source.gcs = Some(GcsSourceConfig {
+                service_account_json: json.to_string(),
+            });
+            cfg.validate(empty_ctx())
+        };
+
+        with(SERVICE_ACCOUNT_JSON).expect("a service-account key is accepted");
+        for (label, json) in [
+            ("empty", ""),
+            ("not json", "not json"),
+            ("not an object", "[]"),
+            ("wrong type", r#"{"type":"authorized_user","client_email":"a@b","private_key":"k"}"#),
+            ("no private key", r#"{"type":"service_account","client_email":"a@b"}"#),
+            ("empty client email", r#"{"type":"service_account","client_email":"","private_key":"k"}"#),
+        ] {
+            let result = with(json);
+            assert!(
+                matches!(result, Err(OnDemandMigrationConfigError::InvalidProviderBlock("gcs", _))),
+                "{label}: {result:?}"
+            );
+        }
+    }
+
+    #[test]
+    fn native_secrets_never_survive_redaction_or_debug() {
+        let mut azure = azure_cfg();
+        azure.source.azure.as_mut().expect("block").sas_token = Some("sv=2021-08-06&sig=top-secret".to_string());
+        azure.source.azure.as_mut().expect("block").account_key = None;
+        let gcs = gcs_native_cfg();
+
+        for rendered in [
+            format!("{:?}", azure.redacted()),
+            format!("{azure:?}"),
+            String::from_utf8(azure.redacted().to_json().expect("json")).expect("utf8"),
+        ] {
+            assert!(!rendered.contains("top-secret"), "{rendered}");
+            assert!(rendered.contains("legacyaccount"), "the account name is not a secret: {rendered}");
+        }
+        for rendered in [
+            format!("{:?}", gcs.redacted()),
+            format!("{gcs:?}"),
+            String::from_utf8(gcs.redacted().to_json().expect("json")).expect("utf8"),
+        ] {
+            assert!(!rendered.contains("PRIVATE KEY-----"), "{rendered}");
+            assert!(!rendered.contains("gserviceaccount"), "{rendered}");
+        }
+    }
+
    #[test]
    fn bucket_rules() {
        let mut cfg = sample();
@@ -0,0 +1,506 @@
+// Copyright 2024 RustFS Team
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//! Native Google Cloud Storage source backend.
+//!
+//! The `gcs` provider already reaches GCS through its S3 interoperability API,
+//! which needs an HMAC key pair. This backend is the other half: it authorizes
+//! with a service-account key, the credential most GCS projects actually issue,
+//! by minting OAuth tokens through the shared `google-cloud-auth` credential
+//! machinery the tier layer already uses.
+//!
+//! Two GCS surfaces are involved, each for the half it describes best. The read
+//! path uses the XML API (`/{bucket}/{object}`), whose responses carry
+//! `x-goog-meta-*` user metadata and the `x-goog-hash` digest in one round trip.
+//! Listing uses the JSON API (`objects.list`), whose `pageToken` maps directly
+//! onto the shared page cursor and whose `prefixes` are the delimiter roll-up.
+//! Both accept the same bearer token.
+//!
+//! Every call this backend makes needs only `storage.objects.get` and
+//! `storage.objects.list`, the two permissions of the `objectViewer` role, so a
+//! key scoped to exactly the migration's needs works.
+//!
+//! `x-goog-hash` carries a base64 MD5 for every non-composite object; it is
+//! converted to hex and becomes the head's ETag, so a pulled object is checked
+//! against the digest GCS itself computed. A composite object has no MD5, and
+//! its ETag is then marked opaque rather than checked.
+
+use super::native_http::{
+    NativeHeadFields, NativeHttp, base64_md5_to_hex, header, native_source_head, parse_http_timestamp, read_text, response_body,
+};
+use super::source_client::{
+    GcsSourceSpec, SourceBackend, SourceError, SourceGet, SourceHead, SourceListRequest, SourceObject, SourcePage,
+    SourceTimeouts, range_header_value,
+};
+use crate::bucket::remote_s3_client::RemoteS3ClientError;
+use crate::storage_api_contracts::range::HTTPRangeSpec;
+use google_cloud_auth::credentials::service_account::{AccessSpecifier, Builder as ServiceAccountBuilder};
+use google_cloud_auth::credentials::{CacheableResource, Credentials};
+use http::{HeaderMap, HeaderValue, Method};
+use serde::Deserialize;
+use std::collections::HashMap;
+use url::Url;
+
+/// Read-only object scope: this backend never writes to the source.
+const READ_ONLY_SCOPE: &str = "https://www.googleapis.com/auth/devstorage.read_only";
+const METADATA_PREFIX: &str = "x-goog-meta-";
+/// GCS reports its error code in the response body, not a header; the shared
+/// transport takes a header name, so it is given one that never matches and
+/// classification falls back to the status.
+const NO_ERROR_CODE_HEADER: &str = "x-goog-unused-error-code";
+/// One `objects.list` page is small; refuse an unbounded document.
+const MAX_JSON_BYTES: usize = 8 * 1024 * 1024;
+
+pub struct GcsNativeSourceBackend {
+    http: NativeHttp,
+    bucket: String,
+    credentials: Credentials,
+}
+
+impl GcsNativeSourceBackend {
+    pub fn new(
+        endpoint: &str,
+        bucket: &str,
+        spec: &GcsSourceSpec,
+        timeouts: SourceTimeouts,
+        skip_tls_verify: bool,
+        ca_cert_pem: Option<&str>,
+    ) -> Result<Self, RemoteS3ClientError> {
+        let key: serde_json::Value = serde_json::from_str(&spec.service_account_json)
+            .map_err(|_| RemoteS3ClientError::Credentials("gcs service account key is not valid JSON"))?;
+        let credentials = ServiceAccountBuilder::new(key)
+            .with_access_specifier(AccessSpecifier::from_scopes([READ_ONLY_SCOPE]))
+            .build()
+            .map_err(|_| RemoteS3ClientError::Credentials("gcs service account key is not usable"))?;
+        Ok(Self {
+            http: NativeHttp::new(endpoint, timeouts, skip_tls_verify, ca_cert_pem)?,
+            bucket: bucket.to_string(),
+            credentials,
+        })
+    }
+
+    /// Authorization headers for one request. A credential failure is reported
+    /// as `AccessDenied` with no message: the renderer of a credential error
+    /// has the key material in scope, and the class is what callers act on.
+    async fn auth_headers(&self) -> Result<HeaderMap, SourceError> {
+        match self.credentials.headers(http::Extensions::new()).await {
+            Ok(CacheableResource::New { data, .. }) => Ok(data),
+            // Only returned when the caller passes an entity tag, which this
+            // backend never does; an empty set is still the honest answer.
+            Ok(CacheableResource::NotModified) => Ok(HeaderMap::new()),
+            Err(_) => Err(SourceError::AccessDenied),
+        }
+    }
+
+    /// XML API URL of one object; `/` in the key stay path separators.
+    fn object_url(&self, key: &str) -> Result<Url, SourceError> {
+        self.http.url(std::iter::once(self.bucket.as_str()).chain(key.split('/')))
+    }
+
+    /// JSON API URL of the bucket's object collection.
+    fn objects_url(&self) -> Result<Url, SourceError> {
+        self.http.url(["storage", "v1", "b", self.bucket.as_str(), "o"])
+    }
+
+    async fn request(&self, method: Method, url: Url, mut headers: HeaderMap) -> Result<reqwest::Request, SourceError> {
+        for (name, value) in self.auth_headers().await? {
+            if let Some(name) = name {
+                headers.insert(name, value);
+            }
+        }
+        let mut request = reqwest::Request::new(method, url);
+        *request.headers_mut() = headers;
+        Ok(request)
+    }
+
+    /// Shared mapping for the XML API's HEAD and GET responses.
+    fn head_from_response(headers: &HeaderMap) -> Result<SourceHead, SourceError> {
+        if header(headers, "x-goog-encryption-key-sha256").is_some() {
+            return Err(SourceError::Unsupported(
+                "source object uses a customer-supplied encryption key; customer-key sources are not supported".to_string(),
+            ));
+        }
+        // `x-goog-hash` lists digests as `name=base64`, comma separated, and may
+        // repeat across header lines. Only the MD5 describes the whole object.
+        let md5 = headers
+            .get_all("x-goog-hash")
+            .iter()
+            .filter_map(|value| value.to_str().ok())
+            .flat_map(|value| value.split(','))
+            .filter_map(|digest| digest.trim().strip_prefix("md5="))
+            .find_map(base64_md5_to_hex);
+
+        let (etag, etag_is_opaque) = match md5 {
+            Some(md5) => (Some(md5), false),
+            // A composite object has no MD5; its ETag describes the composition
+            // rather than the bytes, so it is provenance only.
+            None => (header(headers, "etag").map(str::to_string), true),
+        };
+        native_source_head(
+            headers,
+            METADATA_PREFIX,
+            NativeHeadFields {
+                etag,
+                etag_is_opaque,
+                version_id: header(headers, "x-goog-generation").map(str::to_string),
+                storage_class: header(headers, "x-goog-storage-class").map(str::to_string),
+            },
+        )
+    }
+}
+
+#[async_trait::async_trait]
+impl SourceBackend for GcsNativeSourceBackend {
+    async fn head(&self, key: &str) -> Result<SourceHead, SourceError> {
+        let request = self.request(Method::HEAD, self.object_url(key)?, HeaderMap::new()).await?;
+        let response = self.http.send(request, NO_ERROR_CODE_HEADER).await?;
+        Self::head_from_response(response.headers())
+    }
+
+    async fn get(&self, key: &str, range: Option<&HTTPRangeSpec>) -> Result<SourceGet, SourceError> {
+        let mut headers = HeaderMap::new();
+        if let Some(range) = range.map(range_header_value).transpose()? {
+            headers.insert(
+                http::header::RANGE,
+                HeaderValue::from_str(&range).map_err(|_| SourceError::Other("invalid range header".to_string()))?,
+            );
+        }
+        let request = self.request(Method::GET, self.object_url(key)?, headers).await?;
+        let response = self.http.send(request, NO_ERROR_CODE_HEADER).await?;
+        let head = Self::head_from_response(response.headers())?;
+        let content_range = header(response.headers(), "content-range").map(str::to_string);
+        Ok(SourceGet {
+            head,
+            body: response_body(response),
+            content_range,
+        })
+    }
+
+    async fn list(&self, request: &SourceListRequest<'_>) -> Result<SourcePage, SourceError> {
+        // `objects.list` offers `startOffset`, which is inclusive, so it cannot
+        // express "resume after this key" without silently repeating it.
+        if request.start_after.is_some() {
+            return Err(SourceError::Unsupported(
+                "gcs sources cannot resume a listing from a key; use the continuation token".to_string(),
+            ));
+        }
+        let mut url = self.objects_url()?;
+        {
+            let mut query = url.query_pairs_mut();
+            if let Some(prefix) = request.prefix.filter(|prefix| !prefix.is_empty()) {
+                query.append_pair("prefix", prefix);
+            }
+            if let Some(delimiter) = request.delimiter.filter(|delimiter| !delimiter.is_empty()) {
+                query.append_pair("delimiter", delimiter);
+            }
+            if let Some(token) = request.continuation_token.filter(|token| !token.is_empty()) {
+                query.append_pair("pageToken", token);
+            }
+            if request.max_keys > 0 {
+                query.append_pair("maxResults", &request.max_keys.to_string());
+            }
+        }
+
+        let request = self.request(Method::GET, url, HeaderMap::new()).await?;
+        let response = self.http.send(request, NO_ERROR_CODE_HEADER).await?;
+        let body = read_text(response, MAX_JSON_BYTES).await?;
+        parse_objects_list(&body)
+    }
+
+    /// GCS has no object tagging API; user metadata is already carried by the
+    /// head mapping. An empty map keeps `policy.copy_tags` from failing a pull
+    /// over a concept the provider does not have.
+    async fn tagging(&self, _key: &str) -> Result<HashMap<String, String>, SourceError> {
+        Ok(HashMap::new())
+    }
+
+    /// A one-object listing, not `buckets.get`: the migration pipeline only
+    /// ever needs `storage.objects.list` and `storage.objects.get`, and a key
+    /// scoped to exactly those (the `objectViewer` role) cannot read the bucket
+    /// resource. Probing with `buckets.get` would reject a correct key.
+    async fn probe(&self) -> Result<(), SourceError> {
+        let mut url = self.objects_url()?;
+        url.query_pairs_mut().append_pair("maxResults", "1");
+        let request = self.request(Method::GET, url, HeaderMap::new()).await?;
+        let response = self.http.send(request, NO_ERROR_CODE_HEADER).await?;
+        read_text(response, MAX_JSON_BYTES)
+            .await
+            .and_then(|body| parse_objects_list(&body))?;
+        Ok(())
+    }
+}
+
+#[derive(Debug, Deserialize)]
+#[serde(rename_all = "camelCase")]
+struct ObjectsList {
+    #[serde(default)]
+    items: Vec<ListedObject>,
+    #[serde(default)]
+    prefixes: Vec<String>,
+    #[serde(default)]
+    next_page_token: Option<String>,
+}
+
+#[derive(Debug, Deserialize)]
+#[serde(rename_all = "camelCase")]
+struct ListedObject {
+    name: String,
+    /// GCS renders the size as a decimal string, not a JSON number.
+    #[serde(default)]
+    size: Option<String>,
+    #[serde(default)]
+    updated: Option<String>,
+    #[serde(default)]
+    md5_hash: Option<String>,
+    #[serde(default)]
+    etag: Option<String>,
+    #[serde(default)]
+    storage_class: Option<String>,
+}
+
+fn parse_objects_list(body: &str) -> Result<SourcePage, SourceError> {
+    let listing: ObjectsList =
+        serde_json::from_str(body).map_err(|err| SourceError::Other(format!("source listing is not valid JSON: {err}")))?;
+    let next_continuation_token = listing.next_page_token.filter(|token| !token.is_empty());
+    let objects = listing
+        .items
+        .into_iter()
+        .map(|item| {
+            let etag = item
+                .md5_hash
+                .as_deref()
+                .and_then(base64_md5_to_hex)
+                .or_else(|| item.etag.map(|etag| etag.trim_matches('"').to_string()))
+                .filter(|etag| !etag.is_empty());
+            SourceObject {
+                key: item.name,
+                etag,
+                size: item.size.and_then(|size| size.parse().ok()).unwrap_or(0),
+                last_modified: item.updated.as_deref().and_then(parse_http_timestamp),
+                storage_class: item.storage_class,
+                // GCS never encodes a part count in a digest or an ETag.
+                is_multipart_etag: false,
+            }
+        })
+        .collect();
+
+    Ok(SourcePage {
+        objects,
+        common_prefixes: listing.prefixes,
+        is_truncated: next_continuation_token.is_some(),
+        next_continuation_token,
+    })
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::bucket::on_demand_migration::backend_contract::{BackendCapabilities, assert_backend_contract};
+    use crate::bucket::on_demand_migration::test_http_fixture::{ScriptedResponse, scripted_server};
+    use google_cloud_auth::credentials::anonymous::Builder as AnonymousBuilder;
+
+    const LIST_PAGE_ONE: &str = r#"{
+      "kind": "storage#objects",
+      "nextPageToken": "cursor-1",
+      "prefixes": ["dir/sub/"],
+      "items": [
+        {
+          "name": "dir/a.txt",
+          "size": "5",
+          "updated": "2015-10-21T07:28:00.000Z",
+          "md5Hash": "XUFAKrxLKna5cZ2REBfFkg==",
+          "etag": "CJizy9Wq0McCEAE=",
+          "storageClass": "STANDARD"
+        }
+      ]
+    }"#;
+
+    const LIST_PAGE_TWO: &str = r#"{
+      "kind": "storage#objects",
+      "items": [
+        {
+          "name": "dir/b.txt",
+          "size": "7",
+          "updated": "2015-10-21T07:28:00.000Z",
+          "etag": "\"CJizy9Wq0McCEAI=\""
+        }
+      ]
+    }"#;
+
+    fn backend(endpoint: &Url) -> GcsNativeSourceBackend {
+        GcsNativeSourceBackend {
+            http: NativeHttp::for_test(endpoint.clone()),
+            bucket: "legacy".to_string(),
+            // Anonymous credentials add no headers, so the fixture sees exactly
+            // the request this backend builds.
+            credentials: AnonymousBuilder::new().build(),
+        }
+    }
+
+    fn object_headers() -> Vec<(&'static str, String)> {
+        vec![
+            ("Content-Type", "text/plain".to_string()),
+            ("Last-Modified", "Wed, 21 Oct 2015 07:28:00 GMT".to_string()),
+            ("ETag", "\"CJizy9Wq0McCEAE=\"".to_string()),
+            ("x-goog-hash", "crc32c=AAAAAA==,md5=XUFAKrxLKna5cZ2REBfFkg==".to_string()),
+            ("x-goog-meta-owner", "alice".to_string()),
+            ("x-goog-storage-class", "STANDARD".to_string()),
+            ("x-goog-generation", "1445412480000000".to_string()),
+        ]
+    }
+
+    #[test]
+    fn objects_list_maps_items_prefixes_and_the_page_token() {
+        let page = parse_objects_list(LIST_PAGE_ONE).expect("page should parse");
+        assert_eq!(page.common_prefixes, vec!["dir/sub/"]);
+        assert!(page.is_truncated);
+        assert_eq!(page.next_continuation_token.as_deref(), Some("cursor-1"));
+        assert_eq!(page.objects.len(), 1);
+        assert_eq!(page.objects[0].key, "dir/a.txt");
+        assert_eq!(page.objects[0].size, 5, "the string size is parsed");
+        assert_eq!(
+            page.objects[0].etag.as_deref(),
+            Some("5d41402abc4b2a76b9719d911017c592"),
+            "the base64 md5Hash becomes a hex ETag"
+        );
+        assert_eq!(page.objects[0].storage_class.as_deref(), Some("STANDARD"));
+        assert!(page.objects[0].last_modified.is_some(), "RFC 3339 `updated` is parsed");
+
+        let page = parse_objects_list(LIST_PAGE_TWO).expect("page should parse");
+        assert!(!page.is_truncated);
+        assert!(page.next_continuation_token.is_none());
+        assert_eq!(
+            page.objects[0].etag.as_deref(),
+            Some("CJizy9Wq0McCEAI="),
+            "without md5Hash the raw etag is carried"
+        );
+
+        assert!(parse_objects_list("not json").is_err());
+    }
+
+    #[tokio::test]
+    async fn head_prefers_the_goog_hash_md5_over_the_etag() {
+        let (endpoint, recorded) = scripted_server(vec![ScriptedResponse::new(200, object_headers(), String::new())]).await;
+        let head = backend(&endpoint).head("dir/a b.txt").await.expect("HEAD should map");
+
+        let recorded = recorded.lock().expect("recorder lock").clone();
+        assert_eq!(recorded[0].method, "HEAD");
+        assert_eq!(recorded[0].target, "/legacy/dir/a%20b.txt", "the XML API addresses the object by path");
+        assert_eq!(
+            head.etag.as_deref(),
+            Some("5d41402abc4b2a76b9719d911017c592"),
+            "the x-goog-hash md5 is the content digest"
+        );
+        assert!(!head.etag_is_opaque, "a GCS md5 may be checked against the pulled bytes");
+        assert_eq!(head.user_metadata, HashMap::from([("owner".to_string(), "alice".to_string())]));
+        assert_eq!(head.version_id.as_deref(), Some("1445412480000000"));
+        assert_eq!(head.storage_class.as_deref(), Some("STANDARD"));
+    }
+
+    #[tokio::test]
+    async fn a_composite_object_without_an_md5_keeps_an_opaque_etag() {
+        let headers = object_headers()
+            .into_iter()
+            .map(|(name, value)| {
+                if name == "x-goog-hash" {
+                    (name, "crc32c=AAAAAA==".to_string())
+                } else {
+                    (name, value)
+                }
+            })
+            .collect();
+        let (endpoint, _) = scripted_server(vec![ScriptedResponse::new(200, headers, String::new())]).await;
+        let head = backend(&endpoint).head("composed").await.expect("HEAD should map");
+        assert_eq!(head.etag.as_deref(), Some("CJizy9Wq0McCEAE="));
+        assert!(head.etag_is_opaque, "a composite ETag describes the composition, not the bytes");
+    }
+
+    #[tokio::test]
+    async fn customer_supplied_key_objects_are_refused() {
+        let mut headers = object_headers();
+        headers.push(("x-goog-encryption-key-sha256", "abc".to_string()));
+        let (endpoint, _) = scripted_server(vec![ScriptedResponse::new(200, headers, String::new())]).await;
+        let err = backend(&endpoint)
+            .head("a.txt")
+            .await
+            .expect_err("CSEK objects are unsupported");
+        assert!(matches!(err, SourceError::Unsupported(_)), "{err:?}");
+    }
+
+    #[tokio::test]
+    async fn list_and_probe_address_the_json_api() {
+        let (endpoint, recorded) = scripted_server(vec![
+            ScriptedResponse::new(200, Vec::new(), LIST_PAGE_ONE.to_string()),
+            ScriptedResponse::new(200, Vec::new(), "{}".to_string()),
+        ])
+        .await;
+        let backend = backend(&endpoint);
+
+        backend
+            .list(&SourceListRequest {
+                prefix: Some("dir/"),
+                delimiter: Some("/"),
+                continuation_token: Some("cursor-0"),
+                max_keys: 2,
+                ..Default::default()
+            })
+            .await
+            .expect("listing should succeed");
+        backend.probe().await.expect("probe should succeed");
+
+        let recorded = recorded.lock().expect("recorder lock").clone();
+        assert!(recorded[0].target.starts_with("/storage/v1/b/legacy/o?"), "{}", recorded[0].target);
+        assert!(recorded[0].target.contains("prefix=dir%2F"), "{}", recorded[0].target);
+        assert!(recorded[0].target.contains("delimiter=%2F"), "{}", recorded[0].target);
+        assert!(recorded[0].target.contains("pageToken=cursor-0"), "{}", recorded[0].target);
+        assert!(recorded[0].target.contains("maxResults=2"), "{}", recorded[0].target);
+        assert_eq!(
+            recorded[1].target, "/storage/v1/b/legacy/o?maxResults=1",
+            "the probe uses the listing permission the pipeline already needs"
+        );
+    }
+
+    #[tokio::test]
+    async fn gcs_native_backend_satisfies_the_shared_backend_contract() {
+        let mut ranged = object_headers();
+        ranged.push(("Content-Range", "bytes 1-3/5".to_string()));
+        // A HEAD reports the object size with no body, exactly as GCS does.
+        let mut head_only = object_headers();
+        head_only.push(("Content-Length", "5".to_string()));
+        let (endpoint, _) = scripted_server(vec![
+            ScriptedResponse::new(200, head_only, String::new()),
+            ScriptedResponse::new(200, object_headers(), "hello".to_string()),
+            ScriptedResponse::new(206, ranged, "ell".to_string()),
+            ScriptedResponse::new(200, Vec::new(), LIST_PAGE_ONE.to_string()),
+            ScriptedResponse::new(200, Vec::new(), LIST_PAGE_TWO.to_string()),
+            // GCS has no tagging call, so the contract's tag step issues no
+            // request; the probe is the next one on the wire.
+            ScriptedResponse::new(200, Vec::new(), "{}".to_string()),
+            ScriptedResponse::new(404, Vec::new(), String::new()),
+            ScriptedResponse::new(403, Vec::new(), String::new()),
+        ])
+        .await;
+
+        assert_backend_contract(
+            &backend(&endpoint),
+            BackendCapabilities {
+                etag_is_opaque: false,
+                supports_start_after: false,
+                // GCS objects have no tags; the contract's tag step is skipped.
+                supports_tagging: false,
+            },
+        )
+        .await;
+    }
+}
@@ -25,13 +25,21 @@ use parking_lot::Mutex;
 use serde::{Deserialize, Serialize};
 use std::time::{Duration, Instant};

-/// The only continuation-token envelope version this build reads and writes.
+/// The continuation-token version used by ordinary progressing pages.
 pub const LIST_THROUGH_TOKEN_VERSION: u32 = 1;
+const LIST_THROUGH_PROGRESS_TOKEN_VERSION: u32 = 2;
+
+/// The sixteenth consecutive merged page without a key or new EOF fails.
+/// This also bounds legitimate sparse listings; it is not a cycle detector.
+pub const MAX_LIST_NO_PROGRESS_PAGES: u8 = 16;

 /// Envelope marker. A bucket that is *not* merging hands out the local
 /// listing's own marker, so the decoder needs a positive signal before it
 /// treats an opaque token as a merged one.
 const LIST_THROUGH_TOKEN_TAG: &str = "odm-list";
+// Object keys cannot contain NUL (bucket::utils::is_valid_object_prefix),
+// so this framing cannot collide with a local key used as an opaque marker.
+const LIST_THROUGH_TOKEN_PREFIX: &str = "\0odm-list:";

 /// Pages fetched per side per request: the first page, plus at most one refill
 /// when the first one was mostly consumed by the previous page. Two pages of
@@ -86,8 +94,7 @@ pub struct MergePick {
 }

 /// The continuation-token envelope. Opaque to clients: it is serialized as
-/// JSON and then base64-encoded by the same helper that encodes a plain local
-/// marker, so the wire shape is `base64(json)`.
+/// framed JSON and then base64-encoded by the same helper as a local marker.
 ///
 /// A `null` cursor with `done = false` means "list that side from the start";
 /// `done = true` means the side is finished and must not be listed again.
@@ -111,6 +118,10 @@ pub struct ListThroughToken {
    /// common prefix compares as itself, never as its members.
    #[serde(default)]
    pub last_key: Option<String>,
+    /// Consecutive empty truncated merged pages, present only in v2 tokens.
+    /// Ordinary v1 tokens retain their original serialized shape.
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub no_progress: Option<u8>,
 }

 impl ListThroughToken {
@@ -123,13 +134,14 @@ impl ListThroughToken {
            source: source.token,
            source_done: source.done,
            last_key,
+            no_progress: None,
        }
    }

    pub fn encode(&self) -> String {
        // The envelope is built here from owned strings, so serialization
        // cannot fail; the fallback keeps the signature infallible.
-        serde_json::to_string(self).unwrap_or_default()
+        format!("{LIST_THROUGH_TOKEN_PREFIX}{}", serde_json::to_string(self).unwrap_or_default())
    }
 }

@@ -153,24 +165,35 @@ pub enum ListThroughTokenError {

 /// Classifies an already base64-decoded continuation token.
 ///
-/// Only a JSON object carrying the envelope marker is read as a merged token;
+/// Only a framed JSON object is read as a merged token;
 /// anything else is a local marker, so a bucket that turns `list_through` off
 /// keeps paginating with the tokens it handed out. A token that *is* an
 /// envelope but was tampered with (unknown version, unknown field, truncated
 /// JSON) is an error, never a silent fallback.
 pub fn decode_continuation_token(decoded: &str) -> Result<ListThroughCursor, ListThroughTokenError> {
-    if !decoded.starts_with('{') {
-        return Ok(ListThroughCursor::Local(decoded.to_string()));
-    }
-    let Ok(value) = serde_json::from_str::<serde_json::Value>(decoded) else {
-        // Not JSON at all: an object key may legitimately start with '{'.
+    let Some(payload) = decoded.strip_prefix(LIST_THROUGH_TOKEN_PREFIX) else {
        return Ok(ListThroughCursor::Local(decoded.to_string()));
    };
+    let value = serde_json::from_str::<serde_json::Value>(payload).map_err(|_| ListThroughTokenError::Malformed)?;
    if value.get("t").and_then(serde_json::Value::as_str) != Some(LIST_THROUGH_TOKEN_TAG) {
-        return Ok(ListThroughCursor::Local(decoded.to_string()));
+        return Err(ListThroughTokenError::Malformed);
    }
    match value.get("v").and_then(serde_json::Value::as_u64) {
-        Some(version) if version == u64::from(LIST_THROUGH_TOKEN_VERSION) => {}
+        Some(version) if version == u64::from(LIST_THROUGH_TOKEN_VERSION) => {
+            // v1 readers reject this field even when it is null or zero.
+            if value.get("no_progress").is_some() {
+                return Err(ListThroughTokenError::Malformed);
+            }
+        }
+        Some(version) if version == u64::from(LIST_THROUGH_PROGRESS_TOKEN_VERSION) => {
+            if !value
+                .get("no_progress")
+                .and_then(serde_json::Value::as_u64)
+                .is_some_and(|count| (1..u64::from(MAX_LIST_NO_PROGRESS_PAGES)).contains(&count))
+            {
+                return Err(ListThroughTokenError::Malformed);
+            }
+        }
        Some(version) => return Err(ListThroughTokenError::UnsupportedVersion(version.min(u64::from(u32::MAX)) as u32)),
        None => return Err(ListThroughTokenError::Malformed),
    }
@@ -189,8 +212,8 @@ pub enum SourceListPlan {
    /// delimiter — the source's own roll-up boundary matches the request's.
    Page { prefix: String },
    /// `filter.prefix` reaches past a delimiter, so every key the source could
-    /// contribute rolls into this one common prefix. One bounded probe listing
-    /// decides whether it exists; there is nothing to paginate.
+    /// contribute rolls into this one common prefix. Bounded probes follow
+    /// empty progressing pages until a key proves existence or the source ends.
    Folded { probe_prefix: String, common_prefix: String },
 }

@@ -279,6 +302,31 @@ pub struct FetchRequest {
    pub token: Option<String>,
 }

+/// Invalid pagination metadata. Opaque cursor values are never included in errors.
+#[derive(Clone, Copy, Debug, PartialEq, Eq, thiserror::Error)]
+pub enum ListPageError {
+    #[error("truncated listing has no continuation token")]
+    Missing,
+    #[error("truncated listing has an empty continuation token")]
+    Empty,
+    #[error("truncated listing repeats a continuation token")]
+    Repeated,
+    #[error("listing exhausted its consecutive no-progress page budget")]
+    NoProgress(MergeSide),
+}
+
+pub(crate) fn validate_list_page(is_truncated: bool, token: Option<&str>, next_token: Option<&str>) -> Result<(), ListPageError> {
+    if is_truncated {
+        match next_token {
+            None => return Err(ListPageError::Missing),
+            Some("") => return Err(ListPageError::Empty),
+            Some(next) if Some(next) == token => return Err(ListPageError::Repeated),
+            Some(_) => {}
+        }
+    }
+    Ok(())
+}
+
 #[derive(Debug, Default)]
 struct SideState {
    start: SideCursor,
@@ -329,6 +377,7 @@ pub struct MergeOutcome {
 #[derive(Debug)]
 pub struct ListThroughMerger {
    max_keys: usize,
+    no_progress: Option<u8>,
    last_key: Option<String>,
    local: SideState,
    source: SideState,
@@ -348,6 +397,7 @@ impl ListThroughMerger {
        };
        Self {
            max_keys,
+            no_progress: token.and_then(|token| token.no_progress),
            last_key,
            local,
            source,
@@ -364,6 +414,11 @@ impl ListThroughMerger {
    /// or `filter.prefix` excludes it.
    pub fn disable_source(&mut self) {
        self.source.disabled = true;
+        // A refill can fail after a valid first page. A local-only response
+        // must discard both that source payload and its ordering horizon.
+        self.source.entries.clear();
+        self.source.pages.clear();
+        self.source.more = false;
    }

    pub fn next_fetch(&self) -> Option<FetchRequest> {
@@ -378,7 +433,13 @@ impl ListThroughMerger {
    /// Records one fetched page. `entries` must be sorted by `name` and already
    /// filtered with [`Self::accepts`]; the caller keeps the matching payloads
    /// in the same order.
-    pub fn push_page(&mut self, side: MergeSide, entries: Vec<ListEntryKey>, is_truncated: bool, next_token: Option<String>) {
+    pub fn push_page(
+        &mut self,
+        side: MergeSide,
+        entries: Vec<ListEntryKey>,
+        is_truncated: bool,
+        next_token: Option<String>,
+    ) -> Result<(), ListPageError> {
        let state = match side {
            MergeSide::Local => &mut self.local,
            MergeSide::Source => &mut self.source,
@@ -387,24 +448,33 @@ impl ListThroughMerger {
            Some(last) => last.next_token.clone(),
            None => state.start.token.clone(),
        };
-        // A truncated page without a cursor cannot be continued; treating the
-        // side as finished is the only alternative to looping on it forever.
-        state.more = is_truncated && next_token.is_some();
+        validate_list_page(is_truncated, token.as_deref(), next_token.as_deref())?;
+        // Also reject a cycle through an earlier page in this bounded fetch.
+        if is_truncated && state.pages.iter().any(|page| page.token == next_token) {
+            return Err(ListPageError::Repeated);
+        }
+        state.more = is_truncated;
        state.pages.push(FetchedPage {
            token,
            count: entries.len(),
            next_token: is_truncated.then_some(next_token).flatten(),
        });
        state.entries.extend(entries);
+        Ok(())
    }

-    pub fn finish(self) -> MergeOutcome {
+    /// `issue_progress_tokens` allows a v1 chain to start carrying a budget.
+    /// An existing v2 budget is always enforced, including on reader-only nodes.
+    /// Borrowing lets a source failure re-merge the fetched local buffers.
+    pub fn finish(&self, issue_progress_tokens: bool) -> Result<MergeOutcome, ListPageError> {
        let Self {
            max_keys,
+            no_progress,
            last_key,
            local,
            source,
        } = self;
+        let max_keys = *max_keys;

        // A side with more pages behind it can only be trusted up to the last
        // key it handed over: past that horizon the other side's entries could
@@ -470,12 +540,44 @@ impl ListThroughMerger {
        let source_left = !source.disabled && (!source_cursor.done || consumed_source < source.entries.len());
        let is_truncated = local_left || source_left;

-        let last_key = consumed_key.or(last_key);
-        MergeOutcome {
+        let reached_eof = (!local.start.done && local_cursor.done) || (!source.start.done && source_cursor.done);
+        let next_no_progress = if !is_truncated || !picks.is_empty() || reached_eof {
+            None
+        } else if max_keys == 0 {
+            // A zero-sized request cannot consume entries. Preserve an existing
+            // budget without spending it or starting a new one.
+            *no_progress
+        } else if issue_progress_tokens || no_progress.is_some() {
+            let count = no_progress.unwrap_or(0).saturating_add(1);
+            if count >= MAX_LIST_NO_PROGRESS_PAGES {
+                // An empty truncated side closes the merge horizon. Local
+                // failure takes precedence; disabling the source cannot fix it.
+                let side = if local.more && local.entries.is_empty() {
+                    MergeSide::Local
+                } else if !source.disabled && source.more && source.entries.is_empty() {
+                    MergeSide::Source
+                } else {
+                    MergeSide::Local
+                };
+                return Err(ListPageError::NoProgress(side));
+            }
+            Some(count)
+        } else {
+            None
+        };
+        let last_key = consumed_key.or_else(|| last_key.clone());
+        Ok(MergeOutcome {
            picks,
            is_truncated,
-            next_token: is_truncated.then(|| ListThroughToken::new(local_cursor, source_cursor, last_key)),
-        }
+            next_token: is_truncated.then(|| {
+                let mut token = ListThroughToken::new(local_cursor, source_cursor, last_key);
+                if let Some(count) = next_no_progress {
+                    token.v = LIST_THROUGH_PROGRESS_TOKEN_VERSION;
+                    token.no_progress = Some(count);
+                }
+                token
+            }),
+        })
    }
 }

@@ -599,9 +701,15 @@ mod tests {
                let (entries, truncated, next) = reference_page(keys, prefix, delimiter, fetch.token.as_deref(), max_keys);
                let kept: Vec<ListEntryKey> = entries.into_iter().filter(|entry| merger.accepts(&entry.name)).collect();
                buffers[usize::from(fetch.side == MergeSide::Source)].extend(kept.iter().cloned());
-                merger.push_page(fetch.side, kept, truncated, next);
+                merger
+                    .push_page(fetch.side, kept, truncated, next)
+                    .expect("reference provider pages must advance");
+            }
+            let outcome = merger.finish(false).expect("valid merge outcome");
+            assert_eq!(outcome.is_truncated, outcome.next_token.is_some());
+            if outcome.is_truncated {
+                assert_ne!(outcome.next_token, token, "every truncated merged page must make progress");
            }
-            let outcome = merger.finish();
            page_sizes.push(outcome.picks.len());
            for pick in &outcome.picks {
                let entry = buffers[usize::from(pick.side == MergeSide::Source)][pick.index].clone();
@@ -616,11 +724,25 @@ mod tests {
    }

    fn expected(local: &[String], source: &[String], prefix: &str, delimiter: Option<&str>) -> Vec<ListEntryKey> {
-        let mut all: Vec<String> = local.iter().chain(source.iter()).cloned().collect();
-        all.sort();
-        all.dedup();
-        let (entries, _, _) = reference_page(&all, prefix, delimiter, None, usize::MAX);
-        entries
+        // This oracle builds the complete namespace independently of the
+        // provider's page/marker helper and the production merger.
+        let mut namespace = std::collections::BTreeMap::new();
+        for key in local.iter().chain(source) {
+            let Some(suffix) = key.strip_prefix(prefix) else {
+                continue;
+            };
+            if let Some(delimiter) = delimiter.filter(|delimiter| !delimiter.is_empty())
+                && let Some((directory, _)) = suffix.split_once(delimiter)
+            {
+                namespace.insert(format!("{prefix}{directory}{delimiter}"), true);
+                continue;
+            }
+            namespace.insert(key.clone(), false);
+        }
+        namespace
+            .into_iter()
+            .map(|(name, is_prefix)| ListEntryKey { name, is_prefix })
+            .collect()
    }

    #[test]
@@ -662,9 +784,11 @@ mod tests {
                token: None
            })
        );
-        merger.push_page(MergeSide::Local, vec![ListEntryKey::object("a")], false, None);
+        merger
+            .push_page(MergeSide::Local, vec![ListEntryKey::object("a")], false, None)
+            .expect("local EOF is valid");
        assert_eq!(merger.next_fetch(), None);
-        let outcome = merger.finish();
+        let outcome = merger.finish(false).expect("valid merge outcome");
        assert_eq!(outcome.picks.len(), 1);
        assert!(!outcome.is_truncated);
        assert!(outcome.next_token.is_none());
@@ -680,16 +804,19 @@ mod tests {
            source: Some("source-1".to_string()),
            source_done: false,
            last_key: Some("a".to_string()),
+            no_progress: None,
        };
        let mut merger = ListThroughMerger::new(1, Some(&resume));
        merger.disable_source();
-        merger.push_page(
-            MergeSide::Local,
-            vec![ListEntryKey::object("b"), ListEntryKey::object("c")],
-            true,
-            Some("local-2".to_string()),
-        );
-        let outcome = merger.finish();
+        merger
+            .push_page(
+                MergeSide::Local,
+                vec![ListEntryKey::object("b"), ListEntryKey::object("c")],
+                true,
+                Some("local-2".to_string()),
+            )
+            .expect("local cursor advances");
+        let outcome = merger.finish(false).expect("valid merge outcome");
        assert!(outcome.is_truncated);
        let token = outcome.next_token.expect("truncated page carries a token");
        assert_eq!(token.source.as_deref(), Some("source-1"), "the source cursor must not move");
@@ -698,6 +825,212 @@ mod tests {
        assert_eq!(token.local.as_deref(), Some("local-1"), "a partly read page is re-listed");
    }

+    #[test]
+    fn truncated_pages_require_a_nonempty_advancing_cursor() {
+        for side in [MergeSide::Local, MergeSide::Source] {
+            for entries in [vec![], vec![ListEntryKey::object("a")]] {
+                for (next, expected) in [
+                    (None, Err(ListPageError::Missing)),
+                    (Some(""), Err(ListPageError::Empty)),
+                    (Some("stuck"), Err(ListPageError::Repeated)),
+                    (Some("advances"), Ok(())),
+                ] {
+                    let resume = ListThroughToken::new(
+                        SideCursor {
+                            token: Some("stuck".into()),
+                            done: false,
+                        },
+                        SideCursor {
+                            token: Some("stuck".into()),
+                            done: false,
+                        },
+                        None,
+                    );
+                    let mut merger = ListThroughMerger::new(2, Some(&resume));
+                    let result = merger.push_page(side, entries.clone(), true, next.map(str::to_string));
+                    assert_eq!(result, expected, "{side:?}, {entries:?}, {next:?}");
+                    let state = if side == MergeSide::Local {
+                        &merger.local
+                    } else {
+                        &merger.source
+                    };
+                    assert_eq!(state.pages.len(), usize::from(result.is_ok()), "invalid page must not be accepted");
+                }
+            }
+        }
+    }
+
+    #[test]
+    fn repeated_empty_cursor_is_rejected_before_an_identical_page_can_escape() {
+        let resume = ListThroughToken::new(
+            SideCursor { token: None, done: true },
+            SideCursor {
+                token: Some("stuck".into()),
+                done: false,
+            },
+            None,
+        );
+        let mut merger = ListThroughMerger::new(2, Some(&resume));
+        assert_eq!(
+            merger.next_fetch(),
+            Some(FetchRequest {
+                side: MergeSide::Source,
+                token: Some("stuck".into())
+            })
+        );
+        assert_eq!(
+            merger.push_page(MergeSide::Source, vec![], true, Some("stuck".into())),
+            Err(ListPageError::Repeated)
+        );
+    }
+
+    #[test]
+    fn empty_pages_may_advance_within_the_fetch_budget_until_eof() {
+        let mut merger = ListThroughMerger::new(2, None);
+        merger.push_page(MergeSide::Local, vec![], false, None).expect("local EOF");
+        for next in ["opaque-z", "opaque-a"] {
+            assert_eq!(merger.next_fetch().expect("bounded source fetch").side, MergeSide::Source);
+            merger
+                .push_page(MergeSide::Source, vec![], true, Some(next.into()))
+                .expect("opaque cursor advances regardless of sort order");
+        }
+        assert!(merger.next_fetch().is_none(), "two source fetches exhaust the request budget");
+        let outcome = merger.finish(false).expect("valid merge outcome");
+        assert!(outcome.picks.is_empty());
+        assert!(outcome.is_truncated);
+        let token = outcome.next_token.expect("empty progressing page has a cursor");
+        assert_eq!(token.source.as_deref(), Some("opaque-a"));
+        let mut merger = ListThroughMerger::new(2, Some(&token));
+        assert_eq!(merger.next_fetch().expect("source resumes").token.as_deref(), Some("opaque-a"));
+        merger
+            .push_page(MergeSide::Source, vec![ListEntryKey::object("result")], false, None)
+            .expect("source EOF");
+        let outcome = merger.finish(false).expect("valid merge outcome");
+        assert_eq!(
+            outcome.picks,
+            vec![MergePick {
+                side: MergeSide::Source,
+                index: 0
+            }]
+        );
+        assert!(!outcome.is_truncated);
+        assert!(outcome.next_token.is_none());
+    }
+
+    #[test]
+    fn a_cursor_cycle_inside_the_fetch_budget_is_rejected() {
+        let resume = ListThroughToken::new(
+            SideCursor { token: None, done: true },
+            SideCursor {
+                token: Some("first".into()),
+                done: false,
+            },
+            None,
+        );
+        let mut merger = ListThroughMerger::new(2, Some(&resume));
+        merger
+            .push_page(MergeSide::Source, vec![], true, Some("second".into()))
+            .expect("first page advances");
+        assert_eq!(
+            merger.push_page(MergeSide::Source, vec![], true, Some("first".into())),
+            Err(ListPageError::Repeated)
+        );
+    }
+
+    #[test]
+    fn source_refill_failure_discards_buffered_source_entries_and_horizon() {
+        let mut merger = ListThroughMerger::new(2, None);
+        merger
+            .push_page(MergeSide::Local, vec![ListEntryKey::object("z")], false, None)
+            .expect("local EOF");
+        merger
+            .push_page(MergeSide::Source, vec![ListEntryKey::object("a")], true, Some("stuck".into()))
+            .expect("first source page advances");
+        assert_eq!(merger.next_fetch().expect("source refill is required").token.as_deref(), Some("stuck"));
+        assert_eq!(
+            merger.push_page(MergeSide::Source, vec![], true, Some("stuck".into())),
+            Err(ListPageError::Repeated)
+        );
+        merger.disable_source();
+        let outcome = merger.finish(false).expect("valid merge outcome");
+        assert_eq!(
+            outcome.picks,
+            vec![MergePick {
+                side: MergeSide::Local,
+                index: 0
+            }]
+        );
+        assert!(!outcome.is_truncated);
+        assert!(outcome.next_token.is_none());
+    }
+
+    #[test]
+    fn list_through_static_namespace_boundary_matrix() {
+        let corpus = [
+            "a",
+            "a/",
+            "a/b",
+            "a/b/child",
+            "a0",
+            "b",
+            "b/leaf",
+            "quote\"&<",
+            "space key",
+            "z",
+            "é",
+            "中/文",
+        ];
+        for count in [0, 1, 3, 4, corpus.len()] {
+            let keys: Vec<String> = corpus[..count].iter().map(|key| (*key).to_string()).collect();
+            for placement in 0..3 {
+                let (local, source): (Vec<_>, Vec<_>) =
+                    keys.iter()
+                        .enumerate()
+                        .fold((vec![], vec![]), |(mut local, mut source), (index, key)| {
+                            if placement != 1 || index % 2 == 0 {
+                                local.push(key.clone());
+                            }
+                            if placement != 0 || index % 2 == 0 {
+                                source.push(key.clone());
+                            }
+                            (local, source)
+                        });
+                for prefix in ["", "a", "a/", "中/"] {
+                    for delimiter in [None, Some("/")] {
+                        for max_keys in [1, 3, 4] {
+                            let oracle = expected(&local, &source, prefix, delimiter);
+                            let (emitted, sizes) = walk(&local, &source, prefix, delimiter, max_keys);
+                            assert_eq!(
+                                emitted.iter().map(|(entry, _)| entry.clone()).collect::<Vec<_>>(),
+                                oracle,
+                                "count={count}, placement={placement}, prefix={prefix}, delimiter={delimiter:?}, max={max_keys}"
+                            );
+                            let expected_sizes: Vec<_> = if oracle.is_empty() {
+                                vec![0]
+                            } else {
+                                oracle.chunks(max_keys).map(<[ListEntryKey]>::len).collect()
+                            };
+                            assert_eq!(sizes, expected_sizes, "exact max and max+1 boundaries must agree");
+                        }
+                    }
+                }
+            }
+        }
+    }
+
+    #[test]
+    fn list_through_large_overlap_walk_keeps_all_5300_keys() {
+        let source: Vec<_> = (0..5000).map(|index| format!("k{index:05}")).collect();
+        let local: Vec<_> = (4800..5300).map(|index| format!("k{index:05}")).collect();
+        let (emitted, sizes) = walk(&local, &source, "", None, 333);
+        assert_eq!(emitted.len(), 5300);
+        for (index, (entry, side)) in emitted.iter().enumerate() {
+            assert_eq!(entry.name, format!("k{index:05}"));
+            assert_eq!(*side, if index >= 4800 { MergeSide::Local } else { MergeSide::Source });
+        }
+        assert_eq!(sizes, [vec![333; 15], vec![305]].concat());
+    }
+
    #[test]
    fn token_round_trips_and_rejects_tampering() {
        let token = ListThroughToken::new(
@@ -711,21 +1044,279 @@ mod tests {
        let encoded = token.encode();
        assert_eq!(decode_continuation_token(&encoded), Ok(ListThroughCursor::Merged(Box::new(token))));

-        let bumped = encoded.replace("\"v\":1", "\"v\":2");
-        assert_eq!(decode_continuation_token(&bumped), Err(ListThroughTokenError::UnsupportedVersion(2)));
+        let bumped = encoded.replace("\"v\":1", "\"v\":3");
+        assert_eq!(decode_continuation_token(&bumped), Err(ListThroughTokenError::UnsupportedVersion(3)));

        let extra = encoded.replace("{", "{\"x\":1,");
        assert_eq!(decode_continuation_token(&extra), Err(ListThroughTokenError::Malformed));

        let truncated = &encoded[..encoded.len() - 3];
-        assert_eq!(decode_continuation_token(truncated), Ok(ListThroughCursor::Local(truncated.to_string())));
+        assert_eq!(decode_continuation_token(truncated), Err(ListThroughTokenError::Malformed));

-        let no_version = "{\"t\":\"odm-list\"}";
+        let no_version = "\0odm-list:{\"t\":\"odm-list\"}";
        assert_eq!(decode_continuation_token(no_version), Err(ListThroughTokenError::Malformed));
    }

+    fn progress_token(count: Option<u8>, local_done: bool, source_done: bool) -> ListThroughToken {
+        let mut token = ListThroughToken::new(
+            SideCursor {
+                token: None,
+                done: local_done,
+            },
+            SideCursor {
+                token: Some("A".into()),
+                done: source_done,
+            },
+            Some("last-key".into()),
+        );
+        if let Some(count) = count {
+            token.v = LIST_THROUGH_PROGRESS_TOKEN_VERSION;
+            token.no_progress = Some(count);
+        }
+        token
+    }
+
+    fn push_empty_pages(merger: &mut ListThroughMerger, side: MergeSide) {
+        for _ in 0..MAX_LIST_FETCHES_PER_SIDE {
+            let fetch = merger.next_fetch().expect("empty truncated side must be fetched");
+            assert_eq!(fetch.side, side);
+            let next = format!("{}:next", fetch.token.unwrap_or_default());
+            merger
+                .push_page(side, vec![], true, Some(next))
+                .expect("opaque cursor advances");
+        }
+    }
+
+    #[test]
+    fn progress_tokens_preserve_v1_bytes_and_validate_v2_counts() {
+        let token = progress_token(None, true, false);
+        assert_eq!(
+            token.encode(),
+            r#"{"t":"odm-list","v":1,"local":null,"local_done":true,"source":"A","source_done":false,"last_key":"last-key"}"#
+        );
+        for count in 1..MAX_LIST_NO_PROGRESS_PAGES {
+            let token = progress_token(Some(count), true, false);
+            assert_eq!(decode_continuation_token(&token.encode()), Ok(ListThroughCursor::Merged(Box::new(token))));
+        }
+        for version in [1, 2] {
+            for value in ["null", "0", "16", "-1", "1.5", "256", "18446744073709551616", "\"1\""] {
+                let encoded = format!(r#"{{"t":"odm-list","v":{version},"no_progress":{value}}}"#);
+                assert_eq!(decode_continuation_token(&encoded), Err(ListThroughTokenError::Malformed), "{encoded}");
+            }
+        }
+        for encoded in [
+            r#"{"t":"odm-list","v":1,"no_progress":1}"#,
+            r#"{"t":"odm-list","v":2}"#,
+            r#"{"t":"odm-list","v":2,"no_progress":1,"extra":true}"#,
+        ] {
+            assert_eq!(decode_continuation_token(encoded), Err(ListThroughTokenError::Malformed), "{encoded}");
+        }
+    }
+
+    #[test]
+    fn reader_only_nodes_do_not_start_a_budget_but_mixed_readers_preserve_one() {
+        let mut token = progress_token(None, true, false);
+        for _ in 0..MAX_LIST_NO_PROGRESS_PAGES {
+            let mut merger = ListThroughMerger::new(2, Some(&token));
+            push_empty_pages(&mut merger, MergeSide::Source);
+            token = merger
+                .finish(false)
+                .expect("reader-only v1 behavior")
+                .next_token
+                .expect("truncated cursor");
+            assert_eq!(token.v, 1);
+            assert_eq!(token.no_progress, None);
+        }
+        for count in 1..=MAX_LIST_NO_PROGRESS_PAGES {
+            let mut merger = ListThroughMerger::new(2, Some(&token));
+            push_empty_pages(&mut merger, MergeSide::Source);
+            assert!(merger.next_fetch().is_none(), "the per-request two-fetch limit stays intact");
+            let outcome = merger.finish(count % 2 == 1);
+            if count == MAX_LIST_NO_PROGRESS_PAGES {
+                assert_eq!(outcome, Err(ListPageError::NoProgress(MergeSide::Source)));
+                break;
+            }
+            token = outcome.expect("budget not exhausted").next_token.expect("truncated cursor");
+            assert_eq!(token.no_progress, Some(count));
+            let ListThroughCursor::Merged(decoded) = decode_continuation_token(&token.encode()).expect("round-trip v2") else {
+                panic!("merged cursor expected");
+            };
+            token = *decoded;
+        }
+    }
+
+    #[test]
+    fn objects_and_common_prefixes_reset_a_budget_at_the_boundary() {
+        for entry in [ListEntryKey::object("result"), ListEntryKey::prefix("result/")] {
+            for issue_tokens in [false, true] {
+                let resume = progress_token(Some(MAX_LIST_NO_PROGRESS_PAGES - 1), true, false);
+                let mut merger = ListThroughMerger::new(2, Some(&resume));
+                merger
+                    .push_page(MergeSide::Source, vec![], true, Some("B".into()))
+                    .expect("empty advancing page");
+                merger
+                    .push_page(MergeSide::Source, vec![entry.clone()], true, Some("C".into()))
+                    .expect("real progress");
+                let outcome = merger
+                    .finish(issue_tokens)
+                    .expect("real progress does not exhaust the budget");
+                assert_eq!(
+                    outcome.picks,
+                    vec![MergePick {
+                        side: MergeSide::Source,
+                        index: 0
+                    }]
+                );
+                let next = outcome.next_token.expect("source remains truncated");
+                assert_eq!(next.last_key.as_deref(), Some(entry.name.as_str()));
+                assert_eq!(next.v, 1);
+                assert_eq!(next.no_progress, None);
+                assert!(!next.encode().contains("no_progress"));
+            }
+        }
+    }
+
+    #[test]
+    fn only_a_new_eof_transition_resets_the_empty_page_budget() {
+        for finished_side in [MergeSide::Local, MergeSide::Source] {
+            let resume = progress_token(Some(MAX_LIST_NO_PROGRESS_PAGES - 1), false, false);
+            let mut merger = ListThroughMerger::new(2, Some(&resume));
+            if finished_side == MergeSide::Local {
+                merger
+                    .push_page(MergeSide::Local, vec![], false, None)
+                    .expect("new local EOF");
+                push_empty_pages(&mut merger, MergeSide::Source);
+            } else {
+                push_empty_pages(&mut merger, MergeSide::Local);
+                merger
+                    .push_page(MergeSide::Source, vec![], false, None)
+                    .expect("new source EOF");
+            }
+            let next = merger
+                .finish(false)
+                .expect("new EOF is progress")
+                .next_token
+                .expect("other side truncated");
+            assert_eq!(next.no_progress, None);
+            assert_eq!(next.v, 1);
+            assert_eq!(next.local_done, finished_side == MergeSide::Local);
+            assert_eq!(next.source_done, finished_side == MergeSide::Source);
+            let mut merger = ListThroughMerger::new(2, Some(&next));
+            let remaining = if finished_side == MergeSide::Local {
+                MergeSide::Source
+            } else {
+                MergeSide::Local
+            };
+            push_empty_pages(&mut merger, remaining);
+            let next = merger
+                .finish(true)
+                .expect("a new budget starts")
+                .next_token
+                .expect("truncated");
+            assert_eq!(next.no_progress, Some(1), "an already-done side cannot reset every page");
+        }
+        let resume = progress_token(Some(MAX_LIST_NO_PROGRESS_PAGES - 1), true, false);
+        let mut merger = ListThroughMerger::new(2, Some(&resume));
+        merger.push_page(MergeSide::Source, vec![], false, None).expect("final EOF");
+        let outcome = merger.finish(false).expect("EOF succeeds at the budget boundary");
+        assert!(!outcome.is_truncated);
+        assert!(outcome.next_token.is_none());
+    }
+
+    #[test]
+    fn filtered_duplicates_cannot_reset_the_no_progress_budget() {
+        let resume = progress_token(Some(MAX_LIST_NO_PROGRESS_PAGES - 1), true, false);
+        let mut merger = ListThroughMerger::new(2, Some(&resume));
+        for next in ["B", "C"] {
+            let entries = [ListEntryKey::object("last-key"), ListEntryKey::object("earlier")]
+                .into_iter()
+                .filter(|entry| merger.accepts(&entry.name))
+                .collect::<Vec<_>>();
+            assert!(entries.is_empty(), "both provider entries were already consumed");
+            merger
+                .push_page(MergeSide::Source, entries, true, Some(next.into()))
+                .expect("advancing cursor");
+        }
+        assert_eq!(merger.finish(false), Err(ListPageError::NoProgress(MergeSide::Source)));
+    }
+
+    #[test]
+    fn no_progress_is_attributed_to_local_when_source_cannot_unblock_it() {
+        for source_mode in ["disabled", "done", "empty", "data"] {
+            let resume = progress_token(Some(MAX_LIST_NO_PROGRESS_PAGES - 1), false, source_mode == "done");
+            let mut merger = ListThroughMerger::new(2, Some(&resume));
+            if source_mode == "disabled" {
+                merger.disable_source();
+            }
+            push_empty_pages(&mut merger, MergeSide::Local);
+            match source_mode {
+                "empty" => push_empty_pages(&mut merger, MergeSide::Source),
+                "data" => merger
+                    .push_page(MergeSide::Source, vec![ListEntryKey::object("source")], false, None)
+                    .expect("source data"),
+                _ => {}
+            }
+            assert_eq!(merger.finish(false), Err(ListPageError::NoProgress(MergeSide::Local)), "{source_mode}");
+        }
+    }
+
+    #[test]
+    fn source_budget_failure_remerges_local_objects_and_prefixes_without_refetching() {
+        let resume = progress_token(Some(MAX_LIST_NO_PROGRESS_PAGES - 1), false, false);
+        let mut merger = ListThroughMerger::new(2, Some(&resume));
+        merger
+            .push_page(MergeSide::Local, vec![ListEntryKey::object("local")], true, Some("L1".into()))
+            .expect("local object");
+        merger
+            .push_page(MergeSide::Local, vec![ListEntryKey::prefix("prefix/")], true, Some("L2".into()))
+            .expect("local prefix");
+        push_empty_pages(&mut merger, MergeSide::Source);
+        assert_eq!(merger.finish(false), Err(ListPageError::NoProgress(MergeSide::Source)));
+        merger.disable_source();
+        assert!(merger.next_fetch().is_none(), "fallback does not perform another fetch");
+        let outcome = merger.finish(false).expect("local data makes progress");
+        assert_eq!(
+            outcome.picks,
+            vec![
+                MergePick {
+                    side: MergeSide::Local,
+                    index: 0
+                },
+                MergePick {
+                    side: MergeSide::Local,
+                    index: 1
+                }
+            ]
+        );
+        let token = outcome.next_token.expect("remaining local page");
+        assert_eq!(token.local.as_deref(), Some("L2"));
+        assert_eq!(token.source.as_deref(), Some("A"));
+        assert_eq!(token.last_key.as_deref(), Some("prefix/"));
+        assert_eq!(token.no_progress, None);
+        assert_eq!(token.v, 1);
+    }
+
+    #[test]
+    fn a_zero_sized_merge_preserves_an_existing_budget() {
+        let resume = progress_token(Some(MAX_LIST_NO_PROGRESS_PAGES - 1), true, false);
+        let mut merger = ListThroughMerger::new(0, Some(&resume));
+        merger
+            .push_page(MergeSide::Source, vec![ListEntryKey::object("result")], true, Some("B".into()))
+            .expect("source page");
+        let outcome = merger.finish(false).expect("a zero-sized request cannot consume entries");
+        assert!(outcome.picks.is_empty());
+        assert_eq!(outcome.next_token.expect("unconsumed source").no_progress, resume.no_progress);
+    }
+
    #[test]
    fn a_plain_local_marker_stays_local() {
+        for marker in [
+            r#"{"t":"odm-list","v":1}"#,
+            r#"{"t":"odm-list","v":2,"local_done":true}"#,
+            r#"{"t":"odm-list"}"#,
+        ] {
+            assert_eq!(decode_continuation_token(marker), Ok(ListThroughCursor::Local(marker.to_string())));
+        }
        assert_eq!(
            decode_continuation_token("photos/2024/01.jpg"),
            Ok(ListThroughCursor::Local("photos/2024/01.jpg".to_string()))
@@ -796,7 +1387,10 @@ mod tests {
    }

    proptest! {
-        #![proptest_config(ProptestConfig::with_cases(256))]
+        #![proptest_config(ProptestConfig {
+            rng_seed: proptest::test_runner::RngSeed::Fixed(0xec5706),
+            ..ProptestConfig::with_cases(256)
+        })]

        /// Full pagination of a merged listing equals the sorted, deduplicated
        /// union of both sides, with every shared key served by local, and no
@@ -19,30 +19,42 @@
 //! client, and the per-node runtime (`sys`) that turns configs into live
 //! clients guarded by a breaker, a negative cache, singleflight and a pull
 //! concurrency limit (rustfs/backlog#2147).
+//!
+//! A source is reached through one `SourceBackend`: the S3 dialect for every
+//! S3-compatible provider, and a native backend for the providers that have no
+//! S3 API (`azure`, `gcs_native`).

+pub mod azure;
+#[cfg(test)]
+mod backend_contract;
 pub mod backfill;
 pub mod breaker;
 pub mod config;
+pub mod gcs;
 pub mod list_through;
+mod native_http;
 pub mod negative_cache;
 pub mod pull;
 pub mod source_client;
 pub mod stats;
 pub mod sys;
+#[cfg(test)]
+mod test_http_fixture;

 pub use breaker::{
    BREAKER_FAILURE_THRESHOLD, BREAKER_FAILURE_WINDOW, BREAKER_HALF_OPEN_MAX_PROBES, BREAKER_OPEN_DURATION, Breaker,
    BreakerState, BreakerTransition, BreakerVerdict,
 };
 pub use config::{
-    ConfigPublishHook, FilterConfig, HeadPolicy, ON_DEMAND_MIGRATION_CONFIG_HOOK, ON_DEMAND_MIGRATION_CONFIG_VERSION,
-    OnDemandMigrationConfig, OnDemandMigrationConfigError, PathStyle, PolicyConfig, Provider, RangeGetPolicy, SourceConfig,
-    SourceCredentials, SourceErrorPolicy, SourceTimeout, TlsConfig, ValidationContext,
+    AzureSourceConfig, ConfigPublishHook, FilterConfig, GcsSourceConfig, HeadPolicy, ON_DEMAND_MIGRATION_CONFIG_HOOK,
+    ON_DEMAND_MIGRATION_CONFIG_VERSION, OnDemandMigrationConfig, OnDemandMigrationConfigError, PathStyle, PolicyConfig, Provider,
+    RangeGetPolicy, SourceConfig, SourceCredentials, SourceErrorPolicy, SourceTimeout, TlsConfig, ValidationContext,
 };
 pub use list_through::{
-    FetchRequest, LIST_THROUGH_TOKEN_VERSION, ListEntryKey, ListThroughCursor, ListThroughMerger, ListThroughToken,
-    ListThroughTokenError, MAX_LIST_FETCHES_PER_SIDE, MergeOutcome, MergePick, MergeSide, SOURCE_LIST_MAX_RATE_WAIT,
-    SOURCE_LIST_RATE_PER_SEC, SourceListPlan, SourceListRateLimiter, decode_continuation_token, source_list_plan,
+    FetchRequest, LIST_THROUGH_TOKEN_VERSION, ListEntryKey, ListPageError, ListThroughCursor, ListThroughMerger,
+    ListThroughToken, ListThroughTokenError, MAX_LIST_FETCHES_PER_SIDE, MAX_LIST_NO_PROGRESS_PAGES, MergeOutcome, MergePick,
+    MergeSide, SOURCE_LIST_MAX_RATE_WAIT, SOURCE_LIST_RATE_PER_SEC, SourceListPlan, SourceListRateLimiter,
+    decode_continuation_token, source_list_plan,
 };
 pub use negative_cache::{NEGATIVE_CACHE_MAX_ENTRIES, NegativeCache};
 pub use pull::{
@@ -56,5 +68,6 @@ pub use stats::{
 };
 pub use sys::{
    ApplyOutcome, BucketOdmState, GLOBAL_ON_DEMAND_MIGRATION_SYS, OdmBucketSnapshot, OdmLookup, OdmStateError,
-    OnDemandMigrationSys, PullError, PullFollower, PullLeader, PullOutcome, PullResult, PullSlot, source_client_spec,
+    OnDemandMigrationSys, PullError, PullFollower, PullLeader, PullOutcome, PullResult, PullSlot, source_backend_spec,
+    source_client_spec,
 };
@@ -0,0 +1,415 @@
+// Copyright 2024 RustFS Team
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//! Shared HTTP transport for the on-demand migration source backends that do
+//! not speak S3 (Azure Blob, native GCS).
+//!
+//! The S3 backend rides the AWS SDK; these providers have no SigV4 dialect, so
+//! they talk plain HTTP through one `reqwest` client that carries the same
+//! connect/read timeouts and TLS policy the operator configured for the source.
+//! Redirects are refused: the endpoint passed the outbound policy gate once, and
+//! following a source-chosen `Location` would leave that gate behind.
+//!
+//! Errors never render the request URL. A SAS token lives in the query string,
+//! so a `reqwest` error rendered with its URL would print the credential into
+//! the log line and the admin response.
+
+use super::source_client::{SourceError, SourceHead, SourceTimeouts, USER_AGENT_SUFFIX, classify_status, is_multipart_etag};
+use crate::bucket::remote_s3_client::{RemoteS3ClientError, validate_remote_endpoint, validate_target_ca_pem};
+use aws_sdk_s3::primitives::ByteStream;
+use aws_smithy_types::body::SdkBody;
+use futures::StreamExt;
+use http::HeaderMap;
+use std::collections::HashMap;
+use std::time::SystemTime;
+use time::OffsetDateTime;
+use time::format_description::well_known::{Rfc2822, Rfc3339};
+use url::Url;
+
+/// Origin the native backends are allowed to address, plus the HTTP client
+/// that reaches it.
+pub(super) struct NativeHttp {
+    client: reqwest::Client,
+    endpoint: Url,
+}
+
+impl NativeHttp {
+    /// `endpoint` must be a bare `scheme://host[:port]` origin; it is checked
+    /// against the outbound policy exactly like an S3 source endpoint.
+    pub(super) fn new(
+        endpoint: &str,
+        timeouts: SourceTimeouts,
+        skip_tls_verify: bool,
+        ca_cert_pem: Option<&str>,
+    ) -> Result<Self, RemoteS3ClientError> {
+        let endpoint = Url::parse(endpoint.trim()).map_err(|err| RemoteS3ClientError::InvalidEndpoint(err.to_string()))?;
+        if !matches!(endpoint.scheme(), "http" | "https") {
+            return Err(RemoteS3ClientError::InvalidEndpoint(format!(
+                "unsupported scheme {}; expected http or https",
+                endpoint.scheme()
+            )));
+        }
+        if endpoint.host_str().is_none_or(str::is_empty) {
+            return Err(RemoteS3ClientError::InvalidEndpoint("endpoint has no host".to_string()));
+        }
+        if !endpoint.username().is_empty() || endpoint.password().is_some() {
+            return Err(RemoteS3ClientError::InvalidEndpoint("endpoint must not carry userinfo".to_string()));
+        }
+        if !matches!(endpoint.path(), "" | "/") || endpoint.query().is_some() || endpoint.fragment().is_some() {
+            return Err(RemoteS3ClientError::InvalidEndpoint(
+                "endpoint must be an origin without path, query or fragment".to_string(),
+            ));
+        }
+        validate_remote_endpoint(&endpoint).map_err(RemoteS3ClientError::EndpointNotAllowed)?;
+
+        let mut builder = reqwest::Client::builder()
+            .connect_timeout(timeouts.connect)
+            .read_timeout(timeouts.read)
+            .redirect(reqwest::redirect::Policy::none())
+            .user_agent(USER_AGENT_SUFFIX);
+        if skip_tls_verify {
+            builder = builder.danger_accept_invalid_certs(true);
+        } else if let Some(pem) = ca_cert_pem.map(str::trim).filter(|pem| !pem.is_empty()) {
+            // Reject a malformed bundle the same way the S3 path does, so the
+            // operator sees "invalid CA PEM" instead of a TLS handshake failure.
+            validate_target_ca_pem(pem)?;
+            let certificate = reqwest::Certificate::from_pem(pem.as_bytes())
+                .map_err(|err| RemoteS3ClientError::InvalidCaPem(err.to_string()))?;
+            builder = builder.add_root_certificate(certificate);
+        }
+
+        let client = builder
+            .build()
+            .map_err(|err| RemoteS3ClientError::InvalidEndpoint(format!("http client cannot be built: {err}")))?;
+        Ok(Self { client, endpoint })
+    }
+
+    #[cfg(test)]
+    pub(super) fn for_test(endpoint: Url) -> Self {
+        Self {
+            client: reqwest::Client::builder()
+                .redirect(reqwest::redirect::Policy::none())
+                .build()
+                .expect("test http client should build"),
+            endpoint,
+        }
+    }
+
+    /// A URL under the endpoint origin. `segments` are percent-encoded as
+    /// path segments, so a key containing `?`, `#` or a space cannot rewrite
+    /// the request target.
+    pub(super) fn url<'a>(&self, segments: impl IntoIterator<Item = &'a str>) -> Result<Url, SourceError> {
+        let mut url = self.endpoint.clone();
+        {
+            let mut path = url
+                .path_segments_mut()
+                .map_err(|_| SourceError::Other("source endpoint cannot carry a path".to_string()))?;
+            path.clear();
+            path.extend(segments);
+        }
+        Ok(url)
+    }
+
+    /// Sends the request and returns the response only for a 2xx status.
+    /// Non-2xx statuses are classified from the status and the provider's own
+    /// error-code header; response bodies are not read, so no provider message
+    /// can smuggle credentials or markup into a log line.
+    pub(super) async fn send(
+        &self,
+        request: reqwest::Request,
+        error_code_header: &str,
+    ) -> Result<reqwest::Response, SourceError> {
+        let response = self.client.execute(request).await.map_err(classify_transport_error)?;
+        let status = response.status();
+        if status.is_success() {
+            return Ok(response);
+        }
+        let code = response
+            .headers()
+            .get(error_code_header)
+            .and_then(|value| value.to_str().ok())
+            .map(str::to_string);
+        Err(classify_status(
+            status.as_u16(),
+            None,
+            match &code {
+                Some(code) => format!("source returned HTTP {status} ({code})"),
+                None => format!("source returned HTTP {status}"),
+            },
+        ))
+    }
+}
+
+/// Renders a transport failure without the request URL: a SAS token or a
+/// signed query would otherwise reach logs and admin responses.
+pub(super) fn classify_transport_error(err: reqwest::Error) -> SourceError {
+    let is_timeout = err.is_timeout();
+    let is_connect = err.is_connect();
+    let message = err.without_url().to_string();
+    if is_timeout {
+        SourceError::Timeout
+    } else if is_connect {
+        SourceError::Connect(message)
+    } else {
+        SourceError::Other(message)
+    }
+}
+
+/// Streams the response body without buffering it.
+pub(super) fn response_body(response: reqwest::Response) -> ByteStream {
+    let stream = response.bytes_stream().map(|chunk| {
+        chunk
+            .map(http_body::Frame::data)
+            .map_err(|err| std::io::Error::other(err.without_url().to_string()))
+    });
+    ByteStream::new(SdkBody::from_body_1_x(http_body_util::StreamBody::new(stream)))
+}
+
+/// Reads a bounded response body as UTF-8, for the XML and JSON listings.
+pub(super) async fn read_text(response: reqwest::Response, max_bytes: usize) -> Result<String, SourceError> {
+    let mut body = Vec::new();
+    let mut stream = response.bytes_stream();
+    while let Some(chunk) = stream.next().await {
+        let chunk = chunk.map_err(classify_transport_error)?;
+        if body.len().saturating_add(chunk.len()) > max_bytes {
+            return Err(SourceError::Other("source listing response exceeded the size limit".to_string()));
+        }
+        body.extend_from_slice(&chunk);
+    }
+    String::from_utf8(body).map_err(|_| SourceError::Other("source listing response is not valid UTF-8".to_string()))
+}
+
+/// Base64 digest (`Content-MD5`, `md5Hash`, `x-goog-hash`) as lowercase hex.
+/// `None` when the value is not a 16-byte digest, so a CRC32C never passes as
+/// an MD5.
+pub(super) fn base64_md5_to_hex(value: &str) -> Option<String> {
+    let raw = base64_simd::STANDARD.decode_to_vec(value.trim().as_bytes()).ok()?;
+    (raw.len() == 16).then(|| faster_hex::hex_string(&raw))
+}
+
+pub(super) fn header<'a>(headers: &'a HeaderMap, name: &str) -> Option<&'a str> {
+    headers.get(name).and_then(|value| value.to_str().ok()).map(str::trim)
+}
+
+fn header_string(headers: &HeaderMap, name: &str) -> Option<String> {
+    header(headers, name).filter(|value| !value.is_empty()).map(str::to_string)
+}
+
+/// `Last-Modified` and friends arrive as an HTTP date; the JSON dialects use
+/// RFC 3339 for the same field, so both are accepted.
+pub(super) fn parse_http_timestamp(value: &str) -> Option<SystemTime> {
+    OffsetDateTime::parse(value, &Rfc2822)
+        .or_else(|_| OffsetDateTime::parse(value, &Rfc3339))
+        .ok()
+        .map(SystemTime::from)
+}
+
+/// Provider-specific fields the shared header mapping cannot infer.
+pub(super) struct NativeHeadFields {
+    pub(super) etag: Option<String>,
+    /// The ETag is an opaque token rather than a digest of the bytes.
+    pub(super) etag_is_opaque: bool,
+    pub(super) version_id: Option<String>,
+    pub(super) storage_class: Option<String>,
+}
+
+/// Maps a HEAD or GET response onto [`SourceHead`]. `metadata_prefix` is the
+/// provider's user-metadata header prefix (`x-ms-meta-`, `x-goog-meta-`); the
+/// stored shape drops it, matching the `x-amz-meta-` handling of the S3 path.
+pub(super) fn native_source_head(
+    headers: &HeaderMap,
+    metadata_prefix: &str,
+    fields: NativeHeadFields,
+) -> Result<SourceHead, SourceError> {
+    let size = header(headers, "content-length")
+        .and_then(|value| value.parse::<u64>().ok())
+        .ok_or_else(|| SourceError::Other("source response has no valid content-length".to_string()))?;
+
+    let mut user_metadata = HashMap::new();
+    for (name, value) in headers {
+        let name = name.as_str();
+        if let Some(key) = name.strip_prefix(metadata_prefix)
+            && !key.is_empty()
+            && let Ok(value) = value.to_str()
+        {
+            user_metadata.insert(key.to_string(), value.to_string());
+        }
+    }
+
+    let etag = fields
+        .etag
+        .map(|etag| etag.trim().trim_matches('"').to_string())
+        .filter(|etag| !etag.is_empty());
+    // An opaque ETag never encodes a part count, so the multipart flag stays
+    // false for it however the provider happens to spell the token.
+    let is_multipart_etag = !fields.etag_is_opaque && etag.as_deref().is_some_and(is_multipart_etag);
+
+    Ok(SourceHead {
+        etag,
+        size,
+        last_modified: header(headers, "last-modified").and_then(parse_http_timestamp),
+        content_type: header_string(headers, "content-type"),
+        content_encoding: header_string(headers, "content-encoding"),
+        content_disposition: header_string(headers, "content-disposition"),
+        content_language: header_string(headers, "content-language"),
+        cache_control: header_string(headers, "cache-control"),
+        expires: header_string(headers, "expires"),
+        user_metadata,
+        version_id: fields.version_id,
+        storage_class: fields.storage_class,
+        // Neither native provider hands back ciphertext: a customer-key object
+        // is refused by the backend before it reaches this mapping, and the
+        // service-managed encryption is transparent to the reader.
+        sse: None,
+        is_multipart_etag,
+        etag_is_opaque: fields.etag_is_opaque,
+    })
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use http::HeaderValue;
+
+    fn headers(pairs: &[(&str, &str)]) -> HeaderMap {
+        let mut headers = HeaderMap::new();
+        for (name, value) in pairs {
+            headers.insert(
+                http::HeaderName::from_bytes(name.as_bytes()).expect("test header name"),
+                HeaderValue::from_str(value).expect("test header value"),
+            );
+        }
+        headers
+    }
+
+    fn fields() -> NativeHeadFields {
+        NativeHeadFields {
+            etag: None,
+            etag_is_opaque: false,
+            version_id: None,
+            storage_class: None,
+        }
+    }
+
+    #[test]
+    fn native_source_head_maps_content_headers_and_prefixed_metadata() {
+        let headers = headers(&[
+            ("content-length", "1234"),
+            ("content-type", "text/plain"),
+            ("content-encoding", "gzip"),
+            ("content-language", "en"),
+            ("content-disposition", "attachment"),
+            ("cache-control", "max-age=60"),
+            ("expires", "Thu, 01 Jan 2026 00:00:00 GMT"),
+            ("last-modified", "Wed, 21 Oct 2015 07:28:00 GMT"),
+            ("x-ms-meta-owner", "alice"),
+            ("x-goog-meta-owner", "not-mine"),
+        ]);
+        let head = native_source_head(
+            &headers,
+            "x-ms-meta-",
+            NativeHeadFields {
+                etag: Some("\"0x8DCE1D2\"".to_string()),
+                etag_is_opaque: true,
+                version_id: Some("2026-01-01T00:00:00.0000000Z".to_string()),
+                storage_class: Some("Hot".to_string()),
+            },
+        )
+        .expect("head should map");
+
+        assert_eq!(head.size, 1234);
+        assert_eq!(head.content_type.as_deref(), Some("text/plain"));
+        assert_eq!(head.content_encoding.as_deref(), Some("gzip"));
+        assert_eq!(head.content_language.as_deref(), Some("en"));
+        assert_eq!(head.content_disposition.as_deref(), Some("attachment"));
+        assert_eq!(head.cache_control.as_deref(), Some("max-age=60"));
+        assert_eq!(head.expires.as_deref(), Some("Thu, 01 Jan 2026 00:00:00 GMT"));
+        assert_eq!(
+            head.last_modified,
+            Some(SystemTime::UNIX_EPOCH + std::time::Duration::from_secs(1_445_412_480)),
+            "HTTP-date Last-Modified must parse"
+        );
+        assert_eq!(
+            head.user_metadata,
+            HashMap::from([("owner".to_string(), "alice".to_string())]),
+            "only the provider's own metadata prefix is read"
+        );
+        assert_eq!(head.etag.as_deref(), Some("0x8DCE1D2"), "quotes are stripped, the token is kept");
+        assert!(head.etag_is_opaque);
+        assert!(!head.is_multipart_etag);
+        assert_eq!(head.storage_class.as_deref(), Some("Hot"));
+        assert!(head.sse.is_none());
+    }
+
+    #[test]
+    fn native_source_head_requires_a_content_length() {
+        let err = native_source_head(&headers(&[("content-type", "text/plain")]), "x-ms-meta-", fields())
+            .expect_err("a response without content-length is unusable");
+        assert!(matches!(err, SourceError::Other(_)), "{err:?}");
+    }
+
+    #[test]
+    fn opaque_etag_never_reads_as_a_multipart_etag() {
+        // A digest-shaped ETag keeps the S3 reading; the same string marked
+        // opaque must not be split into "digest-partcount".
+        for (opaque, expected) in [(false, true), (true, false)] {
+            let head = native_source_head(
+                &headers(&[("content-length", "1")]),
+                "x-ms-meta-",
+                NativeHeadFields {
+                    etag: Some("d41d8cd98f00b204e9800998ecf8427e-3".to_string()),
+                    etag_is_opaque: opaque,
+                    ..fields()
+                },
+            )
+            .expect("head should map");
+            assert_eq!(head.is_multipart_etag, expected, "opaque = {opaque}");
+        }
+    }
+
+    #[test]
+    fn base64_md5_converts_only_sixteen_byte_digests() {
+        assert_eq!(
+            base64_md5_to_hex("1B2M2Y8AsgTpgAmY7PhCfg==").as_deref(),
+            Some("d41d8cd98f00b204e9800998ecf8427e")
+        );
+        assert_eq!(base64_md5_to_hex("not base64!").as_deref(), None);
+        // A CRC32C digest is four bytes: it must not pass as an MD5.
+        assert_eq!(base64_md5_to_hex("AAAAAA==").as_deref(), None);
+    }
+
+    #[test]
+    fn native_http_rejects_endpoints_that_are_not_bare_origins() {
+        for bad in [
+            "ftp://source.example.com",
+            "https://user:pw@source.example.com",
+            "https://source.example.com/container",
+            "https://source.example.com/?x=1",
+            "not a url",
+        ] {
+            assert!(
+                NativeHttp::new(bad, SourceTimeouts::default(), false, None).is_err(),
+                "{bad} must be rejected"
+            );
+        }
+    }
+
+    #[test]
+    fn native_http_percent_encodes_every_path_segment() {
+        let http = NativeHttp::for_test(Url::parse("https://acct.blob.core.windows.net").expect("origin"));
+        let url = http.url(["container", "dir", "a b?c#d.txt"]).expect("url should build");
+        assert_eq!(url.as_str(), "https://acct.blob.core.windows.net/container/dir/a%20b%3Fc%23d.txt");
+        assert_eq!(url.query(), None, "a key with '?' must not become a query");
+    }
+}
@@ -46,10 +46,10 @@ use super::stats::{PullFailureReason, PullPath};
 use super::sys::{BucketOdmState, OnDemandMigrationSys, PullError, PullOutcome, PullSlot};
 use async_trait::async_trait;
 use bytes::Bytes;
-use futures::{Stream, StreamExt};
+use futures::{FutureExt, Stream, StreamExt, future::Shared};
 use parking_lot::Mutex;
 use rand::RngExt;
-use std::collections::{HashMap, HashSet};
+use std::collections::HashMap;
 use std::fmt;
 use std::io;
 use std::pin::Pin;
@@ -133,6 +133,8 @@ pub enum QueuedPullOutcome {
    Failed(PullError),
 }

+pub type QueuedPullReport = Shared<oneshot::Receiver<QueuedPullOutcome>>;
+
 /// Result of [`PullQueue::enqueue`].
 #[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
 pub enum EnqueueOutcome {
@@ -251,6 +253,7 @@ pub struct WriteBackRequest {
    pub preserve_etag: bool,
    /// `policy.emit_events`.
    pub emit_events: bool,
+    pub respect_delete_marker: bool,
    /// Source tags to copy (`policy.copy_tags`), `None` to skip.
    pub tags: Option<HashMap<String, String>>,
 }
@@ -266,6 +269,7 @@ impl WriteBackRequest {
            pulled_at: OffsetDateTime::now_utc(),
            preserve_etag: config.policy.preserve_etag,
            emit_events: config.policy.emit_events,
+            respect_delete_marker: config.policy.respect_local_delete_marker,
            tags,
        }
    }
@@ -830,7 +834,7 @@ pub struct PullQueue {
    bucket: String,
    tx: mpsc::Sender<PullJob>,
    /// Keys queued or running; the job removes its key when it ends.
-    pending: Mutex<HashSet<String>>,
+    pending: Mutex<HashMap<String, QueuedPullReport>>,
    capacity: usize,
    cancel: CancellationToken,
    stats: Arc<super::stats::OdmStats>,
@@ -869,7 +873,7 @@ impl PullQueue {
        let queue = Arc::new(Self {
            bucket: state.bucket().to_string(),
            tx,
-            pending: Mutex::new(HashSet::new()),
+            pending: Mutex::new(HashMap::new()),
            capacity,
            cancel: state.cancel_token(),
            stats: Arc::clone(state.stats()),
@@ -903,29 +907,24 @@ impl PullQueue {
        self.enqueue_with_report(key, reason).0
    }

-    /// [`Self::enqueue`] that also hands back the job's report channel when
-    /// a new job was queued (`Coalesced` pulls report to their first
-    /// requester only).
-    pub fn enqueue_with_report(
-        &self,
-        key: &str,
-        reason: PullReason,
-    ) -> (EnqueueOutcome, Option<oneshot::Receiver<QueuedPullOutcome>>) {
+    /// [`Self::enqueue`] with a shared report, including for coalesced pulls.
+    pub fn enqueue_with_report(&self, key: &str, reason: PullReason) -> (EnqueueOutcome, Option<QueuedPullReport>) {
        if self.cancel.is_cancelled() {
            return (EnqueueOutcome::Unavailable, None);
        }
        let mut pending = self.pending.lock();
-        if pending.contains(key) {
-            return (EnqueueOutcome::Coalesced, None);
+        if let Some(report) = pending.get(key) {
+            return (EnqueueOutcome::Coalesced, Some(report.clone()));
        }
        let (report_tx, report_rx) = oneshot::channel();
+        let report_rx = report_rx.shared();
        match self.tx.try_send(PullJob {
            key: key.to_string(),
            reason,
            report: Some(report_tx),
        }) {
            Ok(()) => {
-                pending.insert(key.to_string());
+                pending.insert(key.to_string(), report_rx.clone());
                (EnqueueOutcome::Enqueued, Some(report_rx))
            }
            Err(TrySendError::Full(_)) => {
@@ -1072,7 +1071,7 @@ impl BucketOdmState {
        self: &Arc<Self>,
        key: &str,
        reason: PullReason,
-    ) -> (EnqueueOutcome, Option<oneshot::Receiver<QueuedPullOutcome>>) {
+    ) -> (EnqueueOutcome, Option<QueuedPullReport>) {
        match self.pull_queue() {
            Some(queue) => queue.enqueue_with_report(key, reason),
            None => (EnqueueOutcome::Unavailable, None),
@@ -1119,6 +1118,8 @@ mod tests {
                    session_token: None,
                }),
                tls: TlsConfig::default(),
+                azure: None,
+                gcs: None,
            },
            filter: FilterConfig::default(),
            policy: PolicyConfig::default(),
@@ -1399,13 +1400,21 @@ mod tests {
        assert_eq!(queue.capacity(), 1024);

        let mut outcomes = HashMap::new();
+        let mut shared_report = None;
        for _ in 0..100 {
-            *outcomes.entry(queue.enqueue("a", PullReason::RangeGet)).or_insert(0) += 1;
+            let (outcome, report) = queue.enqueue_with_report("a", PullReason::RangeGet);
+            *outcomes.entry(outcome).or_insert(0) += 1;
+            shared_report = report;
        }
        assert_eq!(outcomes.get(&EnqueueOutcome::Enqueued), Some(&1));
        assert_eq!(outcomes.get(&EnqueueOutcome::Coalesced), Some(&99));
        assert_eq!(queue.pending_keys(), 1);

+        assert_eq!(
+            shared_report.expect("coalesced report").await,
+            Ok(QueuedPullOutcome::Stored { size: 1000 })
+        );
+
        wait_until("first pull to finish", || queue.pending_keys() == 0).await;
        assert_eq!(source.head_calls.load(Ordering::SeqCst), 1);
        assert_eq!(source.get_calls.load(Ordering::SeqCst), 1);
@@ -1438,6 +1447,23 @@ mod tests {
        assert_eq!(queue.enqueue("a", PullReason::RangeGet), EnqueueOutcome::Unavailable);
    }

+    #[tokio::test]
+    async fn coalesced_enqueues_share_failure_reports() {
+        let sys = OnDemandMigrationSys::new();
+        let state = enabled_state(&sys, &config()).await;
+        let source = MockSource::with_object("missing", 1000, BodyKind::Bytes(body_bytes(1000)));
+        let queue = PullQueue::start(Arc::clone(&state), source, Arc::new(MockWriteBack::default()));
+        let (first, first_report) = queue.enqueue_with_report("absent", PullReason::RangeGet);
+        let (second, second_report) = queue.enqueue_with_report("absent", PullReason::Backfill);
+        assert_eq!(first, EnqueueOutcome::Enqueued);
+        assert_eq!(second, EnqueueOutcome::Coalesced);
+        let (first, second) = tokio::join!(first_report.expect("leader report"), second_report.expect("coalesced report"));
+        assert_eq!(first, second);
+        assert!(matches!(first, Ok(QueuedPullOutcome::Failed(_))));
+        sys.remove(BUCKET);
+        queue.wait_until_stopped().await;
+    }
+
    #[tokio::test]
    async fn queue_full_is_reported_and_cancel_drains_without_leaking_tasks() {
        let sys = OnDemandMigrationSys::new();
@@ -1467,7 +1493,8 @@ mod tests {
        wait_until("dispatcher to wait for a slot", || state.stats().queue_depth() == 1).await;
        assert_eq!(queue.enqueue("c", PullReason::LargeObject), EnqueueOutcome::Enqueued);
        assert_eq!(queue.enqueue("d", PullReason::LargeObject), EnqueueOutcome::QueueFull);
-        assert_eq!(queue.enqueue("c", PullReason::LargeObject), EnqueueOutcome::Coalesced);
+        let (coalesced, canceled_report) = queue.enqueue_with_report("c", PullReason::LargeObject);
+        assert_eq!(coalesced, EnqueueOutcome::Coalesced);
        assert_eq!(queue.pending_keys(), 3);
        assert_eq!(failures(&state).get("queue_full"), Some(&1));
        assert!(!queue.is_stopped());
@@ -1477,6 +1504,12 @@ mod tests {
            .await
            .expect("dispatcher and in-flight job must exit after cancel");
        assert!(queue.is_stopped());
+        assert!(
+            tokio::time::timeout(Duration::from_secs(5), canceled_report.expect("coalesced cancellation report"))
+                .await
+                .expect("cancellation closes the report")
+                .is_err()
+        );
        assert_eq!(queue.pending_keys(), 0);
        assert_eq!(state.inflight_keys(), 0);
        assert_eq!(state.stats().inflight_pulls(), 0);
@@ -14,9 +14,9 @@

 //! Outbound client for an on-demand migration source bucket.
 //!
-//! `SourceClient` wraps an `aws_sdk_s3::Client` built through the shared
-//! remote builder and exposes the read-only surface the migration path
-//! needs (HEAD, ranged streaming GET, ListObjectsV2, GetObjectTagging, a
+//! `SourceClient` maps local keys onto a read-only `SourceBackend`. The
+//! S3 backend uses the shared remote builder and exposes the surface the
+//! migration path needs (HEAD, ranged streaming GET, ListObjectsV2, GetObjectTagging, a
 //! probe for admin validation). Every request carries the
 //! `source-proxy-request` anti-loop marker in both the `x-rustfs-` and
 //! `x-minio-` prefixes so a RustFS/MinIO source answers locally instead of
@@ -25,6 +25,9 @@
 //! Client-supplied `If-*`, `Authorization`, `Host` and SSE-C headers are never
 //! forwarded: v1 rejects SSE-C source objects outright.

+use super::azure::AzureSourceBackend;
+use super::gcs::GcsNativeSourceBackend;
+use super::list_through::{ListPageError, validate_list_page};
 use crate::bucket::remote_s3_client::{
    PathStyle, RemoteCredentials, RemoteS3ClientError, RemoteS3EndpointSpec, RemoteS3RetryPolicy, build_remote_s3_config,
 };
@@ -64,6 +67,10 @@ pub enum SourceProvider {
    /// Generic S3-compatible service.
    #[default]
    S3,
+    /// Native Azure Blob service; not an S3 dialect.
+    Azure,
+    /// Native GCS JSON API with a service-account key; not an S3 dialect.
+    GcsNative,
 }

 impl SourceProvider {
@@ -75,6 +82,8 @@ impl SourceProvider {
            "minio" => Some(Self::Minio),
            "rustfs" => Some(Self::Rustfs),
            "s3" => Some(Self::S3),
+            "azure" => Some(Self::Azure),
+            "gcs_native" => Some(Self::GcsNative),
            _ => None,
        }
    }
@@ -87,6 +96,8 @@ impl SourceProvider {
            Self::Minio => "minio",
            Self::Rustfs => "rustfs",
            Self::S3 => "s3",
+            Self::Azure => "azure",
+            Self::GcsNative => "gcs_native",
        }
    }

@@ -152,12 +163,75 @@ pub struct SourceClientSpec {
    /// Wire requests one logical source call may cost. The pull pipeline and
    /// the backfill job own the retry budget (`pull.rs` `PULL_MAX_RETRIES`,
    /// `backfill.rs` `LIST_MAX_RETRIES`) and the breaker counts logical calls,
-    /// so ODM declares [`RemoteS3RetryPolicy::Disabled`] and keeps one counted
-    /// failure equal to one request against a struggling source.
+    /// so ODM declares [`RemoteS3RetryPolicy::Disabled`]. An ambiguous HEAD
+    /// 404 additionally probes the bucket before declaring a key absent.
    pub retry: RemoteS3RetryPolicy,
    /// Bytes per second the pull pipeline may consume from this source;
    /// `None` means unlimited. Enforced by the consumer, not by this client.
    pub bandwidth_limit: Option<NonZeroU64>,
+    /// Which [`SourceBackend`] to build. The S3 variant reads `region`,
+    /// `path_style` and `credentials`; the native variants ignore all three
+    /// and carry their own credentials.
+    pub backend: SourceBackendSpec,
+}
+
+/// Provider-specific half of [`SourceClientSpec`].
+#[derive(Clone, Debug, Default, PartialEq, Eq)]
+pub enum SourceBackendSpec {
+    #[default]
+    S3,
+    Azure(AzureSourceSpec),
+    Gcs(GcsSourceSpec),
+}
+
+/// Native Azure Blob parameters. The container is [`SourceClientSpec::bucket`].
+#[derive(Clone, PartialEq, Eq)]
+pub struct AzureSourceSpec {
+    pub account: String,
+    pub auth: AzureAuth,
+}
+
+impl fmt::Debug for AzureSourceSpec {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_struct("AzureSourceSpec")
+            .field("account", &self.account)
+            .field("auth", &self.auth)
+            .finish()
+    }
+}
+
+/// How Azure requests are authorized.
+#[derive(Clone, PartialEq, Eq)]
+pub enum AzureAuth {
+    /// Base64 storage-account key, signed per request with Shared Key.
+    SharedKey(String),
+    /// SAS query string without the leading `?`, appended to every URL.
+    Sas(String),
+}
+
+impl fmt::Debug for AzureAuth {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        // Both variants are secrets; only the scheme may be rendered.
+        f.write_str(match self {
+            Self::SharedKey(_) => "SharedKey(REDACTED)",
+            Self::Sas(_) => "Sas(REDACTED)",
+        })
+    }
+}
+
+/// Native GCS parameters. The bucket is [`SourceClientSpec::bucket`].
+#[derive(Clone, PartialEq, Eq)]
+pub struct GcsSourceSpec {
+    /// Service-account key JSON.
+    pub service_account_json: String,
+}
+
+impl fmt::Debug for GcsSourceSpec {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_struct("GcsSourceSpec")
+            .field("service_account_json", &"REDACTED")
+            .finish()
+    }
 }

 impl SourceClientSpec {
@@ -223,6 +297,8 @@ pub enum SourceError {
    ServerError(u16),
    #[error("unsupported source object: {0}")]
    Unsupported(String),
+    #[error("invalid source listing: {0}")]
+    InvalidPagination(#[from] ListPageError),
    #[error("source request failed: {0}")]
    Other(String),
 }
@@ -245,6 +321,7 @@ impl SourceError {
            SourceError::Connect(_) => "connect",
            SourceError::ServerError(_) => "server_error",
            SourceError::Unsupported(_) => "unsupported",
+            SourceError::InvalidPagination(_) => "invalid_pagination",
            SourceError::Other(_) => "other",
        }
    }
@@ -258,7 +335,7 @@ const THROTTLE_CODES: &[&str] = &[
    "TooManyRequests",
    "RequestThrottled",
 ];
-const NOT_FOUND_CODES: &[&str] = &["NoSuchKey", "NotFound", "NoSuchBucket", "NoSuchVersion"];
+const NOT_FOUND_CODES: &[&str] = &["NoSuchKey"];
 const ACCESS_DENIED_CODES: &[&str] = &[
    "AccessDenied",
    "InvalidAccessKeyId",
@@ -268,7 +345,7 @@ const ACCESS_DENIED_CODES: &[&str] = &[
    "InvalidToken",
 ];

-fn classify_status(status: u16, code: Option<&str>, message: String) -> SourceError {
+pub(super) fn classify_status(status: u16, code: Option<&str>, message: String) -> SourceError {
    if let Some(code) = code {
        if THROTTLE_CODES.contains(&code) {
            return SourceError::Throttled;
@@ -281,7 +358,6 @@ fn classify_status(status: u16, code: Option<&str>, message: String) -> SourceEr
        }
    }
    match status {
-        404 => SourceError::NotFound,
        401 | 403 => SourceError::AccessDenied,
        429 | 503 => SourceError::Throttled,
        500..=599 => SourceError::ServerError(status),
@@ -341,6 +417,11 @@ pub struct SourceHead {
    pub storage_class: Option<String>,
    pub sse: Option<SourceSse>,
    pub is_multipart_etag: bool,
+    /// The provider's ETag is not derived from the object bytes (Azure
+    /// stamps an opaque concurrency token). Such an ETag is recorded for
+    /// provenance but must never be read as a content digest, so the
+    /// write-back path refuses to use it as the expected MD5.
+    pub etag_is_opaque: bool,
 }

 /// Per-operation fields shared by HEAD and GET outputs.
@@ -362,7 +443,7 @@ struct HeadParts {
    sse_customer_algorithm: Option<String>,
 }

-fn normalize_etag(etag: Option<String>) -> Option<String> {
+pub(super) fn normalize_etag(etag: Option<String>) -> Option<String> {
    etag.map(|etag| etag.trim().trim_matches('"').to_string())
        .filter(|etag| !etag.is_empty())
 }
@@ -411,6 +492,7 @@ fn source_head(parts: HeadParts) -> Result<SourceHead, SourceError> {
        storage_class: parts.storage_class,
        sse,
        is_multipart_etag,
+        etag_is_opaque: false,
    })
 }

@@ -511,7 +593,7 @@ pub struct SourceObject {
 #[derive(Clone, Debug, Default, PartialEq, Eq)]
 pub struct SourcePage {
    pub objects: Vec<SourceObject>,
-    /// Rolled-up prefixes, in the local namespace; always empty when the
+    /// Rolled-up prefixes, in the same namespace as `objects`; always empty when the
    /// request carried no delimiter.
    pub common_prefixes: Vec<String>,
    pub is_truncated: bool,
@@ -519,7 +601,8 @@ pub struct SourcePage {
 }

 /// One `ListObjectsV2` page request against the source. Keys are given in the
-/// local namespace; `SourceClient` maps them through `source_prefix`.
+/// local namespace at `SourceClient`, and in the source namespace at
+/// `SourceBackend`; `SourceClient` maps them through `source_prefix`.
 #[derive(Clone, Debug, Default, PartialEq, Eq)]
 pub struct SourceListRequest<'a> {
    pub prefix: Option<&'a str>,
@@ -575,8 +658,30 @@ impl Intercept for SourceProxyMarkerInterceptor {
    }
 }

-pub struct SourceClient {
+/// Read-only provider operations in the source bucket namespace.
+///
+/// Implementations must preserve streaming, honor the requested range and
+/// pagination cursor, and classify failures without including credentials.
+/// `SourceClient` owns prefix mapping so every provider shares the same local
+/// namespace. Continuation tokens are opaque and must never be prefix-mapped.
+#[async_trait::async_trait]
+pub trait SourceBackend: Send + Sync {
+    async fn head(&self, key: &str) -> Result<SourceHead, SourceError>;
+    async fn get(&self, key: &str, range: Option<&HTTPRangeSpec>) -> Result<SourceGet, SourceError>;
+    async fn list(&self, request: &SourceListRequest<'_>) -> Result<SourcePage, SourceError>;
+    async fn tagging(&self, key: &str) -> Result<HashMap<String, String>, SourceError>;
+    /// Verify bucket access; `SourceClient` separately probes a filtered listing.
+    async fn probe(&self) -> Result<(), SourceError>;
+}
+
+/// S3-compatible implementation, including request signing and anti-loop headers.
+pub struct S3SourceBackend {
    client: S3Client,
+    bucket: String,
+}
+
+pub struct SourceClient {
+    backend: Box<dyn SourceBackend>,
    endpoint: String,
    bucket: String,
    source_prefix: Option<String>,
@@ -598,18 +703,59 @@ impl fmt::Debug for SourceClient {

 impl SourceClient {
    pub async fn new(spec: &SourceClientSpec) -> Result<Self, RemoteS3ClientError> {
-        let endpoint = spec.endpoint_spec()?;
-        let config = build_remote_s3_config(&endpoint).await?;
-        Ok(Self::from_config_builder(config, endpoint.endpoint_url(), spec))
+        match &spec.backend {
+            SourceBackendSpec::S3 => {
+                let endpoint = spec.endpoint_spec()?;
+                let config = build_remote_s3_config(&endpoint).await?;
+                Ok(Self::from_config_builder(config, endpoint.endpoint_url(), spec))
+            }
+            SourceBackendSpec::Azure(azure) => {
+                let backend = AzureSourceBackend::new(
+                    &spec.endpoint,
+                    &spec.bucket,
+                    azure,
+                    spec.timeouts,
+                    spec.skip_tls_verify,
+                    spec.ca_cert_pem.as_deref(),
+                )?;
+                Ok(Self::from_backend(Box::new(backend), spec))
+            }
+            SourceBackendSpec::Gcs(gcs) => {
+                let backend = GcsNativeSourceBackend::new(
+                    &spec.endpoint,
+                    &spec.bucket,
+                    gcs,
+                    spec.timeouts,
+                    spec.skip_tls_verify,
+                    spec.ca_cert_pem.as_deref(),
+                )?;
+                Ok(Self::from_backend(Box::new(backend), spec))
+            }
+        }
+    }
+
+    /// Wraps a ready backend in the prefix-mapping client. The endpoint is
+    /// kept only for `Debug` and admin status.
+    fn from_backend(backend: Box<dyn SourceBackend>, spec: &SourceClientSpec) -> Self {
+        Self {
+            backend,
+            endpoint: spec.endpoint.clone(),
+            bucket: spec.bucket.clone(),
+            source_prefix: spec.source_prefix.clone().filter(|prefix| !prefix.is_empty()),
+            timeouts: spec.timeouts,
+            bandwidth_limit: spec.bandwidth_limit,
+        }
    }

    /// `config` must come from [`SourceClientSpec::endpoint_spec`], which is
-    /// where the retry policy that keeps one logical call equal to one wire
-    /// request is declared.
+    /// where the policy disabling SDK-level retries is declared.
    fn from_config_builder(config: aws_sdk_s3::config::Builder, endpoint: String, spec: &SourceClientSpec) -> Self {
        let client = S3Client::from_conf(config.interceptor(SourceProxyMarkerInterceptor::new()).build());
        Self {
-            client,
+            backend: Box::new(S3SourceBackend {
+                client,
+                bucket: spec.bucket.clone(),
+            }),
            endpoint,
            bucket: spec.bucket.clone(),
            source_prefix: spec.source_prefix.clone().filter(|prefix| !prefix.is_empty()),
@@ -652,35 +798,15 @@ impl SourceClient {
    }

    pub async fn head_object(&self, key: &str) -> Result<SourceHead, SourceError> {
-        let output = self
-            .client
-            .head_object()
-            .bucket(&self.bucket)
-            .key(self.source_key(key))
-            .send()
-            .await
-            .map_err(classify_sdk_error)?;
-        source_head_from_head_output(output)
+        self.backend.head(&self.source_key(key)).await
    }

-    /// Streams the object; `range` is passed through as an HTTP `Range`
-    /// header and omitted entirely when `None`.
+    /// Streams the object, preserving an optional HTTP byte range.
    pub async fn get_object(&self, key: &str, range: Option<&HTTPRangeSpec>) -> Result<SourceGet, SourceError> {
-        let range = range.map(range_header_value).transpose()?;
-        let output = self
-            .client
-            .get_object()
-            .bucket(&self.bucket)
-            .key(self.source_key(key))
-            .set_range(range)
-            .send()
-            .await
-            .map_err(classify_sdk_error)?;
-        source_get_from_output(output)
+        self.backend.get(&self.source_key(key), range).await
    }

-    /// Lists one page under the local `prefix`. Keys are returned in the
-    /// local namespace; entries outside `source_prefix` are skipped.
+    /// Lists one page under the local prefix.
    pub async fn list_objects_v2(
        &self,
        prefix: Option<&str>,
@@ -696,9 +822,83 @@ impl SourceClient {
        .await
    }

-    /// [`Self::list_objects_v2`] with the delimiter and start-after the
-    /// list-through merge needs (rustfs/backlog#2164).
+    /// Maps keys and common prefixes while leaving opaque cursors untouched.
    pub async fn list_page(&self, request: &SourceListRequest<'_>) -> Result<SourcePage, SourceError> {
+        let prefix = self.source_key(request.prefix.unwrap_or_default());
+        let start_after = request.start_after.map(|key| self.source_key(key));
+        let mut page = self
+            .backend
+            .list(&SourceListRequest {
+                prefix: Some(&prefix),
+                start_after: start_after.as_deref(),
+                ..*request
+            })
+            .await?;
+        validate_list_page(page.is_truncated, request.continuation_token, page.next_continuation_token.as_deref())?;
+        page.objects = page
+            .objects
+            .into_iter()
+            .filter_map(|object| self.local_object(object))
+            .collect();
+        page.common_prefixes = page
+            .common_prefixes
+            .into_iter()
+            .filter_map(|prefix| self.local_key(&prefix).map(str::to_string))
+            .collect();
+        Ok(page)
+    }
+
+    fn local_object(&self, mut object: SourceObject) -> Option<SourceObject> {
+        object.key = self.local_key(&object.key)?.to_string();
+        Some(object)
+    }
+
+    pub async fn get_object_tagging(&self, key: &str) -> Result<HashMap<String, String>, SourceError> {
+        self.backend.tagging(&self.source_key(key)).await
+    }
+
+    pub async fn probe(&self) -> Result<SourceProbe, SourceError> {
+        self.backend.probe().await?;
+        let page = self.list_objects_v2(None, None, 1).await?;
+        Ok(SourceProbe {
+            sample_object: page.objects.into_iter().next(),
+            has_more_objects: page.is_truncated,
+        })
+    }
+}
+
+#[async_trait::async_trait]
+impl SourceBackend for S3SourceBackend {
+    async fn head(&self, key: &str) -> Result<SourceHead, SourceError> {
+        match self.client.head_object().bucket(&self.bucket).key(key).send().await {
+            Ok(output) => source_head_from_head_output(output),
+            Err(err) if err.raw_response().is_some_and(|response| response.status().as_u16() == 404) => {
+                // HEAD has no error body: a missing bucket must not poison
+                // the per-key negative cache as though only the key was absent.
+                self.probe().await?;
+                Err(SourceError::NotFound)
+            }
+            Err(err) => Err(classify_sdk_error(err)),
+        }
+    }
+
+    /// Streams the object; `range` is passed through as an HTTP `Range`
+    /// header and omitted entirely when `None`.
+    async fn get(&self, key: &str, range: Option<&HTTPRangeSpec>) -> Result<SourceGet, SourceError> {
+        let range = range.map(range_header_value).transpose()?;
+        let output = self
+            .client
+            .get_object()
+            .bucket(&self.bucket)
+            .key(key)
+            .set_range(range)
+            .send()
+            .await
+            .map_err(classify_sdk_error)?;
+        source_get_from_output(output)
+    }
+
+    async fn list(&self, request: &SourceListRequest<'_>) -> Result<SourcePage, SourceError> {
        // `start_after` is silently ignored by S3 once a continuation token is
        // present; refuse the ambiguous pair rather than list from the wrong
        // position.
@@ -711,9 +911,9 @@ impl SourceClient {
            .client
            .list_objects_v2()
            .bucket(&self.bucket)
-            .prefix(self.source_key(request.prefix.unwrap_or_default()))
+            .prefix(request.prefix.unwrap_or_default())
            .set_delimiter(request.delimiter.map(str::to_string))
-            .set_start_after(request.start_after.map(|after| self.source_key(after)))
+            .set_start_after(request.start_after.map(str::to_string))
            .set_continuation_token(request.continuation_token.map(str::to_string))
            .max_keys(request.max_keys)
            .send()
@@ -722,22 +922,17 @@ impl SourceClient {

        let is_truncated = output.is_truncated.unwrap_or(false);
        let next_continuation_token = output.next_continuation_token;
-        if is_truncated && next_continuation_token.is_none() {
-            return Err(SourceError::Other(
-                "source reported a truncated listing without a continuation token".to_string(),
-            ));
-        }
        let objects = output
            .contents
            .unwrap_or_default()
            .into_iter()
-            .filter_map(|object| self.source_object(object))
-            .collect();
+            .map(s3_source_object)
+            .collect::<Result<Vec<_>, _>>()?;
        let common_prefixes = output
            .common_prefixes
            .unwrap_or_default()
            .into_iter()
-            .filter_map(|prefix| Some(self.local_key(prefix.prefix.as_deref()?)?.to_string()))
+            .filter_map(|prefix| prefix.prefix)
            .collect();

        Ok(SourcePage {
@@ -748,51 +943,53 @@ impl SourceClient {
        })
    }

-    fn source_object(&self, object: SdkObject) -> Option<SourceObject> {
-        let key = self.local_key(object.key.as_deref()?)?.to_string();
-        let etag = normalize_etag(object.e_tag);
-        let is_multipart_etag = etag.as_deref().is_some_and(is_multipart_etag);
-        Some(SourceObject {
-            key,
-            etag,
-            size: object.size.and_then(|size| u64::try_from(size).ok()).unwrap_or(0),
-            last_modified: system_time(object.last_modified),
-            storage_class: object.storage_class.map(|class| class.as_str().to_string()),
-            is_multipart_etag,
-        })
-    }
-
-    pub async fn get_object_tagging(&self, key: &str) -> Result<HashMap<String, String>, SourceError> {
+    async fn tagging(&self, key: &str) -> Result<HashMap<String, String>, SourceError> {
        let output = self
            .client
            .get_object_tagging()
            .bucket(&self.bucket)
-            .key(self.source_key(key))
+            .key(key)
            .send()
            .await
            .map_err(classify_sdk_error)?;
        Ok(output.tag_set.into_iter().map(|tag| (tag.key, tag.value)).collect())
    }

-    /// Admin validation: HeadBucket plus a one-key listing under the prefix.
-    pub async fn probe(&self) -> Result<SourceProbe, SourceError> {
+    async fn probe(&self) -> Result<(), SourceError> {
        self.client
            .head_bucket()
            .bucket(&self.bucket)
            .send()
            .await
            .map_err(classify_sdk_error)?;
-        let page = self.list_objects_v2(None, None, 1).await?;
-        Ok(SourceProbe {
-            sample_object: page.objects.into_iter().next(),
-            has_more_objects: page.is_truncated,
-        })
+        Ok(())
    }
 }

+fn s3_source_object(object: SdkObject) -> Result<SourceObject, SourceError> {
+    let key = object
+        .key
+        .ok_or_else(|| SourceError::Other("source listing object has no key".to_string()))?;
+    let size = object
+        .size
+        .and_then(|size| u64::try_from(size).ok())
+        .ok_or_else(|| SourceError::Other("source listing object has no valid size".to_string()))?;
+    let etag = normalize_etag(object.e_tag);
+    let is_multipart_etag = etag.as_deref().is_some_and(is_multipart_etag);
+    Ok(SourceObject {
+        key,
+        etag,
+        size,
+        last_modified: system_time(object.last_modified),
+        storage_class: object.storage_class.map(|class| class.as_str().to_string()),
+        is_multipart_etag,
+    })
+}
+
 #[cfg(test)]
 mod tests {
    use super::*;
+    use crate::bucket::on_demand_migration::backend_contract::{BackendCapabilities, OBJECT_MD5, assert_backend_contract};
    use aws_smithy_runtime_api::client::http::{HttpConnector, HttpConnectorFuture, SharedHttpConnector, http_client_fn};
    use aws_smithy_runtime_api::client::orchestrator::HttpRequest;
    use aws_smithy_runtime_api::client::result::ConnectorError;
@@ -910,6 +1107,7 @@ mod tests {
            retry: RemoteS3RetryPolicy::Disabled,
            timeouts: SourceTimeouts::default(),
            bandwidth_limit: NonZeroU64::new(1_000_000),
+            backend: SourceBackendSpec::S3,
        }
    }

@@ -1194,6 +1392,70 @@ mod tests {
        assert!(requests[1].uri.contains("continuation-token=token-1"), "{}", requests[1].uri);
    }

+    #[tokio::test]
+    async fn list_page_maps_delimiter_prefixes_and_start_after_but_not_cursors() {
+        let body = r#"<ListBucketResult xmlns="http://s3.amazonaws.com/doc/2006-03-01/">
+<IsTruncated>true</IsTruncated><NextContinuationToken>data/opaque</NextContinuationToken>
+<CommonPrefixes><Prefix>data/photos/</Prefix></CommonPrefixes>
+<CommonPrefixes><Prefix>outside/</Prefix></CommonPrefixes>
+</ListBucketResult>"#;
+        let next_body = body.replace("data/opaque", "data/next");
+        let (client, requests) =
+            scripted_client(&spec(Some("data/")), vec![ok(Vec::new(), body), ok(Vec::new(), &next_body)]).await;
+        let first = client
+            .list_page(&SourceListRequest {
+                prefix: Some("photos/"),
+                delimiter: Some("/"),
+                start_after: Some("photos/a"),
+                max_keys: 2,
+                ..Default::default()
+            })
+            .await
+            .expect("delimiter listing should succeed");
+        assert_eq!(first.common_prefixes, vec!["photos/"]);
+        assert_eq!(first.next_continuation_token.as_deref(), Some("data/opaque"));
+        let second = client
+            .list_page(&SourceListRequest {
+                continuation_token: first.next_continuation_token.as_deref(),
+                max_keys: 2,
+                ..Default::default()
+            })
+            .await
+            .expect("opaque continuation should succeed");
+        assert_eq!(second.common_prefixes, first.common_prefixes);
+        let requests = recorded(&requests);
+        let query = |request: &RecordedRequest| {
+            Url::parse(&request.uri)
+                .expect("request URI")
+                .query_pairs()
+                .into_owned()
+                .collect::<HashMap<_, _>>()
+        };
+        let first_query = query(&requests[0]);
+        assert_eq!(first_query.get("prefix").map(String::as_str), Some("data/photos/"));
+        assert_eq!(first_query.get("start-after").map(String::as_str), Some("data/photos/a"));
+        assert_eq!(first_query.get("delimiter").map(String::as_str), Some("/"));
+        let second_query = query(&requests[1]);
+        assert_eq!(second_query.get("continuation-token").map(String::as_str), Some("data/opaque"));
+        assert!(!second_query.contains_key("start-after"));
+    }
+
+    #[tokio::test]
+    async fn list_page_rejects_ambiguous_cursor_before_sending() {
+        let (client, requests) = scripted_client(&spec(Some("data/")), vec![]).await;
+        let err = client
+            .list_page(&SourceListRequest {
+                start_after: Some("a"),
+                continuation_token: Some("opaque"),
+                max_keys: 1,
+                ..Default::default()
+            })
+            .await
+            .expect_err("ambiguous list position must fail");
+        assert!(matches!(err, SourceError::Other(_)));
+        assert!(recorded(&requests).is_empty(), "invalid request must never reach the source");
+    }
+
    #[tokio::test]
    async fn list_objects_v2_rejects_truncated_page_without_token() {
        let (client, _) = scripted_client(&spec(None), vec![ok(Vec::new(), LIST_TRUNCATED_WITHOUT_TOKEN)]).await;
@@ -1201,7 +1463,104 @@ mod tests {
            .list_objects_v2(None, None, 10)
            .await
            .expect_err("truncated page without token is corrupt");
-        assert!(matches!(err, SourceError::Other(_)), "{err:?}");
+        assert!(matches!(err, SourceError::InvalidPagination(ListPageError::Missing)), "{err:?}");
+    }
+
+    #[tokio::test]
+    async fn list_page_validates_s3_cursor_progress_before_mapping_entries() {
+        for contents in ["", "<Contents><Key>data/a</Key><Size>1</Size></Contents>"] {
+            for (truncated, next, expected) in [
+                (true, None, Some(ListPageError::Missing)),
+                (true, Some(""), Some(ListPageError::Empty)),
+                (true, Some("stuck"), Some(ListPageError::Repeated)),
+                (true, Some("opaque-next"), None),
+                (false, None, None),
+                (false, Some("stuck"), None),
+            ] {
+                let next_xml = next
+                    .map(|next| format!("<NextContinuationToken>{next}</NextContinuationToken>"))
+                    .unwrap_or_default();
+                let body = format!(
+                    "<ListBucketResult xmlns=\"http://s3.amazonaws.com/doc/2006-03-01/\"><IsTruncated>{truncated}</IsTruncated>{next_xml}{contents}</ListBucketResult>"
+                );
+                let (client, requests) = scripted_client(&spec(Some("data/")), vec![ok(Vec::new(), &body)]).await;
+                let result = client
+                    .list_page(&SourceListRequest {
+                        continuation_token: Some("stuck"),
+                        max_keys: 2,
+                        ..Default::default()
+                    })
+                    .await;
+                match expected {
+                    Some(expected) => {
+                        let error = result.expect_err("malformed pagination must fail at the provider boundary");
+                        assert!(
+                            matches!(&error, SourceError::InvalidPagination(actual) if *actual == expected),
+                            "{error:?}"
+                        );
+                        assert_eq!(error.class_label(), "invalid_pagination");
+                        assert!(!error.is_retryable());
+                        assert!(!error.to_string().contains("stuck"), "errors must not echo opaque tokens");
+                    }
+                    None => {
+                        let page = result.expect("progressing empty/nonempty pages and EOF are valid");
+                        assert_eq!(page.is_truncated, truncated);
+                        assert_eq!(page.next_continuation_token.as_deref(), next);
+                        assert_eq!(page.objects.len(), usize::from(!contents.is_empty()));
+                        if let Some(object) = page.objects.first() {
+                            assert_eq!(object.key, "a");
+                        }
+                    }
+                }
+                let requests = recorded(&requests);
+                assert_eq!(requests.len(), 1, "invalid pagination must not be retried");
+                assert!(requests[0].uri.contains("continuation-token=stuck"));
+            }
+        }
+    }
+
+    struct ListOnlyBackend(SourcePage);
+
+    #[async_trait::async_trait]
+    impl SourceBackend for ListOnlyBackend {
+        async fn list(&self, request: &SourceListRequest<'_>) -> Result<SourcePage, SourceError> {
+            assert_eq!(request.continuation_token, Some("stuck"), "opaque cursors reach every provider unchanged");
+            Ok(self.0.clone())
+        }
+
+        async fn head(&self, _key: &str) -> Result<SourceHead, SourceError> {
+            panic!("unexpected HEAD in list test")
+        }
+        async fn get(&self, _key: &str, _range: Option<&HTTPRangeSpec>) -> Result<SourceGet, SourceError> {
+            panic!("unexpected GET in list test")
+        }
+        async fn tagging(&self, _key: &str) -> Result<HashMap<String, String>, SourceError> {
+            panic!("unexpected tagging in list test")
+        }
+        async fn probe(&self) -> Result<(), SourceError> {
+            panic!("unexpected probe in list test")
+        }
+    }
+
+    #[tokio::test]
+    async fn list_page_validates_non_s3_provider_cursors_at_the_common_boundary() {
+        for (next, expected) in [
+            (None, ListPageError::Missing),
+            (Some(""), ListPageError::Empty),
+            (Some("stuck"), ListPageError::Repeated),
+        ] {
+            let mut client = prefix_client(Some("data/".into()));
+            client.backend = Box::new(ListOnlyBackend(SourcePage {
+                is_truncated: true,
+                next_continuation_token: next.map(str::to_string),
+                ..Default::default()
+            }));
+            let error = client
+                .list_objects_v2(None, Some("stuck"), 2)
+                .await
+                .expect_err("all providers must advance pagination");
+            assert!(matches!(error, SourceError::InvalidPagination(actual) if actual == expected));
+        }
    }

    const TAGGING_BODY: &str = r#"<?xml version="1.0" encoding="UTF-8"?>
@@ -1255,7 +1614,10 @@ mod tests {
    #[tokio::test]
    async fn source_error_classification_covers_every_class() {
        let cases: Vec<(Scripted, &str, bool)> = vec![
-            (status(404, ""), "not_found", false),
+            (status(404, ""), "other", false),
+            (status(404, "<Error><Code>NoSuchKey</Code></Error>"), "not_found", false),
+            (status(404, "<Error><Code>NoSuchBucket</Code></Error>"), "other", false),
+            (status(404, "<Error><Code>NoSuchVersion</Code></Error>"), "other", false),
            (status(403, ACCESS_DENIED_BODY), "access_denied", false),
            (status(401, ""), "access_denied", false),
            (status(429, ""), "throttled", true),
@@ -1278,14 +1640,35 @@ mod tests {
            }
        }

-        // HEAD carries no error body, so the classification must work from the
-        // status alone as well.
-        let (client, _) = scripted_client(&spec(None), vec![status(404, "")]).await;
+        let (client, requests) = scripted_client(&spec(None), vec![status(404, ""), status(200, "")]).await;
        assert!(matches!(client.head_object("missing").await, Err(SourceError::NotFound)));
+        assert_eq!(recorded(&requests).len(), 2, "ambiguous HEAD 404 must check the bucket");
+        let (client, _) = scripted_client(&spec(None), vec![status(404, ""), status(404, "")]).await;
+        assert!(matches!(client.head_object("missing").await, Err(SourceError::Other(_))));
+        let (client, _) = scripted_client(&spec(None), vec![status(404, ""), status(403, "")]).await;
+        assert!(matches!(client.head_object("missing").await, Err(SourceError::AccessDenied)));
        let (client, _) = scripted_client(&spec(None), vec![status(403, "")]).await;
        assert!(matches!(client.head_object("secret").await, Err(SourceError::AccessDenied)));
    }

+    #[test]
+    fn source_listing_rejects_missing_and_negative_sizes() {
+        for size in [None, Some(-1)] {
+            let object = SdkObject::builder().key("key").set_size(size).build();
+            assert!(matches!(s3_source_object(object), Err(SourceError::Other(_))));
+        }
+        assert!(matches!(
+            s3_source_object(SdkObject::builder().size(0).build()),
+            Err(SourceError::Other(_))
+        ));
+        assert_eq!(
+            s3_source_object(SdkObject::builder().key("empty").size(0).build())
+                .expect("empty object")
+                .size,
+            0
+        );
+    }
+
    #[tokio::test]
    async fn source_client_debug_redacts_credentials() {
        let (client, _) = scripted_client(&spec(Some("data/")), Vec::new()).await;
@@ -1352,16 +1735,113 @@ mod tests {
        assert_eq!(resolve_path_style(PathStyle::VirtualHost, Minio, "10.0.0.1"), PathStyle::VirtualHost);
        assert_eq!(resolve_path_style(PathStyle::Path, Aws, "s3.amazonaws.com"), PathStyle::Path);
        assert_eq!(SourceProvider::from_label(" AWS "), Some(Aws));
-        assert_eq!(SourceProvider::from_label("azure"), None);
+        assert_eq!(SourceProvider::from_label(" Azure "), Some(Azure));
+        assert_eq!(SourceProvider::from_label("gcs_native"), Some(GcsNative));
+        assert_eq!(SourceProvider::from_label("swift"), None);
+    }
+
+    const CONTRACT_LIST_PAGE_ONE: &str = r#"<?xml version="1.0" encoding="UTF-8"?>
+<ListBucketResult xmlns="http://s3.amazonaws.com/doc/2006-03-01/">
+  <Name>source-bucket</Name>
+  <IsTruncated>true</IsTruncated>
+  <NextContinuationToken>cursor-1</NextContinuationToken>
+  <Contents>
+    <Key>dir/a.txt</Key>
+    <LastModified>2015-10-21T07:28:00.000Z</LastModified>
+    <ETag>&quot;5d41402abc4b2a76b9719d911017c592&quot;</ETag>
+    <Size>5</Size>
+    <StorageClass>STANDARD</StorageClass>
+  </Contents>
+  <CommonPrefixes><Prefix>dir/sub/</Prefix></CommonPrefixes>
+</ListBucketResult>"#;
+
+    const CONTRACT_LIST_PAGE_TWO: &str = r#"<?xml version="1.0" encoding="UTF-8"?>
+<ListBucketResult xmlns="http://s3.amazonaws.com/doc/2006-03-01/">
+  <Name>source-bucket</Name>
+  <IsTruncated>false</IsTruncated>
+  <Contents>
+    <Key>dir/b.txt</Key>
+    <LastModified>2015-10-21T07:28:00.000Z</LastModified>
+    <ETag>&quot;7d41402abc4b2a76b9719d911017c592&quot;</ETag>
+    <Size>7</Size>
+  </Contents>
+</ListBucketResult>"#;
+
+    const CONTRACT_TAGGING: &str = r#"<?xml version="1.0" encoding="UTF-8"?>
+<Tagging xmlns="http://s3.amazonaws.com/doc/2006-03-01/"><TagSet>
+  <Tag><Key>env</Key><Value>prod</Value></Tag>
+</TagSet></Tagging>"#;
+
+    fn contract_object_headers(content_length: u64) -> Vec<(&'static str, String)> {
+        vec![
+            ("etag", format!("\"{OBJECT_MD5}\"")),
+            ("content-length", content_length.to_string()),
+            ("content-type", "text/plain".to_string()),
+            ("last-modified", "Wed, 21 Oct 2015 07:28:00 GMT".to_string()),
+            ("x-amz-meta-owner", "alice".to_string()),
+            ("x-amz-storage-class", "STANDARD".to_string()),
+        ]
+    }
+
+    /// The S3 backend behind the scripted connector, without the prefix-mapping
+    /// client on top: the contract is a property of the backend itself.
+    async fn scripted_s3_backend(responses: Vec<Scripted>) -> S3SourceBackend {
+        let spec = spec(None);
+        let connector = SharedHttpConnector::new(ScriptedConnector {
+            requests: Arc::new(Mutex::new(Vec::new())),
+            responses: Arc::new(Mutex::new(responses.into_iter().collect())),
+        });
+        let http_client = http_client_fn(move |_settings, _components| connector.clone());
+        let endpoint = spec.endpoint_spec().expect("test spec endpoint should parse");
+        let config = build_remote_s3_config(&endpoint)
+            .await
+            .expect("test spec should build")
+            .http_client(http_client)
+            .interceptor(SourceProxyMarkerInterceptor::new());
+        S3SourceBackend {
+            client: S3Client::from_conf(config.build()),
+            bucket: spec.bucket.clone(),
+        }
+    }
+
+    #[tokio::test]
+    async fn s3_backend_satisfies_the_shared_backend_contract() {
+        let mut ranged = contract_object_headers(3);
+        ranged.push(("content-range", "bytes 1-3/5".to_string()));
+        let backend = scripted_s3_backend(vec![
+            ok(contract_object_headers(5), ""),
+            ok(contract_object_headers(5), "hello"),
+            ok(ranged, "ell"),
+            ok(Vec::new(), CONTRACT_LIST_PAGE_ONE),
+            ok(Vec::new(), CONTRACT_LIST_PAGE_TWO),
+            ok(Vec::new(), CONTRACT_TAGGING),
+            ok(Vec::new(), ""),
+            status(404, ""),
+            status(403, ACCESS_DENIED_BODY),
+        ])
+        .await;
+
+        assert_backend_contract(
+            &backend,
+            BackendCapabilities {
+                etag_is_opaque: false,
+                supports_start_after: true,
+                supports_tagging: true,
+            },
+        )
+        .await;
    }

    fn prefix_client(prefix: Option<String>) -> SourceClient {
        SourceClient {
-            client: S3Client::from_conf(
-                aws_sdk_s3::Config::builder()
-                    .behavior_version(aws_sdk_s3::config::BehaviorVersion::latest())
-                    .build(),
-            ),
+            backend: Box::new(S3SourceBackend {
+                client: S3Client::from_conf(
+                    aws_sdk_s3::Config::builder()
+                        .behavior_version(aws_sdk_s3::config::BehaviorVersion::latest())
+                        .build(),
+                ),
+                bucket: "bucket".to_string(),
+            }),
            endpoint: "https://source.example.com".to_string(),
            bucket: "bucket".to_string(),
            source_prefix: prefix.filter(|prefix| !prefix.is_empty()),
@@ -177,7 +177,7 @@ impl From<&SourceError> for PullFailureReason {
            SourceError::Connect(_) => PullFailureReason::SourceConnect,
            SourceError::ServerError(_) => PullFailureReason::SourceServerError,
            SourceError::Unsupported(_) => PullFailureReason::SourceUnsupported,
-            SourceError::Other(_) => PullFailureReason::SourceOther,
+            SourceError::InvalidPagination(_) | SourceError::Other(_) => PullFailureReason::SourceOther,
        }
    }
 }
@@ -47,7 +47,10 @@ use super::config::{
 use super::list_through::{SOURCE_LIST_RATE_PER_SEC, SourceListRateLimiter};
 use super::negative_cache::NegativeCache;
 use super::pull::{OdmWriteBack, PullQueue};
-use super::source_client::{SourceClient, SourceClientSpec, SourceError, SourceProvider, SourceTimeouts};
+use super::source_client::{
+    AzureAuth, AzureSourceSpec, GcsSourceSpec, SourceBackendSpec, SourceClient, SourceClientSpec, SourceError, SourceProvider,
+    SourceTimeouts,
+};
 use super::stats::{GaugeGuard, OdmStats, OdmStatsSnapshot, PullFailureReason};
 use crate::bucket::remote_s3_client::{
    PathStyle as ClientPathStyle, RemoteCredentials, RemoteS3ClientError, RemoteS3RetryPolicy,
@@ -619,6 +622,7 @@ pub fn source_client_spec(config: &OnDemandMigrationConfig) -> SourceClientSpec
        // load on a source that is already failing.
        retry: RemoteS3RetryPolicy::Disabled,
        bandwidth_limit: policy.bandwidth_limit_bytes_per_sec.and_then(NonZeroU64::new),
+        backend: source_backend_spec(source),
    }
 }

@@ -630,6 +634,31 @@ fn source_provider(provider: Provider) -> SourceProvider {
        Provider::Rustfs => SourceProvider::Rustfs,
        Provider::R2 => SourceProvider::R2,
        Provider::Gcs => SourceProvider::Gcs,
+        Provider::Azure => SourceProvider::Azure,
+        Provider::GcsNative => SourceProvider::GcsNative,
+    }
+}
+
+/// Which backend the client builds. A native provider whose block is missing
+/// falls back to the S3 spec, where the builder reports the missing
+/// credentials: the config layer already refuses to store that shape, so this
+/// only covers a config written by an older or hand-edited build.
+pub fn source_backend_spec(source: &SourceConfig) -> SourceBackendSpec {
+    match (source.provider, source.azure.as_ref(), source.gcs.as_ref()) {
+        (Provider::Azure, Some(azure), _) => SourceBackendSpec::Azure(AzureSourceSpec {
+            account: azure.account.clone(),
+            auth: match (&azure.account_key, &azure.sas_token) {
+                (Some(key), _) => AzureAuth::SharedKey(key.clone()),
+                (None, Some(sas)) => AzureAuth::Sas(sas.clone()),
+                // Refused by `SourceConfig::validate`; an empty shared key
+                // fails closed at the builder rather than signing with none.
+                (None, None) => AzureAuth::SharedKey(String::new()),
+            },
+        }),
+        (Provider::GcsNative, _, Some(gcs)) => SourceBackendSpec::Gcs(GcsSourceSpec {
+            service_account_json: gcs.service_account_json.clone(),
+        }),
+        _ => SourceBackendSpec::S3,
    }
 }

@@ -929,6 +958,8 @@ mod tests {
                    session_token: None,
                }),
                tls: TlsConfig::default(),
+                azure: None,
+                gcs: None,
            },
            filter: FilterConfig {
                prefix: prefix.map(str::to_string),
@@ -0,0 +1,120 @@
+// Copyright 2024 RustFS Team
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//! Scripted HTTP server for the native source backends' tests.
+//!
+//! The S3 backend can be driven through the SDK's own connector; the native
+//! backends talk to a real socket, so their tests need a server that answers a
+//! fixed script and records what it was asked. Every response closes its
+//! connection, which keeps one request on one socket and makes the script order
+//! exactly the request order.
+
+use std::sync::{Arc, Mutex};
+use tokio::io::{AsyncReadExt, AsyncWriteExt};
+use tokio::net::TcpListener;
+use url::Url;
+
+pub(super) struct ScriptedResponse {
+    status: u16,
+    headers: Vec<(&'static str, String)>,
+    body: String,
+}
+
+impl ScriptedResponse {
+    pub(super) fn new(status: u16, headers: Vec<(&'static str, String)>, body: String) -> Self {
+        Self { status, headers, body }
+    }
+}
+
+#[derive(Clone, Debug)]
+pub(super) struct RecordedRequest {
+    pub(super) method: String,
+    /// Request target as it appeared on the wire: path plus query.
+    pub(super) target: String,
+    pub(super) headers: Vec<(String, String)>,
+}
+
+impl RecordedRequest {
+    pub(super) fn header(&self, name: &str) -> Option<&str> {
+        self.headers
+            .iter()
+            .find(|(key, _)| key.eq_ignore_ascii_case(name))
+            .map(|(_, value)| value.as_str())
+    }
+}
+
+pub(super) type Recorder = Arc<Mutex<Vec<RecordedRequest>>>;
+
+/// Binds a loopback listener that answers `responses` in order and returns its
+/// origin plus the recorder. The task ends once the script is exhausted.
+pub(super) async fn scripted_server(responses: Vec<ScriptedResponse>) -> (Url, Recorder) {
+    let listener = TcpListener::bind("127.0.0.1:0").await.expect("fixture listener should bind");
+    let port = listener.local_addr().expect("fixture address").port();
+    let recorder: Recorder = Arc::new(Mutex::new(Vec::new()));
+    let sink = Arc::clone(&recorder);
+
+    tokio::spawn(async move {
+        for response in responses {
+            let Ok((mut stream, _)) = listener.accept().await else {
+                return;
+            };
+            let mut request = Vec::new();
+            let mut buffer = [0_u8; 2048];
+            while !request.windows(4).any(|window| window == b"\r\n\r\n") {
+                match stream.read(&mut buffer).await {
+                    Ok(0) | Err(_) => break,
+                    Ok(read) => request.extend_from_slice(&buffer[..read]),
+                }
+            }
+            let text = String::from_utf8_lossy(&request).into_owned();
+            let mut lines = text.lines();
+            let start = lines.next().unwrap_or_default().to_string();
+            let mut parts = start.split_whitespace();
+            sink.lock().expect("recorder lock").push(RecordedRequest {
+                method: parts.next().unwrap_or_default().to_string(),
+                target: parts.next().unwrap_or_default().to_string(),
+                headers: lines
+                    .take_while(|line| !line.is_empty())
+                    .filter_map(|line| line.split_once(':'))
+                    .map(|(name, value)| (name.trim().to_string(), value.trim().to_string()))
+                    .collect(),
+            });
+
+            // A scripted HEAD declares the object size in its own headers while
+            // carrying no body, so an explicit `Content-Length` wins over the
+            // body length.
+            let declares_length = response
+                .headers
+                .iter()
+                .any(|(name, _)| name.eq_ignore_ascii_case("content-length"));
+            let mut rendered = match declares_length {
+                true => format!("HTTP/1.1 {} Scripted\r\nConnection: close\r\n", response.status),
+                false => format!(
+                    "HTTP/1.1 {} Scripted\r\nContent-Length: {}\r\nConnection: close\r\n",
+                    response.status,
+                    response.body.len()
+                ),
+            };
+            for (name, value) in response.headers {
+                rendered.push_str(&format!("{name}: {value}\r\n"));
+            }
+            rendered.push_str("\r\n");
+            rendered.push_str(&response.body);
+            let _ = stream.write_all(rendered.as_bytes()).await;
+            let _ = stream.flush().await;
+        }
+    });
+
+    (Url::parse(&format!("http://127.0.0.1:{port}")).expect("fixture endpoint"), recorder)
+}
@@ -652,9 +652,10 @@ async fn build_aws_s3_http_client_from_tls_path() -> Option<SharedHttpClient> {
 #[cfg(test)]
 mod tests {
    use super::*;
+    use aws_smithy_async::time::TimeSource;
    use aws_smithy_runtime_api::http::StatusCode as SmithyStatusCode;
    use std::sync::Mutex;
-    use std::sync::atomic::{AtomicUsize, Ordering};
+    use std::sync::atomic::{AtomicU64, AtomicUsize, Ordering};

    fn spec(endpoint: &str, secure: bool) -> RemoteS3EndpointSpec {
        RemoteS3EndpointSpec {
@@ -824,6 +825,174 @@ mod tests {
        );
    }

+    #[derive(Clone, Debug)]
+    struct ClockSkewTimeSource(Arc<AtomicU64>);
+
+    impl TimeSource for ClockSkewTimeSource {
+        fn now(&self) -> SystemTime {
+            SystemTime::UNIX_EPOCH + Duration::from_secs(self.0.load(Ordering::SeqCst))
+        }
+    }
+
+    #[derive(Clone, Debug)]
+    struct ClockSkewConnector {
+        request_headers: RecordedHeaders,
+        error_code: &'static str,
+        skew_seconds: i64,
+        clock: ClockSkewTimeSource,
+    }
+
+    fn recorded_header<'a>(headers: &'a [(String, String)], name: &str) -> &'a str {
+        headers
+            .iter()
+            .find(|(key, _)| key.eq_ignore_ascii_case(name))
+            .map(|(_, value)| value.as_str())
+            .unwrap_or_else(|| panic!("signed request must contain {name}"))
+    }
+
+    fn signing_time(headers: &[(String, String)]) -> chrono::NaiveDateTime {
+        chrono::NaiveDateTime::parse_from_str(recorded_header(headers, "x-amz-date"), "%Y%m%dT%H%M%SZ")
+            .expect("SDK signing timestamp must use the SigV4 format")
+    }
+
+    impl SmithyHttpConnector for ClockSkewConnector {
+        fn call(&self, request: HttpRequest) -> HttpConnectorFuture {
+            let mut headers = self.request_headers.lock().expect("clock skew request capture lock");
+            assert!(headers.len() < 3, "clock skew fixture must not exceed two GET attempts and one HEAD");
+            headers.push(
+                request
+                    .headers()
+                    .iter()
+                    .map(|(key, value)| (key.to_string(), value.to_string()))
+                    .collect(),
+            );
+            let server_time = chrono::DateTime::<chrono::Utc>::from(self.clock.now()).naive_utc()
+                + chrono::Duration::seconds(self.skew_seconds);
+            let (status, body) = if headers.len() == 1 {
+                (
+                    403,
+                    format!("<Error><Code>{}</Code><Message>Clock skew fixture</Message></Error>", self.error_code),
+                )
+            } else {
+                (200, String::new())
+            };
+            let response = http::Response::builder()
+                .status(status)
+                .header("date", server_time.format("%a, %d %b %Y %H:%M:%S GMT").to_string())
+                .header("content-type", "application/xml")
+                .header("content-length", body.len())
+                .body(SdkBody::from(body))
+                .expect("clock skew fixture response");
+            HttpConnectorFuture::ready(Ok(HttpResponse::try_from(response).expect("Smithy fixture response")))
+        }
+    }
+
+    async fn clock_skew_client(
+        error_code: &'static str,
+        skew_seconds: i64,
+        retry: RemoteS3RetryPolicy,
+    ) -> (S3Client, RecordedHeaders, ClockSkewTimeSource) {
+        let headers: RecordedHeaders = Arc::new(Mutex::new(Vec::new()));
+        let clock = ClockSkewTimeSource(Arc::new(AtomicU64::new(1_700_000_000)));
+        let connector = SharedHttpConnector::new(ClockSkewConnector {
+            request_headers: Arc::clone(&headers),
+            error_code,
+            skew_seconds,
+            clock: clock.clone(),
+        });
+        let mut spec = spec("s3.example.com", true);
+        spec.retry = retry;
+        let config = build_remote_s3_config(&spec)
+            .await
+            .expect("clock skew fixture uses the production outbound configuration")
+            .http_client(http_client_fn(move |_settings, _components| connector.clone()))
+            .time_source(clock.clone())
+            .build();
+        (S3Client::from_conf(config), headers, clock)
+    }
+
+    #[tokio::test(start_paused = true)]
+    async fn remote_s3_clock_skew_retries_resign_and_seed_next_operation() {
+        for error_code in ["RequestTimeTooSkewed", "SignatureDoesNotMatch"] {
+            for skew_seconds in [-600, 600] {
+                let (client, headers, clock) = clock_skew_client(error_code, skew_seconds, REPLICATION_TARGET_RETRY_POLICY).await;
+                let initial = chrono::DateTime::<chrono::Utc>::from(clock.now()).naive_utc();
+                client
+                    .get_object()
+                    .bucket("bucket")
+                    .key("object")
+                    .send()
+                    .await
+                    .expect("clock skew GET must retry successfully");
+                assert_eq!(
+                    headers.lock().expect("captured requests").len(),
+                    2,
+                    "{error_code}: GET needs exactly one retry"
+                );
+                clock.0.fetch_add(17, Ordering::SeqCst);
+                // SDK signing time is independent of Tokio's retry/scheduler clock.
+                tokio::time::advance(Duration::from_secs(61)).await;
+                client
+                    .head_bucket()
+                    .bucket("bucket")
+                    .send()
+                    .await
+                    .expect("subsequent HEAD must use the client's cached skew");
+                let headers = headers.lock().expect("captured signed requests");
+                assert_eq!(headers.len(), 3, "subsequent operation must succeed on its first attempt");
+                assert_eq!(signing_time(&headers[0]), initial, "the first attempt must use the injected clock");
+                assert_eq!(
+                    signing_time(&headers[1]),
+                    initial + chrono::Duration::seconds(skew_seconds),
+                    "{error_code}: retry must apply the measured offset exactly"
+                );
+                assert_eq!(
+                    signing_time(&headers[2]),
+                    initial + chrono::Duration::seconds(skew_seconds + 17),
+                    "{error_code}: the next operation must apply cached skew to the advanced signing clock"
+                );
+                let signature = |index: usize| {
+                    recorded_header(&headers[index], "authorization")
+                        .rsplit_once("Signature=")
+                        .expect("SigV4 authorization contains a signature")
+                        .1
+                };
+                assert_ne!(
+                    signature(0),
+                    signature(1),
+                    "{error_code}: retry must be signed again after adjusting its date"
+                );
+            }
+        }
+    }
+
+    #[tokio::test(start_paused = true)]
+    async fn remote_s3_clock_skew_respects_one_attempt_policy() {
+        use aws_smithy_types::error::metadata::ProvideErrorMetadata;
+
+        for error_code in ["RequestTimeTooSkewed", "SignatureDoesNotMatch"] {
+            for retry in [
+                RemoteS3RetryPolicy::Disabled,
+                RemoteS3RetryPolicy::Standard { max_attempts: 1 },
+            ] {
+                let (client, headers, _clock) = clock_skew_client(error_code, 600, retry).await;
+                let error = client
+                    .get_object()
+                    .bucket("bucket")
+                    .key("object")
+                    .send()
+                    .await
+                    .expect_err("clock skew must not override the caller's one-attempt budget");
+                assert_eq!(error.as_service_error().and_then(ProvideErrorMetadata::code), Some(error_code));
+                assert_eq!(
+                    headers.lock().expect("captured requests").len(),
+                    1,
+                    "{error_code}: {retry:?} must send exactly one request"
+                );
+            }
+        }
+    }
+
    #[test]
    fn path_style_auto_and_path_force_path_style() {
        assert!(PathStyle::Auto.force_path_style());
@@ -46,7 +46,7 @@ use super::replication_storage_boundary::{
    HTTPPreconditions, ObjectInfo, ObjectOptions, ObjectToDelete, ReplicationDeletedObject, ReplicationObjectIO,
    ReplicationStorage,
 };
-use super::replication_target_boundary::{ReplicationTargetStore, replication_object_is_ssec_encrypted};
+use super::replication_target_boundary::{BucketTargetError, ReplicationTargetStore, replication_object_is_ssec_encrypted};
 use super::replication_versioning_boundary::ReplicationVersioningStore;
 use super::runtime_boundary as runtime_sources;
 use futures_util::stream::{self, StreamExt};
@@ -3084,6 +3084,23 @@ pub async fn queue_replication_heal(bucket: &str, oi: ObjectInfo, retry_count: u

    let tgts = match ReplicationTargetStore::list_bucket_targets(bucket).await {
        Ok(targets) => Some(targets),
+        // A bucket whose persisted target configuration cannot be decoded has
+        // an unknown target set, not an empty one: scheduling against `None`
+        // here would drop every heal for it without a trace
+        // (rustfs/backlog#2282). Report it missed so the object is retried
+        // once the configuration is readable again.
+        Err(BucketTargetError::BucketRemoteTargetsUnreadable { .. }) => {
+            warn!(
+                event = EVENT_REPLICATION_CONFIG_LOOKUP_SKIPPED,
+                component = LOG_COMPONENT_ECSTORE,
+                subsystem = LOG_SUBSYSTEM_REPLICATION,
+                bucket,
+                reason = "target_config_unreadable",
+                "Bucket replication targets are unreadable; replication heal queue fails closed"
+            );
+
+            return ReplicationQueueAdmission::Missed;
+        }
        Err(err) => {
            debug!(
                event = EVENT_REPLICATION_CONFIG_LOOKUP_SKIPPED,
@@ -15,7 +15,8 @@
 use std::collections::HashMap;
 use std::sync::Arc;

-use crate::bucket::bucket_target_sys::{BucketTargetError, BucketTargetSys};
+pub(crate) use crate::bucket::bucket_target_sys::BucketTargetError;
+use crate::bucket::bucket_target_sys::BucketTargetSys;
 use aws_sdk_s3::operation::head_object::HeadObjectOutput;
 use aws_sdk_s3::types::{ObjectLockLegalHoldStatus, ObjectLockRetentionMode};
 use http::HeaderMap;
@@ -0,0 +1,357 @@
+// Copyright 2024 RustFS Team
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//! Sealed remote credentials shared by the three stores that persist one
+//! (rustfs/backlog#2168): replication targets (`bucket-targets.json`), remote
+//! tiers (`tier-config.bin`) and on-demand migration sources
+//! (`on-demand-migration.json`).
+//!
+//! The design record is `docs/architecture/remote-credential-sealing-adr.md`.
+//! What this module owns: the versioned envelope, the encryption context that
+//! binds a ciphertext to the record owning it, the sealer registration point,
+//! and the fail-closed error type. What it deliberately does not own: any KMS
+//! call (ECStore does not depend on `rustfs-kms`; the binary installs a
+//! sealer, exactly like `ON_DEMAND_MIGRATION_CONFIG_HOOK` and the event
+//! dispatch hook in `crates/ecstore/src/services/event_notification.rs`), and
+//! any decision about which stored field a consumer writes.
+
+use async_trait::async_trait;
+use serde::{Deserialize, Serialize};
+use std::collections::BTreeMap;
+use std::fmt;
+use std::sync::{Arc, OnceLock};
+
+/// Envelope format this build writes. A reader accepts only versions it
+/// knows; an unknown version is a typed error, never a fallback.
+pub const SEALED_CREDENTIAL_VERSION: u8 = 1;
+
+/// Which store a sealed value belongs to. Part of the encryption context, so
+/// a ciphertext cannot be replayed into a different store.
+#[derive(Clone, Copy, Debug, PartialEq, Eq)]
+pub enum SealedCredentialStore {
+    /// `bucket-targets.json` (replication and other bucket targets).
+    BucketTargets,
+    /// `tier-config.bin` (remote tiers).
+    TierConfig,
+    /// `on-demand-migration.json` (migration sources).
+    OnDemandMigration,
+}
+
+impl SealedCredentialStore {
+    pub fn as_str(self) -> &'static str {
+        match self {
+            SealedCredentialStore::BucketTargets => "bucket-targets",
+            SealedCredentialStore::TierConfig => "tier-config",
+            SealedCredentialStore::OnDemandMigration => "on-demand-migration",
+        }
+    }
+}
+
+/// Identity of the record a secret belongs to: the store, its owner (bucket
+/// name, tier name, or target ARN) and the field name. Rendered into the KMS
+/// encryption context so a ciphertext moved between buckets, tiers or fields
+/// fails to decrypt instead of silently authorizing a different remote.
+#[derive(Clone, Debug, PartialEq, Eq)]
+pub struct SealScope {
+    pub store: SealedCredentialStore,
+    pub owner: String,
+    pub field: &'static str,
+}
+
+impl SealScope {
+    pub fn new(store: SealedCredentialStore, owner: impl Into<String>, field: &'static str) -> Self {
+        Self {
+            store,
+            owner: owner.into(),
+            field,
+        }
+    }
+
+    /// The encryption context handed to the sealer. Keys are stable: they are
+    /// part of the on-disk contract, because a ciphertext only decrypts under
+    /// the same context.
+    pub fn encryption_context(&self) -> BTreeMap<String, String> {
+        BTreeMap::from([
+            ("rustfs:store".to_string(), self.store.as_str().to_string()),
+            ("rustfs:owner".to_string(), self.owner.clone()),
+            ("rustfs:field".to_string(), self.field.to_string()),
+        ])
+    }
+}
+
+/// A sealed secret as persisted. `Debug` prints no ciphertext: a sealed value
+/// is not a secret, but it is noise in a log line and an operator reading one
+/// should see the key it is wrapped under, not the bytes.
+#[derive(Clone, Serialize, Deserialize, PartialEq, Eq)]
+pub struct SealedCredential {
+    /// Envelope version; see [`SEALED_CREDENTIAL_VERSION`].
+    pub v: u8,
+    /// KMS master key id the data key is wrapped under.
+    pub key_id: String,
+    /// Master key version, when the backend reports one. Carried so the KMS
+    /// re-wrap job (`docs/architecture/kms-bulk-rekey-contract.md`) can tell
+    /// stale envelopes apart; nothing here rotates on its own.
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub key_version: Option<String>,
+    /// Algorithm label reported by the sealer, for forensics and migration.
+    pub alg: String,
+    /// Ciphertext blob as produced by the sealer, base64 (standard, padded)
+    /// in the JSON stores and raw inside the tier msgpack payload.
+    pub ct: String,
+}
+
+impl fmt::Debug for SealedCredential {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_struct("SealedCredential")
+            .field("v", &self.v)
+            .field("key_id", &self.key_id)
+            .field("key_version", &self.key_version)
+            .field("alg", &self.alg)
+            .field("ct", &format_args!("<{} bytes sealed>", self.ct.len()))
+            .finish()
+    }
+}
+
+impl SealedCredential {
+    /// Rejects an envelope this build cannot read. Called before every
+    /// unseal so an unknown version fails here rather than inside a backend.
+    pub fn check_version(&self) -> Result<(), SealedCredentialError> {
+        if self.v == SEALED_CREDENTIAL_VERSION {
+            Ok(())
+        } else {
+            Err(SealedCredentialError::UnsupportedVersion(self.v))
+        }
+    }
+}
+
+/// Why a seal or unseal did not produce a usable value. Every variant is
+/// terminal for the record that carried it: a caller reports the remote as
+/// unusable, and never substitutes a default or empty credential.
+#[derive(Clone, Debug, PartialEq, Eq, thiserror::Error)]
+pub enum SealedCredentialError {
+    /// No sealer is installed: KMS is not configured, or the process has not
+    /// finished startup. Reading a sealed record is impossible here.
+    #[error("no credential sealer is installed")]
+    NoSealer,
+    /// The stored envelope is from a newer (or otherwise unknown) format.
+    #[error("unsupported sealed credential envelope version {0}")]
+    UnsupportedVersion(u8),
+    /// The stored bytes are not a well-formed envelope.
+    #[error("malformed sealed credential: {0}")]
+    Malformed(String),
+    /// The sealer refused: wrong encryption context, missing key, revoked
+    /// access, or a failed authentication tag.
+    #[error("sealed credential could not be unsealed: {0}")]
+    Kms(String),
+}
+
+/// The KMS-backed half, installed by the binary at startup.
+#[async_trait]
+pub trait CredentialSealer: Send + Sync + 'static {
+    /// Wraps `plaintext` under the scope's encryption context.
+    async fn seal(&self, plaintext: &str, scope: &SealScope) -> Result<SealedCredential, SealedCredentialError>;
+
+    /// Unwraps a stored envelope. Must fail when the envelope was sealed
+    /// under a different scope.
+    async fn unseal(&self, sealed: &SealedCredential, scope: &SealScope) -> Result<String, SealedCredentialError>;
+}
+
+static CREDENTIAL_SEALER: OnceLock<Arc<dyn CredentialSealer>> = OnceLock::new();
+
+/// Installs the process-wide sealer. Returns `false` when one is already
+/// installed, matching the other ECStore hooks.
+pub fn install_credential_sealer(sealer: Arc<dyn CredentialSealer>) -> bool {
+    CREDENTIAL_SEALER.set(sealer).is_ok()
+}
+
+/// The installed sealer, or `None` when KMS is not wired. Callers that only
+/// need to know whether sealing is possible use this; callers that must have
+/// it use [`seal_secret`] / [`unseal_secret`] and get the typed error.
+pub fn credential_sealer() -> Option<Arc<dyn CredentialSealer>> {
+    CREDENTIAL_SEALER.get().cloned()
+}
+
+/// Seals one secret field. Fails closed: without a sealer the caller must
+/// reject the write rather than persist the secret in clear text after the
+/// operator asked for sealing.
+pub async fn seal_secret(plaintext: &str, scope: &SealScope) -> Result<SealedCredential, SealedCredentialError> {
+    let sealer = credential_sealer().ok_or(SealedCredentialError::NoSealer)?;
+    sealer.seal(plaintext, scope).await
+}
+
+/// Unseals one secret field, rejecting an unknown envelope version first.
+pub async fn unseal_secret(sealed: &SealedCredential, scope: &SealScope) -> Result<String, SealedCredentialError> {
+    sealed.check_version()?;
+    let sealer = credential_sealer().ok_or(SealedCredentialError::NoSealer)?;
+    sealer.unseal(sealed, scope).await
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use parking_lot::Mutex;
+    use std::collections::BTreeMap;
+
+    fn encode_context(context: &BTreeMap<String, String>) -> String {
+        let ordered = context.iter().collect::<BTreeMap<_, _>>();
+        serde_json::to_string(&ordered).expect("context serializes")
+    }
+
+    /// Stands in for the KMS-backed sealer: records the context it was called
+    /// with, and refuses a ciphertext presented under a different one.
+    #[derive(Default)]
+    struct FakeSealer {
+        sealed_contexts: Mutex<Vec<BTreeMap<String, String>>>,
+    }
+
+    #[async_trait]
+    impl CredentialSealer for FakeSealer {
+        async fn seal(&self, plaintext: &str, scope: &SealScope) -> Result<SealedCredential, SealedCredentialError> {
+            let context = scope.encryption_context();
+            self.sealed_contexts.lock().push(context.clone());
+            let mut bound = encode_context(&context);
+            bound.push('|');
+            bound.push_str(plaintext);
+            Ok(SealedCredential {
+                v: SEALED_CREDENTIAL_VERSION,
+                key_id: "key-1".to_string(),
+                key_version: Some("3".to_string()),
+                alg: "AES-256-GCM".to_string(),
+                ct: base64_simd::STANDARD.encode_to_string(bound.as_bytes()),
+            })
+        }
+
+        async fn unseal(&self, sealed: &SealedCredential, scope: &SealScope) -> Result<String, SealedCredentialError> {
+            let raw = base64_simd::STANDARD
+                .decode_to_vec(sealed.ct.as_bytes())
+                .map_err(|err| SealedCredentialError::Malformed(err.to_string()))?;
+            let bound = String::from_utf8(raw).map_err(|err| SealedCredentialError::Malformed(err.to_string()))?;
+            let expected = encode_context(&scope.encryption_context());
+            bound
+                .strip_prefix(&expected)
+                .and_then(|rest| rest.strip_prefix('|'))
+                .map(str::to_string)
+                .ok_or_else(|| SealedCredentialError::Kms("encryption context mismatch".to_string()))
+        }
+    }
+
+    fn scope(owner: &str) -> SealScope {
+        SealScope::new(SealedCredentialStore::OnDemandMigration, owner, "secret_key")
+    }
+
+    #[tokio::test]
+    async fn seal_round_trips_and_binds_the_scope() {
+        let sealer = Arc::new(FakeSealer::default());
+        let sealed = sealer.seal("super-secret", &scope("photos")).await.expect("seal");
+        assert_eq!(sealed.v, SEALED_CREDENTIAL_VERSION);
+        assert_eq!(sealed.key_version.as_deref(), Some("3"));
+        assert_eq!(sealer.unseal(&sealed, &scope("photos")).await.expect("unseal"), "super-secret");
+
+        // The same ciphertext under another bucket must not unseal.
+        let err = sealer
+            .unseal(&sealed, &scope("other-bucket"))
+            .await
+            .expect_err("a ciphertext must not move between owners");
+        assert!(matches!(err, SealedCredentialError::Kms(_)), "{err}");
+
+        // Nor under another field of the same record.
+        let other_field = SealScope::new(SealedCredentialStore::OnDemandMigration, "photos", "session_token");
+        let err = sealer
+            .unseal(&sealed, &other_field)
+            .await
+            .expect_err("a ciphertext must not move between fields");
+        assert!(matches!(err, SealedCredentialError::Kms(_)), "{err}");
+
+        let contexts = sealer.sealed_contexts.lock();
+        assert_eq!(contexts.len(), 1);
+        assert_eq!(contexts[0]["rustfs:store"], "on-demand-migration");
+        assert_eq!(contexts[0]["rustfs:owner"], "photos");
+        assert_eq!(contexts[0]["rustfs:field"], "secret_key");
+    }
+
+    #[tokio::test]
+    async fn an_unknown_envelope_version_is_rejected_before_the_sealer_is_asked() {
+        let sealed = SealedCredential {
+            v: SEALED_CREDENTIAL_VERSION + 1,
+            key_id: "key-1".to_string(),
+            key_version: None,
+            alg: "AES-256-GCM".to_string(),
+            ct: "Zm9v".to_string(),
+        };
+        assert_eq!(
+            sealed.check_version().expect_err("a newer envelope must not be read"),
+            SealedCredentialError::UnsupportedVersion(SEALED_CREDENTIAL_VERSION + 1)
+        );
+        // The global helper reports the version, not "no sealer", even in a
+        // process where none is installed.
+        assert_eq!(
+            unseal_secret(&sealed, &scope("photos")).await.expect_err("version first"),
+            SealedCredentialError::UnsupportedVersion(SEALED_CREDENTIAL_VERSION + 1)
+        );
+    }
+
+    #[tokio::test]
+    async fn without_a_sealer_both_directions_fail_closed() {
+        // This test binary installs no sealer, so the global helpers must
+        // report NoSealer rather than fall back to clear text.
+        assert!(credential_sealer().is_none(), "no sealer is installed in unit tests");
+        assert_eq!(
+            seal_secret("super-secret", &scope("photos")).await.expect_err("seal"),
+            SealedCredentialError::NoSealer
+        );
+        let sealed = SealedCredential {
+            v: SEALED_CREDENTIAL_VERSION,
+            key_id: "key-1".to_string(),
+            key_version: None,
+            alg: "AES-256-GCM".to_string(),
+            ct: "Zm9v".to_string(),
+        };
+        assert_eq!(
+            unseal_secret(&sealed, &scope("photos")).await.expect_err("unseal"),
+            SealedCredentialError::NoSealer
+        );
+    }
+
+    #[test]
+    fn debug_and_serde_keep_the_on_disk_shape_stable() {
+        let sealed = SealedCredential {
+            v: 1,
+            key_id: "key-1".to_string(),
+            key_version: None,
+            alg: "AES-256-GCM".to_string(),
+            ct: "Zm9v".to_string(),
+        };
+        // key_version is omitted when absent, so an envelope from a backend
+        // without version history stays compact.
+        assert_eq!(
+            serde_json::to_string(&sealed).expect("serialize"),
+            r#"{"v":1,"key_id":"key-1","alg":"AES-256-GCM","ct":"Zm9v"}"#
+        );
+        let parsed: SealedCredential = serde_json::from_str(r#"{"v":1,"key_id":"key-1","alg":"AES-256-GCM","ct":"Zm9v"}"#)
+            .expect("an envelope without key_version parses");
+        assert_eq!(parsed, sealed);
+
+        let rendered = format!("{sealed:?}");
+        assert!(rendered.contains("key-1"), "{rendered}");
+        assert!(!rendered.contains("Zm9v"), "Debug must not print the ciphertext: {rendered}");
+    }
+
+    #[test]
+    fn a_malformed_envelope_is_a_typed_error() {
+        let err = serde_json::from_str::<SealedCredential>(r#"{"v":1,"key_id":"key-1"}"#)
+            .map_err(|err| SealedCredentialError::Malformed(err.to_string()))
+            .expect_err("a truncated envelope must not parse");
+        assert!(matches!(err, SealedCredentialError::Malformed(_)), "{err}");
+    }
+}
@@ -30,6 +30,7 @@ use rustfs_protos::{
    ChannelClass, create_new_channel, get_channel_for_class,
    proto_gen::node_service::{
        heal_control_service_client::HealControlServiceClient, node_service_client::NodeServiceClient,
+        scanner_control_service_client::ScannerControlServiceClient,
        tier_mutation_control_service_client::TierMutationControlServiceClient,
    },
 };
@@ -60,6 +61,24 @@ pub async fn node_service_time_out_client(
    node_service_time_out_client_for_class(addr, interceptor, ChannelClass::Control).await
 }

+pub(crate) async fn scanner_control_time_out_client(
+    addr: &str,
+    interceptor: TonicInterceptor,
+) -> crate::error::Result<ScannerControlServiceClient<InterceptedService<AuthenticatedChannel, TonicInterceptor>>> {
+    let interceptor = interceptor.with_rpc_audience(addr)?;
+    let channel = match runtime_sources::cached_node_channel(addr).await {
+        Some(channel) => channel,
+        None => create_new_channel(addr)
+            .await
+            .map_err(|err| crate::error::Error::other(err.to_string()))?,
+    };
+    let channel = ReplayScopeChannel::new(channel, interceptor.replay_scope_audience());
+    let limit = rustfs_protos::scoped_dirty_usage::SCOPED_DIRTY_USAGE_MAX_REQUEST_BYTES as usize;
+    Ok(ScannerControlServiceClient::with_interceptor(channel, interceptor)
+        .max_decoding_message_size(limit)
+        .max_encoding_message_size(limit))
+}
+
 pub async fn heal_control_time_out_client(
    addr: &str,
    interceptor: TonicInterceptor,
@@ -2050,6 +2050,53 @@ impl PeerRestClient {
        .await
    }

+    /// Probe only: scoped ACK production requires a durable per-bucket proof.
+    pub async fn scanner_scoped_dirty_usage_capability(
+        &self,
+        owner_id: String,
+        instance_id: String,
+        entries: Vec<rustfs_protos::proto_gen::node_service::ScannerScopedDirtyUsageEntry>,
+    ) -> Result<bool> {
+        use rustfs_protos::scoped_dirty_usage::*;
+        let payload = rustfs_protos::proto_gen::node_service::ScannerScopedDirtyUsageAckRequest {
+            challenge: Uuid::new_v4().as_bytes().to_vec().into(),
+            protocol_version: SCOPED_DIRTY_USAGE_PROTOCOL_VERSION,
+            owner_id,
+            instance_id,
+            scope: SCOPED_DIRTY_USAGE_BUCKET_SCOPE,
+            probe_only: true,
+            entries,
+        };
+        let canonical = canonical_scoped_dirty_usage_request(&payload).map_err(|err| Error::other(err.to_string()))?;
+        self.finalize_result(
+            async {
+                let mut client = super::client::scanner_control_time_out_client(
+                    &self.grid_host,
+                    TonicInterceptor::Signature(gen_tonic_signature_interceptor()),
+                )
+                .await?;
+                let mut request = Request::new(payload.clone());
+                set_tonic_canonical_body_digest(&mut request, &canonical)?;
+                let response = client.scanner_scoped_dirty_usage_ack(request).await?.into_inner();
+                let body = canonical_scoped_dirty_usage_response(&canonical, &response)
+                    .map_err(|_| Error::other("scoped dirty usage capability response is too large"))?;
+                verify_tonic_rpc_response_proof(&body, response.response_proof.as_ref())?;
+                if response.protocol_version != SCOPED_DIRTY_USAGE_PROTOCOL_VERSION
+                    || response.owner_id != payload.owner_id
+                    || response.instance_id != payload.instance_id
+                    || response.max_entries != SCOPED_DIRTY_USAGE_MAX_ENTRIES
+                    || response.max_request_bytes != SCOPED_DIRTY_USAGE_MAX_REQUEST_BYTES
+                    || response.cleared != 0
+                {
+                    return Err(Error::other("scoped dirty usage capability response does not match request"));
+                }
+                Ok(response.supported)
+            }
+            .await,
+        )
+        .await
+    }
+
    pub async fn acknowledge_scanner_dirty_usage(&self, instance_id: String, generation: u64) -> Result<ScannerPeerActivity> {
        let result = self
            .scanner_activity_request_with_protocol(instance_id.clone(), generation, SCANNER_ACTIVITY_PROTOCOL_VERSION)
@@ -5493,6 +5493,7 @@ where
    fence.ensure_held()?;
    let mut opts = ObjectOptions {
        max_parity: true,
+        write_completion: crate::object_api::WriteCompletion::TailDrained,
        no_lock: true,
        http_preconditions: Some(pool_meta_cas_preconditions(token, object)?),
        ..Default::default()
@@ -14412,6 +14413,7 @@ impl ECStore {
                encoded.clone(),
                &ObjectOptions {
                    max_parity: true,
+                    write_completion: crate::object_api::WriteCompletion::TailDrained,
                    http_preconditions: Some(HTTPPreconditions {
                        if_none_match: Some("*".to_string()),
                        ..Default::default()
@@ -14566,6 +14568,7 @@ impl ECStore {
                encoded,
                &ObjectOptions {
                    max_parity: true,
+                    write_completion: crate::object_api::WriteCompletion::TailDrained,
                    http_preconditions: Some(http_preconditions),
                    ..Default::default()
                },
@@ -14957,6 +14960,7 @@ impl ECStore {
                encoded,
                &ObjectOptions {
                    max_parity: true,
+                    write_completion: crate::object_api::WriteCompletion::TailDrained,
                    http_preconditions: Some(HTTPPreconditions {
                        if_match: Some(etag),
                        ..Default::default()
@@ -317,6 +317,22 @@ impl DiskStoreRenameDataExt for LocalDiskWrapper {
        dst_path: &str,
        external_guard: Option<Arc<dyn Send + Sync>>,
    ) -> Result<RenameDataResp> {
+        self.rename_data_observed(src_volume, src_path, fi, dst_volume, dst_path, external_guard)
+            .await
+            .result
+    }
+}
+
+impl LocalDiskWrapper {
+    pub(in crate::disk) async fn rename_data_observed(
+        &self,
+        src_volume: &str,
+        src_path: &str,
+        fi: &FileInfo,
+        dst_volume: &str,
+        dst_path: &str,
+        external_guard: Option<Arc<dyn Send + Sync>>,
+    ) -> super::RenameDataObservation {
        let operation = self.clone();
        let src_volume = src_volume.to_owned();
        let src_path = src_path.to_owned();
@@ -333,22 +349,35 @@ impl DiskStoreRenameDataExt for LocalDiskWrapper {
        } else {
            get_max_timeout_duration()
        };
-        run_owned_mutation(external_guard, move || async move {
-            operation
+        let observed = run_owned_mutation(external_guard, move || async move {
+            let mut preflight_rejection = None;
+            let result = operation
                .track_disk_health_mutation(
                    "rename_data",
                    DiskMetricMutation::Write,
                    || async {
-                        operation
-                            .disk
-                            .rename_data_borrowed(&src_volume, &src_path, &fi, &dst_volume, &dst_path)
-                            .await
+                        // Preserve the former DiskAPI future's single boxing boundary.
+                        let observed =
+                            Box::pin(
+                                operation
+                                    .disk
+                                    .rename_data_observed(&src_volume, &src_path, &fi, &dst_volume, &dst_path),
+                            )
+                            .await;
+                        preflight_rejection = observed.preflight_rejection;
+                        observed.result
                    },
                    timeout_duration,
                )
-                .await
+                .await;
+            // Health tracking must observe the real disk error, not an Ok tuple.
+            Ok(super::RenameDataObservation {
+                result,
+                preflight_rejection,
+            })
        })
-        .await
+        .await;
+        observed.unwrap_or_else(|error| super::RenameDataObservation::unknown(Err(error)))
    }
 }

@@ -2588,6 +2617,46 @@ mod tests {
        assert_eq!(wrapper.metrics_snapshot().api_calls.get("unknown"), Some(&1));
    }

+    #[tokio::test]
+    async fn rename_preflight_evidence_preserves_health_errors_and_owned_reply() {
+        for source_exists in [false, true] {
+            for guarded in [false, true] {
+                let dir = tempfile::tempdir().expect("temp dir should be created");
+                let endpoint = Endpoint::try_from(dir.path().to_str().expect("temp dir should be valid UTF-8"))
+                    .expect("endpoint should parse");
+                let disk = Arc::new(LocalDisk::new(&endpoint, false).await.expect("local disk should be created"));
+                if source_exists {
+                    disk.make_volume("source").await.expect("source volume should exist");
+                }
+                let wrapper = LocalDiskWrapper::new(disk, false);
+                let drops = Arc::new(std::sync::atomic::AtomicUsize::new(0));
+                let external_guard = guarded.then(|| Arc::new(DropProbe(Arc::clone(&drops))) as Arc<dyn Send + Sync>);
+                let mut file_info = FileInfo::new("object", 1, 0);
+                file_info.mod_time = Some(::time::OffsetDateTime::now_utc());
+                file_info.erasure.index = 1;
+                let observed = wrapper
+                    .rename_data_observed("source", "object", &file_info, "missing-destination", "object", external_guard)
+                    .await;
+                assert!(observed.rejected_before_publication(), "normal access rejection must carry proof");
+                assert!(matches!(observed.result, Err(DiskError::VolumeNotFound)));
+                let snapshot = wrapper.metrics_snapshot();
+                assert_eq!(snapshot.api_calls.get("rename_data"), Some(&1));
+                assert_eq!(snapshot.total_writes, 0, "health tracking must not observe the rejection as Ok");
+                assert_eq!(drops.load(Ordering::SeqCst), usize::from(guarded));
+
+                wrapper.health.force_runtime_state_for_test(RuntimeDriveHealthState::Offline);
+                let observed = wrapper
+                    .rename_data_observed("source", "object", &file_info, "missing-destination", "object", None)
+                    .await;
+                assert!(!observed.rejected_before_publication(), "wrapper errors carry no local preflight proof");
+                assert!(matches!(observed.result, Err(DiskError::FaultyDisk)));
+                let snapshot = wrapper.metrics_snapshot();
+                assert_eq!(snapshot.total_errors_availability, 1);
+                assert_eq!(snapshot.total_writes, 0);
+            }
+        }
+    }
+
    #[tokio::test]
    async fn local_disk_health_wrapper_counts_returned_availability_errors() {
        let dir = tempfile::tempdir().expect("temp dir should be created");
@@ -75,6 +75,25 @@ use time::OffsetDateTime;
 use tokio::io::{AsyncRead, AsyncWrite};
 use uuid::Uuid;

+/// Local preflight evidence stays outside DiskAPI and the RPC response format.
+pub(crate) struct RenameDataObservation {
+    pub(crate) result: Result<RenameDataResp>,
+    preflight_rejection: Option<local::LocalRenamePreflightRejection>,
+}
+
+impl RenameDataObservation {
+    fn unknown(result: Result<RenameDataResp>) -> Self {
+        Self {
+            result,
+            preflight_rejection: None,
+        }
+    }
+
+    pub(crate) fn rejected_before_publication(&self) -> bool {
+        self.result.is_err() && self.preflight_rejection.is_some()
+    }
+}
+
 const QUOTA_MUTATION_FENCE_PREFIX: &str = "tmp/quota-mutation-fences/";
 pub(crate) const QUOTA_MUTATION_FENCE_METADATA_SUFFIX: &str = "quota-mutation-fence-token";

@@ -711,6 +730,36 @@ impl Disk {
            .await
    }

+    pub(crate) async fn rename_data_borrowed_with_fence_observed(
+        &self,
+        src_volume: &str,
+        src_path: &str,
+        fi: &FileInfo,
+        dst_volume: &str,
+        dst_path: &str,
+        scanner_publication_lease_token: Option<Uuid>,
+    ) -> RenameDataObservation {
+        match self {
+            Disk::Local(local_disk) => {
+                local_disk
+                    .rename_data_observed(src_volume, src_path, fi, dst_volume, dst_path, None)
+                    .await
+            }
+            Disk::Remote(remote_disk) => RenameDataObservation::unknown(
+                remote_disk
+                    .rename_data_borrowed_with_fence(
+                        src_volume,
+                        src_path,
+                        fi,
+                        dst_volume,
+                        dst_path,
+                        scanner_publication_lease_token,
+                    )
+                    .await,
+            ),
+        }
+    }
+
    pub(crate) async fn rename_data_borrowed_with_fence(
        &self,
        src_volume: &str,
@@ -870,6 +870,18 @@ impl TierFreeVersionReceiptSink {
    }
 }

+/// Internal PUT completion boundary; this does not change fsync or write quorum.
+#[doc(hidden)]
+#[derive(Debug, Default, Clone, Copy, PartialEq, Eq)]
+pub enum WriteCompletion {
+    /// Return at write quorum when the commit owner can retain its guards.
+    #[default]
+    Quorum,
+    /// Drain the rename fan-out before returning. Minority failures still heal
+    /// after a successful quorum commit; this does not require every disk to succeed.
+    TailDrained,
+}
+
 #[derive(Default, Clone)]
 pub struct ObjectOptions {
    // Use the maximum parity (N/2), used when saving server configuration files
@@ -896,6 +908,10 @@ pub struct ObjectOptions {
    /// Persisted bucket incarnation observed before authorization.
    pub expected_bucket_incarnation_id: Option<Uuid>,
    pub no_lock: bool,
+    /// Control-plane writers that immediately read or CAS the same namespace
+    /// key use TailDrained without changing namespace lock ownership.
+    #[doc(hidden)]
+    pub write_completion: WriteCompletion,
    /// True when an upper layer already holds the object read lock before
    /// forwarding a no_lock read to the set layer.
    pub metadata_cache_safe: bool,
@@ -940,6 +956,9 @@ pub struct ObjectOptions {
    pub preserve_etag: Option<String>,
    pub metadata_chg: bool,
    pub http_preconditions: Option<HTTPPreconditions>,
+    /// Internal create-only writes may also preserve an acknowledged deletion.
+    /// Evaluated with `http_preconditions` under the namespace commit lock.
+    pub preserve_delete_marker: bool,

    pub delete_replication: Option<ReplicationState>,
    pub delete_replication_config_snapshot: Option<Arc<DeleteReplicationConfigSnapshot>>,
@@ -78,6 +78,21 @@ pub(crate) struct ScannerPublicationLeaseEntry {
    pub(crate) _operation_guard: OwnedRwLockReadGuard<()>,
 }

+pub(crate) struct NamespaceCommitGuard {
+    ctx: Arc<InstanceContext>,
+    counted: bool,
+}
+
+impl Drop for NamespaceCommitGuard {
+    fn drop(&mut self) {
+        if self.counted {
+            // Publish the new generation before a zero-pending publication probe.
+            self.ctx.advance_namespace_commit_generation();
+            self.ctx.namespace_commits.fetch_sub(1, Ordering::AcqRel);
+        }
+    }
+}
+
 /// Runtime state owned by a single `ECStore` instance.
 ///
 /// This is intentionally minimal in the first migration slice; subsequent
@@ -209,9 +224,13 @@ pub struct InstanceContext {
    /// Last storage-owned movement snapshot observed under the operation
    /// gate. SetDisks cache writers fail closed until ECStore refreshes it.
    scanner_publication_state: AtomicU8,
+    namespace_commits: AtomicU64,
+    namespace_commit_generation: AtomicU64,
    /// Resolves object-encryption material at the application boundary.
    object_encryption_resolver: OnceLock<Arc<dyn ObjectEncryptionResolver>>,
    tier_delete_journal_recovery_stores: std::sync::Mutex<HashSet<Uuid>>,
+    #[cfg(test)]
+    suppress_tier_delete_journal_recovery: bool,
    transition_transaction_recovery_stores: std::sync::Mutex<HashSet<Uuid>>,
    tier_delete_journal_recovery_wakeup: tokio::sync::Notify,
 }
@@ -256,8 +275,12 @@ impl InstanceContext {
            data_movement_generation_exhausted: AtomicBool::new(false),
            data_movement_generation_notify: Arc::new(Notify::new()),
            scanner_publication_state: AtomicU8::new(SCANNER_PUBLICATION_STATE_UNKNOWN),
+            namespace_commits: AtomicU64::new(0),
+            namespace_commit_generation: AtomicU64::new(0),
            object_encryption_resolver: OnceLock::new(),
            tier_delete_journal_recovery_stores: std::sync::Mutex::new(HashSet::new()),
+            #[cfg(test)]
+            suppress_tier_delete_journal_recovery: false,
            transition_transaction_recovery_stores: std::sync::Mutex::new(HashSet::new()),
            tier_delete_journal_recovery_wakeup: tokio::sync::Notify::new(),
        }
@@ -385,6 +408,36 @@ impl InstanceContext {
            && self.scanner_publication_state.load(Ordering::Acquire) == SCANNER_PUBLICATION_STATE_ALLOWED
    }

+    pub(crate) fn begin_namespace_commit(self: &Arc<Self>) -> Arc<NamespaceCommitGuard> {
+        let counted = self
+            .namespace_commits
+            .fetch_update(Ordering::AcqRel, Ordering::Acquire, |count| count.checked_add(1))
+            .is_ok();
+        if counted {
+            self.advance_namespace_commit_generation();
+        } else {
+            self.namespace_commit_generation.store(u64::MAX, Ordering::Release);
+        }
+        Arc::new(NamespaceCommitGuard {
+            ctx: Arc::clone(self),
+            counted,
+        })
+    }
+
+    fn advance_namespace_commit_generation(&self) {
+        let _ = self
+            .namespace_commit_generation
+            .fetch_update(Ordering::AcqRel, Ordering::Acquire, |generation| Some(generation.saturating_add(1)));
+    }
+
+    pub(crate) fn namespace_commit_generation(&self) -> u64 {
+        self.namespace_commit_generation.load(Ordering::Acquire)
+    }
+
+    pub(crate) fn namespace_commits_pending(&self) -> bool {
+        self.namespace_commits.load(Ordering::Acquire) != 0 || self.namespace_commit_generation() == u64::MAX
+    }
+
    pub(crate) fn set_scanner_publication_state(&self, blocked: bool) {
        self.scanner_publication_state.store(
            if blocked {
@@ -640,12 +693,21 @@ impl InstanceContext {
    }

    pub(crate) fn mark_tier_delete_journal_recovery_started(&self, store_id: Uuid) -> bool {
+        #[cfg(test)]
+        if self.suppress_tier_delete_journal_recovery {
+            return false;
+        }
        self.tier_delete_journal_recovery_stores
            .lock()
            .unwrap_or_else(std::sync::PoisonError::into_inner)
            .insert(store_id)
    }

+    #[cfg(test)]
+    pub(crate) fn suppress_tier_delete_journal_recovery_for_test(&mut self) {
+        self.suppress_tier_delete_journal_recovery = true;
+    }
+
    pub(crate) fn mark_transition_transaction_recovery_started(&self, store_id: Uuid) -> bool {
        self.transition_transaction_recovery_stores
            .lock()
@@ -756,6 +818,50 @@ pub fn bootstrap_ctx() -> Arc<InstanceContext> {
 mod tests {
    use super::*;

+    #[test]
+    fn namespace_commit_guards_are_instance_local_and_count_until_last_owner() {
+        let first = Arc::new(InstanceContext::new());
+        let other = Arc::new(InstanceContext::new());
+        first.set_scanner_publication_state(false);
+        other.set_scanner_publication_state(false);
+        assert!(first.scanner_publication_state_allowed());
+        let one = first.begin_namespace_commit();
+        let shared_owner = Arc::clone(&one);
+        let two = first.begin_namespace_commit();
+        assert!(first.namespace_commits_pending());
+        assert!(first.scanner_publication_state_allowed(), "pending writes must not block scan admission");
+        assert_eq!(first.namespace_commit_generation(), 2);
+        assert!(!other.namespace_commits_pending());
+        assert_eq!(other.namespace_commit_generation(), 0);
+        assert!(other.scanner_publication_state_allowed());
+        drop(one);
+        assert_eq!(first.namespace_commit_generation(), 2);
+        drop(shared_owner);
+        assert!(first.namespace_commits_pending());
+        assert_eq!(first.namespace_commit_generation(), 3);
+        drop(two);
+        assert!(!first.namespace_commits_pending());
+        assert_eq!(first.namespace_commit_generation(), 4);
+        assert!(first.scanner_publication_state_allowed());
+    }
+
+    #[test]
+    fn namespace_commit_counter_exhaustion_keeps_publication_blocked() {
+        for (count, generation) in [(0, u64::MAX - 1), (u64::MAX, 0)] {
+            let ctx = Arc::new(InstanceContext::new());
+            ctx.set_scanner_publication_state(false);
+            ctx.namespace_commits.store(count, Ordering::Release);
+            ctx.namespace_commit_generation.store(generation, Ordering::Release);
+            let guard = ctx.begin_namespace_commit();
+            assert!(ctx.namespace_commits_pending());
+            assert_eq!(ctx.namespace_commit_generation(), u64::MAX);
+            drop(guard);
+            assert!(ctx.namespace_commits_pending());
+            assert_eq!(ctx.namespace_commit_generation(), u64::MAX);
+            assert_eq!(ctx.namespace_commits.load(Ordering::Acquire), count);
+        }
+    }
+
    // The SetupType inputs must derive the exact (is_erasure,
    // is_dist_erasure, is_erasure_sd) triples that the original three
    // process-global erasure bools produced via update_erasure_type().
@@ -1073,6 +1179,12 @@ mod tests {
        assert!(!ctx_a.mark_tier_delete_journal_recovery_started(store_a));
        assert!(ctx_a.mark_tier_delete_journal_recovery_started(store_b));
        assert!(ctx_b.mark_tier_delete_journal_recovery_started(store_a));
+
+        let mut manual_ctx = InstanceContext::new();
+        manual_ctx.suppress_tier_delete_journal_recovery_for_test();
+        assert!(!manual_ctx.mark_tier_delete_journal_recovery_started(store_a));
+        assert!(!manual_ctx.mark_tier_delete_journal_recovery_started(store_b));
+        assert!(ctx_b.mark_tier_delete_journal_recovery_started(store_b));
    }

    #[test]
@@ -62,12 +62,27 @@ const REMOTE_VERSION_STATE_PROOF_TTL: Duration = Duration::from_secs(30);
 const CROSS_POOL_FENCE_SUPPORTED_VERSION: u32 = 2;
 const TIER_DELETE_JOURNAL_POLICY_SUPPORTED_VERSION: u32 = 3;
 const DECOMMISSION_TARGET_FENCE_POLICY_SUPPORTED_VERSION: u32 = 4;
+// Keep this synchronized with the version served by node_service. Including
+// the local member in the minimum prevents an older coordinator from
+// self-authorizing a policy implemented only by newer remote peers.
+const LOCAL_CROSS_POOL_FENCE_POLICY_SUPPORTED_VERSION: u32 = 4;
+/// Version 5 is reserved for a fleet whose every metadata writer preserves
+/// explicit transition version state and destination identity, and implements
+/// conditional per-generation `xl.meta` writes with strong readback. The node
+/// service must not advertise this version until the conditional writer from
+/// rustfs/backlog#684 is available.
+const LEGACY_TRANSITION_STATE_RECONCILE_POLICY_SUPPORTED_VERSION: u32 = 5;
 type CrossPoolFencePolicyResult = Result<BTreeMap<String, Uuid>>;

 fn cross_pool_fence_policy_results(
    peer_epochs: BTreeMap<String, Uuid>,
    minimum_version: u32,
-) -> (CrossPoolFencePolicyResult, CrossPoolFencePolicyResult, CrossPoolFencePolicyResult) {
+) -> (
+    CrossPoolFencePolicyResult,
+    CrossPoolFencePolicyResult,
+    CrossPoolFencePolicyResult,
+    CrossPoolFencePolicyResult,
+) {
    let journal_result = if minimum_version >= TIER_DELETE_JOURNAL_POLICY_SUPPORTED_VERSION {
        Ok(peer_epochs.clone())
    } else {
@@ -78,7 +93,18 @@ fn cross_pool_fence_policy_results(
    } else {
        Err(Error::other("decommission target fence policy capability version is unsupported"))
    };
-    (Ok(peer_epochs), journal_result, decommission_target_fence_result)
+    let legacy_transition_state_reconcile_result =
+        if minimum_version >= LEGACY_TRANSITION_STATE_RECONCILE_POLICY_SUPPORTED_VERSION {
+            Ok(peer_epochs.clone())
+        } else {
+            Err(Error::other("legacy transition state reconcile policy capability version is unsupported"))
+        };
+    (
+        Ok(peer_epochs),
+        journal_result,
+        decommission_target_fence_result,
+        legacy_transition_state_reconcile_result,
+    )
 }

 #[derive(Clone, Debug)]
@@ -252,10 +278,21 @@ pub(crate) struct TierDeleteJournalFleetProofToken {
    _permit: FleetCapabilityProofPermit,
 }

+/// Effect-window authority for one legacy transition-state reconciliation.
+///
+/// The token intentionally cannot be cloned. Its permit keeps the admitted
+/// fleet generation alive until the caller finishes the final strong
+/// readback, while revocation makes every later validation fail immediately.
+pub struct LegacyTransitionStateReconcileFleetProofToken {
+    token: FleetCapabilityProofToken,
+    _permit: FleetCapabilityProofPermit,
+}
+
 static REMOTE_VERSION_STATE_FLEET_PROOF: OnceLock<std::sync::RwLock<FleetCapabilityProofState>> = OnceLock::new();
 static CROSS_POOL_FENCE_FLEET_PROOF: OnceLock<std::sync::RwLock<FleetCapabilityProofState>> = OnceLock::new();
 static TIER_DELETE_JOURNAL_FLEET_PROOF: OnceLock<std::sync::RwLock<FleetCapabilityProofState>> = OnceLock::new();
 static DECOMMISSION_TARGET_FENCE_FLEET_PROOF: OnceLock<std::sync::RwLock<FleetCapabilityProofState>> = OnceLock::new();
+static LEGACY_TRANSITION_STATE_RECONCILE_FLEET_PROOF: OnceLock<std::sync::RwLock<FleetCapabilityProofState>> = OnceLock::new();
 static REMOTE_VERSION_STATE_PROBE_TOPOLOGY: OnceLock<String> = OnceLock::new();

 fn cross_pool_fence_fleet_proof_slot() -> &'static std::sync::RwLock<FleetCapabilityProofState> {
@@ -274,6 +311,10 @@ fn decommission_target_fence_fleet_proof_slot() -> &'static std::sync::RwLock<Fl
    DECOMMISSION_TARGET_FENCE_FLEET_PROOF.get_or_init(|| std::sync::RwLock::new(FleetCapabilityProofState::default()))
 }

+fn legacy_transition_state_reconcile_fleet_proof_slot() -> &'static std::sync::RwLock<FleetCapabilityProofState> {
+    LEGACY_TRANSITION_STATE_RECONCILE_FLEET_PROOF.get_or_init(|| std::sync::RwLock::new(FleetCapabilityProofState::default()))
+}
+
 fn revoke_fleet_capability_proof_state(state: &mut FleetCapabilityProofState) {
    if let Some(proof) = state.proof.take() {
        proof.generation.revoke();
@@ -444,6 +485,125 @@ pub(crate) fn tier_delete_journal_topology_generation(proof: &TierDeleteJournalF
    stable_tier_delete_journal_topology_generation(&proof.token.topology_fingerprint)
 }

+/// Acquire one non-cloneable authority that must span the complete reconcile
+/// effect window, including its final strong readback.
+pub async fn acquire_legacy_transition_state_reconcile_fleet_proof() -> Option<LegacyTransitionStateReconcileFleetProofToken> {
+    let expected_topology = REMOTE_VERSION_STATE_PROBE_TOPOLOGY.get()?;
+    let proof = {
+        let state = legacy_transition_state_reconcile_fleet_proof_slot()
+            .read()
+            .unwrap_or_else(std::sync::PoisonError::into_inner);
+        acquire_legacy_transition_state_reconcile_fleet_proof_from(&state, expected_topology, Instant::now())?
+    };
+    let observed_peer_epochs = observe_legacy_transition_state_reconcile_fleet(expected_topology).await?;
+    let state = legacy_transition_state_reconcile_fleet_proof_slot()
+        .read()
+        .unwrap_or_else(std::sync::PoisonError::into_inner);
+    legacy_transition_state_reconcile_fleet_proof_matches_observation_at(
+        &state,
+        &proof,
+        expected_topology,
+        &observed_peer_epochs,
+        Instant::now(),
+    )
+    .then_some(proof)
+}
+
+fn acquire_legacy_transition_state_reconcile_fleet_proof_from(
+    state: &FleetCapabilityProofState,
+    expected_topology: &str,
+    now: Instant,
+) -> Option<LegacyTransitionStateReconcileFleetProofToken> {
+    let token = acquire_fleet_capability_proof_from(state, expected_topology, now)?;
+    let permit = state.proof.as_ref()?.generation.try_acquire()?;
+    Some(LegacyTransitionStateReconcileFleetProofToken { token, _permit: permit })
+}
+
+async fn observe_legacy_transition_state_reconcile_fleet(expected_topology: &str) -> Option<BTreeMap<String, Uuid>> {
+    let notification_sys = get_global_notification_sys()?;
+    let (peer_epochs, minimum_version) = timeout(
+        REMOTE_VERSION_STATE_PROBE_TIMEOUT,
+        notification_sys.probe_cross_pool_fence_fleet(expected_topology),
+    )
+    .await
+    .ok()?
+    .ok()?;
+    let (_, _, _, reconcile_result) = cross_pool_fence_policy_results(peer_epochs, minimum_version);
+    reconcile_result.ok()
+}
+
+/// Revalidate the exact fleet generation captured by a reconcile token with a
+/// fresh synchronous observation. Callers must await this before each
+/// conditional metadata write and after the final strong readback.
+pub async fn legacy_transition_state_reconcile_fleet_proof_matches(
+    proof: &LegacyTransitionStateReconcileFleetProofToken,
+) -> bool {
+    let Some(expected_topology) = REMOTE_VERSION_STATE_PROBE_TOPOLOGY.get() else {
+        return false;
+    };
+    legacy_transition_state_reconcile_fleet_proof_matches_with_observer(
+        legacy_transition_state_reconcile_fleet_proof_slot(),
+        proof,
+        expected_topology,
+        || observe_legacy_transition_state_reconcile_fleet(expected_topology),
+    )
+    .await
+}
+
+async fn legacy_transition_state_reconcile_fleet_proof_matches_with_observer<F, Fut>(
+    slot: &std::sync::RwLock<FleetCapabilityProofState>,
+    proof: &LegacyTransitionStateReconcileFleetProofToken,
+    expected_topology: &str,
+    observe: F,
+) -> bool
+where
+    F: FnOnce() -> Fut,
+    Fut: Future<Output = Option<BTreeMap<String, Uuid>>>,
+{
+    {
+        let state = slot.read().unwrap_or_else(std::sync::PoisonError::into_inner);
+        if !legacy_transition_state_reconcile_fleet_proof_matches_at(&state, proof, expected_topology, Instant::now()) {
+            return false;
+        }
+    }
+    let Some(observed_peer_epochs) = observe().await else {
+        return false;
+    };
+    let state = slot.read().unwrap_or_else(std::sync::PoisonError::into_inner);
+    legacy_transition_state_reconcile_fleet_proof_matches_observation_at(
+        &state,
+        proof,
+        expected_topology,
+        &observed_peer_epochs,
+        Instant::now(),
+    )
+}
+
+fn legacy_transition_state_reconcile_fleet_proof_matches_at(
+    state: &FleetCapabilityProofState,
+    proof: &LegacyTransitionStateReconcileFleetProofToken,
+    expected_topology: &str,
+    now: Instant,
+) -> bool {
+    proof._permit.generation.is_accepting()
+        && fleet_capability_proof_matches_at(state, &proof.token, expected_topology, now)
+        && state
+            .proof
+            .as_ref()
+            .is_some_and(|current| Arc::ptr_eq(&current.generation, &proof._permit.generation))
+}
+
+fn legacy_transition_state_reconcile_fleet_proof_matches_observation_at(
+    state: &FleetCapabilityProofState,
+    proof: &LegacyTransitionStateReconcileFleetProofToken,
+    expected_topology: &str,
+    observed_peer_epochs: &BTreeMap<String, Uuid>,
+    now: Instant,
+) -> bool {
+    legacy_transition_state_reconcile_fleet_proof_matches_at(state, proof, expected_topology, now)
+        && proof.token.peer_epochs.as_ref() == observed_peer_epochs
+}
+
 #[cfg(all(test, feature = "test-util"))]
 pub(crate) fn tier_delete_journal_fleet_proof_has_inflight_for_test() -> bool {
    let state = tier_delete_journal_fleet_proof_slot()
@@ -766,6 +926,7 @@ pub fn start_remote_version_state_fleet_probe(topology_fingerprint: String) {
                cross_pool_fence_fleet_proof_slot(),
                tier_delete_journal_fleet_proof_slot(),
                decommission_target_fence_fleet_proof_slot(),
+                legacy_transition_state_reconcile_fleet_proof_slot(),
            ] {
                mark_fleet_capability_topology_conflict(slot);
            }
@@ -798,11 +959,12 @@ pub fn start_remote_version_state_fleet_probe(topology_fingerprint: String) {
                .unwrap_or_else(|_| Err(Error::other("cross-pool fence fleet capability probe timed out"))),
                None => Err(Error::other("cross-pool fence fleet capability notification system is unavailable")),
            };
-            let (fence_result, journal_result, decommission_target_fence_result) = match fence_probe {
+            let (fence_result, journal_result, decommission_target_fence_result, reconcile_result) = match fence_probe {
                Ok((peer_epochs, minimum_version)) => cross_pool_fence_policy_results(peer_epochs, minimum_version),
                Err(err) => {
                    let message = err.to_string();
                    (
+                        Err(Error::other(message.clone())),
                        Err(Error::other(message.clone())),
                        Err(Error::other(message.clone())),
                        Err(Error::other(message)),
@@ -818,6 +980,7 @@ pub fn start_remote_version_state_fleet_probe(topology_fingerprint: String) {
                revoke_fleet_capability_proof(cross_pool_fence_fleet_proof_slot());
                revoke_fleet_capability_proof(tier_delete_journal_fleet_proof_slot());
                revoke_fleet_capability_proof(decommission_target_fence_fleet_proof_slot());
+                revoke_fleet_capability_proof(legacy_transition_state_reconcile_fleet_proof_slot());
            } else if let Some(err) = publish_fleet_capability_probe_result(
                remote_version_state_fleet_proof_slot(),
                &topology_fingerprint,
@@ -880,6 +1043,24 @@ pub fn start_remote_version_state_fleet_probe(topology_fingerprint: String) {
                    "notification capability probe"
                );
            }
+            if !topology_conflict
+                && let Some(err) = publish_fleet_capability_probe_result(
+                    legacy_transition_state_reconcile_fleet_proof_slot(),
+                    &topology_fingerprint,
+                    reconcile_result,
+                    Instant::now(),
+                )
+            {
+                debug!(
+                    event = EVENT_NOTIFICATION_CAPABILITY_PROBE,
+                    component = LOG_COMPONENT_ECSTORE,
+                    subsystem = LOG_SUBSYSTEM_NOTIFICATION,
+                    capability = "legacy_transition_state_reconcile_v1",
+                    state = "failed_closed",
+                    error = %err,
+                    "notification capability probe"
+                );
+            }
            sleep(REMOTE_VERSION_STATE_PROBE_INTERVAL).await;
        }
    });
@@ -959,7 +1140,7 @@ impl NotificationSys {
            client.probe_cross_pool_fence(topology_fingerprint.to_string()).await
        });
        let mut peer_epochs = BTreeMap::new();
-        let mut minimum_version = u32::MAX;
+        let mut minimum_version = LOCAL_CROSS_POOL_FENCE_POLICY_SUPPORTED_VERSION;
        for result in join_all(probes).await {
            let (peer, version, epoch) = result?;
            if version < CROSS_POOL_FENCE_SUPPORTED_VERSION {
@@ -968,11 +1149,6 @@ impl NotificationSys {
            minimum_version = minimum_version.min(version);
            insert_remote_version_state_peer(&mut peer_epochs, peer, epoch)?;
        }
-        // A single-node deployment has no remote member to lower the local
-        // policy version advertised by this binary.
-        if minimum_version == u32::MAX {
-            minimum_version = DECOMMISSION_TARGET_FENCE_POLICY_SUPPORTED_VERSION;
-        }
        Ok((peer_epochs, minimum_version))
    }
 }
@@ -3190,20 +3366,36 @@ mod tests {
    #[test]
    fn cross_pool_policy_versions_authorize_only_their_supported_protocols() {
        let peers = BTreeMap::from([("node-b:9000".to_string(), Uuid::new_v4())]);
-        let (generic_v2, journal_v2, decommission_v2) = cross_pool_fence_policy_results(peers.clone(), 2);
+        let (generic_v2, journal_v2, decommission_v2, reconcile_v2) = cross_pool_fence_policy_results(peers.clone(), 2);
        assert!(generic_v2.is_ok(), "v2 remains valid for existing cross-pool fencing");
        assert!(journal_v2.is_err(), "a mixed v2/v3 fleet must fail closed for journal-v6 deletion");
        assert!(decommission_v2.is_err(), "v2 cannot authorize the sticky per-target decommission fence");
+        assert!(reconcile_v2.is_err(), "v2 cannot authorize legacy transition-state reconciliation");

-        let (generic_v3, journal_v3, decommission_v3) = cross_pool_fence_policy_results(peers.clone(), 3);
+        let (generic_v3, journal_v3, decommission_v3, reconcile_v3) = cross_pool_fence_policy_results(peers.clone(), 3);
        assert!(generic_v3.is_ok());
        assert!(journal_v3.is_ok(), "an all-v3 fleet may authorize journal-v6 deletion");
        assert!(decommission_v3.is_err(), "v3 members do not understand the per-target decommission fence");
+        assert!(reconcile_v3.is_err());

-        let (generic_v4, journal_v4, decommission_v4) = cross_pool_fence_policy_results(peers, 4);
+        let (generic_v4, journal_v4, decommission_v4, reconcile_v4) =
+            cross_pool_fence_policy_results(peers.clone(), LOCAL_CROSS_POOL_FENCE_POLICY_SUPPORTED_VERSION);
        assert!(generic_v4.is_ok());
        assert!(journal_v4.is_ok());
        assert!(decommission_v4.is_ok(), "an all-v4 fleet may create sticky per-target reservations");
+        assert!(
+            reconcile_v4.is_err(),
+            "the current local policy lacks the conditional xl.meta writer required by reconcile"
+        );
+
+        let (generic_v5, journal_v5, decommission_v5, reconcile_v5) = cross_pool_fence_policy_results(peers, 5);
+        assert!(generic_v5.is_ok());
+        assert!(journal_v5.is_ok());
+        assert!(decommission_v5.is_ok());
+        assert!(
+            reconcile_v5.is_ok(),
+            "only an all-v5 fleet preserves destination identity and conditional reconcile writes"
+        );
    }

    #[test]
@@ -3458,6 +3650,234 @@ mod tests {
        );
    }

+    #[test]
+    fn legacy_transition_state_reconcile_admits_only_compatible_single_and_multi_node_fleets() {
+        let now = Instant::now();
+        for peers in [
+            BTreeMap::new(),
+            BTreeMap::from([("peer-a".to_string(), Uuid::new_v4()), ("peer-b".to_string(), Uuid::new_v4())]),
+        ] {
+            let slot = std::sync::RwLock::new(FleetCapabilityProofState::default());
+            let (_, _, _, result) =
+                cross_pool_fence_policy_results(peers, LEGACY_TRANSITION_STATE_RECONCILE_POLICY_SUPPORTED_VERSION);
+            assert!(publish_fleet_capability_probe_result(&slot, "topology-a", result, now).is_none());
+
+            let admitted = {
+                let state = slot.read().expect("reconcile proof slot should not poison");
+                acquire_legacy_transition_state_reconcile_fleet_proof_from(&state, "topology-a", now)
+                    .expect("an all-compatible fleet should admit reconciliation")
+            };
+            let state = slot.read().expect("reconcile proof slot should not poison");
+            assert!(legacy_transition_state_reconcile_fleet_proof_matches_at(
+                &state,
+                &admitted,
+                "topology-a",
+                now,
+            ));
+        }
+    }
+
+    #[test]
+    fn legacy_transition_state_reconcile_restart_drains_concurrent_effect_windows() {
+        let slot = std::sync::RwLock::new(FleetCapabilityProofState::default());
+        let now = Instant::now();
+        let original_peers = BTreeMap::from([("peer-a".to_string(), Uuid::new_v4())]);
+        let (_, _, _, original_result) =
+            cross_pool_fence_policy_results(original_peers, LEGACY_TRANSITION_STATE_RECONCILE_POLICY_SUPPORTED_VERSION);
+        assert!(publish_fleet_capability_probe_result(&slot, "topology-a", original_result, now).is_none());
+
+        let (first, second) = {
+            let state = slot.read().expect("reconcile proof slot should not poison");
+            (
+                acquire_legacy_transition_state_reconcile_fleet_proof_from(&state, "topology-a", now)
+                    .expect("the first reconcile writer should be admitted"),
+                acquire_legacy_transition_state_reconcile_fleet_proof_from(&state, "topology-a", now)
+                    .expect("the second reconcile writer should be admitted"),
+            )
+        };
+
+        let restarted_peers = BTreeMap::from([("peer-a".to_string(), Uuid::new_v4())]);
+        let (_, _, _, restarted_result) =
+            cross_pool_fence_policy_results(restarted_peers.clone(), LEGACY_TRANSITION_STATE_RECONCILE_POLICY_SUPPORTED_VERSION);
+        let blocked =
+            publish_fleet_capability_probe_result(&slot, "topology-a", restarted_result, now + Duration::from_millis(1))
+                .expect("a restarted member must revoke the old generation and wait for both writers");
+        assert!(blocked.to_string().contains("previous generation to drain"));
+        {
+            let state = slot.read().expect("reconcile proof slot should not poison");
+            assert!(state.proof.is_none());
+            assert!(state.draining_generation.is_some());
+            assert!(!legacy_transition_state_reconcile_fleet_proof_matches_at(
+                &state,
+                &first,
+                "topology-a",
+                now + Duration::from_millis(1),
+            ));
+            assert!(!legacy_transition_state_reconcile_fleet_proof_matches_at(
+                &state,
+                &second,
+                "topology-a",
+                now + Duration::from_millis(1),
+            ));
+        }
+
+        drop(first);
+        let (_, _, _, still_blocked_result) =
+            cross_pool_fence_policy_results(restarted_peers.clone(), LEGACY_TRANSITION_STATE_RECONCILE_POLICY_SUPPORTED_VERSION);
+        assert!(
+            publish_fleet_capability_probe_result(&slot, "topology-a", still_blocked_result, now + Duration::from_millis(2),)
+                .is_some(),
+            "one remaining writer must keep the successor generation closed"
+        );
+
+        drop(second);
+        let (_, _, _, admitted_result) =
+            cross_pool_fence_policy_results(restarted_peers, LEGACY_TRANSITION_STATE_RECONCILE_POLICY_SUPPORTED_VERSION);
+        assert!(
+            publish_fleet_capability_probe_result(&slot, "topology-a", admitted_result, now + Duration::from_millis(3),)
+                .is_none(),
+            "the restarted generation may publish only after every old writer drains"
+        );
+    }
+
+    #[test]
+    fn legacy_transition_state_reconcile_fresh_observation_closes_the_polling_window() {
+        let slot = std::sync::RwLock::new(FleetCapabilityProofState::default());
+        let now = Instant::now();
+        let original_peers = BTreeMap::from([("peer-a".to_string(), Uuid::new_v4())]);
+        let (_, _, _, original_result) =
+            cross_pool_fence_policy_results(original_peers.clone(), LEGACY_TRANSITION_STATE_RECONCILE_POLICY_SUPPORTED_VERSION);
+        assert!(publish_fleet_capability_probe_result(&slot, "topology-a", original_result, now).is_none());
+        let admitted = {
+            let state = slot.read().expect("reconcile proof slot should not poison");
+            acquire_legacy_transition_state_reconcile_fleet_proof_from(&state, "topology-a", now)
+                .expect("the original fleet should admit reconciliation")
+        };
+
+        let restarted_peers = BTreeMap::from([("peer-a".to_string(), Uuid::new_v4())]);
+        let state = slot.read().expect("reconcile proof slot should not poison");
+        assert!(
+            legacy_transition_state_reconcile_fleet_proof_matches_at(&state, &admitted, "topology-a", now),
+            "the periodic cache has not observed the restart yet"
+        );
+        assert!(!legacy_transition_state_reconcile_fleet_proof_matches_observation_at(
+            &state,
+            &admitted,
+            "topology-a",
+            &restarted_peers,
+            now,
+        ));
+
+        let (_, _, _, downgraded) = cross_pool_fence_policy_results(original_peers, 4);
+        assert!(
+            downgraded.is_err(),
+            "a synchronous observation of a downgraded peer must fail before any cached proof can authorize a write"
+        );
+    }
+
+    #[tokio::test]
+    async fn legacy_transition_state_reconcile_invalid_token_skips_fleet_observation() {
+        let slot = std::sync::RwLock::new(FleetCapabilityProofState::default());
+        let now = Instant::now();
+        let peers = BTreeMap::from([("peer-a".to_string(), Uuid::new_v4())]);
+        assert!(publish_fleet_capability_probe_result(&slot, "topology-a", Ok(peers), now).is_none());
+        let admitted = {
+            let state = slot.read().expect("reconcile proof slot should not poison");
+            acquire_legacy_transition_state_reconcile_fleet_proof_from(&state, "topology-a", now)
+                .expect("the original fleet should admit reconciliation")
+        };
+        revoke_fleet_capability_proof(&slot);
+
+        assert!(
+            !legacy_transition_state_reconcile_fleet_proof_matches_with_observer(&slot, &admitted, "topology-a", || async {
+                panic!("an invalid local generation must not trigger a fleet observation");
+            },)
+            .await
+        );
+    }
+
+    #[test]
+    fn legacy_transition_state_reconcile_membership_and_topology_changes_revoke_authority() {
+        let now = Instant::now();
+        for replacement in [
+            BTreeMap::from([("peer-a".to_string(), Uuid::new_v4()), ("peer-b".to_string(), Uuid::new_v4())]),
+            BTreeMap::from([("peer-a".to_string(), Uuid::new_v4())]),
+        ] {
+            let slot = std::sync::RwLock::new(FleetCapabilityProofState::default());
+            let original = BTreeMap::from([("peer-a".to_string(), Uuid::new_v4())]);
+            assert!(publish_fleet_capability_probe_result(&slot, "topology-a", Ok(original), now).is_none());
+            let admitted = {
+                let state = slot.read().expect("reconcile proof slot should not poison");
+                acquire_legacy_transition_state_reconcile_fleet_proof_from(&state, "topology-a", now)
+                    .expect("the original fleet should admit reconciliation")
+            };
+
+            assert!(
+                publish_fleet_capability_probe_result(&slot, "topology-a", Ok(replacement), now + Duration::from_millis(1),)
+                    .is_some(),
+                "membership or process-epoch replacement must wait for the admitted writer"
+            );
+            let state = slot.read().expect("reconcile proof slot should not poison");
+            assert!(!legacy_transition_state_reconcile_fleet_proof_matches_at(
+                &state,
+                &admitted,
+                "topology-a",
+                now + Duration::from_millis(1),
+            ));
+        }
+
+        let slot = std::sync::RwLock::new(FleetCapabilityProofState::default());
+        assert!(publish_fleet_capability_probe_result(&slot, "topology-a", Ok(BTreeMap::new()), now).is_none());
+        let admitted = {
+            let state = slot.read().expect("reconcile proof slot should not poison");
+            acquire_legacy_transition_state_reconcile_fleet_proof_from(&state, "topology-a", now)
+                .expect("the original topology should admit reconciliation")
+        };
+        mark_fleet_capability_topology_conflict(&slot);
+        let state = slot.read().expect("reconcile proof slot should not poison");
+        assert!(state.topology_conflict);
+        assert!(!legacy_transition_state_reconcile_fleet_proof_matches_at(
+            &state,
+            &admitted,
+            "topology-a",
+            now,
+        ));
+    }
+
+    #[test]
+    fn legacy_transition_state_reconcile_capability_downgrade_fails_closed() {
+        let slot = std::sync::RwLock::new(FleetCapabilityProofState::default());
+        let now = Instant::now();
+        let peers = BTreeMap::from([("peer-a".to_string(), Uuid::new_v4())]);
+        let (_, _, _, compatible_result) =
+            cross_pool_fence_policy_results(peers.clone(), LEGACY_TRANSITION_STATE_RECONCILE_POLICY_SUPPORTED_VERSION);
+        assert!(publish_fleet_capability_probe_result(&slot, "topology-a", compatible_result, now).is_none());
+        let admitted = {
+            let state = slot.read().expect("reconcile proof slot should not poison");
+            acquire_legacy_transition_state_reconcile_fleet_proof_from(&state, "topology-a", now)
+                .expect("v5 should admit reconciliation")
+        };
+
+        let (_, _, _, downgraded_result) =
+            cross_pool_fence_policy_results(peers, LEGACY_TRANSITION_STATE_RECONCILE_POLICY_SUPPORTED_VERSION - 1);
+        let err = publish_fleet_capability_probe_result(&slot, "topology-a", downgraded_result, now + Duration::from_millis(1))
+            .expect("a v4 member must revoke reconcile authority");
+        assert!(err.to_string().contains("reconcile policy capability version is unsupported"));
+        let state = slot.read().expect("reconcile proof slot should not poison");
+        assert!(state.proof.is_none());
+        assert!(!legacy_transition_state_reconcile_fleet_proof_matches_at(
+            &state,
+            &admitted,
+            "topology-a",
+            now + Duration::from_millis(1),
+        ));
+        assert!(
+            acquire_legacy_transition_state_reconcile_fleet_proof_from(&state, "topology-a", now + Duration::from_millis(1),)
+                .is_none(),
+            "a downgraded fleet must remain inspect-only"
+        );
+    }
+
    #[test]
    fn remote_version_state_fleet_proof_conflict_revokes_atomic_snapshot() {
        let now = Instant::now();
@@ -3539,6 +3959,57 @@ mod tests {
        assert!(err.to_string().contains("incomplete"));
    }

+    #[tokio::test]
+    async fn legacy_transition_state_reconcile_probe_rejects_missing_or_unreachable_members() {
+        let missing = NotificationSys {
+            peer_clients: Vec::new(),
+            all_peer_clients: vec![None],
+            peer_topology_hosts: vec!["peer-a".to_string()],
+            peer_admin_caches: Vec::new(),
+            tier_config_reload_workers: Default::default(),
+        };
+        let missing_err = missing
+            .probe_cross_pool_fence_fleet("topology-a")
+            .await
+            .expect_err("a missing member slot must prevent reconcile capability proof");
+        assert!(missing_err.to_string().contains("incomplete"));
+
+        let unreachable = NotificationSys {
+            peer_clients: vec![None],
+            all_peer_clients: vec![None, None],
+            peer_topology_hosts: vec!["peer-a".to_string()],
+            peer_admin_caches: vec![Mutex::new(PeerAdminCache::new())],
+            tier_config_reload_workers: Default::default(),
+        };
+        let unreachable_err = unreachable
+            .probe_cross_pool_fence_fleet("topology-a")
+            .await
+            .expect_err("an unreachable member must prevent reconcile capability proof");
+        assert!(unreachable_err.to_string().contains("unreachable"));
+    }
+
+    #[tokio::test]
+    async fn legacy_transition_state_reconcile_single_node_stays_closed_before_local_cas_support() {
+        let notification_sys = NotificationSys {
+            peer_clients: Vec::new(),
+            all_peer_clients: vec![None],
+            peer_topology_hosts: Vec::new(),
+            peer_admin_caches: Vec::new(),
+            tier_config_reload_workers: Default::default(),
+        };
+        let (peers, minimum_version) = notification_sys
+            .probe_cross_pool_fence_fleet("topology-a")
+            .await
+            .expect("a single-node capability probe should complete");
+        assert!(peers.is_empty());
+        assert_eq!(minimum_version, LOCAL_CROSS_POOL_FENCE_POLICY_SUPPORTED_VERSION);
+        let (_, _, _, reconcile_result) = cross_pool_fence_policy_results(peers, minimum_version);
+        assert!(
+            reconcile_result.is_err(),
+            "the current node must not self-authorize reconcile before the conditional writer lands"
+        );
+    }
+
    fn build_props(endpoint: &str) -> ServerProperties {
        ServerProperties {
            endpoint: endpoint.to_string(),
@@ -21,6 +21,7 @@ pub mod tier_gen;
 pub mod tier_handlers;
 pub(crate) mod tier_mutation_intent;
 pub mod tier_mutation_peer;
+pub(crate) mod tier_probe_intent;
 pub mod warm_backend;
 pub mod warm_backend_aliyun;
 pub mod warm_backend_azure;
@@ -701,7 +701,7 @@ impl WarmBackend for MockWarmBackend {
        Ok(version)
    }

-    async fn get(&self, object: &str, _rv: &str, opts: WarmBackendGetOpts) -> Result<ReadCloser, std::io::Error> {
+    async fn get(&self, object: &str, rv: &str, opts: WarmBackendGetOpts) -> Result<ReadCloser, std::io::Error> {
        self.precondition().await?;
        let barrier = self.inner.get_barrier.lock().await.take();
        if let Some(barrier) = barrier {
@@ -719,6 +719,9 @@ impl WarmBackend for MockWarmBackend {
        let Some(stored) = objects.get(object) else {
            return Err(std::io::Error::new(std::io::ErrorKind::NotFound, "mock object not found"));
        };
+        if !rv.is_empty() && stored.remote_version_id != rv {
+            return Err(std::io::Error::new(std::io::ErrorKind::NotFound, "NoSuchVersion"));
+        }
        let bytes = &stored.bytes;

        let start = opts.start_offset.max(0) as usize;
@@ -15,28 +15,204 @@
 #![allow(unused_variables)]
 #![allow(unused_mut)]
 #![allow(unused_assignments)]
-#![allow(unused_must_use)]
-#![allow(clippy::all)]

-use serde::{Deserialize, Serialize};
+use serde::{Deserialize, Deserializer, Serialize, Serializer, de};

-#[derive(Serialize, Deserialize, Default, Debug, Clone)]
+#[derive(Serialize, Deserialize, Default, Clone)]
+#[serde(default)]
+pub struct TierServicePrincipalAuth {
+    #[serde(rename = "TenantID", alias = "tenantID", alias = "tenant_id")]
+    pub tenant_id: String,
+    #[serde(rename = "ClientID", alias = "clientID", alias = "client_id")]
+    pub client_id: String,
+    #[serde(rename = "ClientSecret", alias = "clientSecret", alias = "client_secret")]
+    pub client_secret: String,
+}
+
+impl TierServicePrincipalAuth {
+    pub(crate) fn is_empty(&self) -> bool {
+        self.tenant_id.is_empty() && self.client_id.is_empty() && self.client_secret.is_empty()
+    }
+}
+
+impl std::fmt::Debug for TierServicePrincipalAuth {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        f.debug_struct("TierServicePrincipalAuth")
+            .field("tenant_id", &self.tenant_id)
+            .field("client_id", &self.client_id)
+            .field("client_secret", &"REDACTED")
+            .finish()
+    }
+}
+
+#[derive(Serialize, Deserialize, Default, Clone)]
 #[serde(default)]
 pub struct TierCreds {
-    #[serde(rename = "accessKey")]
+    #[serde(rename = "access", alias = "accessKey")]
    pub access_key: String,
-    #[serde(rename = "secretKey")]
+    #[serde(rename = "secret", alias = "secretKey")]
    pub secret_key: String,

-    #[serde(rename = "awsRole")]
+    #[serde(rename = "awsrole", alias = "awsRole")]
    pub aws_role: bool,
-    #[serde(rename = "awsRoleWebIdentityTokenFile")]
+    #[serde(rename = "awsroleWebIdentity", alias = "awsRoleWebIdentityTokenFile")]
    pub aws_role_web_identity_token_file: String,
-    #[serde(rename = "awsRoleArn")]
+    #[serde(rename = "awsroleARN", alias = "awsRoleArn", alias = "awsRoleARN")]
    pub aws_role_arn: String,

-    //azsp: ServicePrincipalAuth,
+    #[serde(rename = "azSP", alias = "azsp", skip_serializing_if = "TierServicePrincipalAuth::is_empty")]
+    pub azure_service_principal: TierServicePrincipalAuth,

-    //#[serde(rename = "credsJson")]
+    #[serde(
+        rename = "creds",
+        alias = "credsJson",
+        alias = "credsJSON",
+        alias = "creds_json",
+        default,
+        skip_serializing_if = "Vec::is_empty",
+        with = "base64_bytes"
+    )]
    pub creds_json: Vec<u8>,
 }
+
+impl std::fmt::Debug for TierCreds {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        f.debug_struct("TierCreds")
+            .field("access_key", &self.access_key)
+            .field("secret_key", &"REDACTED")
+            .field("aws_role", &self.aws_role)
+            .field(
+                "aws_role_web_identity_token_file",
+                &(!self.aws_role_web_identity_token_file.is_empty()).then_some("REDACTED"),
+            )
+            .field("aws_role_arn", &self.aws_role_arn)
+            .field("azure_service_principal", &self.azure_service_principal)
+            .field("creds_json", &(!self.creds_json.is_empty()).then_some("REDACTED"))
+            .finish()
+    }
+}
+
+mod base64_bytes {
+    use super::*;
+
+    pub(super) fn serialize<S>(value: &[u8], serializer: S) -> Result<S::Ok, S::Error>
+    where
+        S: Serializer,
+    {
+        serializer.serialize_str(&base64_simd::STANDARD.encode_to_string(value))
+    }
+
+    pub(super) fn deserialize<'de, D>(deserializer: D) -> Result<Vec<u8>, D::Error>
+    where
+        D: Deserializer<'de>,
+    {
+        #[derive(Deserialize)]
+        #[serde(untagged)]
+        enum EncodedBytes {
+            Base64(String),
+            Legacy(Vec<u8>),
+        }
+
+        match EncodedBytes::deserialize(deserializer)? {
+            EncodedBytes::Base64(value) => base64_simd::STANDARD
+                .decode_to_vec(value.as_bytes())
+                .or_else(|_| base64_simd::STANDARD_NO_PAD.decode_to_vec(value.as_bytes()))
+                .or_else(|_| base64_simd::URL_SAFE.decode_to_vec(value.as_bytes()))
+                .or_else(|_| base64_simd::URL_SAFE_NO_PAD.decode_to_vec(value.as_bytes()))
+                .map_err(de::Error::custom),
+            EncodedBytes::Legacy(value) => Ok(value),
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn tier_creds_accepts_madmin_wire_names_and_base64_gcs_json() {
+        let service_account = r#"{"type":"service_account","project_id":"tier-🚀x"}"#.as_bytes();
+        let encoded = "eyJ0eXBlIjoic2VydmljZV9hY2NvdW50IiwicHJvamVjdF9pZCI6InRpZXIt8J+agHgifQ==";
+        let creds: TierCreds = serde_json::from_value(serde_json::json!({
+            "access": "access",
+            "secret": "secret",
+            "awsrole": false,
+            "creds": encoded,
+        }))
+        .expect("madmin tier credentials should decode");
+
+        assert_eq!(creds.access_key, "access");
+        assert_eq!(creds.secret_key, "secret");
+        assert_eq!(creds.creds_json.as_slice(), service_account);
+
+        let wire = serde_json::to_value(&creds).expect("madmin tier credentials should encode");
+        assert_eq!(wire["access"], "access");
+        assert_eq!(wire["secret"], "secret");
+        assert_eq!(wire["creds"], encoded);
+        assert!(wire.get("accessKey").is_none());
+        assert!(wire.get("secretKey").is_none());
+
+        let legacy: TierCreds = serde_json::from_value(serde_json::json!({
+            "accessKey": "legacy-access",
+            "secretKey": "legacy-secret",
+            "credsJson": service_account,
+        }))
+        .expect("the former RustFS field names and byte-array encoding should remain readable");
+        assert_eq!(legacy.access_key, "legacy-access");
+        assert_eq!(legacy.secret_key, "legacy-secret");
+        assert_eq!(legacy.creds_json.as_slice(), service_account);
+    }
+
+    #[test]
+    fn tier_creds_accepts_all_supported_base64_alphabets_and_padding_modes() {
+        let service_account = r#"{"type":"service_account","project_id":"tier-🚀"}"#.as_bytes();
+        for encoder in [
+            base64_simd::STANDARD,
+            base64_simd::STANDARD_NO_PAD,
+            base64_simd::URL_SAFE,
+            base64_simd::URL_SAFE_NO_PAD,
+        ] {
+            let encoded = encoder.encode_to_string(service_account);
+            let creds: TierCreds = serde_json::from_value(serde_json::json!({ "creds": encoded }))
+                .expect("all supported madmin base64 forms should decode");
+            assert_eq!(creds.creds_json, service_account);
+        }
+    }
+
+    #[test]
+    fn tier_creds_debug_redacts_secret_payloads() {
+        let creds = TierCreds {
+            access_key: "access".to_string(),
+            secret_key: "tier-secret-value".to_string(),
+            aws_role_web_identity_token_file: "/var/run/private-token".to_string(),
+            creds_json: br#"{"private_key":"gcs-private-key-value"}"#.to_vec(),
+            ..Default::default()
+        };
+
+        let rendered = format!("{creds:?}");
+        assert!(!rendered.contains("tier-secret-value"));
+        assert!(!rendered.contains("/var/run/private-token"));
+        assert!(!rendered.contains("gcs-private-key-value"));
+    }
+
+    #[test]
+    fn tier_creds_accepts_canonical_madmin_azure_service_principal_wire_shape() {
+        let creds: TierCreds = serde_json::from_value(serde_json::json!({
+            "azSP": {
+                "TenantID": "tenant",
+                "ClientID": "client",
+                "ClientSecret": "service-principal-secret"
+            }
+        }))
+        .expect("canonical madmin azure service principal credentials should decode");
+
+        assert_eq!(creds.azure_service_principal.tenant_id, "tenant");
+        assert_eq!(creds.azure_service_principal.client_id, "client");
+        assert_eq!(creds.azure_service_principal.client_secret, "service-principal-secret");
+        let wire = serde_json::to_value(&creds).expect("canonical madmin credentials should encode");
+        assert_eq!(wire["azSP"]["TenantID"], "tenant");
+        assert_eq!(wire["azSP"]["ClientID"], "client");
+        assert_eq!(wire["azSP"]["ClientSecret"], "service-principal-secret");
+        assert!(!format!("{creds:?}").contains("service-principal-secret"));
+    }
+}
@@ -42,7 +42,7 @@ const WASABI_ALTERNATIVE_ENDPOINTS: &[(&str, &str)] = &[
 pub enum TierType {
    #[default]
    Unsupported,
-    #[serde(rename = "s3")]
+    #[serde(rename = "s3", alias = "S3")]
    S3,
    #[serde(rename = "wasabi")]
    Wasabi,
@@ -58,7 +58,7 @@ pub enum TierType {
    Huaweicloud,
    #[serde(rename = "azure")]
    Azure,
-    #[serde(rename = "gcs")]
+    #[serde(rename = "gcs", alias = "GCS")]
    GCS,
    #[serde(rename = "r2")]
    R2,
@@ -138,16 +138,18 @@ impl TierType {
    }
 }

-#[derive(Default, Debug, Serialize, Deserialize)]
+pub(crate) const TIER_CREDENTIAL_REDACTED: &str = "REDACTED";
+
+#[derive(Default, Serialize, Deserialize)]
 #[serde(default)]
 pub struct TierConfig {
    #[serde(skip)]
    pub version: String,
-    #[serde(rename = "type")]
+    #[serde(rename = "type", alias = "Type")]
    pub tier_type: TierType,
-    #[serde(skip)]
+    #[serde(rename = "Name", alias = "name", skip_serializing)]
    pub name: String,
-    #[serde(rename = "s3", skip_serializing_if = "Option::is_none")]
+    #[serde(rename = "s3", alias = "S3", skip_serializing_if = "Option::is_none")]
    pub s3: Option<TierS3>,
    #[serde(rename = "wasabi", skip_serializing_if = "Option::is_none")]
    pub wasabi: Option<TierWasabi>,
@@ -159,7 +161,7 @@ pub struct TierConfig {
    pub huaweicloud: Option<TierHuaweicloud>,
    #[serde(rename = "azure", skip_serializing_if = "Option::is_none")]
    pub azure: Option<TierAzure>,
-    #[serde(rename = "gcs", skip_serializing_if = "Option::is_none")]
+    #[serde(rename = "gcs", alias = "GCS", skip_serializing_if = "Option::is_none")]
    pub gcs: Option<TierGCS>,
    #[serde(rename = "r2", skip_serializing_if = "Option::is_none")]
    pub r2: Option<TierR2>,
@@ -170,109 +172,91 @@ pub struct TierConfig {
 }

 impl Clone for TierConfig {
-    fn clone(&self) -> TierConfig {
-        let mut s3 = None;
-        let mut wasabi = None;
-        let mut r = None;
-        let mut compatible_backend = None;
-        let mut aliyun = None;
-        let mut tencent = None;
-        let mut huaweicloud = None;
-        let mut azure = None;
-        let mut gcs = None;
-        let mut r2 = None;
-        match self.tier_type {
-            TierType::S3 => {
-                if let Some(s3_) = self.s3.as_ref() {
-                    let mut s3_clone = s3_.clone();
-                    s3_clone.secret_key = "REDACTED".to_string();
-                    s3 = Some(s3_clone);
-                }
-            }
-            TierType::Wasabi => {
-                if let Some(wasabi_) = self.wasabi.as_ref() {
-                    let mut wasabi_clone = wasabi_.clone();
-                    wasabi_clone.secret_key = "REDACTED".to_string();
-                    wasabi = Some(wasabi_clone);
-                }
-            }
-            TierType::RustFS => {
-                if let Some(r_) = self.rustfs.as_ref() {
-                    let mut r_clone = r_.clone();
-                    r_clone.secret_key = "REDACTED".to_string();
-                    r = Some(r_clone);
-                }
-            }
-            TierType::MinIO => {
-                if let Some(compatible_backend_) = self.minio.as_ref() {
-                    let mut compatible_backend_clone = compatible_backend_.clone();
-                    compatible_backend_clone.secret_key = "REDACTED".to_string();
-                    compatible_backend = Some(compatible_backend_clone);
-                }
-            }
-            TierType::Aliyun => {
-                if let Some(aliyun_) = self.aliyun.as_ref() {
-                    let mut aliyun_clone = aliyun_.clone();
-                    aliyun_clone.secret_key = "REDACTED".to_string();
-                    aliyun = Some(aliyun_clone);
-                }
-            }
-            TierType::Tencent => {
-                if let Some(tencent_) = self.tencent.as_ref() {
-                    let mut tencent_clone = tencent_.clone();
-                    tencent_clone.secret_key = "REDACTED".to_string();
-                    tencent = Some(tencent_clone);
-                }
-            }
-            TierType::Huaweicloud => {
-                if let Some(huaweicloud_) = self.huaweicloud.as_ref() {
-                    let mut huaweicloud_clone = huaweicloud_.clone();
-                    huaweicloud_clone.secret_key = "REDACTED".to_string();
-                    huaweicloud = Some(huaweicloud_clone);
-                }
-            }
-            TierType::Azure => {
-                if let Some(azure_) = self.azure.as_ref() {
-                    let mut azure_clone = azure_.clone();
-                    azure_clone.secret_key = "REDACTED".to_string();
-                    azure = Some(azure_clone);
-                }
-            }
-            TierType::GCS => {
-                if let Some(gcs_) = self.gcs.as_ref() {
-                    let mut gcs_clone = gcs_.clone();
-                    gcs_clone.creds = "REDACTED".to_string();
-                    gcs = Some(gcs_clone);
-                }
-            }
-            TierType::R2 => {
-                if let Some(r2_) = self.r2.as_ref() {
-                    let mut r2_clone = r2_.clone();
-                    r2_clone.secret_key = "REDACTED".to_string();
-                    r2 = Some(r2_clone);
-                }
-            }
-            _ => (),
-        }
-        TierConfig {
-            version: self.version.clone(),
-            tier_type: self.tier_type.clone(),
-            name: self.name.clone(),
-            s3,
-            wasabi,
-            rustfs: r,
-            minio: compatible_backend,
-            aliyun,
-            tencent,
-            huaweicloud,
-            azure,
-            gcs,
-            r2,
-        }
+    fn clone(&self) -> Self {
+        self.redacted()
    }
 }

 impl TierConfig {
+    pub(crate) fn redacted(&self) -> Self {
+        let mut redacted = Self {
+            version: self.version.clone(),
+            tier_type: self.tier_type.clone(),
+            name: self.name.clone(),
+            ..Default::default()
+        };
+        match self.tier_type {
+            TierType::S3 => {
+                redacted.s3 = self.s3.clone().map(|mut backend| {
+                    backend.secret_key = TIER_CREDENTIAL_REDACTED.to_string();
+                    if !backend.aws_role_web_identity_token_file.is_empty() {
+                        backend.aws_role_web_identity_token_file = TIER_CREDENTIAL_REDACTED.to_string();
+                    }
+                    backend
+                });
+            }
+            TierType::Wasabi => {
+                redacted.wasabi = self.wasabi.clone().map(|mut backend| {
+                    backend.secret_key = TIER_CREDENTIAL_REDACTED.to_string();
+                    backend
+                });
+            }
+            TierType::RustFS => {
+                redacted.rustfs = self.rustfs.clone().map(|mut backend| {
+                    backend.secret_key = TIER_CREDENTIAL_REDACTED.to_string();
+                    backend
+                });
+            }
+            TierType::MinIO => {
+                redacted.minio = self.minio.clone().map(|mut backend| {
+                    backend.secret_key = TIER_CREDENTIAL_REDACTED.to_string();
+                    backend
+                });
+            }
+            TierType::Aliyun => {
+                redacted.aliyun = self.aliyun.clone().map(|mut backend| {
+                    backend.secret_key = TIER_CREDENTIAL_REDACTED.to_string();
+                    backend
+                });
+            }
+            TierType::Tencent => {
+                redacted.tencent = self.tencent.clone().map(|mut backend| {
+                    backend.secret_key = TIER_CREDENTIAL_REDACTED.to_string();
+                    backend
+                });
+            }
+            TierType::Huaweicloud => {
+                redacted.huaweicloud = self.huaweicloud.clone().map(|mut backend| {
+                    backend.secret_key = TIER_CREDENTIAL_REDACTED.to_string();
+                    backend
+                });
+            }
+            TierType::Azure => {
+                redacted.azure = self.azure.clone().map(|mut backend| {
+                    backend.secret_key = TIER_CREDENTIAL_REDACTED.to_string();
+                    if !backend.sp_auth.client_secret.is_empty() {
+                        backend.sp_auth.client_secret = TIER_CREDENTIAL_REDACTED.to_string();
+                    }
+                    backend
+                });
+            }
+            TierType::GCS => {
+                redacted.gcs = self.gcs.clone().map(|mut backend| {
+                    backend.creds = TIER_CREDENTIAL_REDACTED.to_string();
+                    backend
+                });
+            }
+            TierType::R2 => {
+                redacted.r2 = self.r2.clone().map(|mut backend| {
+                    backend.secret_key = TIER_CREDENTIAL_REDACTED.to_string();
+                    backend
+                });
+            }
+            TierType::Unsupported => {}
+        }
+        redacted
+    }
+
    pub(crate) fn clone_with_credentials(&self) -> Self {
        Self {
            version: self.version.clone(),
@@ -372,31 +356,61 @@ impl TierConfig {
    }
 }

+impl std::fmt::Debug for TierConfig {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        let redacted = self.redacted();
+        f.debug_struct("TierConfig")
+            .field("version", &redacted.version)
+            .field("tier_type", &redacted.tier_type)
+            .field("name", &redacted.name)
+            .field("s3", &redacted.s3)
+            .field("wasabi", &redacted.wasabi)
+            .field("aliyun", &redacted.aliyun)
+            .field("tencent", &redacted.tencent)
+            .field("huaweicloud", &redacted.huaweicloud)
+            .field("azure", &redacted.azure)
+            .field("gcs", &redacted.gcs)
+            .field("r2", &redacted.r2)
+            .field("rustfs", &redacted.rustfs)
+            .field("minio", &redacted.minio)
+            .finish()
+    }
+}
+
 //type S3Options = impl Fn(TierS3) -> Pin<Box<Result<()>>> + Send + Sync + 'static;

 #[derive(Serialize, Deserialize, Default, Debug, Clone)]
 #[serde(default)]
 pub struct TierS3 {
+    #[serde(alias = "Name")]
    pub name: String,
+    #[serde(alias = "Endpoint")]
    pub endpoint: String,
-    #[serde(rename = "accessKey")]
+    #[serde(rename = "accessKey", alias = "AccessKey")]
    pub access_key: String,
-    #[serde(rename = "secretKey")]
+    #[serde(rename = "secretKey", alias = "SecretKey")]
    pub secret_key: String,
+    #[serde(alias = "Bucket")]
    pub bucket: String,
+    #[serde(alias = "Prefix")]
    pub prefix: String,
+    #[serde(alias = "Region")]
    pub region: String,
-    #[serde(rename = "storageClass")]
+    #[serde(rename = "storageClass", alias = "StorageClass")]
    pub storage_class: String,
-    #[serde(skip)]
+    #[serde(rename = "AWSRole", alias = "awsRole", skip_serializing)]
    pub aws_role: bool,
-    #[serde(skip)]
+    #[serde(
+        rename = "AWSRoleWebIdentityTokenFile",
+        alias = "awsRoleWebIdentityTokenFile",
+        skip_serializing
+    )]
    pub aws_role_web_identity_token_file: String,
-    #[serde(skip)]
+    #[serde(rename = "AWSRoleARN", alias = "awsRoleARN", alias = "awsRoleArn", skip_serializing)]
    pub aws_role_arn: String,
-    #[serde(skip)]
+    #[serde(rename = "AWSRoleSessionName", alias = "awsRoleSessionName", skip_serializing)]
    pub aws_role_session_name: String,
-    #[serde(skip)]
+    #[serde(rename = "AWSRoleDurationSeconds", alias = "awsRoleDurationSeconds", skip_serializing)]
    pub aws_role_duration_seconds: i32,
 }

@@ -623,8 +637,11 @@ pub struct TierHuaweicloud {
 #[derive(Serialize, Deserialize, Default, Debug, Clone)]
 #[serde(default)]
 pub struct ServicePrincipalAuth {
+    #[serde(alias = "TenantID")]
    pub tenant_id: String,
+    #[serde(alias = "ClientID")]
    pub client_id: String,
+    #[serde(alias = "ClientSecret")]
    pub client_secret: String,
 }

@@ -640,9 +657,9 @@ pub struct TierAzure {
    pub bucket: String,
    pub prefix: String,
    pub region: String,
-    #[serde(rename = "storageClass")]
+    #[serde(rename = "storageClass", alias = "StorageClass")]
    pub storage_class: String,
-    #[serde(rename = "spAuth")]
+    #[serde(rename = "spAuth", alias = "SPAuth")]
    pub sp_auth: ServicePrincipalAuth,
 }

@@ -696,14 +713,19 @@ fn AzureStorageClass(sc string) func(az *TierAzure) error {
 #[derive(Serialize, Deserialize, Default, Debug, Clone)]
 #[serde(default)]
 pub struct TierGCS {
+    #[serde(alias = "Name")]
    pub name: String,
+    #[serde(alias = "Endpoint")]
    pub endpoint: String,
-    #[serde(rename = "creds")]
+    #[serde(rename = "creds", alias = "Creds")]
    pub creds: String,
+    #[serde(alias = "Bucket")]
    pub bucket: String,
+    #[serde(alias = "Prefix")]
    pub prefix: String,
+    #[serde(alias = "Region")]
    pub region: String,
-    #[serde(rename = "storageClass")]
+    #[serde(rename = "storageClass", alias = "StorageClass")]
    pub storage_class: String,
 }

@@ -725,6 +747,43 @@ pub struct TierR2 {
 mod tests {
    use super::*;

+    #[test]
+    fn s3_gcs_type_uppercase_aliases_preserve_lowercase_output() {
+        let s3: TierType = serde_json::from_str(r#""S3""#).expect("uppercase S3 wire value should decode");
+        let gcs: TierType = serde_json::from_str(r#""GCS""#).expect("uppercase GCS wire value should decode");
+        assert!(matches!(s3, TierType::S3));
+        assert!(matches!(gcs, TierType::GCS));
+        assert_eq!(serde_json::to_string(&s3).expect("S3 type should encode"), r#""s3""#);
+        assert_eq!(serde_json::to_string(&gcs).expect("GCS type should encode"), r#""gcs""#);
+    }
+
+    #[test]
+    fn azure_service_principal_accepts_canonical_madmin_field_names() {
+        for field in ["TenantID", "ClientID", "ClientSecret"] {
+            let mut sp_auth = serde_json::Map::new();
+            sp_auth.insert(field.to_string(), serde_json::Value::String("present".to_string()));
+            let config: TierConfig = serde_json::from_value(serde_json::json!({
+                "type": "azure",
+                "Name": "COLD-AZURE",
+                "azure": {
+                    "name": "COLD-AZURE",
+                    "endpoint": "https://azure.example.invalid",
+                    "accessKey": "account",
+                    "secretKey": "key",
+                    "bucket": "archive",
+                    "SPAuth": sp_auth
+                }
+            }))
+            .expect("mixed RustFS/madmin Azure payload should decode");
+            let sp_auth = &config.azure.expect("Azure payload should exist").sp_auth;
+
+            assert!(
+                !sp_auth.tenant_id.is_empty() || !sp_auth.client_id.is_empty() || !sp_auth.client_secret.is_empty(),
+                "canonical {field} must not be silently discarded"
+            );
+        }
+    }
+
    fn wasabi_config() -> TierWasabi {
        TierWasabi {
            name: "COLD-WASABI".to_string(),
@@ -838,9 +897,14 @@ mod tests {
        let config = TierConfig {
            tier_type: TierType::Wasabi,
            wasabi: Some(wasabi_config()),
+            rustfs: Some(TierRustFS {
+                access_key: "inactive-access".to_string(),
+                secret_key: "inactive-secret".to_string(),
+                ..Default::default()
+            }),
            ..Default::default()
        };
-        let redacted = config.clone();
+        let redacted = config.redacted();
        assert_eq!(
            redacted
                .wasabi
@@ -849,21 +913,46 @@ mod tests {
                .secret_key,
            "REDACTED"
        );
+        assert!(redacted.rustfs.is_none(), "the external view should retain only the active provider");
+        let cloned = config.clone();
+        assert_eq!(cloned.wasabi.expect("redacted Wasabi clone should remain").secret_key, "REDACTED");
+        assert!(cloned.rustfs.is_none(), "ordinary Clone must retain its redacted API semantics");
+        let preserved = config.clone_with_credentials();
        assert_eq!(
-            config
-                .clone_with_credentials()
+            preserved
                .wasabi
                .as_ref()
-                .expect("credential-bearing Wasabi payload should remain")
+                .expect("credential-bearing Wasabi snapshot should remain")
                .secret_key,
            "secret"
        );
+        assert_eq!(
+            preserved
+                .rustfs
+                .expect("credential-bearing snapshots should preserve inactive provider data")
+                .secret_key,
+            "inactive-secret"
+        );

        let mut debug_config = wasabi_config();
        debug_config.secret_key = "wasabi-debug-secret-value".to_string();
        let debug = format!("{debug_config:?}");
        assert!(debug.contains("REDACTED"));
        assert!(!debug.contains("wasabi-debug-secret-value"));
+
+        let debug = format!(
+            "{:?}",
+            TierConfig {
+                tier_type: TierType::RustFS,
+                rustfs: Some(TierRustFS {
+                    secret_key: "rustfs-debug-secret-value".to_string(),
+                    ..Default::default()
+                }),
+                ..Default::default()
+            }
+        );
+        assert!(debug.contains("REDACTED"));
+        assert!(!debug.contains("rustfs-debug-secret-value"));
    }

    #[test]
@@ -894,7 +983,7 @@ mod tests {
        assert_eq!(encoded, expected);
        let decoded: TierConfig = serde_json::from_value(encoded).expect("Wasabi Admin JSON should decode");
        assert!(matches!(decoded.tier_type, TierType::Wasabi));
-        let redacted = config.clone();
+        let redacted = config.redacted();
        assert_eq!(
            config
                .wasabi
@@ -916,4 +1005,87 @@ mod tests {
            "REDACTED"
        );
    }
+
+    #[test]
+    fn api_serialization_and_debug_redact_s3_gcs_and_azure_credentials() {
+        let cases = [
+            (
+                "s3",
+                TierConfig {
+                    tier_type: TierType::S3,
+                    s3: Some(TierS3 {
+                        secret_key: "s3-secret-bytes".to_string(),
+                        aws_role_web_identity_token_file: "/var/run/s3-private-token".to_string(),
+                        ..Default::default()
+                    }),
+                    ..Default::default()
+                },
+                vec!["s3-secret-bytes", "/var/run/s3-private-token"],
+            ),
+            (
+                "gcs",
+                TierConfig {
+                    tier_type: TierType::GCS,
+                    gcs: Some(TierGCS {
+                        creds: r#"{"type":"service_account","private_key":"gcs-private-key-bytes"}"#.to_string(),
+                        ..Default::default()
+                    }),
+                    ..Default::default()
+                },
+                vec!["gcs-private-key-bytes"],
+            ),
+            (
+                "azure",
+                TierConfig {
+                    tier_type: TierType::Azure,
+                    azure: Some(TierAzure {
+                        secret_key: "azure-account-secret-bytes".to_string(),
+                        sp_auth: ServicePrincipalAuth {
+                            client_secret: "azure-client-secret-bytes".to_string(),
+                            ..Default::default()
+                        },
+                        ..Default::default()
+                    }),
+                    ..Default::default()
+                },
+                vec!["azure-account-secret-bytes", "azure-client-secret-bytes"],
+            ),
+        ];
+
+        for (provider, config, secrets) in cases {
+            let api = serde_json::to_string(&config.redacted()).expect("redacted API config should serialize");
+            let debug = format!("{config:?}");
+            assert!(api.contains(TIER_CREDENTIAL_REDACTED), "{provider} API output should be visibly redacted");
+            assert!(
+                debug.contains(TIER_CREDENTIAL_REDACTED),
+                "{provider} Debug output should be visibly redacted"
+            );
+            for secret in secrets {
+                assert!(!api.contains(secret), "{provider} API output exposed credential bytes");
+                assert!(!debug.contains(secret), "{provider} Debug output exposed credential bytes");
+            }
+        }
+    }
+
+    #[test]
+    fn azure_static_account_redaction_preserves_an_empty_service_principal_secret() {
+        let config = TierConfig {
+            tier_type: TierType::Azure,
+            azure: Some(TierAzure {
+                secret_key: "azure-account-secret-bytes".to_string(),
+                sp_auth: ServicePrincipalAuth::default(),
+                ..Default::default()
+            }),
+            ..Default::default()
+        };
+
+        let api = serde_json::to_value(config.redacted()).expect("redacted Azure API config should serialize");
+        let debug = format!("{config:?}");
+
+        assert_eq!(api["azure"]["secretKey"], TIER_CREDENTIAL_REDACTED);
+        assert_eq!(api["azure"]["spAuth"]["client_secret"], "");
+        assert!(debug.contains("client_secret: \"\""));
+        assert!(!debug.contains("client_secret: \"REDACTED\""));
+        assert!(!debug.contains("azure-account-secret-bytes"));
+    }
 }
@@ -460,6 +460,7 @@ where
        data,
        &ObjectOptions {
            max_parity: true,
+            write_completion: crate::object_api::WriteCompletion::TailDrained,
            http_preconditions: Some(HTTPPreconditions {
                if_none_match: Some("*".to_string()),
                ..Default::default()
@@ -556,6 +557,7 @@ where
        data,
        &ObjectOptions {
            max_parity: true,
+            write_completion: crate::object_api::WriteCompletion::TailDrained,
            http_preconditions: Some(HTTPPreconditions {
                if_match: Some(current_etag.to_string()),
                ..Default::default()
@@ -20,7 +20,7 @@

 use crate::error::is_err_bucket_not_found;
 use crate::services::tier::{
-    tier::{ERR_TIER_INVALID_CONFIG, ERR_TIER_TYPE_UNSUPPORTED},
+    tier::{ERR_TIER_BACKEND_IN_USE, ERR_TIER_INVALID_CONFIG, ERR_TIER_TYPE_UNSUPPORTED},
    tier_config::{TierConfig, TierType},
    tier_handlers::{ERR_TIER_BUCKET_NOT_FOUND, ERR_TIER_NOT_FOUND, ERR_TIER_PERM_ERR},
    warm_backend_aliyun::WarmBackendAliyun,
@@ -37,9 +37,10 @@ use crate::services::tier::{
 use bytes::Bytes;
 use http::StatusCode;
 use rustfs_s3_client::credentials::{Credentials, SignatureType, Static, Value};
-use rustfs_s3_client::transition_api::{BucketLookupType, Options, TransitionClient, TransitionCore};
+use rustfs_s3_client::transition_api::{BucketLookupType, Options, TransitionClient, TransitionClientTimeouts, TransitionCore};
 use rustfs_s3_client::{
    admin_handler_utils::AdminError,
+    api_error_response::to_error_response,
    api_put_object::{AdvancedPutOptions, PutObjectOptions},
    transition_api::{ReadCloser, ReaderImpl},
 };
@@ -48,25 +49,31 @@ use rustfs_utils::egress::validate_outbound_url;
 use rustfs_utils::http::headers::{
    CACHE_CONTROL, CONTENT_DISPOSITION, CONTENT_ENCODING, CONTENT_LANGUAGE, CONTENT_TYPE, EXPIRES, HeaderExt as _,
 };
-use s3s::dto::{ObjectLockLegalHoldStatus, ObjectLockRetentionMode, ReplicationStatus};
 use s3s::header::{
    X_AMZ_OBJECT_LOCK_LEGAL_HOLD, X_AMZ_OBJECT_LOCK_MODE, X_AMZ_OBJECT_LOCK_RETAIN_UNTIL_DATE, X_AMZ_REPLICATION_STATUS,
    X_AMZ_STORAGE_CLASS,
 };
+use s3s::{
+    S3ErrorCode,
+    dto::{ObjectLockLegalHoldStatus, ObjectLockRetentionMode, ReplicationStatus},
+};
 use std::collections::HashMap;
 use std::sync::Arc;
+use std::time::Duration;
 use time::OffsetDateTime;
 use time::format_description::well_known::{Rfc2822, Rfc3339};
+use tokio::io::AsyncReadExt;
 use tracing::{info, warn};

 pub type WarmBackendImpl = Box<dyn WarmBackend + Send + Sync + 'static>;

-const PROBE_OBJECT: &str = "probeobject";
-
 /// Largest object the S3-compatible warm backends accept for a multipart put.
 pub(crate) const MAX_MULTIPART_PUT_OBJECT_SIZE: i64 = 1024 * 1024 * 1024 * 1024 * 5;
 /// Part-count ceiling S3-compatible services impose on a multipart upload.
 pub(crate) const MAX_PARTS_COUNT: i64 = 10000;
+pub(crate) const WARM_BACKEND_PROBE_TIMEOUT: Duration = Duration::from_secs(30);
+const WARM_BACKEND_PROBE_RECONCILE_INTERVAL: Duration = Duration::from_secs(1);
+const WARM_BACKEND_PROBE_FINAL_RECONCILE_TIMEOUT: Duration = Duration::from_secs(1);

 #[derive(Default)]
 pub struct WarmBackendGetOpts {
@@ -138,6 +145,42 @@ pub trait WarmBackend {
    async fn probe_transition_candidate(&self, _object: &str) -> Result<TransitionCandidateProbe, std::io::Error> {
        Ok(TransitionCandidateProbe::Unsupported)
    }
+    async fn probe_transition_version(
+        &self,
+        object: &str,
+        remote_version_id: &str,
+    ) -> Result<TransitionCandidateProbe, std::io::Error> {
+        if remote_version_id.is_empty() {
+            return Err(std::io::Error::new(
+                std::io::ErrorKind::InvalidInput,
+                "an exact tier probe requires a remote version ID",
+            ));
+        }
+        self.validate_remote_version_id(remote_version_id)?;
+        match self
+            .get(
+                object,
+                remote_version_id,
+                WarmBackendGetOpts {
+                    start_offset: 0,
+                    length: 1,
+                },
+            )
+            .await
+        {
+            Ok(_) => Ok(TransitionCandidateProbe::VersionedPresent(remote_version_id.to_string())),
+            Err(err) if matches!(to_error_response(&err).code, S3ErrorCode::InvalidRange) => {
+                Ok(TransitionCandidateProbe::VersionedPresent(remote_version_id.to_string()))
+            }
+            Err(err)
+                if err.kind() == std::io::ErrorKind::NotFound
+                    || matches!(to_error_response(&err).code, S3ErrorCode::NoSuchKey | S3ErrorCode::NoSuchVersion) =>
+            {
+                Ok(TransitionCandidateProbe::Missing)
+            }
+            Err(err) => Err(err),
+        }
+    }
    async fn in_use(&self) -> Result<bool, std::io::Error>;
 }

@@ -260,6 +303,44 @@ pub(crate) struct S3CompatibleWarmBackendParams<'a> {
    pub validate_endpoint: fn(&url::Url) -> Result<(), rustfs_utils::egress::OutboundUrlError>,
 }

+/// Return the authority format accepted by `TransitionClient::new` while
+/// retaining an explicitly configured port. `url::Url::host_str()` omits the
+/// brackets needed when an IPv6 literal is combined with a port.
+pub(crate) fn endpoint_authority(url: &url::Url) -> Result<String, std::io::Error> {
+    let host = url
+        .host_str()
+        .ok_or_else(|| std::io::Error::other("Invalid endpoint URL: missing host"))?;
+    let port = url.port().unwrap_or(if url.scheme() == "https" { 443 } else { 80 });
+    if host.starts_with('[') && host.ends_with(']') {
+        Ok(format!("{host}:{port}"))
+    } else if host.contains(':') {
+        Ok(format!("[{host}]:{port}"))
+    } else {
+        Ok(format!("{host}:{port}"))
+    }
+}
+
+fn transition_timeout_from_env(env_key: &str, default_secs: u64) -> Duration {
+    Duration::from_secs(rustfs_utils::get_env_u64(env_key, default_secs))
+}
+
+pub(crate) fn transition_client_timeouts_from_env() -> TransitionClientTimeouts {
+    TransitionClientTimeouts::new(
+        transition_timeout_from_env(
+            rustfs_config::ENV_TIER_REMOTE_CONNECT_TIMEOUT_SECS,
+            rustfs_config::DEFAULT_TIER_REMOTE_CONNECT_TIMEOUT_SECS,
+        ),
+        transition_timeout_from_env(
+            rustfs_config::ENV_TIER_REMOTE_REQUEST_TIMEOUT_SECS,
+            rustfs_config::DEFAULT_TIER_REMOTE_REQUEST_TIMEOUT_SECS,
+        ),
+        transition_timeout_from_env(
+            rustfs_config::ENV_TIER_REMOTE_RESPONSE_BODY_IDLE_TIMEOUT_SECS,
+            rustfs_config::DEFAULT_TIER_REMOTE_RESPONSE_BODY_IDLE_TIMEOUT_SECS,
+        ),
+    )
+}
+
 /// Build the [`WarmBackendS3`] shared by the S3-compatible warm backend providers.
 ///
 /// Credential, bucket, and endpoint validation run in this order because the
@@ -290,6 +371,7 @@ pub(crate) async fn new_s3_compatible_warm_backend(
        signer_type: SignatureType::SignatureV4,
        ..Default::default()
    }));
+    let timeouts = transition_client_timeouts_from_env();
    let opts = Options {
        creds,
        secure: u.scheme() == "https",
@@ -298,17 +380,11 @@ pub(crate) async fn new_s3_compatible_warm_backend(
        bucket_lookup: params.bucket_lookup,
        ..Default::default()
    };
-    let scheme = u.scheme();
-    let default_port = if scheme == "https" { 443 } else { 80 };
-    let host = u
-        .host_str()
-        .ok_or_else(|| std::io::Error::other("Invalid endpoint URL: missing host"))?;
-    // Runs after the host-presence check above (not immediately after Url::parse) so a
-    // host-less endpoint still reports this constructor's own "missing host" text instead of
-    // validate_endpoint's differently-worded rejection for the same input.
+    let endpoint = endpoint_authority(&u)?;
+    // Run the SSRF guard after the host-presence check so a host-less endpoint
+    // keeps this constructor's stable error text.
    (params.validate_endpoint)(&u).map_err(|err| std::io::Error::other(format!("tier endpoint is not allowed: {err}")))?;
-    let client =
-        TransitionClient::new(&format!("{}:{}", host, u.port().unwrap_or(default_port)), opts, params.provider_tag).await?;
+    let client = TransitionClient::new_with_timeouts(&endpoint, opts, params.provider_tag, timeouts).await?;

    let client = Arc::new(client);
    let core = TransitionCore(Arc::clone(&client));
@@ -423,6 +499,17 @@ impl WarmBackend for MeteredWarmBackend {
        Self::record(TierRequestOperation::Probe, result)
    }

+    async fn probe_transition_version(
+        &self,
+        object: &str,
+        remote_version_id: &str,
+    ) -> Result<TransitionCandidateProbe, std::io::Error> {
+        Self::record(
+            TierRequestOperation::Probe,
+            self.inner.probe_transition_version(object, remote_version_id).await,
+        )
+    }
+
    async fn in_use(&self) -> Result<bool, std::io::Error> {
        Self::record(TierRequestOperation::InUse, self.inner.in_use().await)
    }
@@ -451,25 +538,187 @@ impl TransitionCandidateReconciler for MeteredTransitionCandidateReconciler {
    }
 }

-pub async fn check_warm_backend(w: Option<&WarmBackendImpl>) -> Result<(), AdminError> {
-    let w = w.ok_or_else(|| ERR_TIER_NOT_FOUND.clone())?;
-    w.validate().await.map_err(|_| ERR_TIER_INVALID_CONFIG.clone())?;
-    let remote_version_id = w
-        .put(PROBE_OBJECT, ReaderImpl::Body(Bytes::from("RustFS".as_bytes().to_vec())), 5)
-        .await
-        .map_err(|_| ERR_TIER_PERM_ERR.clone())?;
+async fn remove_discovered_probe_candidate(
+    w: &WarmBackendImpl,
+    probe_object: &str,
+    candidate: TransitionCandidateProbe,
+) -> Result<bool, std::io::Error> {
+    match candidate {
+        TransitionCandidateProbe::Missing => Ok(false),
+        TransitionCandidateProbe::VersionedPresent(remote_version_id) => {
+            w.remove_exact(probe_object, &remote_version_id).await?;
+            Ok(true)
+        }
+        TransitionCandidateProbe::UnversionedPresent => {
+            w.remove(probe_object, "").await?;
+            Ok(true)
+        }
+        TransitionCandidateProbe::Ambiguous => {
+            Err(std::io::Error::other("remote tier probe PUT produced multiple possible versions"))
+        }
+        TransitionCandidateProbe::Unsupported => Err(std::io::Error::new(
+            std::io::ErrorKind::Unsupported,
+            "remote tier cannot discover the outcome of a probe PUT",
+        )),
+    }
+}

-    if w.validate_remote_version_id(&remote_version_id).is_err() {
-        w.remove_exact(PROBE_OBJECT, &remote_version_id)
+async fn compensate_uncertain_probe_put(
+    w: &WarmBackendImpl,
+    probe_object: &str,
+    settle_deadline: tokio::time::Instant,
+) -> Result<(), std::io::Error> {
+    let final_deadline = settle_deadline + WARM_BACKEND_PROBE_FINAL_RECONCILE_TIMEOUT;
+    let mut removed_any = false;
+    while tokio::time::Instant::now() < settle_deadline {
+        let candidate = match tokio::time::timeout_at(settle_deadline, w.probe_transition_candidate(probe_object)).await {
+            Ok(candidate) => candidate?,
+            Err(_) => break,
+        };
+        if matches!(candidate, TransitionCandidateProbe::Missing) && removed_any {
+            break;
+        }
+        removed_any |= tokio::time::timeout_at(settle_deadline, remove_discovered_probe_candidate(w, probe_object, candidate))
            .await
-            .map_err(|_| ERR_TIER_PERM_ERR.clone())?;
-        return Err(ERR_TIER_INVALID_CONFIG.clone());
+            .map_err(|_| std::io::Error::new(std::io::ErrorKind::TimedOut, "timed out reconciling a remote tier probe PUT"))??;
+
+        let now = tokio::time::Instant::now();
+        if now >= settle_deadline {
+            break;
+        }
+        tokio::time::sleep_until(std::cmp::min(settle_deadline, now + WARM_BACKEND_PROBE_RECONCILE_INTERVAL)).await;
    }

-    let read_result = w.get(PROBE_OBJECT, &remote_version_id, WarmBackendGetOpts::default()).await;
-    let remove_result = w.remove(PROBE_OBJECT, &remote_version_id).await;
-    //xhttp.DrainBody(r);
-    if read_result.is_err() || remove_result.is_err() {
+    let candidate = tokio::time::timeout_at(final_deadline, w.probe_transition_candidate(probe_object))
+        .await
+        .map_err(|_| {
+            std::io::Error::new(std::io::ErrorKind::TimedOut, "timed out confirming the final remote tier probe state")
+        })??;
+    if !tokio::time::timeout_at(final_deadline, remove_discovered_probe_candidate(w, probe_object, candidate))
+        .await
+        .map_err(|_| {
+            std::io::Error::new(std::io::ErrorKind::TimedOut, "timed out removing the final remote tier probe candidate")
+        })??
+    {
+        return Ok(());
+    }
+
+    let final_candidate = tokio::time::timeout_at(final_deadline, w.probe_transition_candidate(probe_object))
+        .await
+        .map_err(|_| std::io::Error::new(std::io::ErrorKind::TimedOut, "timed out confirming remote tier probe cleanup"))??;
+    match final_candidate {
+        TransitionCandidateProbe::Missing => Ok(()),
+        _ => Err(std::io::Error::other("remote tier probe cleanup could not be confirmed")),
+    }
+}
+
+fn probe_cleanup_incomplete_error() -> AdminError {
+    let mut err = ERR_TIER_PERM_ERR.clone();
+    err.message = "Remote tier probe outcome is uncertain; cleanup is incomplete".to_string();
+    err
+}
+
+async fn check_warm_backend_with_deadlines(
+    w: Option<&WarmBackendImpl>,
+    deadline: tokio::time::Instant,
+    cleanup_deadline: tokio::time::Instant,
+) -> Result<(), AdminError> {
+    let w = w.ok_or_else(|| ERR_TIER_NOT_FOUND.clone())?;
+    let probe_object = format!("rustfs-tier-probe-{}", uuid::Uuid::new_v4());
+    let timeout_error = || {
+        let mut err = ERR_TIER_BACKEND_IN_USE.clone();
+        err.message = "Timed out validating the remote tier mutation".to_string();
+        err
+    };
+    tokio::time::timeout_at(deadline, w.validate())
+        .await
+        .map_err(|_| timeout_error())?
+        .map_err(|_| ERR_TIER_INVALID_CONFIG.clone())?;
+    let put_result =
+        tokio::time::timeout_at(deadline, w.put(&probe_object, ReaderImpl::Body(Bytes::from_static(b"RustFS")), 6)).await;
+    let remote_version_id = match put_result {
+        Ok(Ok(remote_version_id)) => remote_version_id,
+        Ok(Err(_)) => {
+            return Err(match compensate_uncertain_probe_put(w, &probe_object, cleanup_deadline).await {
+                Ok(()) => ERR_TIER_PERM_ERR.clone(),
+                Err(_) => probe_cleanup_incomplete_error(),
+            });
+        }
+        Err(_) => {
+            let err = timeout_error();
+            return Err(match compensate_uncertain_probe_put(w, &probe_object, cleanup_deadline).await {
+                Ok(()) => err,
+                Err(_) => probe_cleanup_incomplete_error(),
+            });
+        }
+    };
+
+    // S3-family backends do not replay a failed request before returning `Ok`,
+    // while GCS discovers every matching generation. The authoritative probe
+    // below therefore closes the acknowledged-PUT path; only an error or
+    // timeout needs the longer visibility reconciliation above.
+    let authoritative_candidate = match tokio::time::timeout_at(deadline, w.probe_transition_candidate(&probe_object)).await {
+        Ok(Ok(candidate)) => candidate,
+        Ok(Err(_)) | Err(_) => {
+            return Err(match compensate_uncertain_probe_put(w, &probe_object, cleanup_deadline).await {
+                Ok(()) => ERR_TIER_INVALID_CONFIG.clone(),
+                Err(_) => probe_cleanup_incomplete_error(),
+            });
+        }
+    };
+    let response_version_is_valid = w.validate_remote_version_id(&remote_version_id).is_ok();
+    let response_matches_candidate = match &authoritative_candidate {
+        TransitionCandidateProbe::UnversionedPresent => remote_version_id.is_empty(),
+        TransitionCandidateProbe::VersionedPresent(candidate_version) => candidate_version == &remote_version_id,
+        TransitionCandidateProbe::Missing | TransitionCandidateProbe::Ambiguous | TransitionCandidateProbe::Unsupported => false,
+    };
+    if !response_version_is_valid || !response_matches_candidate {
+        return Err(match compensate_uncertain_probe_put(w, &probe_object, cleanup_deadline).await {
+            Ok(()) => ERR_TIER_INVALID_CONFIG.clone(),
+            Err(_) => probe_cleanup_incomplete_error(),
+        });
+    }
+
+    let read_result = tokio::time::timeout_at(deadline, async {
+        let mut reader = w
+            .get(
+                &probe_object,
+                &remote_version_id,
+                WarmBackendGetOpts {
+                    start_offset: 0,
+                    length: 7,
+                },
+            )
+            .await
+            .map_err(|_| ERR_TIER_PERM_ERR.clone())?;
+        let mut body = Vec::new();
+        reader
+            .take(7)
+            .read_to_end(&mut body)
+            .await
+            .map_err(|_| ERR_TIER_PERM_ERR.clone())?;
+        if body != b"RustFS" {
+            return Err(ERR_TIER_PERM_ERR.clone());
+        }
+        Ok(())
+    })
+    .await
+    .map_err(|_| timeout_error())
+    .and_then(|result| result);
+    let cleanup_result = tokio::time::timeout_at(cleanup_deadline, async {
+        if !remove_discovered_probe_candidate(w, &probe_object, authoritative_candidate).await? {
+            return Err(std::io::Error::other("remote tier probe disappeared before cleanup"));
+        }
+        match w.probe_transition_candidate(&probe_object).await? {
+            TransitionCandidateProbe::Missing => Ok(()),
+            _ => Err(std::io::Error::other("remote tier probe remained after cleanup")),
+        }
+    })
+    .await;
+    if !matches!(cleanup_result, Ok(Ok(()))) {
+        return Err(probe_cleanup_incomplete_error());
+    }
+    if let Err(err) = read_result {
        //if is_err_bucket_not_found(&err) {
        //    return Err(ERR_TIER_BUCKET_NOT_FOUND);
        //}
@@ -477,12 +726,28 @@ pub async fn check_warm_backend(w: Option<&WarmBackendImpl>) -> Result<(), Admin
            return Err(ERR_TIER_MISSING_CREDENTIALS);
        }*/
        //else {
-        return Err(ERR_TIER_PERM_ERR.clone());
+        return Err(err);
        //}
    }
    Ok(())
 }

+/// Validate a backend using a caller-owned deadline while retaining a bounded
+/// reconciliation window for an uncertain probe PUT. The validation future is
+/// kept alive through cleanup so an outer timeout cannot abandon the remote
+/// probe object.
+pub(crate) async fn check_warm_backend_until(
+    w: Option<&WarmBackendImpl>,
+    deadline: tokio::time::Instant,
+) -> Result<(), AdminError> {
+    check_warm_backend_with_deadlines(w, deadline, deadline + WARM_BACKEND_PROBE_FINAL_RECONCILE_TIMEOUT).await
+}
+
+pub async fn check_warm_backend(w: Option<&WarmBackendImpl>) -> Result<(), AdminError> {
+    let deadline = tokio::time::Instant::now() + WARM_BACKEND_PROBE_TIMEOUT;
+    check_warm_backend_with_deadlines(w, deadline, deadline + WARM_BACKEND_PROBE_TIMEOUT).await
+}
+
 pub async fn new_warm_backend(tier: &TierConfig, probe: bool) -> Result<WarmBackendImpl, AdminError> {
    let mut d: Option<WarmBackendImpl> = None;
    match tier.tier_type {
@@ -701,7 +966,7 @@ pub async fn new_warm_backend(tier: &TierConfig, probe: bool) -> Result<WarmBack
    let d: WarmBackendImpl = Box::new(MeteredWarmBackend { inner: d });

    if probe {
-        d.validate().await.map_err(|_| ERR_TIER_INVALID_CONFIG.clone())?;
+        check_warm_backend(Some(&d)).await?;
    }
    Ok(d)
 }
@@ -754,6 +1019,7 @@ pub(crate) async fn new_transition_candidate_reconciler(
 #[cfg(test)]
 mod tests {
    use super::*;
+    use crate::services::tier::test_util::{MockWarmBackend, MockWarmOp};
    use crate::services::tier::tier_config::TierWasabi;
    use std::sync::{
        Arc,
@@ -920,13 +1186,38 @@ mod tests {

    struct RejectingProbeVersionBackend {
        gets: Arc<AtomicUsize>,
+        present: Arc<std::sync::atomic::AtomicBool>,
        removed_versions: Arc<tokio::sync::Mutex<Vec<String>>>,
+        returned_version: String,
    }

    struct RecordingProbeBackend {
        get_versions: Arc<tokio::sync::Mutex<Vec<String>>>,
+        present: Arc<std::sync::atomic::AtomicBool>,
        removed_versions: Arc<tokio::sync::Mutex<Vec<String>>>,
+        remove_clears_candidate: bool,
        fail_get: bool,
+        body: ProbeBody,
+    }
+
+    struct HangingProbePutBackend {
+        put_started: Arc<tokio::sync::Notify>,
+        present: Arc<std::sync::atomic::AtomicBool>,
+        probes: Arc<AtomicUsize>,
+        removed_versions: Arc<tokio::sync::Mutex<Vec<String>>>,
+    }
+
+    struct LateVisibleProbeBackend {
+        visible_at: tokio::time::Instant,
+        removed: Arc<std::sync::atomic::AtomicBool>,
+        probes: Arc<AtomicUsize>,
+        removed_versions: Arc<tokio::sync::Mutex<Vec<String>>>,
+    }
+
+    #[derive(Clone, Copy)]
+    enum ProbeBody {
+        Exact,
+        Mismatch,
    }

    #[async_trait::async_trait]
@@ -976,7 +1267,7 @@ mod tests {
        }

        async fn put(&self, _object: &str, _r: ReaderImpl, _length: i64) -> Result<String, std::io::Error> {
-            Ok(uuid::Uuid::nil().to_string())
+            Ok(self.returned_version.clone())
        }

        async fn put_with_meta(
@@ -999,10 +1290,19 @@ mod tests {
        }

        async fn remove_exact(&self, _object: &str, rv: &str) -> Result<(), std::io::Error> {
+            self.present.store(false, Ordering::SeqCst);
            self.removed_versions.lock().await.push(rv.to_string());
            Ok(())
        }

+        async fn probe_transition_candidate(&self, _object: &str) -> Result<TransitionCandidateProbe, std::io::Error> {
+            if self.present.load(Ordering::SeqCst) {
+                Ok(TransitionCandidateProbe::VersionedPresent(PROBE_VERSION.to_string()))
+            } else {
+                Ok(TransitionCandidateProbe::Missing)
+            }
+        }
+
        async fn in_use(&self) -> Result<bool, std::io::Error> {
            Ok(false)
        }
@@ -1029,15 +1329,121 @@ mod tests {
            if self.fail_get {
                Err(std::io::Error::other("probe GET failed"))
            } else {
-                Ok(ReadCloser::new(std::io::Cursor::new(Vec::new())))
+                match self.body {
+                    ProbeBody::Exact => Ok(ReadCloser::new(std::io::Cursor::new(b"RustFS".to_vec()))),
+                    ProbeBody::Mismatch => Ok(ReadCloser::new(std::io::Cursor::new(b"RustFT".to_vec()))),
+                }
            }
        }

        async fn remove(&self, _object: &str, rv: &str) -> Result<(), std::io::Error> {
+            if self.remove_clears_candidate {
+                self.present.store(false, Ordering::SeqCst);
+            }
            self.removed_versions.lock().await.push(rv.to_string());
            Ok(())
        }

+        async fn probe_transition_candidate(&self, _object: &str) -> Result<TransitionCandidateProbe, std::io::Error> {
+            if self.present.load(Ordering::SeqCst) {
+                Ok(TransitionCandidateProbe::VersionedPresent(PROBE_VERSION.to_string()))
+            } else {
+                Ok(TransitionCandidateProbe::Missing)
+            }
+        }
+
+        async fn in_use(&self) -> Result<bool, std::io::Error> {
+            Ok(false)
+        }
+    }
+
+    #[async_trait::async_trait]
+    impl WarmBackend for HangingProbePutBackend {
+        async fn put(&self, _object: &str, _r: ReaderImpl, _length: i64) -> Result<String, std::io::Error> {
+            self.put_started.notify_one();
+            std::future::pending().await
+        }
+
+        async fn put_with_meta(
+            &self,
+            object: &str,
+            r: ReaderImpl,
+            length: i64,
+            _meta: HashMap<String, String>,
+        ) -> Result<String, std::io::Error> {
+            self.put(object, r, length).await
+        }
+
+        async fn get(&self, _object: &str, _rv: &str, _opts: WarmBackendGetOpts) -> Result<ReadCloser, std::io::Error> {
+            Err(std::io::Error::other("GET must not run after a timed out probe PUT"))
+        }
+
+        async fn remove(&self, _object: &str, _rv: &str) -> Result<(), std::io::Error> {
+            Err(std::io::Error::other("generic remove must not replace exact probe cleanup"))
+        }
+
+        async fn remove_exact(&self, _object: &str, rv: &str) -> Result<(), std::io::Error> {
+            self.present.store(false, Ordering::SeqCst);
+            self.removed_versions.lock().await.push(rv.to_string());
+            Ok(())
+        }
+
+        async fn probe_transition_candidate(&self, _object: &str) -> Result<TransitionCandidateProbe, std::io::Error> {
+            self.probes.fetch_add(1, Ordering::SeqCst);
+            if self.present.load(Ordering::SeqCst) {
+                Ok(TransitionCandidateProbe::VersionedPresent(PROBE_VERSION.to_string()))
+            } else {
+                Ok(TransitionCandidateProbe::Missing)
+            }
+        }
+
+        async fn in_use(&self) -> Result<bool, std::io::Error> {
+            Ok(false)
+        }
+    }
+
+    #[async_trait::async_trait]
+    impl WarmBackend for LateVisibleProbeBackend {
+        async fn put(&self, _object: &str, _r: ReaderImpl, _length: i64) -> Result<String, std::io::Error> {
+            Err(std::io::Error::new(
+                std::io::ErrorKind::ConnectionReset,
+                "probe PUT response was lost before the object became visible",
+            ))
+        }
+
+        async fn put_with_meta(
+            &self,
+            object: &str,
+            r: ReaderImpl,
+            length: i64,
+            _meta: HashMap<String, String>,
+        ) -> Result<String, std::io::Error> {
+            self.put(object, r, length).await
+        }
+
+        async fn get(&self, _object: &str, _rv: &str, _opts: WarmBackendGetOpts) -> Result<ReadCloser, std::io::Error> {
+            Err(std::io::Error::other("GET must not run after a lost probe PUT response"))
+        }
+
+        async fn remove(&self, _object: &str, _rv: &str) -> Result<(), std::io::Error> {
+            Err(std::io::Error::other("generic remove must not replace exact probe cleanup"))
+        }
+
+        async fn remove_exact(&self, _object: &str, rv: &str) -> Result<(), std::io::Error> {
+            self.removed.store(true, Ordering::SeqCst);
+            self.removed_versions.lock().await.push(rv.to_string());
+            Ok(())
+        }
+
+        async fn probe_transition_candidate(&self, _object: &str) -> Result<TransitionCandidateProbe, std::io::Error> {
+            self.probes.fetch_add(1, Ordering::SeqCst);
+            if tokio::time::Instant::now() >= self.visible_at && !self.removed.load(Ordering::SeqCst) {
+                Ok(TransitionCandidateProbe::VersionedPresent(PROBE_VERSION.to_string()))
+            } else {
+                Ok(TransitionCandidateProbe::Missing)
+            }
+        }
+
        async fn in_use(&self) -> Result<bool, std::io::Error> {
            Ok(false)
        }
@@ -1098,13 +1504,15 @@ mod tests {
        assert_eq!(probe, TransitionCandidateProbe::Unsupported);
    }

-    #[tokio::test]
+    #[tokio::test(start_paused = true)]
    async fn check_warm_backend_removes_exact_probe_when_versioning_drifts() {
        let gets = Arc::new(AtomicUsize::new(0));
        let removed_versions = Arc::new(tokio::sync::Mutex::new(Vec::new()));
        let backend: WarmBackendImpl = Box::new(RejectingProbeVersionBackend {
            gets: gets.clone(),
+            present: Arc::new(std::sync::atomic::AtomicBool::new(true)),
            removed_versions: removed_versions.clone(),
+            returned_version: uuid::Uuid::nil().to_string(),
        });

        let err = check_warm_backend(Some(&backend))
@@ -1113,7 +1521,27 @@ mod tests {

        assert_eq!(err.code, ERR_TIER_INVALID_CONFIG.code);
        assert_eq!(gets.load(Ordering::SeqCst), 0);
-        assert_eq!(removed_versions.lock().await.as_slice(), [uuid::Uuid::nil().to_string()]);
+        assert_eq!(removed_versions.lock().await.as_slice(), [PROBE_VERSION]);
+    }
+
+    #[tokio::test(start_paused = true)]
+    async fn check_warm_backend_rejects_empty_put_version_for_a_versioned_candidate() {
+        let gets = Arc::new(AtomicUsize::new(0));
+        let removed_versions = Arc::new(tokio::sync::Mutex::new(Vec::new()));
+        let backend: WarmBackendImpl = Box::new(RejectingProbeVersionBackend {
+            gets: gets.clone(),
+            present: Arc::new(std::sync::atomic::AtomicBool::new(true)),
+            removed_versions: removed_versions.clone(),
+            returned_version: String::new(),
+        });
+
+        let err = check_warm_backend(Some(&backend))
+            .await
+            .expect_err("an empty PUT version must not read or generically delete a versioned object");
+
+        assert_eq!(err.code, ERR_TIER_INVALID_CONFIG.code);
+        assert_eq!(gets.load(Ordering::SeqCst), 0);
+        assert_eq!(removed_versions.lock().await.as_slice(), [PROBE_VERSION]);
    }

    #[tokio::test]
@@ -1122,8 +1550,11 @@ mod tests {
        let removed_versions = Arc::new(tokio::sync::Mutex::new(Vec::new()));
        let backend: WarmBackendImpl = Box::new(RecordingProbeBackend {
            get_versions: get_versions.clone(),
+            present: Arc::new(std::sync::atomic::AtomicBool::new(true)),
            removed_versions: removed_versions.clone(),
+            remove_clears_candidate: true,
            fail_get: false,
+            body: ProbeBody::Exact,
        });

        check_warm_backend(Some(&backend))
@@ -1140,8 +1571,11 @@ mod tests {
        let removed_versions = Arc::new(tokio::sync::Mutex::new(Vec::new()));
        let backend: WarmBackendImpl = Box::new(RecordingProbeBackend {
            get_versions: get_versions.clone(),
+            present: Arc::new(std::sync::atomic::AtomicBool::new(true)),
            removed_versions: removed_versions.clone(),
+            remove_clears_candidate: true,
            fail_get: true,
+            body: ProbeBody::Exact,
        });

        let err = check_warm_backend(Some(&backend))
@@ -1153,6 +1587,169 @@ mod tests {
        assert_eq!(removed_versions.lock().await.as_slice(), [PROBE_VERSION]);
    }

+    #[tokio::test]
+    async fn check_warm_backend_removes_probe_after_body_mismatch() {
+        let get_versions = Arc::new(tokio::sync::Mutex::new(Vec::new()));
+        let removed_versions = Arc::new(tokio::sync::Mutex::new(Vec::new()));
+        let backend: WarmBackendImpl = Box::new(RecordingProbeBackend {
+            get_versions,
+            present: Arc::new(std::sync::atomic::AtomicBool::new(true)),
+            removed_versions: removed_versions.clone(),
+            remove_clears_candidate: true,
+            fail_get: false,
+            body: ProbeBody::Mismatch,
+        });
+
+        let err = check_warm_backend(Some(&backend))
+            .await
+            .expect_err("a mismatched body should fail after cleanup");
+
+        assert_eq!(err.code, ERR_TIER_PERM_ERR.code);
+        assert_eq!(removed_versions.lock().await.as_slice(), [PROBE_VERSION]);
+    }
+
+    #[tokio::test]
+    async fn check_warm_backend_rejects_a_stale_candidate_after_successful_delete() {
+        let removed_versions = Arc::new(tokio::sync::Mutex::new(Vec::new()));
+        let backend: WarmBackendImpl = Box::new(RecordingProbeBackend {
+            get_versions: Arc::new(tokio::sync::Mutex::new(Vec::new())),
+            present: Arc::new(std::sync::atomic::AtomicBool::new(true)),
+            removed_versions: removed_versions.clone(),
+            remove_clears_candidate: false,
+            fail_get: false,
+            body: ProbeBody::Exact,
+        });
+
+        let err = check_warm_backend(Some(&backend))
+            .await
+            .expect_err("cleanup must not succeed while the deleted candidate remains visible");
+
+        assert_eq!(err.code, ERR_TIER_PERM_ERR.code);
+        assert!(err.message.contains("cleanup is incomplete"));
+        assert_eq!(removed_versions.lock().await.as_slice(), [PROBE_VERSION]);
+    }
+
+    #[tokio::test(start_paused = true)]
+    async fn check_warm_backend_reconciles_a_lost_put_response() {
+        let backend = MockWarmBackend::new();
+        backend.lose_next_put_response();
+        let driver: WarmBackendImpl = Box::new(backend.clone());
+
+        let err = check_warm_backend(Some(&driver))
+            .await
+            .expect_err("a lost probe PUT response must fail after compensation");
+
+        assert_eq!(err.code, ERR_TIER_PERM_ERR.code);
+        assert_eq!(backend.object_count().await, 0);
+        assert_eq!(backend.exact_remove_count(), 1);
+        let operations = backend.op_log().await;
+        let put = operations.iter().find_map(|operation| match operation {
+            MockWarmOp::Put { object } => Some(object),
+            _ => None,
+        });
+        let probe = operations.iter().find_map(|operation| match operation {
+            MockWarmOp::Probe { object } => Some(object),
+            _ => None,
+        });
+        let remove = operations.iter().find_map(|operation| match operation {
+            MockWarmOp::Remove { object } => Some(object),
+            _ => None,
+        });
+        let (Some(put), Some(probe), Some(remove)) = (put, probe, remove) else {
+            panic!("lost-response compensation should PUT, probe, and remove");
+        };
+        assert_eq!(put, probe);
+        assert_eq!(probe, remove);
+    }
+
+    #[tokio::test(start_paused = true)]
+    async fn check_warm_backend_retries_until_a_late_put_becomes_visible() {
+        let probes = Arc::new(AtomicUsize::new(0));
+        let removed_versions = Arc::new(tokio::sync::Mutex::new(Vec::new()));
+        let driver: WarmBackendImpl = Box::new(LateVisibleProbeBackend {
+            visible_at: tokio::time::Instant::now() + Duration::from_secs(5),
+            removed: Arc::new(std::sync::atomic::AtomicBool::new(false)),
+            probes: probes.clone(),
+            removed_versions: removed_versions.clone(),
+        });
+
+        let err = check_warm_backend(Some(&driver))
+            .await
+            .expect_err("a late-visible probe PUT must still report the lost response");
+
+        assert_eq!(err.code, ERR_TIER_PERM_ERR.code);
+        assert!(
+            probes.load(Ordering::SeqCst) > 5,
+            "reconciliation must not stop at the first Missing result"
+        );
+        assert_eq!(removed_versions.lock().await.as_slice(), [PROBE_VERSION]);
+    }
+
+    #[tokio::test]
+    async fn check_warm_backend_reports_incomplete_cleanup_without_guessing() {
+        for candidate in [TransitionCandidateProbe::Unsupported, TransitionCandidateProbe::Ambiguous] {
+            let backend = MockWarmBackend::new();
+            backend.set_transition_candidate_probe_override(Some(candidate)).await;
+            backend.lose_next_put_response();
+            let driver: WarmBackendImpl = Box::new(backend.clone());
+
+            let err = check_warm_backend(Some(&driver))
+                .await
+                .expect_err("an uncertain candidate must fail without a guessed delete");
+
+            assert_eq!(err.code, ERR_TIER_PERM_ERR.code);
+            assert!(err.message.contains("cleanup is incomplete"));
+            assert_eq!(backend.remove_count().await, 0);
+            assert_eq!(backend.object_count().await, 1);
+        }
+    }
+
+    #[tokio::test]
+    async fn check_warm_backend_reports_an_exact_cleanup_failure() {
+        let backend = MockWarmBackend::new();
+        backend.set_remove_failure(true);
+        backend.lose_next_put_response();
+        let driver: WarmBackendImpl = Box::new(backend.clone());
+
+        let err = check_warm_backend(Some(&driver))
+            .await
+            .expect_err("an exact cleanup failure must replace the ambiguous PUT error");
+
+        assert_eq!(err.code, ERR_TIER_PERM_ERR.code);
+        assert!(err.message.contains("cleanup is incomplete"));
+        assert_eq!(backend.exact_remove_count(), 1);
+        assert_eq!(backend.object_count().await, 1);
+    }
+
+    #[tokio::test(start_paused = true)]
+    async fn check_warm_backend_reconciles_a_timed_out_put() {
+        let put_started = Arc::new(tokio::sync::Notify::new());
+        let probes = Arc::new(AtomicUsize::new(0));
+        let removed_versions = Arc::new(tokio::sync::Mutex::new(Vec::new()));
+        let driver: WarmBackendImpl = Box::new(HangingProbePutBackend {
+            put_started: put_started.clone(),
+            present: Arc::new(std::sync::atomic::AtomicBool::new(true)),
+            probes: probes.clone(),
+            removed_versions: removed_versions.clone(),
+        });
+        let check = check_warm_backend(Some(&driver));
+        tokio::pin!(check);
+        tokio::select! {
+            _ = put_started.notified() => {}
+            result = &mut check => panic!("probe completed before the PUT timeout: {result:?}"),
+        }
+
+        tokio::time::advance(WARM_BACKEND_PROBE_TIMEOUT + Duration::from_millis(1)).await;
+        let err = check.await.expect_err("a timed out probe PUT must fail after compensation");
+
+        assert_eq!(err.code, ERR_TIER_BACKEND_IN_USE.code);
+        assert!(
+            probes.load(Ordering::SeqCst) > 1,
+            "timed-out PUT reconciliation must keep checking through the visibility window"
+        );
+        assert_eq!(removed_versions.lock().await.as_slice(), [PROBE_VERSION]);
+    }
+
    #[tokio::test]
    async fn new_wasabi_backend_honors_probe_flag() {
        let tier = TierConfig {
@@ -1298,6 +1895,15 @@ mod tests {
        assert_eq!(insecure.client.endpoint_url.port_or_known_default(), Some(80));
    }

+    #[test]
+    fn endpoint_authority_preserves_ipv6_brackets_and_explicit_port() {
+        let url = url::Url::parse("https://[2001:db8::1]:9443").expect("the IPv6 endpoint should parse");
+        assert_eq!(
+            endpoint_authority(&url).expect("the endpoint should have an authority"),
+            "[2001:db8::1]:9443"
+        );
+    }
+
    #[tokio::test]
    async fn s3_compatible_backend_strips_only_a_trailing_prefix_separator() {
        let mut params = s3_compatible_params("http://tier.example.com:9000");
@@ -15,15 +15,13 @@
 #![allow(unused_variables)]
 #![allow(unused_mut)]
 #![allow(unused_assignments)]
-#![allow(unused_must_use)]
-#![allow(clippy::all)]

 use std::collections::HashMap;

 use crate::services::tier::{
    tier_config::TierAliyun,
    warm_backend::{
-        S3CompatibleWarmBackendParams, WarmBackend, WarmBackendGetOpts, build_transition_put_options,
+        S3CompatibleWarmBackendParams, TransitionCandidateProbe, WarmBackend, WarmBackendGetOpts, build_transition_put_options,
        new_s3_compatible_warm_backend, optimal_part_size,
    },
    warm_backend_s3::WarmBackendS3,
@@ -89,6 +87,10 @@ impl WarmBackend for WarmBackendAliyun {
        self.0.remove(object, rv).await
    }

+    async fn probe_transition_candidate(&self, object: &str) -> Result<TransitionCandidateProbe, std::io::Error> {
+        self.0.probe_transition_candidate(object).await
+    }
+
    async fn in_use(&self) -> Result<bool, std::io::Error> {
        self.0.in_use().await
    }
--- a/Show More
+++ b/Show More