diff --git a/.github/workflows/minio-interop.yml b/.github/workflows/minio-interop.yml
new file mode 100644
index 000000000..585dca543
--- /dev/null
+++ b/.github/workflows/minio-interop.yml
@@ -0,0 +1,70 @@
+# 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.
+
+# MinIO on-disk interop: prove RustFS reads MinIO-written erasure-coded SSE
+# objects with byte-identical data and correct logical size.
+#
+# This is NOT a PR gate. The fixtures are real MinIO backend trees generated on
+# the fly (they are gitignored, never committed), so the job regenerates them
+# each run with Docker and then runs the `#[ignore]` reader tests in
+# crates/ecstore/tests/minio_generated_read_test.rs.
+#
+# Runner: GitHub-hosted `ubuntu-latest`. It reliably ships Docker + Python,
+# unlike the self-hosted fleet, whose pods drift in Docker/pip availability
+# (see the infra note in e2e-s3tests.yml). Nightly + manual only.
+name: minio-interop
+
+on:
+  workflow_dispatch:
+  schedule:
+    # Nightly at 03:17 UTC (offset from other nightly jobs).
+    - cron: "17 3 * * *"
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+
+permissions:
+  contents: read
+
+jobs:
+  minio-interop:
+    name: MinIO interop (EC + SSE read parity)
+    # Skip on forks: needs the repo's runners and is not a contributor gate.
+    if: github.repository == 'rustfs/rustfs'
+    runs-on: ubuntu-latest
+    timeout-minutes: 40
+    env:
+      # Fixed 32-byte test KMS key baked into the fixture lab; not a secret.
+      RUSTFS_MINIO_STATIC_KMS_KEY_B64: IyqsU3kMFloCNup4BsZtf/rmfHVcTgznO2F25CkEH1g=
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0 # v7
+
+      - name: Setup Rust environment
+        uses: ./.github/actions/setup
+        with:
+          rust-version: stable
+          cache-shared-key: ci-minio-interop
+          github-token: ${{ secrets.GITHUB_TOKEN }}
+          cache-save-if: ${{ github.ref == 'refs/heads/main' }}
+
+      - name: Generate real MinIO fixtures via Docker
+        run: bash crates/rio-v2/tests/minio_fixture_lab/capture_via_docker.sh
+
+      - name: Run MinIO interop reader tests
+        run: |
+          cargo nextest run --run-ignored ignored-only \
+            -p rustfs-ecstore --features rio-v2 \
+            -E 'binary(minio_generated_read_test)'
diff --git a/crates/ecstore/tests/minio_generated_read_test.rs b/crates/ecstore/tests/minio_generated_read_test.rs
index e2d11bcc2..875aa9be9 100644
--- a/crates/ecstore/tests/minio_generated_read_test.rs
+++ b/crates/ecstore/tests/minio_generated_read_test.rs
@@ -280,14 +280,20 @@ async fn rejects_minio_generated_sse_s3_fixture_with_truncated_ciphertext() {
 
 async fn assert_fixture_round_trip(case_id: &str, expected_size: i64) {
     let (object_info, encrypted, expected_sha256) = load_fixture_reader_input(case_id).await;
-    let object_size = object_info.size;
+    // `ObjectInfo.size` is the on-disk size. For SSE objects that is the
+    // DARE-encrypted size (plaintext + 32 bytes per 64 KiB block), which is
+    // deliberately larger than the logical object size. The size a client sees
+    // (and what MinIO records via `x-*-internal-actual-size`) comes from
+    // `decrypted_size()`/`get_actual_size()`, so assert against that — the raw
+    // `size` field would never equal the plaintext length for encrypted objects.
+    let decrypted_size = object_info.decrypted_size().expect("decrypted size from MinIO metadata");
     let kms_key_b64 = minio_static_kms_key_b64();
 
     let plaintext = read_fixture_plaintext(encrypted, object_info, kms_key_b64)
         .await
         .expect("fixture must restore with the configured KMS key");
 
-    assert_eq!(object_size, expected_size);
+    assert_eq!(decrypted_size, expected_size);
     assert_eq!(plaintext.len(), expected_size as usize);
     assert_eq!(sha256_hex(&plaintext), expected_sha256);
 }
diff --git a/crates/rio-v2/tests/minio_fixture_lab/Dockerfile b/crates/rio-v2/tests/minio_fixture_lab/Dockerfile
new file mode 100644
index 000000000..8e6e50069
--- /dev/null
+++ b/crates/rio-v2/tests/minio_fixture_lab/Dockerfile
@@ -0,0 +1,17 @@
+# Throwaway image for generating real MinIO on-disk fixtures without installing
+# a MinIO server on the host. Multi-stage: pull the official MinIO server binary
+# from the published image (linux, no dl.min.io download), then drop it into a
+# small Python image that runs the fixture lab (lab.py needs only python3 +
+# openssl; it drives MinIO's S3 API directly, so no `mc` is required).
+#
+# The MinIO release is pinned so the captured fixture format is reproducible;
+# this is the release the interop tests were validated against.
+FROM minio/minio:RELEASE.2025-09-07T16-13-09Z AS minio
+
+FROM python:3.12-slim
+RUN apt-get update \
+    && apt-get install -y --no-install-recommends openssl ca-certificates \
+    && rm -rf /var/lib/apt/lists/*
+COPY --from=minio /usr/bin/minio /usr/local/bin/minio
+RUN chmod +x /usr/local/bin/minio && /usr/local/bin/minio --version
+WORKDIR /repo
diff --git a/crates/rio-v2/tests/minio_fixture_lab/README.md b/crates/rio-v2/tests/minio_fixture_lab/README.md
index 4f5f96243..f20abe205 100644
--- a/crates/rio-v2/tests/minio_fixture_lab/README.md
+++ b/crates/rio-v2/tests/minio_fixture_lab/README.md
@@ -121,6 +121,30 @@ uv run python D:\Github\rustfs\crates\rio-v2\tests\minio_fixture_lab\lab.py capt
 
 That is a runner smoke path only. Real compatibility fixtures should still prefer the intended multi-disk backend layout when the local environment can support it.
 
+## Via Docker (Linux/macOS, no local `minio` install)
+
+When you don't have a `minio` binary on the host, `capture_via_docker.sh`
+generates the fixtures the ignored round-trip tests consume using Docker only.
+It builds a throwaway image (the official MinIO server binary pulled from
+`minio/minio` plus this lab on a small Python base — `lab.py` drives MinIO's S3
+API directly, so no `mc` is needed) and runs `capture-matrix` inside it, writing
+fixtures under `crates/rio-v2/tests/fixtures/minio-generated/` (the root the Rust
+tests read):
+
+```bash
+# Default: the two 8 MiB multipart cases the round-trip tests need.
+# Pass case ids to override, or "all" for the full default matrix.
+./capture_via_docker.sh
+
+RUSTFS_MINIO_STATIC_KMS_KEY_B64=IyqsU3kMFloCNup4BsZtf/rmfHVcTgznO2F25CkEH1g= \
+  cargo test -p rustfs-ecstore --features rio-v2 --test minio_generated_read_test -- --ignored
+```
+
+This is exactly what the nightly `minio-interop` GitHub Actions workflow runs
+(`.github/workflows/minio-interop.yml`), so the local and CI paths stay in sync.
+SSE-C cases still need the host-`minio` + TLS path above; the Docker helper
+targets the SSE-S3 / SSE-KMS multipart cases the interop tests assert on.
+
 ## Capture Guidance
 
 For each case, preserve these inputs when possible:
diff --git a/crates/rio-v2/tests/minio_fixture_lab/capture_via_docker.sh b/crates/rio-v2/tests/minio_fixture_lab/capture_via_docker.sh
new file mode 100755
index 000000000..77f6e4687
--- /dev/null
+++ b/crates/rio-v2/tests/minio_fixture_lab/capture_via_docker.sh
@@ -0,0 +1,48 @@
+#!/usr/bin/env bash
+# Generate real MinIO on-disk fixtures via Docker — no host `minio`/`mc` install.
+#
+# Builds a throwaway image carrying the official MinIO server binary plus the
+# fixture lab, runs `lab.py capture-matrix` inside it, and writes the captured
+# backend fixtures under crates/rio-v2/tests/fixtures/minio-generated (which is
+# gitignored — regenerate as needed). The same script is used locally and by the
+# nightly `minio-interop` CI workflow so both paths stay in sync.
+#
+# Usage:
+#   ./capture_via_docker.sh                       # the two multipart cases the
+#                                                 # ignored interop tests consume
+#   ./capture_via_docker.sh sse-s3-singlepart-64k # specific case id(s)
+#   ./capture_via_docker.sh all                   # full SSE/size matrix
+set -euo pipefail
+
+IMAGE="${MINIO_LAB_IMAGE:-rustfs-minio-lab:latest}"
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+# repo root is four levels up: crates/rio-v2/tests/minio_fixture_lab -> repo
+REPO_ROOT="$(cd "$SCRIPT_DIR/../../../.." && pwd)"
+LAB_REL="crates/rio-v2/tests/minio_fixture_lab"
+FIXTURE_REL="crates/rio-v2/tests/fixtures/minio-generated"
+
+# Default to the two multipart cases the ignored round-trip tests consume; pass
+# case ids to override, or "all" for the full default matrix.
+cases=("$@")
+if [ "${#cases[@]}" -eq 0 ]; then
+  cases=(sse-s3-multipart-8m sse-kms-multipart-8m)
+fi
+case_args=()
+if [ "${cases[0]}" != "all" ]; then
+  for c in "${cases[@]}"; do
+    case_args+=(--case-id "$c")
+  done
+fi
+
+echo ">> building ${IMAGE}"
+docker build -f "${SCRIPT_DIR}/Dockerfile" -t "${IMAGE}" "${SCRIPT_DIR}"
+
+echo ">> capturing fixtures into ${FIXTURE_REL}"
+docker run --rm -v "${REPO_ROOT}:/repo" "${IMAGE}" \
+  python3 "/repo/${LAB_REL}/lab.py" capture-matrix \
+    --root "/repo/${FIXTURE_REL}" \
+    --work-root /tmp/minio-lab-work \
+    --minio-binary /usr/local/bin/minio \
+    "${case_args[@]}"
+
+echo ">> done — fixtures under ${REPO_ROOT}/${FIXTURE_REL}/cases/"