Merge branch 'main' into reatang/fix-replication-switches

.github/workflows/ci.yml

@@ -173,6 +173,10 @@ jobs:
         run: cargo clippy --all-targets -- -D warnings
 
       - name: Run nextest tests
+        env:
+          # Three concurrent workspace test links saturate the self-hosted
+          # runner's overlay I/O and can wedge Cargo until the 75m timeout.
+          CARGO_BUILD_JOBS: "2"
         run: |
           mkdir -p artifacts/test-and-lint
           # Evidence sampler for issue #5394: the post-mortem pgrep below runs

Cargo.lock

@@ -7237,12 +7237,6 @@ dependencies = [
  "path-dedot",
 ]
 
-[[package]]
-name = "path-clean"
-version = "1.0.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "17359afc20d7ab31fdb42bb844c8b3bb1dabd7dcf7e68428492da7f16966fcef"
-
 [[package]]
 name = "path-dedot"
 version = "4.0.1"
@@ -9096,7 +9090,6 @@ name = "rustfs-data-usage"
 version = "1.0.0-beta.11"
 dependencies = [
  "async-trait",
- "path-clean",
  "rmp-serde",
  "rustfs-filemeta",
  "serde",
@@ -9218,6 +9211,8 @@ dependencies = [
  "url",
  "urlencoding",
  "uuid",
+ "winapi-util",
+ "windows-sys 0.61.2",
  "xxhash-rust",
 ]
 

Cargo.toml

@@ -314,7 +314,9 @@ uuid = { version = "1.24.0" }
 vaultrs = { version = "0.8.0" }
 tar = "0.4.46"
 walkdir = "2.5.0"
+winapi-util = "0.1.11"
 windows = { version = "0.62.2" }
+windows-sys = "0.61.2"
 xxhash-rust = { version = "0.8.18" }
 zip = "8.6.0"
 zstd = "0.13.3"

crates/config/src/constants/internode.rs

@@ -158,17 +158,33 @@ pub const DEFAULT_INTERNODE_RPC_BODY_DIGEST_STRICT: bool = false;
 // rolling upgrades until the fleet-wide body-digest fallback counter reads zero.
 const _: () = assert!(!DEFAULT_INTERNODE_RPC_BODY_DIGEST_STRICT);
 
-/// Capacity (distinct nonces) of the process-local internode RPC replay cache that enforces
-/// one-time consumption of body-bound v2 signatures.
+/// Require the replay-scoped internode RPC signature after the fleet has converged on it.
 ///
-/// The cache retains each nonce for the ~10-minute signature freshness envelope, so the steady
-/// state holds roughly `mutating RPS x 601s` entries; the default sustains ~1,700 body-bound
-/// mutating RPCs per second (about 120 MiB worst case, allocated only under sustained load).
-/// Overflow fails closed — legitimate signed traffic is the only thing that can fill the cache
-/// (replays are rejected before insertion, and an attacker cannot mint valid nonces without the
-/// shared secret) — and increments
+/// The default keeps v1/v2 peers available during a rolling upgrade. Operators may set this only
+/// after `rustfs_system_network_internode_replay_scope_fallback_total` remains zero for a full
+/// release window. The node still accepts a v2-authenticated `Ping` carrying an epoch challenge:
+/// that narrowly scoped bootstrap lets an upgraded client learn the receiving process epoch and
+/// immediately retry with the replay-scoped signature after a peer restart.
+pub const ENV_INTERNODE_RPC_REPLAY_SCOPE_STRICT: &str = "RUSTFS_INTERNODE_RPC_REPLAY_SCOPE_STRICT";
+pub const DEFAULT_INTERNODE_RPC_REPLAY_SCOPE_STRICT: bool = false;
+
+// Compile-time invariant: mixed-version clusters must remain available until operators make the
+// observed fallback counter an explicit strictness decision.
+const _: () = assert!(!DEFAULT_INTERNODE_RPC_REPLAY_SCOPE_STRICT);
+
+/// Capacity (distinct nonces) of the process-local internode RPC replay cache that enforces
+/// one-time consumption of authenticated RPC signatures.
+///
+/// The cache retains each nonce for the ~10-minute signature freshness envelope. Once peers use
+/// replay-scoped v3 authentication, every authenticated RPC consumes one entry, so the steady
+/// state holds roughly `authenticated RPC RPS x 601s` entries. The default sustains about 1,700
+/// authenticated RPCs per second (about 120 MiB worst case, allocated only under sustained load);
+/// operators must size it for the node's aggregate peak RPC rate before enabling strict replay
+/// scope. Overflow fails closed — legitimate signed traffic is the only thing that can fill the
+/// cache (replays are rejected before insertion, and an attacker cannot mint valid nonces without
+/// the shared secret) — and increments
 /// `rustfs_system_network_internode_replay_cache_overflow_total`, so a sustained non-zero overflow
-/// counter means this capacity is undersized for the node's peak mutation rate.
+/// counter means this capacity is undersized for the node's peak authenticated RPC rate.
 pub const ENV_INTERNODE_RPC_REPLAY_CACHE_CAPACITY: &str = "RUSTFS_INTERNODE_RPC_REPLAY_CACHE_CAPACITY";
 pub const DEFAULT_INTERNODE_RPC_REPLAY_CACHE_CAPACITY: usize = 1_048_576;
 
@@ -354,6 +370,12 @@ mod tests {
         assert_eq!(ENV_INTERNODE_RPC_BODY_DIGEST_STRICT, "RUSTFS_INTERNODE_RPC_BODY_DIGEST_STRICT");
     }
 
+    #[test]
+    fn internode_replay_scope_strict_env_name_is_stable() {
+        // The fail-open default invariant is asserted at compile time next to the definition.
+        assert_eq!(ENV_INTERNODE_RPC_REPLAY_SCOPE_STRICT, "RUSTFS_INTERNODE_RPC_REPLAY_SCOPE_STRICT");
+    }
+
     #[test]
     fn internode_replay_cache_capacity_defaults_and_env_name() {
         assert_eq!(ENV_INTERNODE_RPC_REPLAY_CACHE_CAPACITY, "RUSTFS_INTERNODE_RPC_REPLAY_CACHE_CAPACITY");

crates/data-usage/Cargo.toml

@@ -29,7 +29,6 @@ workspace = true
 
 [dependencies]
 serde = { workspace = true, features = ["derive"] }
-path-clean = { workspace = true }
 rmp-serde = { workspace = true }
 async-trait = { workspace = true }
 rustfs-filemeta = { workspace = true }

crates/data-usage/src/data_usage.rs

@@ -12,12 +12,10 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-use path_clean::PathClean;
 use serde::{Deserialize, Serialize};
 use std::{
     collections::{HashMap, HashSet},
     hash::{DefaultHasher, Hash, Hasher},
-    path::Path,
     time::{Duration, SystemTime},
 };
 
@@ -334,7 +332,7 @@ impl<'de> Deserialize<'de> for SizeHistogram {
 impl SizeHistogram {
     pub fn add(&mut self, size: u64) {
         let intervals = [
-            (0, 1024),                                  // LESS_THAN_1024_B
+            (0, 1024 - 1),                              // LESS_THAN_1024_B
             (1024, 64 * 1024 - 1),                      // BETWEEN_1024_B_AND_64_KB
             (64 * 1024, 256 * 1024 - 1),                // BETWEEN_64_KB_AND_256_KB
             (256 * 1024, 512 * 1024 - 1),               // BETWEEN_256_KB_AND_512_KB
@@ -362,7 +360,7 @@ impl SizeHistogram {
         // the sub-ranges in [1 KiB, 512 KiB).
         const ONE_MIB: u64 = 1024 * 1024;
         let intervals = [
-            (0, 1024),                          // LESS_THAN_1024_B
+            (0, 1024 - 1),                      // LESS_THAN_1024_B
             (1024, 64 * 1024 - 1),              // BETWEEN_1024_B_AND_64_KB
             (64 * 1024, 256 * 1024 - 1),        // BETWEEN_64_KB_AND_256_KB
             (256 * 1024, 512 * 1024 - 1),       // BETWEEN_256_KB_AND_512_KB
@@ -1110,9 +1108,39 @@ fn mark(duc: &DataUsageCache, entry: &DataUsageEntry, found: &mut HashSet<String
     }
 }
 
-/// Hash a path for data usage caching
+fn clean_data_usage_path(data: &str) -> String {
+    let rooted = data.starts_with('/');
+    let mut parts = Vec::new();
+
+    for part in data.split('/') {
+        match part {
+            "" | "." => {}
+            ".." => {
+                if parts.last().is_some_and(|last| *last != "..") {
+                    parts.pop();
+                } else if !rooted {
+                    parts.push(part);
+                }
+            }
+            _ => parts.push(part),
+        }
+    }
+
+    let clean = parts.join("/");
+    match (rooted, clean.is_empty()) {
+        (true, true) => "/".to_string(),
+        (true, false) => format!("/{clean}"),
+        (false, true) => ".".to_string(),
+        (false, false) => clean,
+    }
+}
+
+/// Hash a slash-separated path for data usage caching.
+///
+/// Cache identifiers are persisted and exchanged across nodes, so their
+/// normalization must not depend on the host operating system.
 pub fn hash_path(data: &str) -> DataUsageHash {
-    DataUsageHash(Path::new(&data).clean().to_string_lossy().to_string())
+    DataUsageHash(clean_data_usage_path(data))
 }
 
 impl DataUsageInfo {
@@ -1497,6 +1525,23 @@ mod tests {
         buckets_count: u64,
     }
 
+    #[test]
+    fn hash_path_uses_portable_slash_semantics() {
+        for (input, expected) in [
+            ("", "."),
+            (".", "."),
+            ("/", "/"),
+            ("//bucket///prefix/", "/bucket/prefix"),
+            ("bucket/./prefix//object", "bucket/prefix/object"),
+            ("bucket/a/../b", "bucket/b"),
+            ("../bucket/..", ".."),
+            ("/../../bucket", "/bucket"),
+            ("bucket\\prefix/object", "bucket\\prefix/object"),
+        ] {
+            assert_eq!(hash_path(input).key(), expected, "unexpected portable cache key for {input:?}");
+        }
+    }
+
     #[test]
     fn completeness_marker_is_additive_for_legacy_named_readers() {
         let current = DataUsageInfo {
@@ -1601,6 +1646,49 @@ mod tests {
         assert_eq!(map["BETWEEN_512_KB_AND_1_MB"], 1);
     }
 
+    #[test]
+    fn test_size_histogram_classifies_adjacent_boundaries_once() {
+        let cases = [
+            (1023, 0),
+            (1024, 1),
+            (64 * 1024 - 1, 1),
+            (64 * 1024, 2),
+            (256 * 1024 - 1, 2),
+            (256 * 1024, 3),
+            (512 * 1024 - 1, 3),
+            (512 * 1024, 4),
+            (1024 * 1024 - 1, 4),
+            (1024 * 1024, 6),
+            (10 * 1024 * 1024 - 1, 6),
+            (10 * 1024 * 1024, 7),
+            (64 * 1024 * 1024 - 1, 7),
+            (64 * 1024 * 1024, 8),
+            (128 * 1024 * 1024 - 1, 8),
+            (128 * 1024 * 1024, 9),
+            (512 * 1024 * 1024 - 1, 9),
+            (512 * 1024 * 1024, 10),
+        ];
+
+        for (size, expected_bucket) in cases {
+            let mut hist = SizeHistogram::default();
+            hist.add(size);
+
+            assert_eq!(hist.0.iter().sum::<u64>(), 1, "size {size} must have exactly one physical bucket");
+            assert_eq!(hist.0[expected_bucket], 1, "size {size} must select the expected bucket");
+        }
+    }
+
+    #[test]
+    fn test_size_histogram_1024_bytes_contributes_to_compat_rollup() {
+        let mut hist = SizeHistogram::default();
+        hist.add(1024);
+
+        let map = hist.to_map();
+        assert_eq!(map["LESS_THAN_1024_B"], 0);
+        assert_eq!(map["BETWEEN_1024_B_AND_64_KB"], 1);
+        assert_eq!(map["BETWEEN_1024B_AND_1_MB"], 1);
+    }
+
     #[test]
     fn test_size_histogram_compat_rollup_saturates_on_corrupt_counts() {
         let mut hist = SizeHistogram::default();

crates/e2e_test/src/internode_rpc_signature_e2e_test.rs

@@ -13,8 +13,9 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-//! Cross-process replay / tamper acceptance for the internode NodeService v2 RPC
-//! signature (<https://github.com/rustfs/backlog/issues/1327>).
+//! Cross-process replay / tamper acceptance for internode NodeService RPC
+//! signatures (<https://github.com/rustfs/backlog/issues/1327>,
+//! <https://github.com/rustfs/backlog/issues/1542>).
 //!
 //! # Why this exists on top of the in-process tests
 //!
@@ -78,6 +79,8 @@
 //! | mixed version: legacy-only still served, not blocked | [`legacy_only_signature_is_accepted_in_default_posture`] |
 //! | strict flip closes the signature downgrade | [`signature_strict_rejects_legacy_only_downgrade`] |
 //! | strict flip closes the body-digest downgrade, incl. v1 | [`body_digest_strict_rejects_digestless_mutation`] |
+//! | replay scope binds every RPC and rejects restart replay | [`replay_scope_rejects_replay_path_transplant_and_stale_epoch_e2e`] |
+//! | strict replay scope allows only Ping bootstrap before v3 | [`replay_scope_strict_requires_v3_after_ping_bootstrap_e2e`] |
 //!
 //! Two acceptance items are deliberately left to the in-process tests. A stale
 //! timestamp cannot be forged from outside — it is inside the HMAC — so
@@ -88,18 +91,20 @@
 
 use crate::common::{RustFSTestEnvironment, init_logging};
 use crate::storage_api::internode_rpc_signature::{
-    TONIC_RPC_PREFIX, gen_signature_headers, gen_tonic_signature_headers, node_service_time_out_client_no_auth,
+    TONIC_RPC_PREFIX, gen_signature_headers, gen_tonic_replay_scope_headers, gen_tonic_signature_headers,
+    node_service_time_out_client_no_auth, verify_tonic_boot_epoch_response,
 };
 use http::{HeaderMap, Method};
 use rustfs_config::{
-    ENV_INTERNODE_RPC_BODY_DIGEST_STRICT, ENV_INTERNODE_RPC_REPLAY_CACHE_CAPACITY, ENV_INTERNODE_RPC_SIGNATURE_STRICT,
+    ENV_INTERNODE_RPC_BODY_DIGEST_STRICT, ENV_INTERNODE_RPC_REPLAY_CACHE_CAPACITY, ENV_INTERNODE_RPC_REPLAY_SCOPE_STRICT,
+    ENV_INTERNODE_RPC_SIGNATURE_STRICT,
 };
 use rustfs_protos::canonical_make_volume_request_body;
-use rustfs_protos::proto_gen::node_service::{MakeVolumeRequest, MakeVolumeResponse};
+use rustfs_protos::proto_gen::node_service::{MakeVolumeRequest, MakeVolumeResponse, PingRequest, PingResponse};
 use serial_test::serial;
 use sha2::{Digest, Sha256};
 use std::error::Error;
-use tonic::{Code, Request, Status};
+use tonic::{Code, Request, Response, Status};
 use uuid::Uuid;
 
 type TestResult = Result<(), Box<dyn Error + Send + Sync>>;
@@ -115,12 +120,14 @@ const TEST_RPC_SECRET: &str = "rustfs-internode-signature-e2e-secret";
 /// clears authentication stops harmlessly at `find_disk`.
 const ABSENT_DISK: &str = "/nonexistent/rustfs-signature-e2e-disk";
 
-/// Wire names of the two v2 headers these tests edit. They are `pub(crate)` in
-/// ecstore, so they are repeated here rather than imported — [`overwrite_header`]
-/// asserts the header it replaces was actually present, which turns a rename
-/// into a loud failure instead of silently reducing an attack to a no-op.
+/// Wire names of the v2 and replay-scope headers these black-box tests edit. They are
+/// `pub(crate)` in ecstore, so they are repeated here rather than imported.
+/// [`overwrite_header`] asserts the header it replaces was actually present, which turns a
+/// rename into a loud failure instead of silently reducing an attack to a no-op.
 const CONTENT_SHA256_HEADER: &str = "x-rustfs-content-sha256";
 const NONCE_HEADER: &str = "x-rustfs-rpc-nonce";
+const TIMESTAMP_HEADER: &str = "x-rustfs-timestamp";
+const BOOT_EPOCH_CHALLENGE_HEADER: &str = "x-rustfs-rpc-boot-epoch-challenge";
 
 /// gRPC service name carried in the signed scope, i.e. `TONIC_RPC_PREFIX`
 /// without its leading `/`.
@@ -155,19 +162,28 @@ fn align_rpc_secret_with_server() {
 ///
 /// Uses the no-cleanup spawn so a `pkill` pattern cannot reap servers belonging
 /// to other tests running in the same binary.
-async fn start_server(extra_env: &[(&str, &str)]) -> Result<RustFSTestEnvironment, Box<dyn Error + Send + Sync>> {
-    let mut env = RustFSTestEnvironment::new().await?;
+fn server_env(extra_env: &[(&'static str, &'static str)]) -> Vec<(&'static str, &'static str)> {
     let mut child_env = vec![
         ("RUSTFS_RPC_SECRET", TEST_RPC_SECRET),
         (ENV_INTERNODE_RPC_SIGNATURE_STRICT, "false"),
         (ENV_INTERNODE_RPC_BODY_DIGEST_STRICT, "false"),
+        (ENV_INTERNODE_RPC_REPLAY_SCOPE_STRICT, "false"),
         (ENV_INTERNODE_RPC_REPLAY_CACHE_CAPACITY, "1048576"),
     ];
     child_env.extend_from_slice(extra_env);
-    env.start_rustfs_server_without_cleanup_with_env(&child_env).await?;
+    child_env
+}
+
+async fn start_server_with_env(child_env: &[(&str, &str)]) -> Result<RustFSTestEnvironment, Box<dyn Error + Send + Sync>> {
+    let mut env = RustFSTestEnvironment::new().await?;
+    env.start_rustfs_server_without_cleanup_with_env(child_env).await?;
     Ok(env)
 }
 
+async fn start_server(extra_env: &[(&'static str, &'static str)]) -> Result<RustFSTestEnvironment, Box<dyn Error + Send + Sync>> {
+    start_server_with_env(&server_env(extra_env)).await
+}
+
 /// Stop the child and drop the cached gRPC channel for its address.
 ///
 /// `node_service_time_out_client_no_auth` memoises channels in a process-global
@@ -238,12 +254,83 @@ fn overwrite_header(headers: &mut HeaderMap, name: &'static str, value: &str) {
 /// and nothing else — no interceptor adds or rewrites auth metadata, so the
 /// bytes on the wire are the ones the test chose.
 async fn call_make_volume(url: &str, request: MakeVolumeRequest, headers: HeaderMap) -> Result<MakeVolumeResponse, Status> {
+    call_make_volume_response(url, request, headers)
+        .await
+        .map(Response::into_inner)
+}
+
+async fn call_make_volume_response(
+    url: &str,
+    request: MakeVolumeRequest,
+    headers: HeaderMap,
+) -> Result<Response<MakeVolumeResponse>, Status> {
     let mut client = node_service_time_out_client_no_auth(&url.to_string())
         .await
         .map_err(|err| Status::unavailable(format!("cannot reach the node service: {err}")))?;
     let mut rpc_request = Request::new(request);
     rpc_request.metadata_mut().as_mut().extend(headers);
-    client.make_volume(rpc_request).await.map(|response| response.into_inner())
+    client.make_volume(rpc_request).await
+}
+
+async fn call_ping_response(url: &str, headers: HeaderMap) -> Result<Response<PingResponse>, Status> {
+    let mut client = node_service_time_out_client_no_auth(&url.to_string())
+        .await
+        .map_err(|err| Status::unavailable(format!("cannot reach the node service: {err}")))?;
+    let mut rpc_request = Request::new(PingRequest {
+        version: 1,
+        body: bytes::Bytes::new(),
+    });
+    rpc_request.metadata_mut().as_mut().extend(headers);
+    client.ping(rpc_request).await
+}
+
+fn attach_boot_epoch_challenge(headers: &mut HeaderMap) -> Uuid {
+    let challenge = Uuid::new_v4();
+    headers.insert(
+        BOOT_EPOCH_CHALLENGE_HEADER,
+        challenge.to_string().parse().expect("UUID must be a valid header value"),
+    );
+    challenge
+}
+
+fn mint_replay_scope_headers(audience: &str, path: &str, content_sha256: &str, boot_epoch: Uuid) -> HeaderMap {
+    let mut headers = mint_v2_headers(audience, "MakeVolume", Some(content_sha256));
+    let timestamp = headers
+        .get(TIMESTAMP_HEADER)
+        .and_then(|value| value.to_str().ok())
+        .expect("v2 headers must carry a timestamp")
+        .to_string();
+    headers.extend(
+        gen_tonic_replay_scope_headers(audience, path, &timestamp, content_sha256, boot_epoch)
+            .expect("replay-scope headers must mint with the aligned RPC secret"),
+    );
+    headers
+}
+
+async fn learn_boot_epoch_from_make_volume(url: &str, audience: &str) -> Uuid {
+    let request = make_volume_request("signature-e2e-epoch-bootstrap");
+    let mut headers = mint_v2_headers(audience, "MakeVolume", Some(&canonical_digest(&request)));
+    let challenge = attach_boot_epoch_challenge(&mut headers);
+    let response = call_make_volume_response(url, request, headers)
+        .await
+        .expect("v2 request with epoch challenge must clear default authentication");
+    let boot_epoch = verify_tonic_boot_epoch_response(audience, challenge, response.metadata().as_ref())
+        .expect("server must HMAC-authenticate the advertised boot epoch");
+    assert_authenticated(
+        Ok(response.into_inner()),
+        "a v2 epoch-challenge request in the default replay-scope posture",
+    );
+    boot_epoch
+}
+
+async fn learn_boot_epoch_from_ping(url: &str, audience: &str) -> Uuid {
+    let mut headers = mint_v2_headers(audience, "Ping", None);
+    let challenge = attach_boot_epoch_challenge(&mut headers);
+    let response = call_ping_response(url, headers)
+        .await
+        .expect("v2 Ping with an epoch challenge must bootstrap strict replay scope");
+    verify_tonic_boot_epoch_response(audience, challenge, response.metadata().as_ref())
+        .expect("strict replay-scope Ping must return a valid boot epoch proof")
 }
 
 /// Assert a call cleared authentication.
@@ -332,6 +419,122 @@ async fn internode_rpc_signature_default_posture_e2e() -> TestResult {
     Ok(())
 }
 
+/// A replay-scoped signature is usable exactly once against the exact gRPC path and the server
+/// process epoch that minted it. This crosses the child-process boundary twice: the HMAC-protected
+/// epoch is learned from a real response, then the same server is restarted in place to prove its
+/// replacement epoch rejects the captured request even though the nonce cache is necessarily new.
+#[tokio::test]
+#[serial]
+async fn replay_scope_rejects_replay_path_transplant_and_stale_epoch_e2e() -> TestResult {
+    init_logging();
+    align_rpc_secret_with_server();
+    let child_env = server_env(&[]);
+    let mut env = start_server_with_env(&child_env).await?;
+    let url = env.url.clone();
+    let audience = audience_of(&env);
+    let boot_epoch = learn_boot_epoch_from_make_volume(&url, &audience).await;
+
+    let request = make_volume_request("replay-scope-e2e-once");
+    let captured = mint_replay_scope_headers(
+        &audience,
+        &format!("{TONIC_RPC_PREFIX}/MakeVolume"),
+        &canonical_digest(&request),
+        boot_epoch,
+    );
+    assert_authenticated(
+        call_make_volume(&url, request.clone(), captured.clone()).await,
+        "the first replay-scoped mutation delivery",
+    );
+    assert_rejected(
+        call_make_volume(&url, request.clone(), captured).await,
+        Code::Unauthenticated,
+        None,
+        "the same replay-scoped mutation delivered twice",
+    );
+
+    let transplanted =
+        mint_replay_scope_headers(&audience, &format!("{TONIC_RPC_PREFIX}/Ping"), &canonical_digest(&request), boot_epoch);
+    assert_rejected(
+        call_make_volume(&url, request.clone(), transplanted).await,
+        Code::Unauthenticated,
+        None,
+        "a replay-scoped Ping signature transplanted onto MakeVolume",
+    );
+
+    let stale_epoch = mint_replay_scope_headers(
+        &audience,
+        &format!("{TONIC_RPC_PREFIX}/MakeVolume"),
+        &canonical_digest(&request),
+        boot_epoch,
+    );
+    env.restart_server_preserving_data(Vec::new(), &child_env).await?;
+    rustfs_protos::evict_failed_connection(&url).await;
+    assert_rejected(
+        call_make_volume(&url, request.clone(), stale_epoch).await,
+        Code::Unauthenticated,
+        None,
+        "a replay-scoped signature captured before the receiving process restart",
+    );
+
+    let restarted_epoch = learn_boot_epoch_from_make_volume(&url, &audience).await;
+    assert_ne!(boot_epoch, restarted_epoch, "a restarted child process must advertise a new boot epoch");
+    let fresh_epoch = mint_replay_scope_headers(
+        &audience,
+        &format!("{TONIC_RPC_PREFIX}/MakeVolume"),
+        &canonical_digest(&request),
+        restarted_epoch,
+    );
+    assert_authenticated(
+        call_make_volume(&url, request, fresh_epoch).await,
+        "a replay-scoped mutation signed with the replacement process epoch",
+    );
+
+    stop_server(env, &url).await;
+    Ok(())
+}
+
+/// Strict replay scope leaves one authenticated v2 bootstrap: `Ping` carrying a fresh challenge.
+/// A mutating v2 request cannot use that lane; once the epoch proof is returned, the first v3
+/// mutation succeeds. This protects a server restart without reopening a general downgrade path.
+#[tokio::test]
+#[serial]
+async fn replay_scope_strict_requires_v3_after_ping_bootstrap_e2e() -> TestResult {
+    init_logging();
+    align_rpc_secret_with_server();
+    let env = start_server(&[(ENV_INTERNODE_RPC_REPLAY_SCOPE_STRICT, "true")]).await?;
+    let url = env.url.clone();
+    let audience = audience_of(&env);
+
+    let v2_request = make_volume_request("replay-scope-e2e-strict-v2");
+    assert_rejected(
+        call_make_volume(
+            &url,
+            v2_request.clone(),
+            mint_v2_headers(&audience, "MakeVolume", Some(&canonical_digest(&v2_request))),
+        )
+        .await,
+        Code::Unauthenticated,
+        None,
+        "a v2 mutation after replay-scope strictness is enabled",
+    );
+
+    let boot_epoch = learn_boot_epoch_from_ping(&url, &audience).await;
+    let request = make_volume_request("replay-scope-e2e-strict-v3");
+    let replay_scoped = mint_replay_scope_headers(
+        &audience,
+        &format!("{TONIC_RPC_PREFIX}/MakeVolume"),
+        &canonical_digest(&request),
+        boot_epoch,
+    );
+    assert_authenticated(
+        call_make_volume(&url, request, replay_scoped).await,
+        "a replay-scoped mutation after Ping bootstrap under strict replay scope",
+    );
+
+    stop_server(env, &url).await;
+    Ok(())
+}
+
 /// Baseline: correctly signed mutations are accepted, both with and without a
 /// body digest.
 ///

crates/e2e_test/src/reliant/grpc_lock_client.rs

@@ -24,7 +24,7 @@ use rustfs_protos::proto_gen::node_service::{BatchGenerallyLockRequest, Generall
 use tonic::Request;
 use tracing::{info, warn};
 
-use crate::storage_api::grpc_lock::{TonicInterceptor, node_service_time_out_client_no_auth};
+use crate::storage_api::grpc_lock::{AuthenticatedChannel, TonicInterceptor, node_service_time_out_client_no_auth};
 
 /// gRPC lock client without authentication for testing
 /// Similar to RemoteClient but uses no_auth client
@@ -42,7 +42,7 @@ impl GrpcLockClient {
         &self,
     ) -> Result<
         rustfs_protos::proto_gen::node_service::node_service_client::NodeServiceClient<
-            tonic::service::interceptor::InterceptedService<tonic::transport::Channel, TonicInterceptor>,
+            tonic::service::interceptor::InterceptedService<AuthenticatedChannel, TonicInterceptor>,
         >,
     > {
         node_service_time_out_client_no_auth(&self.addr)

crates/e2e_test/src/storage_api.rs

@@ -16,9 +16,12 @@
 pub(crate) use rustfs_ecstore::api::bucket::bucket_target_sys::BucketTargetSys;
 #[cfg(test)]
 pub(crate) use rustfs_ecstore::api::disk::{VolumeInfo, WalkDirOptions};
+pub(crate) use rustfs_ecstore::api::rpc::{AuthenticatedChannel, TonicInterceptor, node_service_time_out_client_no_auth};
 #[cfg(test)]
-pub(crate) use rustfs_ecstore::api::rpc::{TONIC_RPC_PREFIX, gen_signature_headers, gen_tonic_signature_headers};
-pub(crate) use rustfs_ecstore::api::rpc::{TonicInterceptor, node_service_time_out_client_no_auth};
+pub(crate) use rustfs_ecstore::api::rpc::{
+    TONIC_RPC_PREFIX, gen_signature_headers, gen_tonic_replay_scope_headers, gen_tonic_signature_headers,
+    verify_tonic_boot_epoch_response,
+};
 #[cfg(test)]
 pub(crate) use rustfs_ecstore::api::rpc::{gen_tonic_signature_interceptor, node_service_time_out_client};
 
@@ -30,7 +33,7 @@ pub(crate) mod node_interact {
 }
 
 pub(crate) mod grpc_lock {
-    pub(crate) use super::{TonicInterceptor, node_service_time_out_client_no_auth};
+    pub(crate) use super::{AuthenticatedChannel, TonicInterceptor, node_service_time_out_client_no_auth};
 }
 
 /// Signing/transport surface used by the cross-process internode RPC signature
@@ -40,7 +43,8 @@ pub(crate) mod grpc_lock {
 #[cfg(test)]
 pub(crate) mod internode_rpc_signature {
     pub(crate) use super::{
-        TONIC_RPC_PREFIX, gen_signature_headers, gen_tonic_signature_headers, node_service_time_out_client_no_auth,
+        TONIC_RPC_PREFIX, gen_signature_headers, gen_tonic_replay_scope_headers, gen_tonic_signature_headers,
+        node_service_time_out_client_no_auth, verify_tonic_boot_epoch_response,
     };
 }
 

crates/ecstore/Cargo.toml

@@ -153,6 +153,10 @@ metrics = { workspace = true }
 [target.'cfg(target_os = "linux")'.dependencies]
 rustfs-uring = "0.2.1"
 
+[target.'cfg(windows)'.dependencies]
+winapi-util.workspace = true
+windows-sys = { workspace = true, features = ["Win32_Foundation", "Win32_Storage_FileSystem"] }
+
 [dev-dependencies]
 tokio = { workspace = true, features = ["rt-multi-thread", "macros", "test-util", "fs"] }
 criterion = { workspace = true, features = ["html_reports"] }

crates/ecstore/src/api/mod.rs

@@ -67,6 +67,14 @@ pub mod bucket {
             };
         }
 
+        pub mod transition_transaction {
+            pub use crate::bucket::lifecycle::transition_transaction::{
+                TransitionOperatorDeleteResult, TransitionOperatorError, TransitionOperatorProbe, TransitionOperatorStatus,
+                delete_transition_candidate_for_operator, finalize_missing_transition_transaction_for_operator,
+                inspect_transition_transaction_for_operator,
+            };
+        }
+
         pub mod evaluator {
             pub use crate::bucket::lifecycle::evaluator::Evaluator;
         }
@@ -377,6 +385,7 @@ pub mod metrics {
 pub mod notification {
     pub use crate::services::notification_sys::{
         NotificationPeerErr, NotificationSys, get_global_notification_sys, new_global_notification_sys,
+        start_remote_version_state_fleet_probe,
     };
 }
 
@@ -407,13 +416,15 @@ pub mod rio {
 
 pub mod rpc {
     pub use crate::cluster::rpc::{
-        LocalPeerS3Client, PEER_RESTDRY_RUN, PEER_RESTSIGNAL, PEER_RESTSUB_SYS, PeerRestClient, PeerS3Client, S3PeerSys,
-        SERVICE_SIGNAL_REFRESH_CONFIG, SERVICE_SIGNAL_RELOAD_DYNAMIC, ScannerBucketListing, ScannerPeerActivity,
-        TONIC_RPC_PREFIX, TonicInterceptor, gen_signature_headers, gen_tonic_signature_headers, gen_tonic_signature_interceptor,
-        node_service_time_out_client, node_service_time_out_client_no_auth, normalize_tonic_rpc_audience,
-        set_tonic_canonical_body_digest, sign_ns_scanner_capability, sign_tonic_rpc_response_proof, verify_rpc_signature,
-        verify_tonic_canonical_body_digest, verify_tonic_mutation_body_digest, verify_tonic_rpc_response_proof,
-        verify_tonic_rpc_signature,
+        AuthenticatedChannel, LocalPeerS3Client, PEER_RESTDRY_RUN, PEER_RESTSIGNAL, PEER_RESTSUB_SYS, PeerRestClient,
+        PeerS3Client, S3PeerSys, SERVICE_SIGNAL_REFRESH_CONFIG, SERVICE_SIGNAL_RELOAD_DYNAMIC, ScannerBucketListing,
+        ScannerPeerActivity, TONIC_RPC_PREFIX, TonicInterceptor, gen_signature_headers, gen_tonic_replay_scope_headers,
+        gen_tonic_signature_headers, gen_tonic_signature_interceptor, node_service_time_out_client,
+        node_service_time_out_client_no_auth, normalize_tonic_rpc_audience, set_tonic_canonical_body_digest,
+        sign_ns_scanner_capability, sign_tonic_rpc_response_proof, tonic_boot_epoch_challenge, tonic_boot_epoch_response_headers,
+        verify_rpc_signature, verify_tonic_boot_epoch_response, verify_tonic_canonical_body_digest,
+        verify_tonic_mutation_body_digest, verify_tonic_rpc_response_proof, verify_tonic_rpc_signature,
+        verify_tonic_rpc_signature_with_bootstrap,
     };
 }
 

crates/ecstore/src/bucket/lifecycle/transition_transaction.rs

@@ -23,6 +23,7 @@ use uuid::Uuid;
 use crate::bucket::lifecycle::config_boundary;
 use crate::bucket::lifecycle::lifecycle::TRANSITION_COMPLETE;
 use crate::bucket::lifecycle::tier_sweeper::{
+    delete_confirmed_transition_candidate_exact_with_lease_idempotent,
     delete_confirmed_transition_candidate_exact_with_manager_and_identity,
     delete_object_from_remote_tier_idempotent_with_manager_and_identity,
 };
@@ -616,6 +617,199 @@ pub enum TransitionTransactionRecoveryOutcome {
     Retained,
 }
 
+#[derive(Debug, Clone, PartialEq, Eq, Serialize)]
+#[serde(rename_all = "snake_case")]
+pub enum TransitionOperatorProbe {
+    Missing,
+    UnversionedPresent,
+    VersionedPresent(String),
+    Ambiguous,
+    Unsupported,
+}
+
+impl From<TransitionCandidateProbe> for TransitionOperatorProbe {
+    fn from(value: TransitionCandidateProbe) -> Self {
+        match value {
+            TransitionCandidateProbe::Missing => Self::Missing,
+            TransitionCandidateProbe::UnversionedPresent => Self::UnversionedPresent,
+            TransitionCandidateProbe::VersionedPresent(version_id) => Self::VersionedPresent(version_id),
+            TransitionCandidateProbe::Ambiguous => Self::Ambiguous,
+            TransitionCandidateProbe::Unsupported => Self::Unsupported,
+        }
+    }
+}
+
+#[derive(Debug, Clone, PartialEq, Eq, Serialize)]
+pub struct TransitionOperatorStatus {
+    pub transaction_id: Uuid,
+    pub state: TransitionTransactionState,
+    pub tier_name: String,
+    pub remote_object: String,
+    pub not_after_unix_nanos: i64,
+    pub probe: TransitionOperatorProbe,
+}
+
+#[derive(Debug, Clone, PartialEq, Eq, Serialize)]
+pub struct TransitionOperatorDeleteResult {
+    pub status: TransitionOperatorStatus,
+    pub journal_observed_after_delete: bool,
+}
+
+#[derive(Debug, thiserror::Error)]
+pub enum TransitionOperatorError {
+    #[error("transition transaction was not found")]
+    NotFound,
+    #[error("transition transaction is still inside its active ownership window")]
+    NotExpired,
+    #[error("transition transaction state is not eligible for operator reconciliation: {0:?}")]
+    InvalidState(TransitionTransactionState),
+    #[error("an exact non-empty remote version is required")]
+    RemoteVersionRequired,
+    #[error("remote candidate is not proven missing: {0:?}")]
+    CandidateNotMissing(TransitionOperatorProbe),
+    #[error("remote candidate version does not match requested exact version: expected {expected}, observed {actual:?}")]
+    CandidateVersionMismatch {
+        expected: String,
+        actual: TransitionOperatorProbe,
+    },
+    #[error("transition transaction store failed: {0}")]
+    Store(#[source] Error),
+    #[error("remote tier reconciliation failed: {0}")]
+    Remote(#[source] std::io::Error),
+}
+
+type TransitionOperatorResult<T> = std::result::Result<T, TransitionOperatorError>;
+
+fn validate_operator_reconcile_transaction(
+    transaction: &TransitionTransaction,
+    now_unix_nanos: i128,
+) -> TransitionOperatorResult<()> {
+    transaction
+        .validate()
+        .map_err(|err| TransitionOperatorError::Store(Error::other(err)))?;
+    if transaction.state != TransitionTransactionState::UploadOutcomeUnknown {
+        return Err(TransitionOperatorError::InvalidState(transaction.state));
+    }
+    if now_unix_nanos < i128::from(transaction.not_after_unix_nanos) {
+        return Err(TransitionOperatorError::NotExpired);
+    }
+    Ok(())
+}
+
+async fn load_operator_reconcile_transaction(
+    api: Arc<ECStore>,
+    transaction_id: Uuid,
+) -> TransitionOperatorResult<TransitionTransaction> {
+    match load_transition_transaction_record(api, transaction_id).await {
+        Ok(transaction) => Ok(transaction),
+        Err(Error::ConfigNotFound) => Err(TransitionOperatorError::NotFound),
+        Err(err) => Err(TransitionOperatorError::Store(err)),
+    }
+}
+
+async fn operator_probe_transition_candidate(
+    api: Arc<ECStore>,
+    transaction: &TransitionTransaction,
+) -> TransitionOperatorResult<TransitionOperatorProbe> {
+    let lease = TierConfigMgr::acquire_operation_lease_for_backend_identity(
+        &api.tier_config_mgr(),
+        &transaction.tier_name,
+        transaction.backend_fingerprint,
+    )
+    .await
+    .map_err(|err| TransitionOperatorError::Remote(std::io::Error::other(err)))?;
+    lease
+        .probe_transition_candidate_for(&transaction.remote_object, transaction.transaction_id)
+        .await
+        .map(TransitionOperatorProbe::from)
+        .map_err(TransitionOperatorError::Remote)
+}
+
+pub async fn inspect_transition_transaction_for_operator(
+    api: Arc<ECStore>,
+    transaction_id: Uuid,
+) -> TransitionOperatorResult<TransitionOperatorStatus> {
+    let transaction = load_operator_reconcile_transaction(api.clone(), transaction_id).await?;
+    validate_operator_reconcile_transaction(&transaction, time::OffsetDateTime::now_utc().unix_timestamp_nanos())?;
+    let probe = operator_probe_transition_candidate(api, &transaction).await?;
+    Ok(TransitionOperatorStatus {
+        transaction_id,
+        state: transaction.state,
+        tier_name: transaction.tier_name,
+        remote_object: transaction.remote_object,
+        not_after_unix_nanos: transaction.not_after_unix_nanos,
+        probe,
+    })
+}
+
+pub async fn delete_transition_candidate_for_operator(
+    api: Arc<ECStore>,
+    transaction_id: Uuid,
+    remote_version_id: &str,
+) -> TransitionOperatorResult<TransitionOperatorDeleteResult> {
+    if remote_version_id.is_empty() {
+        return Err(TransitionOperatorError::RemoteVersionRequired);
+    }
+    let transaction = load_operator_reconcile_transaction(api.clone(), transaction_id).await?;
+    validate_operator_reconcile_transaction(&transaction, time::OffsetDateTime::now_utc().unix_timestamp_nanos())?;
+    let lease = TierConfigMgr::acquire_operation_lease_for_backend_identity(
+        &api.tier_config_mgr(),
+        &transaction.tier_name,
+        transaction.backend_fingerprint,
+    )
+    .await
+    .map_err(|err| TransitionOperatorError::Remote(std::io::Error::other(err)))?;
+    lease
+        .validate_remote_version_id(remote_version_id)
+        .map_err(TransitionOperatorError::Remote)?;
+    let before_delete_probe = lease
+        .probe_transition_candidate_for(&transaction.remote_object, transaction.transaction_id)
+        .await
+        .map(TransitionOperatorProbe::from)
+        .map_err(TransitionOperatorError::Remote)?;
+    if !matches!(&before_delete_probe, TransitionOperatorProbe::VersionedPresent(version_id) if version_id == remote_version_id) {
+        return Err(TransitionOperatorError::CandidateVersionMismatch {
+            expected: remote_version_id.to_string(),
+            actual: before_delete_probe,
+        });
+    }
+    delete_confirmed_transition_candidate_exact_with_lease_idempotent(&transaction.remote_object, remote_version_id, &lease)
+        .await
+        .map_err(TransitionOperatorError::Remote)?;
+    let probe = operator_probe_transition_candidate(api.clone(), &transaction).await?;
+    let journal_observed_after_delete = match load_transition_transaction_record(api, transaction_id).await {
+        Ok(_) => true,
+        Err(Error::ConfigNotFound) => false,
+        Err(err) => return Err(TransitionOperatorError::Store(err)),
+    };
+    Ok(TransitionOperatorDeleteResult {
+        status: TransitionOperatorStatus {
+            transaction_id,
+            state: transaction.state,
+            tier_name: transaction.tier_name,
+            remote_object: transaction.remote_object,
+            not_after_unix_nanos: transaction.not_after_unix_nanos,
+            probe,
+        },
+        journal_observed_after_delete,
+    })
+}
+
+pub async fn finalize_missing_transition_transaction_for_operator(
+    api: Arc<ECStore>,
+    transaction_id: Uuid,
+) -> TransitionOperatorResult<()> {
+    let transaction = load_operator_reconcile_transaction(api.clone(), transaction_id).await?;
+    validate_operator_reconcile_transaction(&transaction, time::OffsetDateTime::now_utc().unix_timestamp_nanos())?;
+    let probe = operator_probe_transition_candidate(api.clone(), &transaction).await?;
+    if probe != TransitionOperatorProbe::Missing {
+        return Err(TransitionOperatorError::CandidateNotMissing(probe));
+    }
+    delete_transition_transaction_record(api, transaction_id)
+        .await
+        .map_err(TransitionOperatorError::Store)
+}
+
 pub(crate) fn decode_transition_transaction_record(object: &str, data: &[u8]) -> Result<TransitionTransaction> {
     let transaction_id = transition_transaction_id_from_record_object_name(object)?;
     TransitionTransaction::decode(transaction_id, data)
@@ -700,7 +894,7 @@ async fn recover_unknown_upload_outcome(
     .map_err(Error::other)?;
 
     match lease
-        .probe_transition_candidate(&transaction.remote_object)
+        .probe_transition_candidate_for(&transaction.remote_object, transaction.transaction_id)
         .await
         .map_err(Error::other)?
     {
@@ -1097,6 +1291,27 @@ mod tests {
             .expect("upload state change should succeed")
     }
 
+    #[test]
+    fn operator_reconcile_requires_expired_unknown_upload_outcome() {
+        let mut transaction = new_transaction();
+        let active_deadline = transaction.not_after_unix_nanos;
+
+        assert!(matches!(
+            validate_operator_reconcile_transaction(&transaction, i128::from(active_deadline) + 1),
+            Err(TransitionOperatorError::InvalidState(TransitionTransactionState::UploadStarted))
+        ));
+
+        transaction
+            .advance(transaction.fence(), TransitionTransactionState::UploadOutcomeUnknown, None)
+            .expect("unknown upload outcome should be recorded");
+        assert!(matches!(
+            validate_operator_reconcile_transaction(&transaction, i128::from(active_deadline) - 1),
+            Err(TransitionOperatorError::NotExpired)
+        ));
+        validate_operator_reconcile_transaction(&transaction, i128::from(active_deadline))
+            .expect("expired unknown upload outcome should be eligible");
+    }
+
     fn cleanup_proof(transaction: &TransitionTransaction, decision: TransitionCleanupDecision) -> TransitionCleanupProof {
         TransitionCleanupProof {
             transaction_id: transaction.transaction_id,

crates/ecstore/src/cluster/rpc/background_monitor.rs

@@ -84,44 +84,6 @@ where
     )
 }
 
-/// Stop a sibling test thread from poisoning tracing's process-global callsite
-/// interest cache while this test asserts on span or event context.
-///
-/// `tracing` caches every callsite's `Interest` in **process-global** state, and
-/// the first thread to reach a callsite fixes that value. While at most one
-/// dispatcher is registered, tracing-core takes a fast path
-/// (`Dispatchers::rebuilder` -> `Rebuilder::JustOne`) that derives a
-/// newly-registered callsite's interest from whichever subscriber is current
-/// *on the registering thread*.
-///
-/// In a multi-threaded `cargo test` binary a sibling test therefore routinely
-/// reaches a production callsite first, from a thread with no subscriber
-/// installed: the interest is derived from that thread's `NoSubscriber` and
-/// cached as `Interest::never()` for the whole process. From then on the
-/// callsite is dead for *every* later caller, including a test that installed
-/// its own subscriber — an `info_span!` silently evaluates to `Span::none()`
-/// (so the monitor's log line lands under the caller's span instead of
-/// `recovery-monitor`), and a `warn!`/`info!` event never fires at all.
-///
-/// Registering a second, inert dispatcher closes both halves of that race:
-///
-/// * constructing it rebuilds every *already-registered* callsite's interest
-///   against the live dispatcher set — which includes the caller's subscriber —
-///   repairing whatever a sibling may already have poisoned; and
-/// * holding it alive keeps tracing-core off the single-dispatcher fast path, so
-///   a callsite registered *later* by any thread is resolved against that live
-///   set instead of the registering thread's `NoSubscriber`.
-///
-/// Call this **after** installing the test's subscriber, and hold the returned
-/// guard for the rest of the test. Only the `cargo test` fallback needs it:
-/// nextest runs each test in its own process, where there is no sibling thread
-/// to lose the race to (see `docs/testing/README.md`).
-#[cfg(test)]
-#[must_use = "callsite interest is only pinned while the returned guard is held"]
-pub(crate) fn pin_callsite_interest_for_test() -> tracing::Dispatch {
-    tracing::Dispatch::new(tracing_core::subscriber::NoSubscriber::default())
-}
-
 #[cfg(test)]
 mod tests {
     use super::*;

crates/ecstore/src/cluster/rpc/client.rs

@@ -12,11 +12,20 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-use crate::cluster::rpc::http_auth::RPC_CONTENT_SHA256_HEADER;
-use crate::cluster::rpc::{gen_tonic_signature_headers, normalize_tonic_rpc_audience};
+#[cfg(test)]
+use crate::cluster::rpc::http_auth::RPC_REPLAY_SCOPE_VERSION_HEADER;
+use crate::cluster::rpc::http_auth::{
+    RPC_AUTH_VERSION_HEADER, RPC_AUTH_VERSION_V2, RPC_BOOT_EPOCH_CHALLENGE_HEADER, RPC_BOOT_EPOCH_HEADER,
+    RPC_BOOT_EPOCH_PROOF_HEADER, RPC_CONTENT_SHA256_HEADER, TIMESTAMP_HEADER,
+};
+use crate::cluster::rpc::{
+    gen_tonic_replay_scope_headers, gen_tonic_signature_headers, normalize_tonic_rpc_audience, verify_tonic_boot_epoch_response,
+};
+#[cfg(test)]
+use crate::cluster::rpc::{tonic_boot_epoch_challenge, tonic_boot_epoch_response_headers};
 use crate::disk::error::{DiskError, Error as DiskErrorType, RpcStatusError};
 use crate::runtime::sources as runtime_sources;
-use http::Uri;
+use http::{Request as HttpRequest, Response as HttpResponse, Uri};
 use rustfs_protos::{
     ChannelClass, create_new_channel, get_channel_for_class,
     proto_gen::node_service::{
@@ -24,9 +33,19 @@ use rustfs_protos::{
         tier_mutation_control_service_client::TierMutationControlServiceClient,
     },
 };
-use std::{error::Error, io::ErrorKind};
+use std::{
+    collections::HashMap,
+    error::Error,
+    future::Future,
+    io::ErrorKind,
+    pin::Pin,
+    sync::{LazyLock, Mutex},
+    task::{Context, Poll},
+};
 use tonic::{service::interceptor::InterceptedService, transport::Channel};
+use tower::Service;
 use tracing::debug;
+use uuid::Uuid;
 
 use super::context_propagation::{inject_request_id_into_metadata, inject_trace_context_into_metadata};
 
@@ -35,7 +54,7 @@ use super::context_propagation::{inject_request_id_into_metadata, inject_trace_c
 pub async fn node_service_time_out_client(
     addr: &String,
     interceptor: TonicInterceptor,
-) -> Result<NodeServiceClient<InterceptedService<Channel, TonicInterceptor>>, Box<dyn Error>> {
+) -> Result<NodeServiceClient<InterceptedService<AuthenticatedChannel, TonicInterceptor>>, Box<dyn Error>> {
     // Default to the latency-sensitive control channel; bulk `bytes` RPCs opt in via the
     // `_for_class` variant below (grpc-optimization P1).
     node_service_time_out_client_for_class(addr, interceptor, ChannelClass::Control).await
@@ -44,13 +63,14 @@ pub async fn node_service_time_out_client(
 pub async fn heal_control_time_out_client(
     addr: &str,
     interceptor: TonicInterceptor,
-) -> Result<HealControlServiceClient<InterceptedService<Channel, TonicInterceptor>>, Box<dyn Error>> {
+) -> Result<HealControlServiceClient<InterceptedService<AuthenticatedChannel, TonicInterceptor>>, Box<dyn Error>> {
     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?,
     };
     let max_message_size = rustfs_protos::HEAL_CONTROL_RPC_MAX_MESSAGE_SIZE;
+    let channel = ReplayScopeChannel::new(channel, interceptor.replay_scope_audience());
     Ok(HealControlServiceClient::with_interceptor(channel, interceptor)
         .max_decoding_message_size(max_message_size)
         .max_encoding_message_size(max_message_size))
@@ -59,13 +79,14 @@ pub async fn heal_control_time_out_client(
 pub async fn tier_mutation_control_time_out_client(
     addr: &str,
     interceptor: TonicInterceptor,
-) -> Result<TierMutationControlServiceClient<InterceptedService<Channel, TonicInterceptor>>, Box<dyn Error>> {
+) -> Result<TierMutationControlServiceClient<InterceptedService<AuthenticatedChannel, TonicInterceptor>>, Box<dyn Error>> {
     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?,
     };
     let max_message_size = rustfs_protos::TIER_MUTATION_RPC_MAX_MESSAGE_SIZE;
+    let channel = ReplayScopeChannel::new(channel, interceptor.replay_scope_audience());
     Ok(TierMutationControlServiceClient::with_interceptor(channel, interceptor)
         .max_decoding_message_size(max_message_size)
         .max_encoding_message_size(max_message_size))
@@ -81,7 +102,7 @@ pub async fn node_service_time_out_client_for_class(
     addr: &String,
     interceptor: TonicInterceptor,
     class: ChannelClass,
-) -> Result<NodeServiceClient<InterceptedService<Channel, TonicInterceptor>>, Box<dyn Error>> {
+) -> Result<NodeServiceClient<InterceptedService<AuthenticatedChannel, TonicInterceptor>>, Box<dyn Error>> {
     let interceptor = interceptor.with_rpc_audience(addr)?;
     let channel = match class {
         ChannelClass::Control => match runtime_sources::cached_node_channel(addr).await {
@@ -96,6 +117,7 @@ pub async fn node_service_time_out_client_for_class(
     };
 
     let max_message_size = rustfs_protos::internode_rpc_max_message_size();
+    let channel = ReplayScopeChannel::new(channel, interceptor.replay_scope_audience());
     Ok(NodeServiceClient::with_interceptor(channel, interceptor)
         .max_decoding_message_size(max_message_size)
         .max_encoding_message_size(max_message_size))
@@ -103,7 +125,7 @@ pub async fn node_service_time_out_client_for_class(
 
 pub async fn node_service_time_out_client_no_auth(
     addr: &String,
-) -> Result<NodeServiceClient<InterceptedService<Channel, TonicInterceptor>>, Box<dyn Error>> {
+) -> Result<NodeServiceClient<InterceptedService<AuthenticatedChannel, TonicInterceptor>>, Box<dyn Error>> {
     node_service_time_out_client(addr, TonicInterceptor::NoOp(NoOpInterceptor)).await
 }
 
@@ -199,6 +221,104 @@ pub(crate) fn is_network_like_disk_error(err: &DiskErrorType) -> bool {
     }
 }
 
+/// The transport service that learns an authenticated peer boot epoch and adds the replay-scoped
+/// signature only after one has been observed. The v1/v2 interceptor stays inside this wrapper so
+/// old servers continue receiving precisely the metadata they understand.
+#[derive(Clone, Debug)]
+pub struct ReplayScopeChannel<S> {
+    inner: S,
+    audience: Option<String>,
+}
+
+/// The channel type used by internode clients after v2 authentication and replay-scope handling.
+pub type AuthenticatedChannel = ReplayScopeChannel<Channel>;
+
+static PEER_BOOT_EPOCHS: LazyLock<Mutex<HashMap<String, Uuid>>> = LazyLock::new(|| Mutex::new(HashMap::new()));
+
+impl<S> ReplayScopeChannel<S> {
+    fn new(inner: S, audience: Option<String>) -> Self {
+        Self { inner, audience }
+    }
+}
+
+fn cached_peer_boot_epoch(audience: &str) -> Option<Uuid> {
+    PEER_BOOT_EPOCHS.lock().ok().and_then(|epochs| epochs.get(audience).copied())
+}
+
+fn remember_peer_boot_epoch(audience: String, epoch: Uuid) {
+    if let Ok(mut epochs) = PEER_BOOT_EPOCHS.lock() {
+        epochs.insert(audience, epoch);
+    }
+}
+
+impl<S, ReqBody, ResBody> Service<HttpRequest<ReqBody>> for ReplayScopeChannel<S>
+where
+    S: Service<HttpRequest<ReqBody>, Response = HttpResponse<ResBody>>,
+    S::Error: Send + 'static,
+    S::Future: Send + 'static,
+    ReqBody: Send + 'static,
+    ResBody: Send + 'static,
+{
+    type Response = HttpResponse<ResBody>;
+    type Error = S::Error;
+    type Future = Pin<Box<dyn Future<Output = Result<Self::Response, Self::Error>> + Send>>;
+
+    fn poll_ready(&mut self, cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>> {
+        self.inner.poll_ready(cx)
+    }
+
+    fn call(&mut self, mut request: HttpRequest<ReqBody>) -> Self::Future {
+        let authenticated = self.audience.as_ref().is_some_and(|_| {
+            request
+                .headers()
+                .get(RPC_AUTH_VERSION_HEADER)
+                .and_then(|value| value.to_str().ok())
+                == Some(RPC_AUTH_VERSION_V2)
+        });
+        let challenge = authenticated.then(Uuid::new_v4);
+        if let (Some(audience), Some(challenge)) = (self.audience.as_deref(), challenge) {
+            // The challenge is independently HMAC-authenticated by the response proof. It is not
+            // part of v2 so old peers ignore it, while a new peer can safely advertise its epoch.
+            request.headers_mut().insert(
+                RPC_BOOT_EPOCH_CHALLENGE_HEADER,
+                challenge.to_string().parse().expect("UUID must be a valid header value"),
+            );
+            if let (Some(boot_epoch), Some(timestamp), Some(content_sha256)) = (
+                cached_peer_boot_epoch(audience),
+                request.headers().get(TIMESTAMP_HEADER).and_then(|value| value.to_str().ok()),
+                request
+                    .headers()
+                    .get(RPC_CONTENT_SHA256_HEADER)
+                    .and_then(|value| value.to_str().ok()),
+            ) {
+                match gen_tonic_replay_scope_headers(audience, request.uri().path(), timestamp, content_sha256, boot_epoch) {
+                    Ok(headers) => request.headers_mut().extend(headers),
+                    Err(error) => debug!(error = %error, "could not attach replay-scoped RPC signature"),
+                }
+            }
+        }
+
+        let audience = self.audience.clone();
+        let future = self.inner.call(request);
+        Box::pin(async move {
+            let response = future.await?;
+            if let (Some(audience), Some(challenge)) = (audience, challenge) {
+                match verify_tonic_boot_epoch_response(&audience, challenge, response.headers()) {
+                    Ok(epoch) => remember_peer_boot_epoch(audience, epoch),
+                    Err(error)
+                        if response.headers().contains_key(RPC_BOOT_EPOCH_HEADER)
+                            || response.headers().contains_key(RPC_BOOT_EPOCH_PROOF_HEADER) =>
+                    {
+                        debug!(error = %error, "peer boot epoch response proof was rejected")
+                    }
+                    Err(_) => {}
+                }
+            }
+            Ok(response)
+        })
+    }
+}
+
 pub struct TonicSignatureInterceptor {
     audience: Option<String>,
 }
@@ -257,6 +377,13 @@ impl TonicInterceptor {
         }
         Ok(self)
     }
+
+    fn replay_scope_audience(&self) -> Option<String> {
+        match self {
+            Self::Signature(interceptor) => interceptor.audience.clone(),
+            Self::NoOp(_) => None,
+        }
+    }
 }
 
 impl tonic::service::Interceptor for TonicInterceptor {
@@ -279,6 +406,38 @@ mod tests {
     use tracing_opentelemetry::OpenTelemetrySpanExt;
     use tracing_subscriber::{Registry, layer::SubscriberExt};
 
+    #[derive(Clone)]
+    struct EpochProofService {
+        audience: String,
+        seen_headers: std::sync::Arc<Mutex<Vec<http::HeaderMap>>>,
+    }
+
+    impl Service<HttpRequest<()>> for EpochProofService {
+        type Response = HttpResponse<()>;
+        type Error = std::convert::Infallible;
+        type Future = std::future::Ready<Result<Self::Response, Self::Error>>;
+
+        fn poll_ready(&mut self, _cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>> {
+            Poll::Ready(Ok(()))
+        }
+
+        fn call(&mut self, request: HttpRequest<()>) -> Self::Future {
+            self.seen_headers
+                .lock()
+                .expect("test header capture lock must not be poisoned")
+                .push(request.headers().clone());
+            let challenge = tonic_boot_epoch_challenge(request.headers())
+                .expect("client challenge must be syntactically valid")
+                .expect("authenticated client request must carry a boot epoch challenge");
+            let mut response = HttpResponse::new(());
+            response.headers_mut().extend(
+                tonic_boot_epoch_response_headers(&self.audience, challenge)
+                    .expect("test server must be able to sign an epoch proof"),
+            );
+            std::future::ready(Ok(response))
+        }
+    }
+
     fn ensure_test_rpc_secret() {
         runtime_sources::ensure_test_rpc_secret();
     }
@@ -420,6 +579,52 @@ mod tests {
         assert_eq!(interceptor.audience.as_deref(), Some("node-a:9000"));
     }
 
+    #[test]
+    fn replay_scope_channel_uses_epoch_proof_before_sending_v3() {
+        ensure_test_rpc_secret();
+        let audience = "replay-scope-client-test:9000";
+        PEER_BOOT_EPOCHS
+            .lock()
+            .expect("peer epoch cache lock must not be poisoned")
+            .remove(audience);
+        let seen_headers = std::sync::Arc::new(Mutex::new(Vec::new()));
+        let service = EpochProofService {
+            audience: audience.to_string(),
+            seen_headers: seen_headers.clone(),
+        };
+        let mut channel = ReplayScopeChannel::new(service, Some(audience.to_string()));
+        let make_request = || {
+            let mut request = HttpRequest::builder()
+                .uri("/node_service.NodeService/Ping")
+                .body(())
+                .expect("test RPC request must build");
+            request.headers_mut().extend(
+                gen_tonic_signature_headers(audience, "node_service.NodeService", "Ping", None)
+                    .expect("v2 test headers must mint"),
+            );
+            request
+        };
+
+        futures::executor::block_on(channel.call(make_request())).expect("first request must complete");
+        futures::executor::block_on(channel.call(make_request())).expect("second request must complete");
+
+        let headers = seen_headers.lock().expect("test header capture lock must not be poisoned");
+        assert_eq!(headers.len(), 2);
+        assert!(headers[0].contains_key(RPC_BOOT_EPOCH_CHALLENGE_HEADER));
+        assert!(
+            !headers[0].contains_key(RPC_REPLAY_SCOPE_VERSION_HEADER),
+            "the first request must remain v2-compatible until the peer proves its epoch"
+        );
+        assert!(
+            headers[1].contains_key(RPC_REPLAY_SCOPE_VERSION_HEADER),
+            "the second request must carry the replay-scoped v3 signature"
+        );
+        PEER_BOOT_EPOCHS
+            .lock()
+            .expect("peer epoch cache lock must not be poisoned")
+            .remove(audience);
+    }
+
     #[test]
     fn test_signature_interceptor_requires_generated_method_metadata() {
         ensure_test_rpc_secret();

crates/ecstore/src/cluster/rpc/http_auth.rs

@@ -20,8 +20,8 @@
 //! rustfs/rustfs#4402) is anchored by the `ghsa_r5qv_*` tests in the module
 //! below, plus the broader negative-signature suite. The advisory class is: a
 //! node must never accept an RPC whose auth is missing, malformed, or signed
-//! with the default/empty shared secret. Body-bound v2 requests additionally
-//! receive process-local replay protection. See
+//! with the default/empty shared secret. Body-bound v2 requests and all replay-scoped v3
+//! requests additionally receive process-local replay protection. See
 //! `docs/testing/security-regressions.md` for the full advisory -> test map.
 //!
 //! Advisory: <https://github.com/rustfs/rustfs/security/advisories/GHSA-r5qv-rc46-hv8q>
@@ -50,13 +50,22 @@ use uuid::Uuid;
 type HmacSha256 = Hmac<Sha256>;
 
 const SIGNATURE_HEADER: &str = "x-rustfs-signature";
-const TIMESTAMP_HEADER: &str = "x-rustfs-timestamp";
-const RPC_AUTH_VERSION_HEADER: &str = "x-rustfs-rpc-auth-version";
+pub(crate) const TIMESTAMP_HEADER: &str = "x-rustfs-timestamp";
+pub(crate) const RPC_AUTH_VERSION_HEADER: &str = "x-rustfs-rpc-auth-version";
 const RPC_SIGNATURE_V2_HEADER: &str = "x-rustfs-rpc-signature-v2";
 const RPC_NONCE_HEADER: &str = "x-rustfs-rpc-nonce";
 pub(crate) const RPC_CONTENT_SHA256_HEADER: &str = "x-rustfs-content-sha256";
-const RPC_AUTH_VERSION_V2: &str = "2";
+pub(crate) const RPC_AUTH_VERSION_V2: &str = "2";
+pub const RPC_REPLAY_SCOPE_VERSION_HEADER: &str = "x-rustfs-rpc-replay-scope-version";
+pub const RPC_REPLAY_SCOPE_SIGNATURE_HEADER: &str = "x-rustfs-rpc-signature-v3";
+pub const RPC_REPLAY_SCOPE_NONCE_HEADER: &str = "x-rustfs-rpc-replay-nonce";
+pub const RPC_BOOT_EPOCH_HEADER: &str = "x-rustfs-rpc-boot-epoch";
+pub const RPC_BOOT_EPOCH_CHALLENGE_HEADER: &str = "x-rustfs-rpc-boot-epoch-challenge";
+pub const RPC_BOOT_EPOCH_PROOF_HEADER: &str = "x-rustfs-rpc-boot-epoch-proof";
+const RPC_REPLAY_SCOPE_VERSION_V3: &str = "3";
 const RPC_RESPONSE_PROOF_DOMAIN: &[u8] = b"rustfs-rpc-response-proof-v1\0";
+const RPC_REPLAY_SCOPE_DOMAIN: &[u8] = b"rustfs-rpc-replay-scope-v3\0";
+const RPC_BOOT_EPOCH_PROOF_DOMAIN: &[u8] = b"rustfs-rpc-boot-epoch-proof-v1\0";
 const UNSIGNED_PAYLOAD: &str = "UNSIGNED-PAYLOAD";
 const UNSIGNED_PAYLOAD_NONCE: &str = "unsigned";
 const SIGNATURE_VALID_DURATION: i64 = 300; // 5 minutes
@@ -75,9 +84,15 @@ static INTERNODE_RPC_BODY_DIGEST_STRICT: LazyLock<bool> = LazyLock::new(|| {
         rustfs_config::DEFAULT_INTERNODE_RPC_BODY_DIGEST_STRICT,
     )
 });
-// Sized for peak legitimate body-bound mutation RPS x the retention window; overflow fails closed
-// and increments the replay-cache overflow counter. Clamped to at least 1 so a misconfigured zero
-// cannot disable replay protection by rejecting every body-bound request.
+static INTERNODE_RPC_REPLAY_SCOPE_STRICT: LazyLock<bool> = LazyLock::new(|| {
+    get_env_bool(
+        rustfs_config::ENV_INTERNODE_RPC_REPLAY_SCOPE_STRICT,
+        rustfs_config::DEFAULT_INTERNODE_RPC_REPLAY_SCOPE_STRICT,
+    )
+});
+// Sized for peak legitimate authenticated RPC RPS x the retention window once replay scope is
+// active; overflow fails closed and increments the replay-cache overflow counter. Clamped to at
+// least 1 so a misconfigured zero cannot disable replay protection by rejecting every request.
 static REPLAY_CACHE_CAPACITY: LazyLock<usize> = LazyLock::new(|| {
     rustfs_utils::get_env_usize(
         rustfs_config::ENV_INTERNODE_RPC_REPLAY_CACHE_CAPACITY,
@@ -86,6 +101,7 @@ static REPLAY_CACHE_CAPACITY: LazyLock<usize> = LazyLock::new(|| {
     .max(1)
 });
 static RPC_SECRET_RESOLUTION_LOG_ONCE: Once = Once::new();
+static RPC_BOOT_EPOCH: LazyLock<Uuid> = LazyLock::new(Uuid::new_v4);
 
 #[derive(Default)]
 struct RpcNonceCache {
@@ -313,6 +329,189 @@ fn verify_signature_v2(secret: &str, scope: SignatureV2Scope<'_>, signature: &st
     mac.verify_slice(&signature).is_ok()
 }
 
+#[derive(Clone, Copy)]
+struct ReplayScope<'a> {
+    audience: &'a str,
+    path: &'a str,
+    timestamp: &'a str,
+    nonce: Uuid,
+    content_sha256: &'a str,
+    boot_epoch: Uuid,
+}
+
+fn update_replay_scope(mac: &mut HmacSha256, scope: ReplayScope<'_>) {
+    mac.update(RPC_REPLAY_SCOPE_DOMAIN);
+    for part in [
+        scope.audience.as_bytes(),
+        b"|",
+        scope.path.as_bytes(),
+        b"|POST|",
+        scope.timestamp.as_bytes(),
+        b"|",
+        scope.nonce.as_bytes(),
+        b"|",
+        scope.content_sha256.as_bytes(),
+        b"|",
+        scope.boot_epoch.as_bytes(),
+    ] {
+        mac.update(part);
+    }
+}
+
+fn generate_replay_scope_signature(secret: &str, scope: ReplayScope<'_>) -> std::io::Result<String> {
+    let mut mac =
+        <HmacSha256 as KeyInit>::new_from_slice(secret.as_bytes()).map_err(|_| std::io::Error::other("Invalid RPC HMAC key"))?;
+    update_replay_scope(&mut mac, scope);
+    Ok(general_purpose::STANDARD.encode(mac.finalize().into_bytes()))
+}
+
+fn verify_replay_scope_signature(secret: &str, scope: ReplayScope<'_>, signature: &str) -> bool {
+    let Ok(signature) = general_purpose::STANDARD.decode(signature) else {
+        return false;
+    };
+    let Ok(mut mac) = <HmacSha256 as KeyInit>::new_from_slice(secret.as_bytes()) else {
+        return false;
+    };
+    update_replay_scope(&mut mac, scope);
+    mac.verify_slice(&signature).is_ok()
+}
+
+fn update_boot_epoch_proof(mac: &mut HmacSha256, audience: &str, challenge: Uuid, boot_epoch: Uuid) {
+    mac.update(RPC_BOOT_EPOCH_PROOF_DOMAIN);
+    mac.update(audience.as_bytes());
+    mac.update(b"|");
+    mac.update(challenge.as_bytes());
+    mac.update(boot_epoch.as_bytes());
+}
+
+fn generate_boot_epoch_proof(secret: &str, audience: &str, challenge: Uuid, boot_epoch: Uuid) -> std::io::Result<String> {
+    if audience.is_empty() || challenge.is_nil() || boot_epoch.is_nil() {
+        return Err(std::io::Error::other("Invalid RPC boot epoch proof scope"));
+    }
+    let mut mac =
+        <HmacSha256 as KeyInit>::new_from_slice(secret.as_bytes()).map_err(|_| std::io::Error::other("Invalid RPC HMAC key"))?;
+    update_boot_epoch_proof(&mut mac, audience, challenge, boot_epoch);
+    Ok(general_purpose::STANDARD.encode(mac.finalize().into_bytes()))
+}
+
+fn verify_boot_epoch_proof(secret: &str, audience: &str, challenge: Uuid, boot_epoch: Uuid, proof: &str) -> std::io::Result<()> {
+    if audience.is_empty() || challenge.is_nil() || boot_epoch.is_nil() {
+        return Err(std::io::Error::other("Invalid RPC boot epoch proof scope"));
+    }
+    let proof = general_purpose::STANDARD
+        .decode(proof)
+        .map_err(|_| std::io::Error::other("Invalid RPC boot epoch proof"))?;
+    let mut mac =
+        <HmacSha256 as KeyInit>::new_from_slice(secret.as_bytes()).map_err(|_| std::io::Error::other("Invalid RPC HMAC key"))?;
+    update_boot_epoch_proof(&mut mac, audience, challenge, boot_epoch);
+    mac.verify_slice(&proof)
+        .map_err(|_| std::io::Error::new(std::io::ErrorKind::PermissionDenied, "Invalid RPC boot epoch proof"))
+}
+
+fn non_nil_uuid(value: &str, name: &str) -> std::io::Result<Uuid> {
+    let value = Uuid::parse_str(value).map_err(|_| std::io::Error::other(format!("Invalid {name}")))?;
+    (!value.is_nil())
+        .then_some(value)
+        .ok_or_else(|| std::io::Error::other(format!("Invalid {name}")))
+}
+
+fn parse_tonic_rpc_path(path: &str) -> std::io::Result<(&str, &str)> {
+    path.strip_prefix('/')
+        .and_then(|path| path.split_once('/'))
+        .filter(|(service, rpc_method)| !service.is_empty() && !rpc_method.is_empty() && !rpc_method.contains('/'))
+        .ok_or_else(|| std::io::Error::other("Invalid RPC request path"))
+}
+
+/// The process-unique epoch included in every replay-scoped server verification.
+///
+/// A fresh process gets a fresh value, so a signature captured before a server restart cannot be
+/// admitted even though the bounded in-memory nonce cache necessarily starts empty again.
+pub fn tonic_rpc_boot_epoch() -> Uuid {
+    *RPC_BOOT_EPOCH
+}
+
+/// Build the additive replay-scope headers for a request that already carries rolling-upgrade-safe
+/// v1/v2 metadata. `timestamp` and `content_sha256` are deliberately reused from the v2 scope so
+/// old servers can continue validating the same request unchanged.
+pub fn gen_tonic_replay_scope_headers(
+    audience: &str,
+    path: &str,
+    timestamp: &str,
+    content_sha256: &str,
+    boot_epoch: Uuid,
+) -> std::io::Result<HeaderMap> {
+    if audience.is_empty() || !path.starts_with('/') || !valid_content_sha256(content_sha256) || boot_epoch.is_nil() {
+        return Err(std::io::Error::other("Invalid replay-scoped RPC signing scope"));
+    }
+    parse_tonic_rpc_path(path)?;
+    timestamp
+        .parse::<i64>()
+        .map_err(|_| std::io::Error::other("Invalid timestamp format"))?;
+
+    let nonce = Uuid::new_v4();
+    let signature = generate_replay_scope_signature(
+        &get_shared_secret()?,
+        ReplayScope {
+            audience,
+            path,
+            timestamp,
+            nonce,
+            content_sha256,
+            boot_epoch,
+        },
+    )?;
+    let mut headers = HeaderMap::new();
+    headers.insert(RPC_REPLAY_SCOPE_VERSION_HEADER, HeaderValue::from_static(RPC_REPLAY_SCOPE_VERSION_V3));
+    headers.insert(
+        RPC_REPLAY_SCOPE_SIGNATURE_HEADER,
+        header_value(&signature, RPC_REPLAY_SCOPE_SIGNATURE_HEADER)?,
+    );
+    headers.insert(
+        RPC_REPLAY_SCOPE_NONCE_HEADER,
+        header_value(&nonce.to_string(), RPC_REPLAY_SCOPE_NONCE_HEADER)?,
+    );
+    headers.insert(RPC_BOOT_EPOCH_HEADER, header_value(&boot_epoch.to_string(), RPC_BOOT_EPOCH_HEADER)?);
+    Ok(headers)
+}
+
+/// Parse the optional client challenge used to authenticate a server boot-epoch advertisement.
+pub fn tonic_boot_epoch_challenge(headers: &HeaderMap) -> std::io::Result<Option<Uuid>> {
+    headers
+        .get(RPC_BOOT_EPOCH_CHALLENGE_HEADER)
+        .map(|value| {
+            value
+                .to_str()
+                .map_err(|_| std::io::Error::other("Invalid RPC boot epoch challenge"))
+                .and_then(|value| non_nil_uuid(value, "RPC boot epoch challenge"))
+        })
+        .transpose()
+}
+
+/// Build the authenticated response headers for a client boot-epoch challenge.
+pub fn tonic_boot_epoch_response_headers(audience: &str, challenge: Uuid) -> std::io::Result<HeaderMap> {
+    let boot_epoch = tonic_rpc_boot_epoch();
+    let proof = generate_boot_epoch_proof(&get_shared_secret()?, audience, challenge, boot_epoch)?;
+    let mut headers = HeaderMap::new();
+    headers.insert(RPC_BOOT_EPOCH_HEADER, header_value(&boot_epoch.to_string(), RPC_BOOT_EPOCH_HEADER)?);
+    headers.insert(RPC_BOOT_EPOCH_PROOF_HEADER, header_value(&proof, RPC_BOOT_EPOCH_PROOF_HEADER)?);
+    Ok(headers)
+}
+
+/// Verify the server boot-epoch response for a challenge generated by this client.
+pub fn verify_tonic_boot_epoch_response(audience: &str, challenge: Uuid, headers: &HeaderMap) -> std::io::Result<Uuid> {
+    let boot_epoch = headers
+        .get(RPC_BOOT_EPOCH_HEADER)
+        .and_then(|value| value.to_str().ok())
+        .ok_or_else(|| std::io::Error::other("Missing RPC boot epoch"))
+        .and_then(|value| non_nil_uuid(value, "RPC boot epoch"))?;
+    let proof = headers
+        .get(RPC_BOOT_EPOCH_PROOF_HEADER)
+        .and_then(|value| value.to_str().ok())
+        .ok_or_else(|| std::io::Error::other("Missing RPC boot epoch proof"))?;
+    verify_boot_epoch_proof(&get_shared_secret()?, audience, challenge, boot_epoch, proof)?;
+    Ok(boot_epoch)
+}
+
 fn valid_content_sha256(value: &str) -> bool {
     value == UNSIGNED_PAYLOAD
         || (value.len() == 64
@@ -531,6 +730,17 @@ fn has_v2_auth_headers(headers: &HeaderMap) -> bool {
     .any(|name| headers.contains_key(*name))
 }
 
+fn has_replay_scope_headers(headers: &HeaderMap) -> bool {
+    [
+        RPC_REPLAY_SCOPE_VERSION_HEADER,
+        RPC_REPLAY_SCOPE_SIGNATURE_HEADER,
+        RPC_REPLAY_SCOPE_NONCE_HEADER,
+        RPC_BOOT_EPOCH_HEADER,
+    ]
+    .iter()
+    .any(|name| headers.contains_key(*name))
+}
+
 /// Whether the server requires target-bound v2 authentication on every internode gRPC request,
 /// rejecting the legacy constant-target fallback instead of accepting it. Default-off rollout
 /// lever gated on the v1-fallback counter reading zero fleet-wide; see
@@ -540,9 +750,127 @@ fn internode_rpc_signature_strict() -> bool {
     *INTERNODE_RPC_SIGNATURE_STRICT
 }
 
+fn internode_rpc_replay_scope_strict() -> bool {
+    *INTERNODE_RPC_REPLAY_SCOPE_STRICT
+}
+
+fn verify_tonic_replay_scope_signature(audience: &str, path: &str, headers: &HeaderMap) -> std::io::Result<()> {
+    if audience.is_empty() {
+        return Err(std::io::Error::other("Missing RPC audience"));
+    }
+    parse_tonic_rpc_path(path)?;
+
+    let version = headers
+        .get(RPC_REPLAY_SCOPE_VERSION_HEADER)
+        .and_then(|value| value.to_str().ok())
+        .ok_or_else(|| std::io::Error::other("Missing RPC replay scope version"))?;
+    if version != RPC_REPLAY_SCOPE_VERSION_V3 {
+        return Err(std::io::Error::other("Unsupported RPC replay scope version"));
+    }
+    let signature = headers
+        .get(RPC_REPLAY_SCOPE_SIGNATURE_HEADER)
+        .and_then(|value| value.to_str().ok())
+        .ok_or_else(|| std::io::Error::other("Missing RPC replay scope signature"))?;
+    let timestamp = headers
+        .get(TIMESTAMP_HEADER)
+        .and_then(|value| value.to_str().ok())
+        .ok_or_else(|| std::io::Error::other("Missing timestamp header"))?;
+    let signed_at = timestamp
+        .parse::<i64>()
+        .map_err(|_| std::io::Error::other("Invalid timestamp format"))?;
+    check_timestamp(signed_at)?;
+    let nonce = headers
+        .get(RPC_REPLAY_SCOPE_NONCE_HEADER)
+        .and_then(|value| value.to_str().ok())
+        .ok_or_else(|| std::io::Error::other("Missing RPC replay scope nonce"))
+        .and_then(|value| non_nil_uuid(value, "RPC replay scope nonce"))?;
+    let content_sha256 = headers
+        .get(RPC_CONTENT_SHA256_HEADER)
+        .and_then(|value| value.to_str().ok())
+        .ok_or_else(|| std::io::Error::other("Missing RPC content SHA-256"))?;
+    if !valid_content_sha256(content_sha256) {
+        return Err(std::io::Error::other("Invalid RPC content SHA-256"));
+    }
+    let boot_epoch = headers
+        .get(RPC_BOOT_EPOCH_HEADER)
+        .and_then(|value| value.to_str().ok())
+        .ok_or_else(|| std::io::Error::other("Missing RPC boot epoch"))
+        .and_then(|value| non_nil_uuid(value, "RPC boot epoch"))?;
+    let secret = get_shared_secret()?;
+    if !verify_replay_scope_signature(
+        &secret,
+        ReplayScope {
+            audience,
+            path,
+            timestamp,
+            nonce,
+            content_sha256,
+            boot_epoch,
+        },
+        signature,
+    ) {
+        return Err(std::io::Error::other("Invalid RPC replay scope signature"));
+    }
+    if boot_epoch != tonic_rpc_boot_epoch() {
+        return Err(std::io::Error::other("RPC boot epoch is stale"));
+    }
+    check_and_record_nonce(nonce, signed_at)
+}
+
 /// Verify gRPC authentication, preferring v2 without downgrade on malformed v2 metadata.
 pub fn verify_tonic_rpc_signature(audience: &str, path: &str, headers: &HeaderMap) -> std::io::Result<()> {
-    verify_tonic_rpc_signature_with_strictness(audience, path, headers, internode_rpc_signature_strict())
+    verify_tonic_rpc_signature_with_policy(
+        audience,
+        path,
+        headers,
+        internode_rpc_signature_strict(),
+        internode_rpc_replay_scope_strict(),
+        false,
+    )
+}
+
+/// Verify gRPC authentication while allowing the narrowly scoped v2 `Ping` bootstrap used to
+/// obtain an authenticated server boot epoch when replay-scope strictness is enabled.
+pub fn verify_tonic_rpc_signature_with_bootstrap(
+    audience: &str,
+    path: &str,
+    headers: &HeaderMap,
+    allow_replay_scope_bootstrap: bool,
+) -> std::io::Result<()> {
+    verify_tonic_rpc_signature_with_policy(
+        audience,
+        path,
+        headers,
+        internode_rpc_signature_strict(),
+        internode_rpc_replay_scope_strict(),
+        allow_replay_scope_bootstrap,
+    )
+}
+
+fn verify_tonic_rpc_signature_with_policy(
+    audience: &str,
+    path: &str,
+    headers: &HeaderMap,
+    signature_strict: bool,
+    replay_scope_strict: bool,
+    allow_replay_scope_bootstrap: bool,
+) -> std::io::Result<()> {
+    if has_replay_scope_headers(headers) {
+        return verify_tonic_replay_scope_signature(audience, path, headers);
+    }
+
+    // Only a method-bound v2 Ping with a syntactically valid challenge may bootstrap a strict
+    // client after its peer restarts. Legacy metadata never gets this exception.
+    let bootstrap = allow_replay_scope_bootstrap
+        && has_v2_auth_headers(headers)
+        && tonic_boot_epoch_challenge(headers).is_ok_and(|challenge| challenge.is_some());
+    if replay_scope_strict && !bootstrap {
+        return Err(std::io::Error::other("RPC replay-scoped authentication required"));
+    }
+
+    verify_tonic_rpc_signature_with_strictness(audience, path, headers, signature_strict)?;
+    global_internode_metrics().record_replay_scope_fallback();
+    Ok(())
 }
 
 /// [`verify_tonic_rpc_signature`] with the strict gate injected as a parameter, so both rollout
@@ -1273,6 +1601,104 @@ mod tests {
         assert_eq!(error.to_string(), "Invalid RPC v2 signature");
     }
 
+    #[test]
+    fn replay_scope_binds_path_epoch_and_random_nonce() {
+        ensure_test_rpc_secret();
+        let path = "/node_service.NodeService/Ping";
+        let mut headers = gen_tonic_signature_headers("node-a:9000", "node_service.NodeService", "Ping", None)
+            .expect("v2 compatibility headers should build");
+        let timestamp = headers
+            .get(TIMESTAMP_HEADER)
+            .and_then(|value| value.to_str().ok())
+            .expect("v2 timestamp")
+            .to_string();
+        let content_sha256 = headers
+            .get(RPC_CONTENT_SHA256_HEADER)
+            .and_then(|value| value.to_str().ok())
+            .expect("v2 content digest")
+            .to_string();
+        headers.extend(
+            gen_tonic_replay_scope_headers("node-a:9000", path, &timestamp, &content_sha256, tonic_rpc_boot_epoch())
+                .expect("replay-scope headers should build"),
+        );
+
+        assert!(
+            verify_tonic_rpc_signature_with_policy("node-a:9000", path, &headers, false, false, false).is_ok(),
+            "the first replay-scoped request must be accepted"
+        );
+        let replay = verify_tonic_rpc_signature_with_policy("node-a:9000", path, &headers, false, false, false)
+            .expect_err("the random replay-scope nonce must be single-use");
+        assert_eq!(replay.to_string(), "RPC request replay detected");
+
+        let path_error = verify_tonic_replay_scope_signature("node-a:9000", "/node_service.NodeService/SignalService", &headers)
+            .expect_err("a replay-scoped signature must not move to another method");
+        assert_eq!(path_error.to_string(), "Invalid RPC replay scope signature");
+    }
+
+    #[test]
+    fn replay_scope_rejects_partial_metadata_and_stale_epoch_without_fallback() {
+        ensure_test_rpc_secret();
+        let path = "/node_service.NodeService/Ping";
+        let mut partial = gen_tonic_signature_headers("node-a:9000", "node_service.NodeService", "Ping", None)
+            .expect("v2 compatibility headers should build");
+        partial.insert(RPC_REPLAY_SCOPE_VERSION_HEADER, HeaderValue::from_static(RPC_REPLAY_SCOPE_VERSION_V3));
+        let error = verify_tonic_rpc_signature_with_policy("node-a:9000", path, &partial, false, false, false)
+            .expect_err("partial replay-scope metadata must never downgrade to v2");
+        assert_eq!(error.to_string(), "Missing RPC replay scope signature");
+
+        let timestamp = partial
+            .get(TIMESTAMP_HEADER)
+            .and_then(|value| value.to_str().ok())
+            .expect("v2 timestamp")
+            .to_string();
+        let content_sha256 = partial
+            .get(RPC_CONTENT_SHA256_HEADER)
+            .and_then(|value| value.to_str().ok())
+            .expect("v2 content digest")
+            .to_string();
+        let stale_epoch = Uuid::new_v4();
+        partial.extend(
+            gen_tonic_replay_scope_headers("node-a:9000", path, &timestamp, &content_sha256, stale_epoch)
+                .expect("replay-scope headers should build"),
+        );
+        let stale = verify_tonic_rpc_signature_with_policy("node-a:9000", path, &partial, false, false, false)
+            .expect_err("a signature from a prior server boot epoch must be rejected");
+        assert_eq!(stale.to_string(), "RPC boot epoch is stale");
+    }
+
+    #[test]
+    fn replay_scope_strictness_allows_only_authenticated_ping_bootstrap() {
+        ensure_test_rpc_secret();
+        let mut headers = gen_tonic_signature_headers("node-a:9000", "node_service.NodeService", "Ping", None)
+            .expect("v2 compatibility headers should build");
+        let rejected =
+            verify_tonic_rpc_signature_with_policy("node-a:9000", "/node_service.NodeService/Ping", &headers, false, true, false)
+                .expect_err("strict replay scope must reject stripped new metadata");
+        assert_eq!(rejected.to_string(), "RPC replay-scoped authentication required");
+
+        headers.insert(
+            RPC_BOOT_EPOCH_CHALLENGE_HEADER,
+            HeaderValue::from_str(&Uuid::new_v4().to_string()).expect("UUID header"),
+        );
+        assert!(
+            verify_tonic_rpc_signature_with_policy("node-a:9000", "/node_service.NodeService/Ping", &headers, false, true, true,)
+                .is_ok(),
+            "only the signed Ping bootstrap may obtain a new server epoch in strict mode"
+        );
+    }
+
+    #[test]
+    fn boot_epoch_response_proof_binds_audience_challenge_and_epoch() {
+        ensure_test_rpc_secret();
+        let challenge = Uuid::new_v4();
+        let headers = tonic_boot_epoch_response_headers("node-a:9000", challenge).expect("proof headers should build");
+        let epoch =
+            verify_tonic_boot_epoch_response("node-a:9000", challenge, &headers).expect("matching proof headers should verify");
+        assert_eq!(epoch, tonic_rpc_boot_epoch());
+        assert!(verify_tonic_boot_epoch_response("node-b:9000", challenge, &headers).is_err());
+        assert!(verify_tonic_boot_epoch_response("node-a:9000", Uuid::new_v4(), &headers).is_err());
+    }
+
     #[test]
     fn malformed_v2_auth_does_not_downgrade_to_valid_legacy_signature() {
         ensure_test_rpc_secret();

crates/ecstore/src/cluster/rpc/mod.rs

@@ -23,18 +23,21 @@ pub(crate) mod remote_disk;
 pub(crate) mod remote_locker;
 pub(crate) mod runtime_sources;
 
-#[cfg(test)]
-pub(crate) use background_monitor::pin_callsite_interest_for_test;
 pub use background_monitor::shutdown_background_monitors;
 pub(crate) use background_monitor::spawn_background_monitor;
 pub use client::{
-    TonicInterceptor, gen_tonic_signature_interceptor, node_service_time_out_client, node_service_time_out_client_no_auth,
+    AuthenticatedChannel, TonicInterceptor, gen_tonic_signature_interceptor, node_service_time_out_client,
+    node_service_time_out_client_no_auth,
 };
+// Re-exported through `api::rpc`; not every item is consumed inside this crate.
+#[allow(unused_imports)]
 pub use http_auth::{
-    TONIC_RPC_PREFIX, build_auth_headers, gen_signature_headers, gen_tonic_signature_headers, normalize_tonic_rpc_audience,
-    set_tonic_canonical_body_digest, set_tonic_mutation_body_digest, sign_ns_scanner_capability, sign_tonic_rpc_response_proof,
-    verify_ns_scanner_capability, verify_rpc_signature, verify_tonic_canonical_body_digest, verify_tonic_mutation_body_digest,
-    verify_tonic_rpc_response_proof, verify_tonic_rpc_signature,
+    TONIC_RPC_PREFIX, build_auth_headers, gen_signature_headers, gen_tonic_replay_scope_headers, gen_tonic_signature_headers,
+    normalize_tonic_rpc_audience, set_tonic_canonical_body_digest, set_tonic_mutation_body_digest, sign_ns_scanner_capability,
+    sign_tonic_rpc_response_proof, tonic_boot_epoch_challenge, tonic_boot_epoch_response_headers, verify_ns_scanner_capability,
+    verify_rpc_signature, verify_tonic_boot_epoch_response, verify_tonic_canonical_body_digest,
+    verify_tonic_mutation_body_digest, verify_tonic_rpc_response_proof, verify_tonic_rpc_signature,
+    verify_tonic_rpc_signature_with_bootstrap,
 };
 #[cfg(test)]
 pub(crate) use internode_data_transport::TcpHttpInternodeDataTransport;

crates/ecstore/src/cluster/rpc/peer_rest_client.rs

@@ -13,7 +13,7 @@
 // limitations under the License.
 
 use crate::cluster::rpc::client::{
-    TonicInterceptor, embedded_tonic_status, gen_tonic_signature_interceptor, heal_control_time_out_client,
+    AuthenticatedChannel, TonicInterceptor, embedded_tonic_status, gen_tonic_signature_interceptor, heal_control_time_out_client,
     is_network_like_status, message_has_network_needle, node_service_time_out_client, tier_mutation_control_time_out_client,
 };
 use crate::cluster::rpc::{set_tonic_canonical_body_digest, set_tonic_mutation_body_digest, verify_tonic_rpc_response_proof};
@@ -66,7 +66,6 @@ use std::{
 use tokio::{net::TcpStream, time::Duration};
 use tonic::Request;
 use tonic::service::interceptor::InterceptedService;
-use tonic::transport::Channel;
 use tracing::{debug, info, warn};
 use uuid::Uuid;
 
@@ -222,6 +221,21 @@ fn validate_heal_control_response_proof(canonical_response: &[u8], proof: &[u8])
         .map_err(|_| Error::other("peer returned an invalid heal control response proof"))
 }
 
+fn decode_remote_version_state_capability(expected_member: &str, result: &[u8]) -> Result<Uuid> {
+    let (topology_member, process_epoch) = rustfs_protos::decode_remote_version_state_capability(result).map_err(Error::other)?;
+    if topology_member != expected_member {
+        return Err(Error::other(
+            "peer returned a remote version state capability for a different topology member",
+        ));
+    }
+    let server_epoch =
+        Uuid::from_slice(process_epoch).map_err(|_| Error::other("peer returned an invalid remote version state epoch"))?;
+    if server_epoch.is_nil() {
+        return Err(Error::other("peer returned a nil remote version state epoch"));
+    }
+    Ok(server_epoch)
+}
+
 #[derive(Clone, Debug)]
 pub struct PeerLiveEventsBatch {
     pub events: Vec<u8>,
@@ -233,6 +247,7 @@ pub struct PeerLiveEventsBatch {
 pub struct PeerRestClient {
     pub host: XHost,
     pub grid_host: String,
+    topology_member: String,
     offline: Arc<AtomicBool>,
     recovery_running: Arc<AtomicBool>,
 }
@@ -325,9 +340,11 @@ impl PeerRestClient {
     }
 
     pub fn new(host: XHost, grid_host: String) -> Self {
+        let topology_member = host.to_string();
         Self {
             host,
             grid_host,
+            topology_member,
             offline: Arc::new(AtomicBool::new(false)),
             recovery_running: Arc::new(AtomicBool::new(false)),
         }
@@ -347,7 +364,11 @@ impl PeerRestClient {
 
             let client = match grid_host {
                 Some(grid_host) => match XHost::try_from(peer_host_port.clone()) {
-                    Ok(host) => Some(PeerRestClient::new(host, grid_host)),
+                    Ok(host) => {
+                        let mut client = PeerRestClient::new(host, grid_host);
+                        client.topology_member = peer_host_port.clone();
+                        Some(client)
+                    }
                     Err(err) => {
                         warn!(peer = %peer_host_port, "Xhost parse failed while constructing peer client: {err:?}");
                         None
@@ -390,7 +411,7 @@ impl PeerRestClient {
         (remote, all, remote_topology_hosts)
     }
 
-    pub async fn get_client(&self) -> Result<NodeServiceClient<InterceptedService<Channel, TonicInterceptor>>> {
+    pub async fn get_client(&self) -> Result<NodeServiceClient<InterceptedService<AuthenticatedChannel, TonicInterceptor>>> {
         if self.offline.load(Ordering::Acquire) {
             self.mark_offline_and_spawn_recovery();
             return Err(Error::other(format!("peer {} is temporarily offline", self.grid_host)));
@@ -411,7 +432,7 @@ impl PeerRestClient {
         &self,
     ) -> Result<
         rustfs_protos::proto_gen::node_service::heal_control_service_client::HealControlServiceClient<
-            InterceptedService<Channel, TonicInterceptor>,
+            InterceptedService<AuthenticatedChannel, TonicInterceptor>,
         >,
     > {
         if self.offline.load(Ordering::Acquire) {
@@ -432,7 +453,7 @@ impl PeerRestClient {
 
     async fn get_tier_mutation_control_client(
         &self,
-    ) -> Result<TierMutationControlServiceClient<InterceptedService<Channel, TonicInterceptor>>> {
+    ) -> Result<TierMutationControlServiceClient<InterceptedService<AuthenticatedChannel, TonicInterceptor>>> {
         if self.offline.load(Ordering::Acquire) {
             self.mark_offline_and_spawn_recovery();
             return Err(Error::other(format!("peer {} is temporarily offline", self.grid_host)));
@@ -1154,6 +1175,15 @@ impl PeerRestClient {
         validate_heal_control_capability_proof(&canonical_ack, &proof)
     }
 
+    pub async fn probe_remote_version_state(&self, topology_fingerprint: String) -> Result<(String, Uuid)> {
+        let probe = rustfs_protos::remote_version_state_capability_probe(Uuid::new_v4().as_bytes());
+        let result = self
+            .heal_control(rustfs_protos::HEAL_CONTROL_PROTOCOL_VERSION, topology_fingerprint, probe)
+            .await?;
+        let epoch = decode_remote_version_state_capability(&self.topology_member, &result)?;
+        Ok((self.topology_member.clone(), epoch))
+    }
+
     pub async fn load_bucket_metadata(&self, bucket: &str, scanner_maintenance_change: bool) -> Result<()> {
         self.finalize_result(
             async {
@@ -2470,6 +2500,22 @@ mod tests {
         }
     }
 
+    #[test]
+    fn remote_version_state_capability_decoder_fails_closed() {
+        let epoch = Uuid::new_v4();
+        let result = rustfs_protos::encode_remote_version_state_capability("node-a:9000", epoch.as_bytes())
+            .expect("small capability response should encode");
+        assert_eq!(
+            decode_remote_version_state_capability("node-a:9000", &result).expect("valid epoch should decode"),
+            epoch
+        );
+        assert!(decode_remote_version_state_capability("node-b:9000", &result).is_err());
+        assert!(decode_remote_version_state_capability("node-a:9000", &result[..result.len() - 1]).is_err());
+        let nil = rustfs_protos::encode_remote_version_state_capability("node-a:9000", Uuid::nil().as_bytes())
+            .expect("small capability response should encode");
+        assert!(decode_remote_version_state_capability("node-a:9000", &nil).is_err());
+    }
+
     struct TierMutationResponseFixture<'a> {
         version: u32,
         phase: TierMutationRpcPhase,
@@ -2745,7 +2791,7 @@ mod tests {
         // `mark_offline_and_spawn_recovery` path that sibling tests exercise from
         // subscriber-less threads; without this the span can be cached as
         // `Interest::never()` and silently degrade to `Span::none()`.
-        let _callsite_pin = crate::cluster::rpc::pin_callsite_interest_for_test();
+        let _callsite_pin = crate::test_tracing::pin_callsite_interest_for_test();
 
         let client = test_peer_client();
         let span = tracing::info_span!("request-span", request_id = "req-peer-rest");

crates/ecstore/src/cluster/rpc/peer_s3_client.rs

@@ -14,7 +14,8 @@
 
 use crate::bucket::metadata_sys;
 use crate::cluster::rpc::client::{
-    TonicInterceptor, gen_tonic_signature_interceptor, is_network_like_disk_error, node_service_time_out_client,
+    AuthenticatedChannel, TonicInterceptor, gen_tonic_signature_interceptor, is_network_like_disk_error,
+    node_service_time_out_client,
 };
 use crate::cluster::rpc::set_tonic_mutation_body_digest;
 use crate::disk::error::DiskError;
@@ -40,16 +41,84 @@ use rustfs_protos::proto_gen::node_service::node_service_client::NodeServiceClie
 use rustfs_protos::proto_gen::node_service::{
     DeleteBucketRequest, GetBucketInfoRequest, HealBucketRequest, ListBucketRequest, MakeBucketRequest,
 };
+#[cfg(test)]
+use std::sync::{
+    Mutex as StdMutex,
+    atomic::{AtomicBool, Ordering},
+};
 use std::{collections::HashMap, fmt::Debug, sync::Arc, time::Duration};
+#[cfg(test)]
+use tokio::sync::Notify;
 use tokio::{net::TcpStream, sync::RwLock, time};
 use tokio_util::sync::CancellationToken;
 use tonic::Request;
 use tonic::service::interceptor::InterceptedService;
-use tonic::transport::Channel;
 use tracing::{debug, info, warn};
 
 type Client = Arc<Box<dyn PeerS3Client>>;
 
+#[cfg(test)]
+#[derive(Default)]
+pub(crate) struct DeleteBucketEmptyScanBarrier {
+    arrived: AtomicBool,
+    arrived_notify: Notify,
+    released: AtomicBool,
+    release_notify: Notify,
+}
+
+#[cfg(test)]
+impl DeleteBucketEmptyScanBarrier {
+    pub(crate) async fn wait_until_paused(&self) {
+        loop {
+            let notified = self.arrived_notify.notified();
+            if self.arrived.load(Ordering::Acquire) {
+                return;
+            }
+            notified.await;
+        }
+    }
+
+    pub(crate) fn release(&self) {
+        self.released.store(true, Ordering::Release);
+        self.release_notify.notify_waiters();
+    }
+
+    async fn pause(&self) {
+        self.arrived.store(true, Ordering::Release);
+        self.arrived_notify.notify_waiters();
+        loop {
+            let notified = self.release_notify.notified();
+            if self.released.load(Ordering::Acquire) {
+                return;
+            }
+            notified.await;
+        }
+    }
+}
+
+#[cfg(test)]
+static DELETE_BUCKET_EMPTY_SCAN_BARRIER: StdMutex<Option<Arc<DeleteBucketEmptyScanBarrier>>> = StdMutex::new(None);
+
+#[cfg(test)]
+pub(crate) fn install_delete_bucket_empty_scan_barrier() -> Arc<DeleteBucketEmptyScanBarrier> {
+    let barrier = Arc::new(DeleteBucketEmptyScanBarrier::default());
+    *DELETE_BUCKET_EMPTY_SCAN_BARRIER
+        .lock()
+        .expect("empty scan barrier lock should not be poisoned") = Some(barrier.clone());
+    barrier
+}
+
+#[cfg(test)]
+async fn pause_after_delete_bucket_empty_scan() {
+    let barrier = DELETE_BUCKET_EMPTY_SCAN_BARRIER
+        .lock()
+        .expect("empty scan barrier lock should not be poisoned")
+        .take();
+    if let Some(barrier) = barrier {
+        barrier.pause().await;
+    }
+}
+
 #[derive(Clone, Debug)]
 pub struct ScannerBucketListing {
     pub buckets: Vec<BucketInfo>,
@@ -650,24 +719,22 @@ impl PeerS3Client for LocalPeerS3Client {
             return Err(Error::ErasureWriteQuorum);
         }
 
-        let force = if opts.force_if_empty && !opts.force {
+        if opts.force_if_empty && !opts.force {
             for disk in local_disks.iter() {
                 if has_xlmeta_files(&disk.path().join(bucket)).await.map_err(Error::Io)? {
                     return Err(Error::VolumeNotEmpty);
                 }
             }
-            true
-        } else {
-            opts.force
-        };
+            #[cfg(test)]
+            pause_after_delete_bucket_empty_scan().await;
+        }
 
         let mut futures = Vec::with_capacity(local_disks.len());
 
         for disk in local_disks.iter() {
-            // Non-force delete refuses a non-empty bucket (VolumeNotEmpty), which
-            // the recreate loop below turns into BucketNotEmpty; only an explicit
-            // force delete removes recursively (backlog#799 B1).
-            futures.push(disk.delete_volume(bucket, force));
+            // `force_if_empty` is validation-only. Passing it as force would let
+            // a PutObject committed after the scan be removed recursively.
+            futures.push(disk.delete_volume(bucket, opts.force));
         }
 
         let results = join_all(futures).await;
@@ -730,6 +797,15 @@ pub struct RemotePeerS3Client {
 }
 
 impl RemotePeerS3Client {
+    fn encode_delete_bucket_options(opts: &DeleteBucketOptions) -> Result<String> {
+        let mut remote_opts = opts.clone();
+        // Older peers promote `force_if_empty` to recursive force after their
+        // metadata scan. Keep this coordinator-only hint off the wire so a
+        // mixed-version delete fails closed on non-empty directory remnants.
+        remote_opts.force_if_empty = false;
+        serde_json::to_string(&remote_opts).map_err(Into::into)
+    }
+
     fn recovery_monitor_span(addr: &str) -> tracing::Span {
         tracing::info_span!(
             "recovery-monitor",
@@ -756,7 +832,7 @@ impl RemotePeerS3Client {
         client
     }
 
-    pub async fn get_client(&self) -> Result<NodeServiceClient<InterceptedService<Channel, TonicInterceptor>>> {
+    pub async fn get_client(&self) -> Result<NodeServiceClient<InterceptedService<AuthenticatedChannel, TonicInterceptor>>> {
         node_service_time_out_client(&self.addr, TonicInterceptor::Signature(gen_tonic_signature_interceptor()))
             .await
             .map_err(|err| Error::other(format!("can not get client, err: {err}")))
@@ -1040,7 +1116,7 @@ impl PeerS3Client for RemotePeerS3Client {
     async fn delete_bucket(&self, bucket: &str, opts: &DeleteBucketOptions) -> Result<()> {
         self.execute_with_timeout(
             || async {
-                let options = serde_json::to_string(opts)?;
+                let options = Self::encode_delete_bucket_options(opts)?;
                 let mut client = self.get_client().await?;
 
                 let mut request = Request::new(DeleteBucketRequest {
@@ -1414,6 +1490,49 @@ mod tests {
         }
     }
 
+    #[test]
+    fn remote_delete_bucket_options_fail_closed_for_legacy_peers() {
+        let encoded = RemotePeerS3Client::encode_delete_bucket_options(&DeleteBucketOptions {
+            no_lock: true,
+            no_recreate: true,
+            force_if_empty: true,
+            ..Default::default()
+        })
+        .expect("remote delete options should serialize");
+        let legacy_opts: DeleteBucketOptions =
+            serde_json::from_str(&encoded).expect("legacy peer should decode remote delete options");
+
+        assert!(legacy_opts.no_lock);
+        assert!(legacy_opts.no_recreate);
+        assert!(!legacy_opts.force);
+        assert!(!legacy_opts.force_if_empty);
+
+        let legacy_recursive_force = if legacy_opts.force_if_empty && !legacy_opts.force {
+            true
+        } else {
+            legacy_opts.force
+        };
+        assert!(
+            !legacy_recursive_force,
+            "legacy peer must not upgrade empty-only delete to recursive force"
+        );
+    }
+
+    #[test]
+    fn remote_delete_bucket_options_preserve_explicit_force() {
+        let encoded = RemotePeerS3Client::encode_delete_bucket_options(&DeleteBucketOptions {
+            force: true,
+            force_if_empty: true,
+            ..Default::default()
+        })
+        .expect("remote force-delete options should serialize");
+        let remote_opts: DeleteBucketOptions =
+            serde_json::from_str(&encoded).expect("remote peer should decode force-delete options");
+
+        assert!(remote_opts.force);
+        assert!(!remote_opts.force_if_empty);
+    }
+
     #[tokio::test]
     async fn test_execute_with_timeout_marks_remote_peer_faulty_on_network_like_error() {
         let client = test_remote_peer("http://peer-network-error:9000");
@@ -1571,6 +1690,54 @@ mod tests {
         reset_local_disk_test_state().await;
     }
 
+    #[tokio::test]
+    #[serial]
+    async fn local_peer_force_if_empty_preserves_unclassified_file_in_selected_pool() {
+        reset_local_disk_test_state().await;
+
+        let temp_dir = TempDir::new().expect("create temp dir for empty-only delete regression");
+        let disks = init_test_local_disks_for_pools(
+            &temp_dir,
+            &[(0, 1), (1, 1)],
+            "local-peer-force-if-empty-preserves-unclassified-file",
+        )
+        .await;
+        let bucket = "empty-only-delete-bucket";
+        let marker = "object/commit-marker";
+        let data = bytes::Bytes::from_static(b"committed object data");
+
+        disks[1]
+            .make_volume(bucket)
+            .await
+            .expect("bucket should be created in the selected pool");
+        disks[1]
+            .write_all(bucket, marker, data.clone())
+            .await
+            .expect("unclassified committed file should be written");
+
+        let err = LocalPeerS3Client::new_with_local_disks(None, Some(vec![1]), disks.clone())
+            .delete_bucket(
+                bucket,
+                &DeleteBucketOptions {
+                    force_if_empty: true,
+                    ..Default::default()
+                },
+            )
+            .await
+            .expect_err("empty-only delete must not recursively remove an unclassified file");
+
+        assert_eq!(err, Error::VolumeNotEmpty);
+        assert_eq!(
+            disks[1]
+                .read_all(bucket, marker)
+                .await
+                .expect("unclassified committed file should be preserved"),
+            data
+        );
+
+        reset_local_disk_test_state().await;
+    }
+
     #[tokio::test]
     #[serial]
     async fn heal_bucket_local_recreates_missing_bucket_volumes() {

crates/ecstore/src/cluster/rpc/remote_disk.rs

@@ -13,8 +13,8 @@
 // limitations under the License.
 
 use crate::cluster::rpc::client::{
-    TonicInterceptor, gen_tonic_signature_interceptor, is_network_like_disk_error, node_service_time_out_client,
-    node_service_time_out_client_for_class, node_service_time_out_client_no_auth,
+    AuthenticatedChannel, TonicInterceptor, gen_tonic_signature_interceptor, is_network_like_disk_error,
+    node_service_time_out_client, node_service_time_out_client_for_class, node_service_time_out_client_no_auth,
 };
 use crate::cluster::rpc::http_auth::set_tonic_canonical_body_digest;
 use crate::cluster::rpc::internode_data_transport::{
@@ -71,7 +71,7 @@ use tokio::{
     time::timeout,
 };
 use tokio_util::sync::CancellationToken;
-use tonic::{Code, Request, service::interceptor::InterceptedService, transport::Channel};
+use tonic::{Code, Request, service::interceptor::InterceptedService};
 use tracing::{debug, trace, warn};
 use uuid::Uuid;
 
@@ -1083,7 +1083,7 @@ impl RemoteDisk {
         internode_offline_bypass_reason(&self.addr).map(Error::other)
     }
 
-    async fn get_client(&self) -> Result<NodeServiceClient<InterceptedService<Channel, TonicInterceptor>>> {
+    async fn get_client(&self) -> Result<NodeServiceClient<InterceptedService<AuthenticatedChannel, TonicInterceptor>>> {
         if let Some(err) = self.offline_bypass_error() {
             return Err(err);
         }
@@ -1096,7 +1096,7 @@ impl RemoteDisk {
     /// Routes onto the isolated bulk channel pool so large transfers cannot head-of-line block
     /// lock/health RPCs (grpc-optimization P1). Falls back to the control channel when isolation
     /// is disabled.
-    async fn get_bulk_client(&self) -> Result<NodeServiceClient<InterceptedService<Channel, TonicInterceptor>>> {
+    async fn get_bulk_client(&self) -> Result<NodeServiceClient<InterceptedService<AuthenticatedChannel, TonicInterceptor>>> {
         if let Some(err) = self.offline_bypass_error() {
             return Err(err);
         }
@@ -5336,7 +5336,7 @@ mod tests {
         // production callsites that sibling tests exercise from subscriber-less
         // threads; without this they can be cached as `Interest::never()` and go
         // silently missing here.
-        let _callsite_pin = crate::cluster::rpc::pin_callsite_interest_for_test();
+        let _callsite_pin = crate::test_tracing::pin_callsite_interest_for_test();
 
         let endpoint = Endpoint {
             url: url::Url::parse("http://127.0.0.1:59996/data").expect("endpoint URL should parse"),
@@ -5395,7 +5395,7 @@ mod tests {
         // production callsites that sibling tests exercise from subscriber-less
         // threads; without this they can be cached as `Interest::never()` and go
         // silently missing here.
-        let _callsite_pin = crate::cluster::rpc::pin_callsite_interest_for_test();
+        let _callsite_pin = crate::test_tracing::pin_callsite_interest_for_test();
 
         let addr = "http://127.0.0.1:59997".to_string();
         let endpoint = Endpoint {

crates/ecstore/src/cluster/rpc/remote_locker.rs

@@ -12,7 +12,9 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-use crate::cluster::rpc::client::{TonicInterceptor, gen_tonic_signature_interceptor, node_service_time_out_client};
+use crate::cluster::rpc::client::{
+    AuthenticatedChannel, TonicInterceptor, gen_tonic_signature_interceptor, node_service_time_out_client,
+};
 use crate::cluster::rpc::set_tonic_mutation_body_digest;
 use async_trait::async_trait;
 use bytes::Bytes;
@@ -29,7 +31,6 @@ use std::time::Duration;
 use tokio::time::timeout;
 use tonic::Request;
 use tonic::service::interceptor::InterceptedService;
-use tonic::transport::Channel;
 use tracing::{debug, info, warn};
 
 /// Remote lock client implementation
@@ -78,7 +79,7 @@ impl RemoteClient {
         }
     }
 
-    pub async fn get_client(&self) -> Result<NodeServiceClient<InterceptedService<Channel, TonicInterceptor>>> {
+    pub async fn get_client(&self) -> Result<NodeServiceClient<InterceptedService<AuthenticatedChannel, TonicInterceptor>>> {
         // P3-2 offline bypass (now covering the lock path too): fast-fail a peer already marked
         // offline instead of paying the connect timeout, so dsync reaches quorum sooner. Does not
         // change quorum; the self-healing re-probe keeps the peer recoverable.

crates/ecstore/src/disk/local.rs

@@ -381,6 +381,291 @@ fn classify_delete_volume_error(err: std::io::Error) -> DiskError {
     }
 }
 
+#[cfg(unix)]
+struct EmptyDirectoryFrame {
+    path: PathBuf,
+    name_in_parent: std::ffi::CString,
+    entries: rustix::fs::Dir,
+}
+
+#[cfg(unix)]
+fn empty_tree_io_error(err: rustix::io::Errno) -> std::io::Error {
+    match err {
+        rustix::io::Errno::NOTDIR | rustix::io::Errno::LOOP => std::io::Error::from(ErrorKind::DirectoryNotEmpty),
+        _ => err.into(),
+    }
+}
+
+#[cfg(unix)]
+fn remove_empty_directory_tree_unix_with(
+    root: &Path,
+    mut before_descend: impl FnMut(&Path) -> std::io::Result<()>,
+    mut before_remove: impl FnMut(&Path) -> std::io::Result<()>,
+) -> std::io::Result<()> {
+    use rustix::{
+        fs::{AtFlags, Dir, Mode, OFlags, fstat, open, openat, statat, unlinkat},
+        io::Errno,
+    };
+    use std::os::fd::AsFd;
+    use std::os::unix::ffi::OsStrExt;
+
+    let flags = OFlags::RDONLY | OFlags::DIRECTORY | OFlags::NOFOLLOW | OFlags::CLOEXEC;
+    let root_parent_path = root
+        .parent()
+        .ok_or_else(|| std::io::Error::from(ErrorKind::DirectoryNotEmpty))?;
+    let root_name = root
+        .file_name()
+        .ok_or_else(|| std::io::Error::from(ErrorKind::DirectoryNotEmpty))?
+        .as_bytes();
+    let root_name = std::ffi::CString::new(root_name).map_err(|_| std::io::Error::from(ErrorKind::DirectoryNotEmpty))?;
+    let root_parent = open(root_parent_path, flags, Mode::empty()).map_err(empty_tree_io_error)?;
+    let root_fd = openat(&root_parent, root_name.as_c_str(), flags, Mode::empty()).map_err(empty_tree_io_error)?;
+    // Each frame owns one directory iterator/FD, so memory and descriptors are
+    // bounded by path depth rather than by the number of empty remnants.
+    let mut stack = vec![EmptyDirectoryFrame {
+        path: root.to_path_buf(),
+        name_in_parent: root_name,
+        entries: Dir::new(root_fd).map_err(empty_tree_io_error)?,
+    }];
+
+    while let Some(mut frame) = stack.pop() {
+        let next_child = loop {
+            let Some(entry) = frame.entries.next() else {
+                break None;
+            };
+            let entry = entry.map_err(std::io::Error::from)?;
+            let name = entry.file_name();
+            if name.to_bytes() == b"." || name.to_bytes() == b".." {
+                continue;
+            }
+
+            let name = name.to_owned();
+            let child_path = frame.path.join(std::ffi::OsStr::from_bytes(name.as_bytes()));
+            before_descend(&child_path)?;
+            break Some((child_path, name));
+        };
+
+        if let Some((child_path, name)) = next_child {
+            let parent = frame.entries.fd().map_err(std::io::Error::from)?;
+            let child = match openat(parent, name.as_c_str(), flags, Mode::empty()) {
+                Ok(child) => child,
+                // A concurrent cleanup may remove an empty child after readdir
+                // returns it. Resume the parent instead of treating the whole
+                // bucket as missing and leaving its root behind.
+                Err(Errno::NOENT) => {
+                    stack.push(frame);
+                    continue;
+                }
+                Err(err) => return Err(empty_tree_io_error(err)),
+            };
+            stack.push(frame);
+            stack.push(EmptyDirectoryFrame {
+                path: child_path,
+                name_in_parent: name,
+                entries: Dir::new(child).map_err(empty_tree_io_error)?,
+            });
+            continue;
+        }
+        before_remove(&frame.path)?;
+        let parent = if let Some(parent) = stack.last() {
+            parent.entries.fd().map_err(std::io::Error::from)?
+        } else {
+            root_parent.as_fd()
+        };
+        let expected = fstat(frame.entries.fd().map_err(std::io::Error::from)?).map_err(empty_tree_io_error)?;
+        let current = statat(parent, frame.name_in_parent.as_c_str(), AtFlags::SYMLINK_NOFOLLOW).map_err(empty_tree_io_error)?;
+        if current.st_dev != expected.st_dev || current.st_ino != expected.st_ino {
+            return Err(std::io::Error::from(ErrorKind::DirectoryNotEmpty));
+        }
+        match unlinkat(parent, frame.name_in_parent.as_c_str(), AtFlags::REMOVEDIR).map_err(empty_tree_io_error) {
+            Ok(()) => {}
+            Err(err) if err.kind() == ErrorKind::NotFound => {}
+            Err(err) => return Err(err),
+        }
+    }
+
+    Ok(())
+}
+
+#[cfg(unix)]
+async fn remove_empty_directory_tree_with(
+    root: &Path,
+    before_descend: impl FnMut(&Path) -> std::io::Result<()>,
+    before_remove: impl FnMut(&Path) -> std::io::Result<()>,
+) -> std::io::Result<()> {
+    remove_empty_directory_tree_unix_with(root, before_descend, before_remove)
+}
+
+#[cfg(unix)]
+async fn remove_empty_directory_tree(root: &Path) -> std::io::Result<()> {
+    let root = root.to_path_buf();
+    tokio::task::spawn_blocking(move || remove_empty_directory_tree_unix_with(&root, |_| Ok(()), |_| Ok(()))).await?
+}
+
+#[cfg(windows)]
+#[derive(Debug)]
+struct LockedEmptyDirectory {
+    handle: winapi_util::Handle,
+}
+
+#[cfg(windows)]
+fn validate_windows_empty_directory(file_attributes: u64) -> std::io::Result<()> {
+    const FILE_ATTRIBUTE_DIRECTORY: u64 = 0x10;
+    const FILE_ATTRIBUTE_REPARSE_POINT: u64 = 0x400;
+
+    if file_attributes & FILE_ATTRIBUTE_DIRECTORY == 0 || file_attributes & FILE_ATTRIBUTE_REPARSE_POINT != 0 {
+        return Err(std::io::Error::from(ErrorKind::DirectoryNotEmpty));
+    }
+    Ok(())
+}
+
+#[cfg(windows)]
+async fn lock_windows_empty_directory(path: &Path, canonical_root: Option<&Path>) -> std::io::Result<LockedEmptyDirectory> {
+    use std::os::windows::fs::OpenOptionsExt;
+    use windows_sys::Win32::{
+        Foundation::GENERIC_READ,
+        Storage::FileSystem::{DELETE, FILE_SHARE_READ},
+    };
+
+    const FILE_FLAG_BACKUP_SEMANTICS: u32 = 0x0200_0000;
+    const FILE_FLAG_OPEN_REPARSE_POINT: u32 = 0x0020_0000;
+
+    let path = path.to_path_buf();
+    let canonical_root = canonical_root.map(Path::to_path_buf);
+    tokio::task::spawn_blocking(move || {
+        let file = std::fs::OpenOptions::new()
+            .access_mode(GENERIC_READ | DELETE)
+            .share_mode(FILE_SHARE_READ)
+            .custom_flags(FILE_FLAG_BACKUP_SEMANTICS | FILE_FLAG_OPEN_REPARSE_POINT)
+            .open(&path)?;
+        let handle = winapi_util::Handle::from_file(file);
+        let info = winapi_util::file::information(&handle)?;
+        validate_windows_empty_directory(info.file_attributes())?;
+        if let Some(canonical_root) = canonical_root {
+            let canonical_path = std::fs::canonicalize(path)?;
+            if !canonical_path.starts_with(canonical_root) {
+                return Err(std::io::Error::from(ErrorKind::DirectoryNotEmpty));
+            }
+        }
+        Ok::<_, std::io::Error>(LockedEmptyDirectory { handle })
+    })
+    .await?
+}
+
+#[cfg(windows)]
+// SAFETY: This helper only passes an owned live handle and one initialized
+// FILE_DISPOSITION_INFO to the synchronous Windows deletion API.
+#[allow(unsafe_code)]
+async fn remove_windows_empty_directory(directory: LockedEmptyDirectory) -> std::io::Result<()> {
+    tokio::task::spawn_blocking(move || {
+        use std::os::windows::io::AsRawHandle;
+        use windows_sys::Win32::Storage::FileSystem::{FILE_DISPOSITION_INFO, FileDispositionInfo, SetFileInformationByHandle};
+
+        let disposition = FILE_DISPOSITION_INFO { DeleteFile: true };
+        let disposition_size = u32::try_from(std::mem::size_of_val(&disposition))
+            .map_err(|_| std::io::Error::other("FILE_DISPOSITION_INFO size exceeds the Win32 API limit"))?;
+        let handle = directory.handle.as_raw_handle();
+        // SAFETY: `handle` is owned by `directory` and stays live for this synchronous
+        // call. `disposition` is initialized with the exact structure and byte size
+        // required by `FileDispositionInfo`; Windows does not retain the pointer.
+        let deleted = unsafe {
+            SetFileInformationByHandle(handle, FileDispositionInfo, std::ptr::from_ref(&disposition).cast(), disposition_size)
+        };
+        if deleted == 0 {
+            Err(std::io::Error::last_os_error())
+        } else {
+            Ok(())
+        }
+    })
+    .await?
+}
+
+#[cfg(windows)]
+struct WindowsEmptyDirectoryFrame {
+    path: PathBuf,
+    directory: LockedEmptyDirectory,
+    entries: fs::ReadDir,
+}
+
+#[cfg(windows)]
+async fn remove_empty_directory_tree_with(
+    root: &Path,
+    mut before_descend: impl FnMut(&Path) -> std::io::Result<()>,
+    mut before_remove: impl FnMut(&Path) -> std::io::Result<()>,
+) -> std::io::Result<()> {
+    let root_directory = lock_windows_empty_directory(root, None).await?;
+    let canonical_root = fs::canonicalize(root).await?;
+    let root_entries = fs::read_dir(root).await?;
+
+    // Holding each validated directory without delete sharing keeps its path
+    // generation stable until handle-relative deletion. State is O(depth).
+    let mut stack = vec![WindowsEmptyDirectoryFrame {
+        path: root.to_path_buf(),
+        directory: root_directory,
+        entries: root_entries,
+    }];
+
+    while let Some(mut frame) = stack.pop() {
+        match frame.entries.next_entry().await {
+            Ok(Some(entry)) => {
+                let child = entry.path();
+                before_descend(&child)?;
+                let child_directory = match lock_windows_empty_directory(&child, Some(&canonical_root)).await {
+                    Ok(directory) => directory,
+                    Err(err) if err.kind() == ErrorKind::NotFound => {
+                        stack.push(frame);
+                        continue;
+                    }
+                    Err(err) => return Err(err),
+                };
+                let child_entries = match fs::read_dir(&child).await {
+                    Ok(entries) => entries,
+                    Err(err) if err.kind() == ErrorKind::NotFound => {
+                        stack.push(frame);
+                        continue;
+                    }
+                    Err(err) if err.kind() == ErrorKind::NotADirectory => {
+                        return Err(std::io::Error::from(ErrorKind::DirectoryNotEmpty));
+                    }
+                    Err(err) => return Err(err),
+                };
+                stack.push(frame);
+                stack.push(WindowsEmptyDirectoryFrame {
+                    path: child,
+                    directory: child_directory,
+                    entries: child_entries,
+                });
+            }
+            Ok(None) => {
+                before_remove(&frame.path)?;
+                drop(frame.entries);
+                match remove_windows_empty_directory(frame.directory).await {
+                    Ok(()) => {}
+                    Err(err) if err.kind() == ErrorKind::NotFound => {}
+                    Err(err) if err.kind() == ErrorKind::NotADirectory => {
+                        return Err(std::io::Error::from(ErrorKind::DirectoryNotEmpty));
+                    }
+                    Err(err) => return Err(err),
+                }
+            }
+            Err(err) if err.kind() == ErrorKind::NotFound => {}
+            Err(err) => return Err(err),
+        }
+    }
+
+    Ok(())
+}
+
+#[cfg(windows)]
+async fn remove_empty_directory_tree(root: &Path) -> std::io::Result<()> {
+    remove_empty_directory_tree_with(root, |_| Ok(()), |_| Ok(())).await
+}
+
+#[cfg(all(not(unix), not(windows)))]
+async fn remove_empty_directory_tree(root: &Path) -> std::io::Result<()> {
+    fs::remove_dir(root).await
+}
+
 const LOG_COMPONENT_ECSTORE: &str = "ecstore";
 const LOG_SUBSYSTEM_DISK_LOCAL: &str = "disk_local";
 const EVENT_DISK_LOCAL_STARTUP_CLEANUP: &str = "disk_local_startup_cleanup";
@@ -1556,6 +1841,8 @@ static RENAME_DATA_FAIL_COMMIT_RENAME: std::sync::Mutex<Option<String>> = std::s
 #[cfg(test)]
 static LOCAL_INLINE_ROLLBACK_HARDLINK_FAILURE: std::sync::Mutex<Option<PathBuf>> = std::sync::Mutex::new(None);
 #[cfg(test)]
+static RENAME_DATA_REMOVE_DST_BASE_BEFORE_COMMIT: std::sync::Mutex<Option<(String, PathBuf)>> = std::sync::Mutex::new(None);
+#[cfg(test)]
 static DELETE_VERSION_FAIL_AFTER_DATA_STAGED: std::sync::Mutex<Vec<String>> = std::sync::Mutex::new(Vec::new());
 #[cfg(test)]
 static DELETE_VERSION_FAIL_AFTER_COMMIT: std::sync::Mutex<Vec<(PathBuf, String)>> = std::sync::Mutex::new(Vec::new());
@@ -1588,6 +1875,13 @@ fn set_local_inline_rollback_hardlink_failure(dst_path: &Path) {
         .expect("test failpoint lock should not be poisoned") = Some(dst_path.to_path_buf());
 }
 
+#[cfg(test)]
+fn set_rename_data_remove_dst_base_before_commit(dst_path: &str, dst_base: &Path) {
+    *RENAME_DATA_REMOVE_DST_BASE_BEFORE_COMMIT
+        .lock()
+        .expect("test failpoint lock should not be poisoned") = Some((dst_path.to_string(), dst_base.to_path_buf()));
+}
+
 #[cfg(test)]
 fn set_delete_version_fail_after_data_staged(path: &str) {
     DELETE_VERSION_FAIL_AFTER_DATA_STAGED
@@ -1656,6 +1950,19 @@ fn should_fail_local_inline_rollback_hardlink(dst_path: &Path) -> bool {
     }
 }
 
+#[cfg(test)]
+fn remove_dst_base_before_commit(dst_path: &str) -> std::io::Result<()> {
+    let mut target = RENAME_DATA_REMOVE_DST_BASE_BEFORE_COMMIT
+        .lock()
+        .expect("test failpoint lock should not be poisoned");
+    let Some((_, base)) = target.as_ref().filter(|(target_path, _)| target_path == dst_path) else {
+        return Ok(());
+    };
+    std::fs::remove_dir_all(base)?;
+    target.take();
+    Ok(())
+}
+
 #[cfg(test)]
 fn should_fail_after_delete_data_staged(path: &str) -> bool {
     let mut targets = DELETE_VERSION_FAIL_AFTER_DATA_STAGED
@@ -1705,6 +2012,11 @@ fn should_fail_local_inline_rollback_hardlink(_dst_path: &Path) -> bool {
     false
 }
 
+#[cfg(not(test))]
+fn remove_dst_base_before_commit(_dst_path: &str) -> std::io::Result<()> {
+    Ok(())
+}
+
 #[cfg(not(test))]
 fn should_fail_after_delete_data_staged(_path: &str) -> bool {
     false
@@ -4243,9 +4555,11 @@ impl LocalDisk {
         let tmp_path = Self::meta_path(root, RUSTFS_META_TMP_BUCKET);
         let tmp_old_path = Self::meta_path(root, RUSTFS_META_TMP_OLD_BUCKET).join(Uuid::new_v4().to_string());
 
-        rename_all(&tmp_path, &tmp_old_path, root).await.inspect_err(|err| {
-            log_startup_disk_error("cleanup_tmp_rename_all", &tmp_path, err);
-        })?;
+        rename_all_ignore_missing_source(&tmp_path, &tmp_old_path, root)
+            .await
+            .inspect_err(|err| {
+                log_startup_disk_error("cleanup_tmp_rename_all", &tmp_path, err);
+            })?;
 
         let tmp_deleted_path = Self::meta_path(root, RUSTFS_META_TMP_DELETED_BUCKET);
         tokio::fs::create_dir_all(&tmp_deleted_path).await.inspect_err(|err| {
@@ -7359,6 +7673,10 @@ impl DiskAPI for LocalDisk {
         dst_path: &str,
     ) -> Result<RenameDataResp> {
         crate::hp_guard!("LocalDisk::rename_data");
+        // A non-force DeleteBucket must not remove a directory while a local
+        // object commit is publishing into it. The peer's empty scan remains
+        // optimistic; this guard establishes the local commit/delete order.
+        let _volume_mutation_guard = os::disk_volume_mutation_lock(&self.root, dst_volume).read_owned().await;
         if fi.is_legacy_indexed_delete_marker() {
             fi.erasure.index = 0;
         }
@@ -7555,6 +7873,7 @@ impl DiskAPI for LocalDisk {
             // sequential version did.
             tmp_meta_res?;
             shard_sync_res?;
+            remove_dst_base_before_commit(dst_path).map_err(to_file_error)?;
 
             if let Some((src_data_path, dst_data_path)) = has_data_dir_path.as_ref()
                 && let Err(err) = rename_all(src_data_path, dst_data_path, &skip_parent).await
@@ -7814,6 +8133,7 @@ impl DiskAPI for LocalDisk {
                 xlmeta.add_version(fi)?;
                 let version_signature = rename_data_versions_signature(&xlmeta);
                 let new_buf = xlmeta.marshal_msg()?;
+                remove_dst_base_before_commit(&dst_path_for_failpoint).map_err(to_file_error)?;
 
                 // Write new xl.meta + rename. Inline objects carry their data
                 // inside xl.meta, so this whole sequence is a metadata commit:
@@ -7838,9 +8158,11 @@ impl DiskAPI for LocalDisk {
                 {
                     let old_path = dst_parent.join(old_dir.to_string()).join(STORAGE_FORMAT_FILE_BACKUP);
                     let old_parent = old_path.parent().map(|p| p.to_path_buf());
-                    if let Some(ref old_parent) = old_parent {
-                        std::fs::create_dir_all(old_parent)?;
-                    }
+                    let _old_parent_guard = old_parent
+                        .as_deref()
+                        .map(|parent| os::mkdir_all_below_existing_base_std(parent, &bucket_dir))
+                        .transpose()
+                        .map_err(to_file_error)?;
                     // This rollback backup is the sole restore source for a later
                     // undo_write when the set-level write quorum fails. Persist it as
                     // durably as the new xl.meta written above (and as the non-inline
@@ -7866,6 +8188,12 @@ impl DiskAPI for LocalDisk {
                     local_rollback_path = Some(create_local_inline_rollback_backup(&dst, &src, old_metadata)?);
                 }
 
+                #[cfg(windows)]
+                let _commit_parent_guard = if let Some(parent) = dst.parent() {
+                    Some(os::mkdir_all_below_existing_base_std(parent, &bucket_dir).map_err(to_file_error)?)
+                } else {
+                    None
+                };
                 let commit_result = if should_fail_commit_rename(&dst_path_for_failpoint) {
                     Err(std::io::Error::other("test fail during metadata commit rename"))
                 } else {
@@ -7874,7 +8202,8 @@ impl DiskAPI for LocalDisk {
                         Err(err) if err.kind() == ErrorKind::NotFound && !src.exists() => Ok(()),
                         Err(err) if err.kind() == ErrorKind::NotFound => {
                             if let Some(parent) = dst.parent() {
-                                std::fs::create_dir_all(parent)?;
+                                let _parent_guard =
+                                    os::mkdir_all_below_existing_base_std(parent, &bucket_dir).map_err(to_file_error)?;
                             }
                             std::fs::rename(&src, &dst).map_err(to_file_error)?;
                             Ok(())
@@ -8791,18 +9120,16 @@ impl DiskAPI for LocalDisk {
     #[tracing::instrument(level = "trace", skip_all)]
     async fn delete_volume(&self, volume: &str, force_delete: bool) -> Result<()> {
         let p = self.get_bucket_path(volume)?;
+        let _volume_mutation_guard = os::disk_volume_mutation_lock(&self.root, volume).write_owned().await;
 
-        // Non-force is non-recursive: `remove_dir` (rmdir) fails atomically with
-        // `DirectoryNotEmpty` -> VolumeNotEmpty if the bucket still holds any
-        // object data, so a misclassified "dangling" bucket on the heal path
-        // (or a non-force S3 DeleteBucket on a populated bucket) can never be
-        // recursively wiped. Only an explicit `force_delete` (e.g. S3 force
-        // bucket delete) removes recursively. Mirrors MinIO's
-        // xlStorage.DeleteVol (Remove vs RemoveAll). (backlog#799 B1)
+        // Non-force removes empty directory remnants children-first with
+        // non-recursive rmdir calls. A file that exists during the scan, or
+        // appears before its parent is removed, fails closed with
+        // VolumeNotEmpty. Only an explicit force delete removes recursively.
         let res = if force_delete {
             fs::remove_dir_all(&p).await
         } else {
-            fs::remove_dir(&p).await
+            remove_empty_directory_tree(&p).await
         };
 
         if let Err(err) = res {
@@ -9061,6 +9388,35 @@ mod test {
         }
     }
 
+    #[cfg(windows)]
+    #[test]
+    fn windows_empty_tree_requires_non_reparse_directory() {
+        validate_windows_empty_directory(0x10).expect("ordinary directories should be accepted");
+        assert!(validate_windows_empty_directory(0).is_err());
+        assert!(validate_windows_empty_directory(0x10 | 0x400).is_err());
+    }
+
+    #[cfg(windows)]
+    #[tokio::test]
+    async fn windows_empty_tree_blocks_replacement_at_final_delete_boundary() {
+        let root = tempfile::tempdir().expect("temporary root should be created");
+        let bucket_path = root.path().join("bucket");
+        let child_path = bucket_path.join("child");
+        fs::create_dir_all(&child_path).await.expect("bucket child should be created");
+        let canonical_root = fs::canonicalize(&bucket_path).await.expect("bucket path should canonicalize");
+        let directory = lock_windows_empty_directory(&child_path, Some(&canonical_root))
+            .await
+            .expect("child directory should be locked");
+
+        std::fs::rename(&child_path, bucket_path.join("replacement"))
+            .expect_err("the locked directory must not be replaceable at the final deletion boundary");
+        remove_windows_empty_directory(directory)
+            .await
+            .expect("handle-relative deletion should remove the locked directory");
+
+        assert!(!child_path.exists(), "the exact locked directory should be removed");
+    }
+
     async fn ensure_test_volume(disk: &LocalDisk, volume: &str) {
         match disk.make_volume(volume).await {
             Ok(()) | Err(DiskError::VolumeExists) => {}
@@ -10787,6 +11143,72 @@ mod test {
         );
     }
 
+    #[tokio::test]
+    #[serial_test::serial(rename_data_deleted_bucket)]
+    async fn rename_data_non_inline_does_not_recreate_bucket_deleted_before_commit() {
+        let dir = tempfile::tempdir().expect("temp dir should be created");
+        let endpoint = Endpoint::try_from(dir.path().to_string_lossy().as_ref()).expect("endpoint should parse");
+        let disk = LocalDisk::new(&endpoint, false).await.expect("local disk should be created");
+        let bucket = "deleted-before-non-inline-commit";
+        let object = "prefix/object";
+        let tmp_object = "tmp-non-inline-delete-race";
+        let data_dir = Uuid::parse_str("aaaaaaaa-bbbb-cccc-dddd-eeeeeeeeeeee").expect("data dir should parse");
+        ensure_test_volume(&disk, bucket).await;
+        ensure_test_volume(&disk, RUSTFS_META_TMP_BUCKET).await;
+
+        let staged_data = disk
+            .get_object_path(RUSTFS_META_TMP_BUCKET, &format!("{tmp_object}/{data_dir}/part.1"))
+            .expect("staged data path should resolve");
+        fs::create_dir_all(staged_data.parent().expect("staged data should have a parent"))
+            .await
+            .expect("staged data parent should be created");
+        fs::write(&staged_data, b"payload")
+            .await
+            .expect("staged shard should be written");
+
+        let bucket_path = disk.get_bucket_path(bucket).expect("bucket path should resolve");
+        set_rename_data_remove_dst_base_before_commit(object, &bucket_path);
+        let fi = test_file_info(object, Uuid::new_v4(), Some(data_dir), None);
+        let err = disk
+            .rename_data(RUSTFS_META_TMP_BUCKET, tmp_object, fi, bucket, object)
+            .await
+            .expect_err("commit must fail after the destination bucket is deleted");
+
+        assert_eq!(err, DiskError::FileNotFound);
+        assert!(!bucket_path.exists(), "rename_data must not recreate the deleted bucket");
+        assert!(staged_data.exists(), "failed commit must preserve the staged shard");
+    }
+
+    #[tokio::test]
+    #[serial_test::serial(rename_data_deleted_bucket)]
+    async fn rename_data_inline_does_not_recreate_bucket_deleted_before_commit() {
+        let dir = tempfile::tempdir().expect("temp dir should be created");
+        let endpoint = Endpoint::try_from(dir.path().to_string_lossy().as_ref()).expect("endpoint should parse");
+        let disk = LocalDisk::new(&endpoint, false).await.expect("local disk should be created");
+        let bucket = "deleted-before-inline-commit";
+        let object = "prefix/object";
+        let tmp_object = "tmp-inline-delete-race";
+        ensure_test_volume(&disk, bucket).await;
+        ensure_test_volume(&disk, RUSTFS_META_TMP_BUCKET).await;
+
+        let bucket_path = disk.get_bucket_path(bucket).expect("bucket path should resolve");
+        set_rename_data_remove_dst_base_before_commit(object, &bucket_path);
+        let fi = test_file_info(object, Uuid::new_v4(), None, Some(Bytes::from_static(b"inline payload")));
+        let err = disk
+            .rename_data(RUSTFS_META_TMP_BUCKET, tmp_object, fi, bucket, object)
+            .await
+            .expect_err("inline commit must fail after the destination bucket is deleted");
+
+        assert_eq!(err, DiskError::FileNotFound);
+        assert!(!bucket_path.exists(), "inline rename_data must not recreate the deleted bucket");
+        assert!(
+            disk.get_object_path(RUSTFS_META_TMP_BUCKET, &format!("{tmp_object}/{STORAGE_FORMAT_FILE}"))
+                .expect("staged metadata path should resolve")
+                .exists(),
+            "failed inline commit must preserve staged metadata"
+        );
+    }
+
     #[test]
     fn test_resolve_durability_mode_mapping() {
         // Default: nothing set -> strict (current main behavior).
@@ -12645,6 +13067,19 @@ mod test {
         assert!(format_info.last_check.is_none(), "cached format timestamp should be cleared");
     }
 
+    #[tokio::test]
+    async fn cleanup_tmp_on_startup_allows_missing_tmp_directory() {
+        use tempfile::tempdir;
+
+        let dir = tempdir().expect("operation should succeed");
+
+        LocalDisk::cleanup_tmp_on_startup(dir.path(), Arc::new(AtomicU32::new(0)), Arc::new(Notify::new()))
+            .await
+            .expect("missing temporary directory should already be clean");
+
+        assert!(LocalDisk::meta_path(dir.path(), RUSTFS_META_TMP_DELETED_BUCKET).exists());
+    }
+
     #[tokio::test]
     async fn cleanup_tmp_on_startup_moves_existing_tmp_and_recreates_trash() {
         use tempfile::tempdir;
@@ -14517,6 +14952,154 @@ mod test {
         let _ = fs::remove_dir_all(&test_dir).await;
     }
 
+    #[tokio::test]
+    async fn delete_volume_non_force_removes_nested_empty_directories() {
+        let root = tempfile::tempdir().expect("temporary disk root should be created");
+        let endpoint = Endpoint::try_from(root.path().to_string_lossy().as_ref()).expect("endpoint should parse");
+        let disk = LocalDisk::new(&endpoint, false).await.expect("local disk should be created");
+        let bucket = "nested-empty-bucket";
+
+        disk.make_volume(bucket).await.expect("bucket should be created");
+        fs::create_dir_all(disk.path().join(bucket).join("a/b/c"))
+            .await
+            .expect("nested empty directories should be created");
+
+        disk.delete_volume(bucket, false)
+            .await
+            .expect("non-force delete should remove an empty directory tree");
+
+        assert!(matches!(disk.stat_volume(bucket).await, Err(DiskError::VolumeNotFound)));
+    }
+
+    #[tokio::test]
+    async fn empty_tree_delete_preserves_xlmeta_published_after_scan() {
+        let root = tempfile::tempdir().expect("temporary disk root should be created");
+        let bucket_path = root.path().join("bucket");
+        let object_path = bucket_path.join("object").join(STORAGE_FORMAT_FILE);
+        fs::create_dir_all(object_path.parent().expect("object path should have a parent"))
+            .await
+            .expect("empty object directory should be created");
+
+        let data = b"committed object metadata";
+        let mut published = false;
+        let err = remove_empty_directory_tree_with(
+            &bucket_path,
+            |_| Ok(()),
+            |directory| {
+                if !published && directory == object_path.parent().expect("object path should have a parent") {
+                    std::fs::write(&object_path, data)?;
+                    published = true;
+                }
+                Ok(())
+            },
+        )
+        .await
+        .expect_err("rmdir should refuse metadata published after the directory scan");
+
+        assert!(published, "test barrier should publish metadata before rmdir");
+        assert!(matches!(classify_delete_volume_error(err), DiskError::VolumeNotEmpty));
+        assert_eq!(std::fs::read(&object_path).expect("object metadata should be preserved"), data);
+    }
+
+    #[cfg(unix)]
+    #[tokio::test]
+    async fn empty_tree_delete_rejects_child_replaced_with_external_symlink() {
+        use std::os::unix::fs::symlink;
+
+        let root = tempfile::tempdir().expect("temporary root should be created");
+        let bucket_path = root.path().join("bucket");
+        let child_path = bucket_path.join("child");
+        let outside_path = root.path().join("outside");
+        let outside_empty = outside_path.join("must-remain");
+        fs::create_dir_all(&child_path).await.expect("bucket child should be created");
+        fs::create_dir_all(&outside_empty)
+            .await
+            .expect("outside directory should be created");
+
+        let mut replaced = false;
+        let err = remove_empty_directory_tree_with(
+            &bucket_path,
+            |child| {
+                if !replaced && child == child_path {
+                    std::fs::remove_dir(&child_path)?;
+                    symlink(&outside_path, &child_path)?;
+                    replaced = true;
+                }
+                Ok(())
+            },
+            |_| Ok(()),
+        )
+        .await
+        .expect_err("a replaced child must fail closed");
+
+        assert!(replaced, "test barrier should replace the child before it is opened");
+        assert!(matches!(classify_delete_volume_error(err), DiskError::VolumeNotEmpty));
+        assert!(outside_empty.exists(), "bucket deletion must not remove directories outside the bucket");
+        assert!(
+            std::fs::symlink_metadata(&child_path)
+                .expect("replacement symlink should remain")
+                .file_type()
+                .is_symlink()
+        );
+    }
+
+    #[cfg(unix)]
+    #[tokio::test]
+    async fn empty_tree_delete_rechecks_parent_after_child_disappears() {
+        let root = tempfile::tempdir().expect("temporary root should be created");
+        let bucket_path = root.path().join("bucket");
+        let child_path = bucket_path.join("child");
+        fs::create_dir_all(&child_path).await.expect("bucket child should be created");
+
+        let mut removed = false;
+        remove_empty_directory_tree_with(
+            &bucket_path,
+            |child| {
+                if !removed && child == child_path {
+                    std::fs::remove_dir(&child_path)?;
+                    removed = true;
+                }
+                Ok(())
+            },
+            |_| Ok(()),
+        )
+        .await
+        .expect("a vanished empty child should not leave the bucket root behind");
+
+        assert!(removed, "test hook should remove the child before openat");
+        assert!(!bucket_path.exists(), "parent should be rechecked and removed after the child disappears");
+    }
+
+    #[cfg(unix)]
+    #[tokio::test]
+    async fn empty_tree_delete_rejects_root_generation_replacement() {
+        let root = tempfile::tempdir().expect("temporary root should be created");
+        let bucket_path = root.path().join("bucket");
+        let moved_path = root.path().join("bucket-before-replacement");
+        fs::create_dir(&bucket_path).await.expect("bucket should be created");
+
+        let mut replaced = false;
+        let err = remove_empty_directory_tree_with(
+            &bucket_path,
+            |_| Ok(()),
+            |directory| {
+                if !replaced && directory == bucket_path {
+                    std::fs::rename(&bucket_path, &moved_path)?;
+                    std::fs::create_dir(&bucket_path)?;
+                    replaced = true;
+                }
+                Ok(())
+            },
+        )
+        .await
+        .expect_err("a replacement root directory must fail closed");
+
+        assert!(replaced, "test hook should replace the root generation before rmdir");
+        assert!(matches!(classify_delete_volume_error(err), DiskError::VolumeNotEmpty));
+        assert!(moved_path.exists(), "the originally scanned root should not be removed by its old name");
+        assert!(bucket_path.exists(), "the replacement root should remain after identity validation fails");
+    }
+
     #[tokio::test]
     async fn test_local_disk_volume_operations() {
         let test_dir = "./test_local_disk_volumes";

crates/ecstore/src/disk/os.rs

@@ -25,7 +25,7 @@ use std::{
     sync::{Arc, LazyLock, Weak},
 };
 use tokio::fs;
-use tokio::sync::{OwnedSemaphorePermit, Semaphore, SemaphorePermit};
+use tokio::sync::{OwnedSemaphorePermit, RwLock, Semaphore, SemaphorePermit};
 use tracing::warn;
 
 /// Check path length according to OS limits.
@@ -123,6 +123,8 @@ const TEST_GLOBAL_FILE_SYNCS: usize = 64;
 
 static FILE_SYNC_PERMITS: LazyLock<Semaphore> = LazyLock::new(|| Semaphore::new(global_file_sync_limit()));
 static DISK_FILE_SYNC_LIMITERS: LazyLock<Mutex<HashMap<PathBuf, Weak<Semaphore>>>> = LazyLock::new(|| Mutex::new(HashMap::new()));
+static DISK_VOLUME_MUTATION_LOCKS: LazyLock<Mutex<HashMap<PathBuf, Weak<RwLock<()>>>>> =
+    LazyLock::new(|| Mutex::new(HashMap::new()));
 
 fn default_global_file_sync_limit(cpu_count: usize, max_blocking_threads: usize) -> usize {
     let cpu_scaled = cpu_count
@@ -157,6 +159,24 @@ pub(crate) fn disk_file_sync_limiter(root: &Path) -> Arc<Semaphore> {
     limiter
 }
 
+/// Serialize a bucket's local metadata commits with physical bucket removal.
+///
+/// The key includes the canonical disk root, so independently reconnected
+/// [`LocalDisk`](super::local::LocalDisk) instances share the same lock while
+/// disconnected disks do not keep the registry alive.
+pub(crate) fn disk_volume_mutation_lock(root: &Path, volume: &str) -> Arc<RwLock<()>> {
+    let key = root.join(volume);
+    let mut locks = DISK_VOLUME_MUTATION_LOCKS.lock();
+    locks.retain(|_, lock| lock.strong_count() > 0);
+    if let Some(lock) = locks.get(&key).and_then(Weak::upgrade) {
+        return lock;
+    }
+
+    let lock = Arc::new(RwLock::new(()));
+    locks.insert(key, Arc::downgrade(&lock));
+    lock
+}
+
 /// Always acquire the per-disk permit before the process-wide permit. Keeping
 /// this order uniform prevents one slow disk from reserving global capacity
 /// while it waits for its own concurrency slot.
@@ -572,15 +592,14 @@ async fn reliable_rename_inner(
     base_dir: impl AsRef<Path>,
     warn_on_missing_source: bool,
 ) -> io::Result<()> {
-    if let Some(parent) = dst_file_path.as_ref().parent()
-        && !file_exists(parent)
-    {
-        reliable_mkdir_all(parent, base_dir.as_ref()).await?;
-    }
+    let parent_guard = match dst_file_path.as_ref().parent() {
+        Some(parent) => Some(mkdir_all_below_existing_base(parent, base_dir.as_ref()).await?),
+        None => None,
+    };
 
     let mut i = 0;
     loop {
-        if let Err(e) = super::fs::rename_std(src_file_path.as_ref(), dst_file_path.as_ref()) {
+        if let Err(e) = rename_into_existing_parent(src_file_path.as_ref(), dst_file_path.as_ref(), parent_guard.as_ref()) {
             if should_retry_rename(&e, i) {
                 i += 1;
                 continue;
@@ -597,6 +616,159 @@ async fn reliable_rename_inner(
     Ok(())
 }
 
+#[cfg(unix)]
+fn rename_into_existing_parent(
+    src_file_path: &Path,
+    dst_file_path: &Path,
+    parent_guard: Option<&ExistingBaseDirectoryGuard>,
+) -> io::Result<()> {
+    use rustix::fs::{Mode, OFlags, open, renameat};
+
+    let Some(parent_guard) = parent_guard else {
+        return super::fs::rename_std(src_file_path, dst_file_path);
+    };
+    let src_parent = src_file_path
+        .parent()
+        .ok_or_else(|| io::Error::new(io::ErrorKind::InvalidInput, "rename source must have a parent directory"))?;
+    let src_name = src_file_path
+        .file_name()
+        .ok_or_else(|| io::Error::new(io::ErrorKind::InvalidInput, "rename source must have a file name"))?;
+    let dst_name = dst_file_path
+        .file_name()
+        .ok_or_else(|| io::Error::new(io::ErrorKind::InvalidInput, "rename destination must have a file name"))?;
+    let src_parent = open(
+        src_parent,
+        OFlags::RDONLY | OFlags::DIRECTORY | OFlags::NOFOLLOW | OFlags::CLOEXEC,
+        Mode::empty(),
+    )
+    .map_err(io::Error::from)?;
+    let dst_parent = parent_guard
+        .last()
+        .ok_or_else(|| io::Error::other("rename destination parent guard is empty"))?;
+
+    renameat(&src_parent, src_name, dst_parent, dst_name).map_err(io::Error::from)
+}
+
+#[cfg(not(unix))]
+fn rename_into_existing_parent(
+    src_file_path: &Path,
+    dst_file_path: &Path,
+    _parent_guard: Option<&ExistingBaseDirectoryGuard>,
+) -> io::Result<()> {
+    super::fs::rename_std(src_file_path, dst_file_path)
+}
+
+async fn mkdir_all_below_existing_base(dir_path: &Path, base_dir: &Path) -> io::Result<ExistingBaseDirectoryGuard> {
+    let dir_path = dir_path.to_path_buf();
+    let base_dir = base_dir.to_path_buf();
+
+    tokio::task::spawn_blocking(move || mkdir_all_below_existing_base_std(&dir_path, &base_dir)).await?
+}
+
+#[cfg(windows)]
+pub(crate) type ExistingBaseDirectoryGuard = Vec<winapi_util::Handle>;
+
+#[cfg(unix)]
+pub(crate) type ExistingBaseDirectoryGuard = Vec<std::os::fd::OwnedFd>;
+
+#[cfg(all(not(unix), not(windows)))]
+pub(crate) type ExistingBaseDirectoryGuard = ();
+
+#[cfg(windows)]
+fn lock_windows_directory(path: &Path) -> io::Result<winapi_util::Handle> {
+    use std::os::windows::fs::OpenOptionsExt;
+
+    const FILE_ATTRIBUTE_DIRECTORY: u64 = 0x10;
+    const FILE_ATTRIBUTE_REPARSE_POINT: u32 = 0x400;
+    const FILE_FLAG_BACKUP_SEMANTICS: u32 = 0x0200_0000;
+    const FILE_FLAG_OPEN_REPARSE_POINT: u32 = 0x0020_0000;
+    const FILE_SHARE_READ: u32 = 0x1;
+
+    let file = std::fs::OpenOptions::new()
+        .read(true)
+        .share_mode(FILE_SHARE_READ)
+        .custom_flags(FILE_FLAG_BACKUP_SEMANTICS | FILE_FLAG_OPEN_REPARSE_POINT)
+        .open(path)?;
+    let handle = winapi_util::Handle::from_file(file);
+    let info = winapi_util::file::information(&handle)?;
+    if info.file_attributes() & FILE_ATTRIBUTE_DIRECTORY == 0
+        || info.file_attributes() & u64::from(FILE_ATTRIBUTE_REPARSE_POINT) != 0
+    {
+        return Err(io::Error::from(io::ErrorKind::NotADirectory));
+    }
+    Ok(handle)
+}
+
+pub(crate) fn mkdir_all_below_existing_base_std(dir_path: &Path, base_dir: &Path) -> io::Result<ExistingBaseDirectoryGuard> {
+    let relative = dir_path
+        .strip_prefix(base_dir)
+        .map_err(|_| io::Error::new(io::ErrorKind::InvalidInput, "rename destination must remain below its base directory"))?;
+    for component in relative.components() {
+        if !matches!(component, Component::Normal(_) | Component::CurDir) {
+            return Err(io::Error::new(
+                io::ErrorKind::InvalidInput,
+                "rename destination contains an invalid path component",
+            ));
+        }
+    }
+
+    #[cfg(unix)]
+    {
+        use rustix::fs::{Mode, OFlags, mkdirat, open, openat};
+        use rustix::io::Errno;
+
+        let flags = OFlags::RDONLY | OFlags::DIRECTORY | OFlags::NOFOLLOW | OFlags::CLOEXEC;
+        let mode = Mode::RWXU | Mode::RWXG | Mode::RWXO;
+        let mut parents = vec![open(base_dir, flags, Mode::empty()).map_err(io::Error::from)?];
+
+        for component in relative.components() {
+            let Component::Normal(component) = component else {
+                continue;
+            };
+            let parent = parents
+                .last()
+                .expect("base directory guard should contain the base directory");
+            match mkdirat(parent, component, mode) {
+                Ok(()) => {}
+                Err(Errno::EXIST) => {}
+                Err(err) => return Err(err.into()),
+            }
+            parents.push(openat(parent, component, flags, Mode::empty()).map_err(io::Error::from)?);
+        }
+
+        Ok(parents)
+    }
+
+    #[cfg(windows)]
+    {
+        let mut handles = vec![lock_windows_directory(base_dir)?];
+        let mut current = base_dir.to_path_buf();
+        for component in relative.components() {
+            let Component::Normal(component) = component else {
+                continue;
+            };
+            current.push(component);
+            match std::fs::create_dir(&current) {
+                Ok(()) => {}
+                Err(err) if err.kind() == io::ErrorKind::AlreadyExists => {}
+                Err(err) => return Err(err),
+            }
+            handles.push(lock_windows_directory(&current)?);
+        }
+
+        Ok(handles)
+    }
+
+    #[cfg(all(not(unix), not(windows)))]
+    {
+        let _ = relative;
+        Err(io::Error::new(
+            io::ErrorKind::Unsupported,
+            "safe recursive directory creation is unavailable on this platform",
+        ))
+    }
+}
+
 fn warn_reliable_rename_failure(src_file_path: &Path, dst_file_path: &Path, base_dir: &Path, err: &io::Error) {
     warn!(
         "reliable_rename failed. src_file_path: {:?}, dst_file_path: {:?}, base_dir: {:?}, err: {:?}",
@@ -727,6 +899,20 @@ mod tests {
         Arc::new(Semaphore::new(MAX_PARALLEL_FILE_SYNCS))
     }
 
+    #[tokio::test]
+    async fn disk_volume_mutation_lock_is_shared_per_root_and_volume() {
+        let temp_dir = tempdir().expect("create temp dir");
+        let first = disk_volume_mutation_lock(temp_dir.path(), "bucket");
+        let second = disk_volume_mutation_lock(temp_dir.path(), "bucket");
+        let other = disk_volume_mutation_lock(temp_dir.path(), "other-bucket");
+
+        assert!(Arc::ptr_eq(&first, &second), "reconnected disks must share a bucket mutation lock");
+        assert!(!Arc::ptr_eq(&first, &other), "different buckets must not serialize each other");
+
+        let _write_guard = first.write().await;
+        assert!(second.try_read().is_err(), "a bucket delete lock must exclude local commits");
+    }
+
     #[derive(Clone, Default)]
     struct CapturedLogs {
         buffer: Arc<Mutex<Vec<u8>>>,
@@ -771,9 +957,26 @@ mod tests {
         }
     }
 
+    /// Holds a `warn_capture()` capture alive: the thread-local subscriber, plus
+    /// the pin that keeps tracing's process-global callsite-interest cache from
+    /// being decided by some other test's thread.
+    struct WarnCaptureGuard {
+        _subscriber: tracing::subscriber::DefaultGuard,
+        _callsite_pin: tracing::Dispatch,
+    }
+
     /// Capture WARN-level output on the current thread; tokio tests here run on
     /// the current-thread runtime, so the guard covers the whole test body.
-    fn warn_capture() -> (CapturedLogs, tracing::subscriber::DefaultGuard) {
+    ///
+    /// The callsite pin matters because `warn_reliable_rename_failure` is a
+    /// single production callsite shared with tests that call `rename_all`
+    /// *without* installing a subscriber — `rename_all_missing_source_returns_file_not_found`
+    /// is one. Whichever thread reaches it first fixes its `Interest`
+    /// process-wide, so without the pin that sibling can cache
+    /// `Interest::never()` and the WARN never fires here at all, leaving the
+    /// "must keep the WARN" assertions staring at empty output. See
+    /// [`crate::test_tracing::pin_callsite_interest_for_test`].
+    fn warn_capture() -> (CapturedLogs, WarnCaptureGuard) {
         let logs = CapturedLogs::default();
         let subscriber = tracing_subscriber::fmt()
             .with_max_level(tracing::Level::WARN)
@@ -781,7 +984,10 @@ mod tests {
             .with_ansi(false)
             .without_time()
             .finish();
-        let guard = tracing::subscriber::set_default(subscriber);
+        let guard = WarnCaptureGuard {
+            _subscriber: tracing::subscriber::set_default(subscriber),
+            _callsite_pin: crate::test_tracing::pin_callsite_interest_for_test(),
+        };
         (logs, guard)
     }
 
@@ -968,6 +1174,112 @@ mod tests {
         assert_eq!(std::fs::read(dst.join("nested").join("part.1")).expect("read moved part"), b"payload");
     }
 
+    #[tokio::test]
+    async fn rename_all_does_not_recreate_missing_base_directory() {
+        let temp_dir = tempdir().expect("create temp dir");
+        let base = temp_dir.path().join("bucket");
+        std::fs::create_dir(&base).expect("create destination base");
+        let src = temp_dir.path().join("staged-object");
+        std::fs::write(&src, b"payload").expect("write staged object");
+        let dst = base.join("object").join("xl.meta");
+        std::fs::remove_dir(&base).expect("delete destination base before commit");
+
+        let err = rename_all(&src, &dst, &base)
+            .await
+            .expect_err("rename must not recreate a deleted destination base");
+
+        assert!(matches!(err, DiskError::FileNotFound));
+        assert!(src.exists(), "failed commit must preserve the staged source");
+        assert!(!base.exists(), "failed commit must not recreate the deleted bucket");
+    }
+
+    #[cfg(unix)]
+    #[tokio::test]
+    async fn rename_all_rejects_a_replaced_base_with_an_existing_parent() {
+        use std::os::unix::fs::symlink;
+
+        let temp_dir = tempdir().expect("create temp dir");
+        let base = temp_dir.path().join("bucket");
+        let outside = temp_dir.path().join("outside");
+        std::fs::create_dir(&base).expect("create destination base");
+        std::fs::create_dir_all(outside.join("object")).expect("create outside destination parent");
+        let src = temp_dir.path().join("staged-object");
+        std::fs::write(&src, b"payload").expect("write staged object");
+        let dst = base.join("object").join("xl.meta");
+
+        std::fs::remove_dir(&base).expect("remove destination base before replacement");
+        symlink(&outside, &base).expect("replace destination base with a symlink");
+
+        rename_all(&src, &dst, &base)
+            .await
+            .expect_err("rename must reject an existing destination parent below a replaced base");
+
+        assert!(src.exists(), "rejected rename must preserve the staged source");
+        assert!(
+            !outside.join("object/xl.meta").exists(),
+            "rename must not publish through the replacement symlink"
+        );
+    }
+
+    #[cfg(windows)]
+    #[test]
+    fn windows_parent_guard_blocks_base_and_intermediate_replacement() {
+        let temp_dir = tempdir().expect("create temp dir");
+        let base = temp_dir.path().join("bucket");
+        std::fs::create_dir(&base).expect("create destination base");
+        let parent = base.join("object").join("nested");
+        let guard = mkdir_all_below_existing_base_std(&parent, &base).expect("create and lock destination parents");
+
+        std::fs::rename(&base, temp_dir.path().join("replacement-base"))
+            .expect_err("the locked base must not be replaceable before commit");
+        std::fs::rename(base.join("object"), base.join("replacement-object"))
+            .expect_err("a locked intermediate directory must not be replaceable before commit");
+
+        drop(guard);
+        std::fs::rename(base.join("object"), base.join("replacement-object"))
+            .expect("replacement should succeed after the commit guard is released");
+    }
+
+    #[cfg(unix)]
+    #[tokio::test]
+    async fn rename_parent_creation_rejects_symlinked_base() {
+        use std::os::unix::fs::symlink;
+
+        let temp_dir = tempdir().expect("create temp dir");
+        let outside = temp_dir.path().join("outside");
+        std::fs::create_dir(&outside).expect("create outside directory");
+        let base = temp_dir.path().join("bucket");
+        symlink(&outside, &base).expect("create symlinked base");
+
+        mkdir_all_below_existing_base(&base.join("object"), &base)
+            .await
+            .expect_err("symlinked base must be rejected");
+
+        assert!(!outside.join("object").exists(), "parent creation must remain confined to the base");
+    }
+
+    #[cfg(unix)]
+    #[tokio::test]
+    async fn rename_parent_creation_rejects_symlink_below_base() {
+        use std::os::unix::fs::symlink;
+
+        let temp_dir = tempdir().expect("create temp dir");
+        let base = temp_dir.path().join("bucket");
+        let outside = temp_dir.path().join("outside");
+        std::fs::create_dir(&base).expect("create destination base");
+        std::fs::create_dir(&outside).expect("create outside directory");
+        symlink(&outside, base.join("linked")).expect("create symlink below base");
+
+        mkdir_all_below_existing_base(&base.join("linked/object"), &base)
+            .await
+            .expect_err("symlink below base must be rejected");
+
+        assert!(
+            !outside.join("object").exists(),
+            "parent creation must not follow a symlink outside the base"
+        );
+    }
+
     #[tokio::test]
     async fn fsync_dir_succeeds_on_directory() {
         let temp_dir = tempdir().expect("create temp dir");

crates/ecstore/src/lib.rs

@@ -93,3 +93,6 @@ pub(crate) mod ecstore_validation_blackbox;
 
 #[cfg(test)]
 pub(crate) mod test_metrics;
+
+#[cfg(test)]
+pub(crate) mod test_tracing;

crates/ecstore/src/services/notification_sys.rs

@@ -29,11 +29,11 @@ use rustfs_madmin::metrics::RealtimeMetrics;
 use rustfs_madmin::net::NetInfo;
 use rustfs_madmin::{ItemState, ServerProperties, StorageInfo};
 use rustfs_utils::XHost;
-use std::collections::{HashMap, hash_map::DefaultHasher};
+use std::collections::{BTreeMap, HashMap, hash_map::DefaultHasher};
 use std::future::Future;
 use std::hash::{Hash, Hasher};
 use std::sync::{Arc, Mutex, OnceLock};
-use std::time::{Duration, SystemTime};
+use std::time::{Duration, Instant, SystemTime};
 use tokio::time::{sleep, timeout};
 use tokio_util::sync::CancellationToken;
 use tracing::{debug, error, info, warn};
@@ -47,6 +47,9 @@ const EVENT_NOTIFICATION_PEER_PROPAGATION: &str = "notification_peer_propagation
 const SCANNER_ACTIVITY_PROBE_TIMEOUT: Duration = Duration::from_secs(5);
 const TIER_CONFIG_RELOAD_RETRY_BASE: Duration = Duration::from_millis(100);
 const TIER_CONFIG_RELOAD_RETRY_CAP: Duration = Duration::from_secs(5);
+const REMOTE_VERSION_STATE_PROBE_INTERVAL: Duration = Duration::from_secs(10);
+const REMOTE_VERSION_STATE_PROBE_TIMEOUT: Duration = Duration::from_secs(5);
+const REMOTE_VERSION_STATE_PROOF_TTL: Duration = Duration::from_secs(30);
 
 /// Cached result from the last successful admin call to a peer.
 struct PeerAdminCache {
@@ -91,6 +94,180 @@ lazy_static! {
     pub static ref GLOBAL_NOTIFICATION_SYS: OnceLock<Arc<NotificationSys>> = OnceLock::new();
 }
 
+#[derive(Clone)]
+struct RemoteVersionStateFleetProof {
+    topology_fingerprint: String,
+    peer_epochs: Arc<BTreeMap<String, Uuid>>,
+    expires_at: Instant,
+}
+
+impl RemoteVersionStateFleetProof {
+    fn token(&self) -> RemoteVersionStateFleetProofToken {
+        RemoteVersionStateFleetProofToken {
+            topology_fingerprint: self.topology_fingerprint.clone(),
+            peer_epochs: self.peer_epochs.clone(),
+        }
+    }
+}
+
+#[derive(Clone, PartialEq, Eq)]
+pub(crate) struct RemoteVersionStateFleetProofToken {
+    topology_fingerprint: String,
+    peer_epochs: Arc<BTreeMap<String, Uuid>>,
+}
+
+#[derive(Default)]
+struct RemoteVersionStateFleetProofState {
+    proof: Option<RemoteVersionStateFleetProof>,
+    topology_conflict: bool,
+}
+
+static REMOTE_VERSION_STATE_FLEET_PROOF: OnceLock<std::sync::RwLock<RemoteVersionStateFleetProofState>> = OnceLock::new();
+static REMOTE_VERSION_STATE_PROBE_TOPOLOGY: OnceLock<String> = OnceLock::new();
+
+fn remote_version_state_fleet_proof_slot() -> &'static std::sync::RwLock<RemoteVersionStateFleetProofState> {
+    REMOTE_VERSION_STATE_FLEET_PROOF.get_or_init(|| std::sync::RwLock::new(RemoteVersionStateFleetProofState::default()))
+}
+
+fn replace_remote_version_state_fleet_proof(proof: Option<RemoteVersionStateFleetProof>) {
+    replace_remote_version_state_fleet_proof_in(remote_version_state_fleet_proof_slot(), proof);
+}
+
+fn replace_remote_version_state_fleet_proof_in(
+    slot: &std::sync::RwLock<RemoteVersionStateFleetProofState>,
+    proof: Option<RemoteVersionStateFleetProof>,
+) {
+    slot.write().unwrap_or_else(std::sync::PoisonError::into_inner).proof = proof;
+}
+
+fn publish_remote_version_state_probe_result(
+    slot: &std::sync::RwLock<RemoteVersionStateFleetProofState>,
+    topology_fingerprint: &str,
+    result: Result<BTreeMap<String, Uuid>>,
+    observed_at: Instant,
+) -> Option<Error> {
+    match result {
+        Ok(peer_epochs) => {
+            let mut state = slot.write().unwrap_or_else(std::sync::PoisonError::into_inner);
+            let peer_epochs = state
+                .proof
+                .as_ref()
+                .filter(|proof| proof.topology_fingerprint == topology_fingerprint && proof.peer_epochs.as_ref() == &peer_epochs)
+                .map(|proof| Arc::clone(&proof.peer_epochs))
+                .unwrap_or_else(|| Arc::new(peer_epochs));
+            state.proof = Some(RemoteVersionStateFleetProof {
+                topology_fingerprint: topology_fingerprint.to_string(),
+                peer_epochs,
+                expires_at: observed_at + REMOTE_VERSION_STATE_PROOF_TTL,
+            });
+            None
+        }
+        Err(err) => {
+            replace_remote_version_state_fleet_proof_in(slot, None);
+            Some(err)
+        }
+    }
+}
+
+pub(crate) fn acquire_remote_version_state_fleet_proof() -> Option<RemoteVersionStateFleetProofToken> {
+    let expected_topology = REMOTE_VERSION_STATE_PROBE_TOPOLOGY.get()?;
+    let state = remote_version_state_fleet_proof_slot()
+        .read()
+        .unwrap_or_else(std::sync::PoisonError::into_inner);
+    acquire_remote_version_state_fleet_proof_from(&state, expected_topology, Instant::now())
+}
+
+fn acquire_remote_version_state_fleet_proof_from(
+    state: &RemoteVersionStateFleetProofState,
+    expected_topology: &str,
+    now: Instant,
+) -> Option<RemoteVersionStateFleetProofToken> {
+    if state.topology_conflict || !remote_version_state_fleet_proof_valid_at(state.proof.as_ref(), expected_topology, now) {
+        return None;
+    }
+    state.proof.as_ref().map(RemoteVersionStateFleetProof::token)
+}
+
+pub(crate) fn remote_version_state_fleet_proof_matches(proof: &RemoteVersionStateFleetProofToken) -> bool {
+    let Some(expected_topology) = REMOTE_VERSION_STATE_PROBE_TOPOLOGY.get() else {
+        return false;
+    };
+    let state = remote_version_state_fleet_proof_slot()
+        .read()
+        .unwrap_or_else(std::sync::PoisonError::into_inner);
+    if state.topology_conflict {
+        return false;
+    }
+    state.proof.as_ref().is_some_and(|current| {
+        current.topology_fingerprint == *expected_topology
+            && current.topology_fingerprint == proof.topology_fingerprint
+            && Arc::ptr_eq(&current.peer_epochs, &proof.peer_epochs)
+            && Instant::now() < current.expires_at
+    })
+}
+
+fn remote_version_state_fleet_proof_valid_at(
+    proof: Option<&RemoteVersionStateFleetProof>,
+    expected_topology: &str,
+    now: Instant,
+) -> bool {
+    proof.is_some_and(|proof| proof.topology_fingerprint == expected_topology && now < proof.expires_at)
+}
+
+fn insert_remote_version_state_peer(peer_epochs: &mut BTreeMap<String, Uuid>, peer: String, epoch: Uuid) -> Result<()> {
+    if epoch.is_nil() || peer_epochs.values().any(|existing| *existing == epoch) || peer_epochs.insert(peer, epoch).is_some() {
+        return Err(Error::other("remote version state capability peer identity is invalid"));
+    }
+    Ok(())
+}
+
+pub fn start_remote_version_state_fleet_probe(topology_fingerprint: String) {
+    if REMOTE_VERSION_STATE_PROBE_TOPOLOGY.set(topology_fingerprint.clone()).is_err() {
+        if REMOTE_VERSION_STATE_PROBE_TOPOLOGY.get() != Some(&topology_fingerprint) {
+            let mut state = remote_version_state_fleet_proof_slot()
+                .write()
+                .unwrap_or_else(std::sync::PoisonError::into_inner);
+            state.topology_conflict = true;
+            state.proof = None;
+        }
+        return;
+    }
+
+    tokio::spawn(async move {
+        loop {
+            let result = match get_global_notification_sys() {
+                Some(notification_sys) => {
+                    match timeout(
+                        REMOTE_VERSION_STATE_PROBE_TIMEOUT,
+                        notification_sys.probe_remote_version_state_fleet(&topology_fingerprint),
+                    )
+                    .await
+                    {
+                        Ok(result) => result,
+                        Err(_) => Err(Error::other("remote version state fleet capability probe timed out")),
+                    }
+                }
+                None => Err(Error::other("remote version state fleet capability notification system is unavailable")),
+            };
+            let topology_conflict = remote_version_state_fleet_proof_slot()
+                .read()
+                .unwrap_or_else(std::sync::PoisonError::into_inner)
+                .topology_conflict;
+            if topology_conflict {
+                replace_remote_version_state_fleet_proof(None);
+            } else if let Some(err) = publish_remote_version_state_probe_result(
+                remote_version_state_fleet_proof_slot(),
+                &topology_fingerprint,
+                result,
+                Instant::now(),
+            ) {
+                debug!(error = %err, "remote version state fleet capability probe failed closed");
+            }
+            sleep(REMOTE_VERSION_STATE_PROBE_INTERVAL).await;
+        }
+    });
+}
+
 pub async fn new_global_notification_sys(eps: EndpointServerPools) -> Result<()> {
     let _ = GLOBAL_NOTIFICATION_SYS
         .set(Arc::new(NotificationSys::new(eps).await))
@@ -115,7 +292,17 @@ pub struct NotificationSys {
 
 impl NotificationSys {
     pub async fn new(eps: EndpointServerPools) -> Self {
+        let expected_remote_hosts = eps
+            .peer_grid_host_slots_sorted()
+            .into_iter()
+            .filter_map(|(peer, _, is_local)| (!is_local).then_some(peer))
+            .collect::<Vec<_>>();
         let (peer_clients, all_peer_clients, peer_topology_hosts) = PeerRestClient::new_clients_with_topology(eps).await;
+        let peer_topology_hosts = if peer_topology_hosts.is_empty() {
+            expected_remote_hosts
+        } else {
+            peer_topology_hosts
+        };
         let peer_admin_caches = (0..peer_clients.len()).map(|_| Mutex::new(PeerAdminCache::new())).collect();
         Self {
             peer_clients,
@@ -125,6 +312,24 @@ impl NotificationSys {
             tier_config_reload_workers: Default::default(),
         }
     }
+
+    async fn probe_remote_version_state_fleet(&self, topology_fingerprint: &str) -> Result<BTreeMap<String, Uuid>> {
+        if self.peer_clients.len() != self.peer_topology_hosts.len() {
+            return Err(Error::other("remote version state capability fleet membership is incomplete"));
+        }
+        let probes = self.peer_clients.iter().map(|client| async {
+            let client = client
+                .as_ref()
+                .ok_or_else(|| Error::other("remote version state capability peer is unreachable"))?;
+            client.probe_remote_version_state(topology_fingerprint.to_string()).await
+        });
+        let mut peer_epochs = BTreeMap::new();
+        for result in join_all(probes).await {
+            let (peer, epoch) = result?;
+            insert_remote_version_state_peer(&mut peer_epochs, peer, epoch)?;
+        }
+        Ok(peer_epochs)
+    }
 }
 
 pub struct NotificationPeerErr {
@@ -1890,6 +2095,183 @@ fn aggregate_scanner_dirty_usage_acknowledgement_results(
 mod tests {
     use super::*;
 
+    #[test]
+    fn remote_version_state_fleet_proof_rejects_stale_or_mismatched_membership() {
+        let now = Instant::now();
+        let mut peer_epochs = BTreeMap::new();
+        peer_epochs.insert("peer-a".to_string(), Uuid::new_v4());
+        let proof = RemoteVersionStateFleetProof {
+            topology_fingerprint: "topology-a".to_string(),
+            peer_epochs: Arc::new(peer_epochs),
+            expires_at: now + Duration::from_secs(1),
+        };
+
+        assert!(remote_version_state_fleet_proof_valid_at(Some(&proof), "topology-a", now));
+        assert!(!remote_version_state_fleet_proof_valid_at(Some(&proof), "topology-b", now));
+        assert!(!remote_version_state_fleet_proof_valid_at(Some(&proof), "topology-a", proof.expires_at));
+        assert!(!remote_version_state_fleet_proof_valid_at(None, "topology-a", now));
+    }
+
+    #[test]
+    fn remote_version_state_fleet_proof_rejects_nil_process_epoch() {
+        let mut peer_epochs = BTreeMap::new();
+
+        assert!(insert_remote_version_state_peer(&mut peer_epochs, "peer-a".to_string(), Uuid::nil()).is_err());
+        assert!(peer_epochs.is_empty());
+    }
+
+    #[test]
+    fn remote_version_state_fleet_proof_accepts_single_node_membership() {
+        let now = Instant::now();
+        let proof = RemoteVersionStateFleetProof {
+            topology_fingerprint: "topology-a".to_string(),
+            peer_epochs: Arc::new(BTreeMap::new()),
+            expires_at: now + Duration::from_secs(1),
+        };
+
+        assert!(remote_version_state_fleet_proof_valid_at(Some(&proof), "topology-a", now));
+    }
+
+    #[test]
+    fn remote_version_state_fleet_proof_token_changes_with_process_epoch() {
+        let now = Instant::now();
+        let proof = RemoteVersionStateFleetProof {
+            topology_fingerprint: "topology-a".to_string(),
+            peer_epochs: Arc::new(BTreeMap::from([("peer-a".to_string(), Uuid::new_v4())])),
+            expires_at: now + Duration::from_secs(1),
+        };
+        let captured = proof.token();
+        let restarted = RemoteVersionStateFleetProof {
+            topology_fingerprint: proof.topology_fingerprint.clone(),
+            peer_epochs: Arc::new(BTreeMap::from([("peer-a".to_string(), Uuid::new_v4())])),
+            expires_at: proof.expires_at,
+        };
+
+        assert!(captured != restarted.token());
+    }
+
+    #[test]
+    fn remote_version_state_fleet_proof_renewal_preserves_only_same_epoch_token() {
+        let slot = std::sync::RwLock::new(RemoteVersionStateFleetProofState::default());
+        let now = Instant::now();
+        let epoch = Uuid::new_v4();
+        let peers = BTreeMap::from([("peer-a".to_string(), epoch)]);
+        assert!(publish_remote_version_state_probe_result(&slot, "topology-a", Ok(peers.clone()), now).is_none());
+        let original = slot
+            .read()
+            .expect("proof slot should not poison")
+            .proof
+            .as_ref()
+            .expect("successful probe should publish proof")
+            .token();
+
+        assert!(
+            publish_remote_version_state_probe_result(&slot, "topology-a", Ok(peers), now + Duration::from_millis(1)).is_none()
+        );
+        let renewed = slot
+            .read()
+            .expect("proof slot should not poison")
+            .proof
+            .as_ref()
+            .expect("renewal should retain proof")
+            .token();
+        assert!(Arc::ptr_eq(&original.peer_epochs, &renewed.peer_epochs));
+
+        let restarted = BTreeMap::from([("peer-a".to_string(), Uuid::new_v4())]);
+        assert!(
+            publish_remote_version_state_probe_result(&slot, "topology-a", Ok(restarted), now + Duration::from_millis(2))
+                .is_none()
+        );
+        let replaced = slot
+            .read()
+            .expect("proof slot should not poison")
+            .proof
+            .as_ref()
+            .expect("restarted peer should publish a new proof")
+            .token();
+        assert!(!Arc::ptr_eq(&original.peer_epochs, &replaced.peer_epochs));
+    }
+
+    #[test]
+    fn remote_version_state_fleet_proof_conflict_revokes_atomic_snapshot() {
+        let now = Instant::now();
+        let mut state = RemoteVersionStateFleetProofState {
+            proof: Some(RemoteVersionStateFleetProof {
+                topology_fingerprint: "topology-a".to_string(),
+                peer_epochs: Arc::new(BTreeMap::new()),
+                expires_at: now + Duration::from_secs(1),
+            }),
+            topology_conflict: false,
+        };
+        assert!(acquire_remote_version_state_fleet_proof_from(&state, "topology-a", now).is_some());
+
+        state.topology_conflict = true;
+        assert!(acquire_remote_version_state_fleet_proof_from(&state, "topology-a", now).is_none());
+    }
+
+    #[test]
+    fn remote_version_state_fleet_probe_rejects_duplicate_member_or_process_epoch() {
+        let epoch = Uuid::new_v4();
+        let mut peer_epochs = BTreeMap::new();
+        insert_remote_version_state_peer(&mut peer_epochs, "node-a:9000".to_string(), epoch)
+            .expect("first member should be admitted");
+        assert!(insert_remote_version_state_peer(&mut peer_epochs, "node-b:9000".to_string(), epoch).is_err());
+        assert!(insert_remote_version_state_peer(&mut peer_epochs, "node-a:9000".to_string(), Uuid::new_v4()).is_err());
+        assert!(insert_remote_version_state_peer(&mut peer_epochs, "node-c:9000".to_string(), Uuid::nil()).is_err());
+    }
+
+    #[test]
+    fn remote_version_state_fleet_probe_failure_revokes_previous_proof() {
+        let slot = std::sync::RwLock::new(RemoteVersionStateFleetProofState::default());
+        let now = Instant::now();
+        let peer_epochs = BTreeMap::from([("node-a:9000".to_string(), Uuid::new_v4())]);
+        assert!(publish_remote_version_state_probe_result(&slot, "topology-a", Ok(peer_epochs), now).is_none());
+        assert!(slot.read().expect("proof slot should not poison").proof.is_some());
+
+        assert!(
+            publish_remote_version_state_probe_result(&slot, "topology-a", Err(Error::other("peer unavailable")), now,).is_some()
+        );
+        assert!(slot.read().expect("proof slot should not poison").proof.is_none());
+
+        let peer_epochs = BTreeMap::from([("node-a:9000".to_string(), Uuid::new_v4())]);
+        assert!(publish_remote_version_state_probe_result(&slot, "topology-a", Ok(peer_epochs), now).is_none());
+        assert!(slot.read().expect("proof slot should not poison").proof.is_some());
+    }
+
+    #[tokio::test]
+    async fn remote_version_state_fleet_probe_rejects_unreachable_member() {
+        let notification_sys = 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 err = notification_sys
+            .probe_remote_version_state_fleet("topology-a")
+            .await
+            .expect_err("an unreachable configured member must fail the fleet proof");
+        assert!(err.to_string().contains("unreachable"));
+    }
+
+    #[tokio::test]
+    async fn remote_version_state_fleet_probe_rejects_missing_member_slot() {
+        let notification_sys = 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 err = notification_sys
+            .probe_remote_version_state_fleet("topology-a")
+            .await
+            .expect_err("a missing configured member slot must fail the fleet proof");
+        assert!(err.to_string().contains("incomplete"));
+    }
+
     fn build_props(endpoint: &str) -> ServerProperties {
         ServerProperties {
             endpoint: endpoint.to_string(),

crates/ecstore/src/services/tier/tier.rs

@@ -236,6 +236,7 @@ struct TierPublishTransition {
 
 struct PreparedTierDriver {
     tier_name: String,
+    tier_config: TierConfig,
     config_fingerprint: TierDriverFingerprint,
     backend_identity: TierDestinationId,
     exact_get_delete: bool,
@@ -1342,6 +1343,7 @@ fn tier_exact_get_delete(config: &TierConfig) -> bool {
 
 struct TierDriverGeneration {
     tier_name: Arc<str>,
+    tier_config: TierConfig,
     generation: DriverRevision,
     // Process-local only: this may reflect credential changes and must never be persisted or logged.
     config_fingerprint: TierDriverFingerprint,
@@ -1349,6 +1351,9 @@ struct TierDriverGeneration {
     backend_identity: TierDestinationId,
     exact_get_delete: bool,
     driver: SharedWarmBackend,
+    reconciler: tokio::sync::OnceCell<
+        Option<Arc<dyn crate::services::tier::warm_backend::TransitionCandidateReconciler + Send + Sync + 'static>>,
+    >,
     accepting: AtomicBool,
     active_leases: AtomicUsize,
     drained: tokio::sync::Notify,
@@ -1473,6 +1478,35 @@ impl TierOperationLease {
         self.inner.backend_identity
     }
 
+    pub(crate) async fn probe_transition_candidate_for(
+        &self,
+        object: &str,
+        transaction_id: uuid::Uuid,
+    ) -> io::Result<TransitionCandidateProbe> {
+        let Some(reconciler) = self
+            .inner
+            .reconciler
+            .get_or_try_init(|| async {
+                crate::services::tier::warm_backend::new_transition_candidate_reconciler(&self.inner.tier_config)
+                    .await
+                    .map(|reconciler| reconciler.map(Arc::from))
+            })
+            .await
+            .map_err(|err| io::Error::other(err.message))?
+        else {
+            return self.inner.driver.probe_transition_candidate(object).await;
+        };
+        reconciler
+            .probe_transition_candidate_for(
+                object,
+                crate::services::tier::warm_backend::TransitionCandidateIdentity {
+                    transaction_id,
+                    destination_id: self.backend_identity(),
+                },
+            )
+            .await
+    }
+
     pub(crate) fn validate_remote_version_id(&self, remote_version_id: &str) -> io::Result<()> {
         self.inner.driver.validate_remote_version_id(remote_version_id)?;
         if !remote_version_id.is_empty() && !self.inner.exact_get_delete {
@@ -2833,6 +2867,7 @@ impl TierConfigMgr {
                     let exact_get_delete = tier_exact_get_delete(config);
                     Some(PreparedTierDriver {
                         tier_name: tier_name.to_string(),
+                        tier_config: config.clone(),
                         config_fingerprint,
                         backend_identity,
                         exact_get_delete,
@@ -2861,11 +2896,13 @@ impl TierConfigMgr {
             })?;
             let entry = Arc::new(TierDriverGeneration {
                 tier_name: Arc::from(prepared.tier_name.as_str()),
+                tier_config: prepared.tier_config.clone(),
                 generation,
                 config_fingerprint: prepared.config_fingerprint,
                 backend_identity: prepared.backend_identity,
                 exact_get_delete: prepared.exact_get_delete,
                 driver: prepared.driver.clone(),
+                reconciler: tokio::sync::OnceCell::new(),
                 accepting: AtomicBool::new(true),
                 active_leases: AtomicUsize::new(0),
                 drained: tokio::sync::Notify::new(),
@@ -3609,11 +3646,13 @@ impl TierConfigMgr {
         let driver: SharedWarmBackend = Arc::from(driver);
         let entry = Arc::new(TierDriverGeneration {
             tier_name: Arc::from(tier_name),
+            tier_config: config.clone(),
             generation,
             config_fingerprint,
             backend_identity,
             exact_get_delete,
             driver: driver.clone(),
+            reconciler: tokio::sync::OnceCell::new(),
             accepting: AtomicBool::new(true),
             active_leases: AtomicUsize::new(0),
             drained: tokio::sync::Notify::new(),

crates/ecstore/src/services/tier/warm_backend.rs

@@ -73,6 +73,21 @@ pub enum TransitionCandidateProbe {
     Unsupported,
 }
 
+#[derive(Clone, Copy)]
+pub(crate) struct TransitionCandidateIdentity {
+    pub transaction_id: uuid::Uuid,
+    pub destination_id: [u8; 32],
+}
+
+#[async_trait::async_trait]
+pub(crate) trait TransitionCandidateReconciler {
+    async fn probe_transition_candidate_for(
+        &self,
+        object: &str,
+        identity: TransitionCandidateIdentity,
+    ) -> Result<TransitionCandidateProbe, std::io::Error>;
+}
+
 #[async_trait::async_trait]
 pub trait WarmBackend {
     async fn validate(&self) -> Result<(), std::io::Error> {
@@ -189,6 +204,20 @@ pub fn build_transition_put_options(storage_class: String, mut metadata: HashMap
         metadata.remove(key);
     }
 
+    for suffix in [
+        rustfs_utils::http::metadata_compat::SUFFIX_TRANSITION_TRANSACTION_ID,
+        rustfs_utils::http::metadata_compat::SUFFIX_TRANSITION_TIER_DESTINATION_ID,
+    ] {
+        for key in [
+            rustfs_utils::http::metadata_compat::internal_key_rustfs(suffix),
+            format!("{}{}", rustfs_utils::http::metadata_compat::MINIO_INTERNAL_PREFIX, suffix),
+        ] {
+            if let Some(value) = metadata.remove(&key) {
+                metadata.insert(format!("x-amz-meta-{key}"), value);
+            }
+        }
+    }
+
     opts.user_metadata = metadata;
     opts
 }
@@ -446,6 +475,51 @@ pub async fn new_warm_backend(tier: &TierConfig, probe: bool) -> Result<WarmBack
     Ok(d)
 }
 
+pub(crate) async fn new_transition_candidate_reconciler(
+    tier: &TierConfig,
+) -> Result<Option<Box<dyn TransitionCandidateReconciler + Send + Sync + 'static>>, AdminError> {
+    let reconciler: Box<dyn TransitionCandidateReconciler + Send + Sync + 'static> = match tier.tier_type {
+        TierType::S3 => Box::new(
+            WarmBackendS3::new(tier.s3.as_ref().ok_or_else(|| ERR_TIER_INVALID_CONFIG.clone())?, &tier.name)
+                .await
+                .map_err(|err| {
+                    let mut admin_err = ERR_TIER_INVALID_CONFIG.clone();
+                    admin_err.message = err.to_string();
+                    admin_err
+                })?,
+        ),
+        TierType::MinIO => Box::new(
+            WarmBackendMinIO::new(tier.minio.as_ref().ok_or_else(|| ERR_TIER_INVALID_CONFIG.clone())?, &tier.name)
+                .await
+                .map_err(|err| {
+                    let mut admin_err = ERR_TIER_INVALID_CONFIG.clone();
+                    admin_err.message = err.to_string();
+                    admin_err
+                })?,
+        ),
+        TierType::RustFS => Box::new(
+            WarmBackendRustFS::new(tier.rustfs.as_ref().ok_or_else(|| ERR_TIER_INVALID_CONFIG.clone())?, &tier.name)
+                .await
+                .map_err(|err| {
+                    let mut admin_err = ERR_TIER_INVALID_CONFIG.clone();
+                    admin_err.message = err.to_string();
+                    admin_err
+                })?,
+        ),
+        TierType::R2 => Box::new(
+            WarmBackendR2::new(tier.r2.as_ref().ok_or_else(|| ERR_TIER_INVALID_CONFIG.clone())?, &tier.name)
+                .await
+                .map_err(|err| {
+                    let mut admin_err = ERR_TIER_INVALID_CONFIG.clone();
+                    admin_err.message = err.to_string();
+                    admin_err
+                })?,
+        ),
+        _ => return Ok(None),
+    };
+    Ok(Some(reconciler))
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
@@ -775,6 +849,37 @@ mod tests {
         assert!(!opts.user_metadata.contains_key(X_AMZ_REPLICATION_STATUS.as_str()));
     }
 
+    #[test]
+    fn build_transition_put_options_persists_both_candidate_identity_keys_as_s3_metadata() {
+        let mut metadata = HashMap::new();
+        rustfs_utils::http::metadata_compat::insert_str(
+            &mut metadata,
+            rustfs_utils::http::metadata_compat::SUFFIX_TRANSITION_TRANSACTION_ID,
+            "aaaaaaaa-aaaa-4aaa-8aaa-aaaaaaaaaaaa".to_string(),
+        );
+        rustfs_utils::http::metadata_compat::insert_str(
+            &mut metadata,
+            rustfs_utils::http::metadata_compat::SUFFIX_TRANSITION_TIER_DESTINATION_ID,
+            "5a".repeat(32),
+        );
+
+        let opts = build_transition_put_options("COLD".to_string(), metadata);
+
+        for suffix in [
+            rustfs_utils::http::metadata_compat::SUFFIX_TRANSITION_TRANSACTION_ID,
+            rustfs_utils::http::metadata_compat::SUFFIX_TRANSITION_TIER_DESTINATION_ID,
+        ] {
+            assert!(opts.user_metadata.contains_key(&format!(
+                "x-amz-meta-{}",
+                rustfs_utils::http::metadata_compat::internal_key_rustfs(suffix)
+            )));
+            assert!(opts.user_metadata.contains_key(&format!(
+                "x-amz-meta-{}{suffix}",
+                rustfs_utils::http::metadata_compat::MINIO_INTERNAL_PREFIX
+            )));
+        }
+    }
+
     #[test]
     fn build_transition_put_options_requests_no_checksum_and_content_md5() {
         // Regression for rustfs/rustfs#4811: transition uploads must leave the

crates/ecstore/src/services/tier/warm_backend_minio.rs

@@ -135,6 +135,20 @@ impl WarmBackend for WarmBackendMinIO {
     }
 }
 
+#[async_trait::async_trait]
+impl crate::services::tier::warm_backend::TransitionCandidateReconciler for WarmBackendMinIO {
+    async fn probe_transition_candidate_for(
+        &self,
+        object: &str,
+        identity: crate::services::tier::warm_backend::TransitionCandidateIdentity,
+    ) -> Result<TransitionCandidateProbe, std::io::Error> {
+        crate::services::tier::warm_backend::TransitionCandidateReconciler::probe_transition_candidate_for(
+            &self.0, object, identity,
+        )
+        .await
+    }
+}
+
 fn optimal_part_size(object_size: i64) -> Result<i64, std::io::Error> {
     let mut object_size = object_size;
     if object_size == -1 {

crates/ecstore/src/services/tier/warm_backend_r2.rs

@@ -135,6 +135,20 @@ impl WarmBackend for WarmBackendR2 {
     }
 }
 
+#[async_trait::async_trait]
+impl crate::services::tier::warm_backend::TransitionCandidateReconciler for WarmBackendR2 {
+    async fn probe_transition_candidate_for(
+        &self,
+        object: &str,
+        identity: crate::services::tier::warm_backend::TransitionCandidateIdentity,
+    ) -> Result<TransitionCandidateProbe, std::io::Error> {
+        crate::services::tier::warm_backend::TransitionCandidateReconciler::probe_transition_candidate_for(
+            &self.0, object, identity,
+        )
+        .await
+    }
+}
+
 fn optimal_part_size(object_size: i64) -> Result<i64, std::io::Error> {
     let mut object_size = object_size;
     if object_size == -1 {

crates/ecstore/src/services/tier/warm_backend_rustfs.rs

@@ -132,6 +132,20 @@ impl WarmBackend for WarmBackendRustFS {
     }
 }
 
+#[async_trait::async_trait]
+impl crate::services::tier::warm_backend::TransitionCandidateReconciler for WarmBackendRustFS {
+    async fn probe_transition_candidate_for(
+        &self,
+        object: &str,
+        identity: crate::services::tier::warm_backend::TransitionCandidateIdentity,
+    ) -> Result<TransitionCandidateProbe, std::io::Error> {
+        crate::services::tier::warm_backend::TransitionCandidateReconciler::probe_transition_candidate_for(
+            &self.0, object, identity,
+        )
+        .await
+    }
+}
+
 fn optimal_part_size(object_size: i64) -> Result<i64, std::io::Error> {
     let mut object_size = object_size;
     if object_size == -1 {

crates/ecstore/src/services/tier/warm_backend_s3.rs

@@ -37,7 +37,10 @@ use crate::error::ErrorResponse;
 use crate::error::error_resp_to_object_err;
 use crate::services::tier::{
     tier_config::TierS3,
-    warm_backend::{TransitionCandidateProbe, WarmBackend, WarmBackendGetOpts, build_transition_put_options},
+    warm_backend::{
+        TransitionCandidateIdentity, TransitionCandidateProbe, TransitionCandidateReconciler, WarmBackend, WarmBackendGetOpts,
+        build_transition_put_options,
+    },
 };
 use http::HeaderMap;
 use rustfs_utils::egress::validate_outbound_url;
@@ -219,6 +222,92 @@ impl WarmBackendS3 {
             advance_version_markers(&mut key_marker, &mut version_id_marker, &versions)?;
         }
     }
+
+    async fn probe_transition_candidate_identity(
+        &self,
+        object: &str,
+        identity: TransitionCandidateIdentity,
+        bucket_versioning: RemoteBucketVersioning,
+    ) -> Result<TransitionCandidateProbe, std::io::Error> {
+        let remote_object = self.get_dest(object);
+        let mut opts = ListObjectsOptions::default();
+        opts.set("prefix", &remote_object);
+        opts.set("max-keys", "1000");
+        let mut key_marker = String::new();
+        let mut version_id_marker = String::new();
+        let mut matched_version = None;
+        let mut saw_unproven_candidate = false;
+
+        loop {
+            let versions = self
+                .client
+                .list_object_versions_query(&self.bucket, &opts, &key_marker, &version_id_marker, "")
+                .await?;
+            for version in versions.versions.iter().filter(|version| version.key == remote_object) {
+                let mut stat_opts = GetObjectOptions::default();
+                stat_opts.version_id.clone_from(&version.version_id);
+                let info = self.client.stat_object(&self.bucket, &remote_object, &stat_opts).await?;
+                let mut metadata = info.user_metadata;
+                for (name, value) in &info.metadata {
+                    if (name
+                        .as_str()
+                        .starts_with(rustfs_utils::http::metadata_compat::RUSTFS_INTERNAL_PREFIX)
+                        || name
+                            .as_str()
+                            .starts_with(rustfs_utils::http::metadata_compat::MINIO_INTERNAL_PREFIX))
+                        && let Ok(value) = value.to_str()
+                    {
+                        metadata.insert(name.as_str().to_string(), value.to_string());
+                    }
+                }
+                if transition_candidate_metadata_matches(&metadata, identity)? {
+                    if matched_version.is_some() {
+                        return Ok(TransitionCandidateProbe::Ambiguous);
+                    }
+                    matched_version = Some(version.version_id.clone());
+                } else {
+                    saw_unproven_candidate = true;
+                }
+            }
+            if !versions.is_truncated {
+                if matched_version.is_none() && saw_unproven_candidate {
+                    return Ok(TransitionCandidateProbe::Unsupported);
+                }
+                let candidates = TransitionCandidateVersions {
+                    version_id: matched_version,
+                    ambiguous: false,
+                };
+                return classify_transition_candidates(candidates, bucket_versioning);
+            }
+            advance_version_markers(&mut key_marker, &mut version_id_marker, &versions)?;
+        }
+    }
+}
+
+fn transition_candidate_metadata_matches(
+    metadata: &HashMap<String, String>,
+    identity: TransitionCandidateIdentity,
+) -> Result<bool, std::io::Error> {
+    use rustfs_utils::http::metadata_compat::{
+        SUFFIX_TRANSITION_TIER_DESTINATION_ID, SUFFIX_TRANSITION_TRANSACTION_ID, contains_key_str, get_consistent_str,
+    };
+
+    let transaction_id = get_consistent_str(metadata, SUFFIX_TRANSITION_TRANSACTION_ID);
+    let destination_id = get_consistent_str(metadata, SUFFIX_TRANSITION_TIER_DESTINATION_ID);
+    if transaction_id.is_none() || destination_id.is_none() {
+        if contains_key_str(metadata, SUFFIX_TRANSITION_TRANSACTION_ID)
+            || contains_key_str(metadata, SUFFIX_TRANSITION_TIER_DESTINATION_ID)
+        {
+            return Err(std::io::Error::new(
+                std::io::ErrorKind::InvalidData,
+                "transition candidate identity metadata is empty or conflicting",
+            ));
+        }
+        return Ok(false);
+    }
+    let expected_transaction_id = identity.transaction_id.to_string();
+    let expected_destination_id = rustfs_utils::crypto::hex(identity.destination_id);
+    Ok(transaction_id == Some(expected_transaction_id.as_str()) && destination_id == Some(expected_destination_id.as_str()))
 }
 
 fn classify_transition_candidates(
@@ -342,6 +431,60 @@ mod tests {
         candidates.classify(bucket_versioning)
     }
 
+    fn candidate_identity() -> TransitionCandidateIdentity {
+        TransitionCandidateIdentity {
+            transaction_id: uuid::Uuid::parse_str("aaaaaaaa-aaaa-4aaa-8aaa-aaaaaaaaaaaa").unwrap(),
+            destination_id: [0x5a; 32],
+        }
+    }
+
+    fn candidate_metadata(identity: TransitionCandidateIdentity) -> HashMap<String, String> {
+        let mut metadata = HashMap::new();
+        rustfs_utils::http::metadata_compat::insert_str(
+            &mut metadata,
+            rustfs_utils::http::metadata_compat::SUFFIX_TRANSITION_TRANSACTION_ID,
+            identity.transaction_id.to_string(),
+        );
+        rustfs_utils::http::metadata_compat::insert_str(
+            &mut metadata,
+            rustfs_utils::http::metadata_compat::SUFFIX_TRANSITION_TIER_DESTINATION_ID,
+            rustfs_utils::crypto::hex(identity.destination_id),
+        );
+        metadata
+    }
+
+    #[test]
+    fn transition_candidate_identity_requires_exact_compatible_metadata() {
+        let identity = candidate_identity();
+        let metadata = candidate_metadata(identity);
+        assert!(transition_candidate_metadata_matches(&metadata, identity).unwrap());
+
+        let mut adjacent = metadata;
+        rustfs_utils::http::metadata_compat::insert_str(
+            &mut adjacent,
+            rustfs_utils::http::metadata_compat::SUFFIX_TRANSITION_TRANSACTION_ID,
+            uuid::Uuid::parse_str("bbbbbbbb-bbbb-4bbb-8bbb-bbbbbbbbbbbb")
+                .unwrap()
+                .to_string(),
+        );
+        assert!(!transition_candidate_metadata_matches(&adjacent, identity).unwrap());
+
+        assert!(!transition_candidate_metadata_matches(&HashMap::new(), identity).unwrap());
+    }
+
+    #[test]
+    fn transition_candidate_identity_rejects_conflicting_compatibility_keys() {
+        let identity = candidate_identity();
+        let mut metadata = candidate_metadata(identity);
+        metadata.insert(
+            rustfs_utils::http::metadata_compat::internal_key_rustfs(
+                rustfs_utils::http::metadata_compat::SUFFIX_TRANSITION_TRANSACTION_ID,
+            ),
+            uuid::Uuid::new_v4().to_string(),
+        );
+        assert!(transition_candidate_metadata_matches(&metadata, identity).is_err());
+    }
+
     #[test]
     fn transition_candidate_probe_classifier_is_fail_closed() {
         assert_eq!(
@@ -503,3 +646,16 @@ impl WarmBackend for WarmBackendS3 {
         Ok(result.common_prefixes.len() > 0 || result.contents.len() > 0)
     }
 }
+
+#[async_trait::async_trait]
+impl TransitionCandidateReconciler for WarmBackendS3 {
+    async fn probe_transition_candidate_for(
+        &self,
+        object: &str,
+        identity: TransitionCandidateIdentity,
+    ) -> Result<TransitionCandidateProbe, std::io::Error> {
+        let bucket_versioning = self.remote_bucket_versioning().await?;
+        self.probe_transition_candidate_identity(object, identity, bucket_versioning)
+            .await
+    }
+}

crates/ecstore/src/set_disk/ops/multipart.rs

@@ -3379,85 +3379,98 @@ mod tests {
     #[tokio::test(flavor = "multi_thread")]
     #[serial]
     async fn complete_holds_object_then_upload_lock_through_commit() {
-        temp_env::async_with_vars([(crate::object_api::ENV_RUSTFS_ENCRYPTED_RANGE_SEEK, Some("true"))], async {
-            let manager = Arc::new(rustfs_lock::GlobalLockManager::new());
-            let signaling = Arc::new(SignalingLockClient::new(Arc::new(LocalClient::with_manager(manager))));
-            let lockers: Vec<Arc<dyn LockClient>> = vec![signaling.clone()];
-            let (_temp_dirs, disk_stores, set_disks) = hermetic_set_disks_with_lockers(4, 0, 2, lockers).await;
-            let bucket = "multipart-layout-lock-order-bucket";
-            let object = "object";
-            make_bucket_on_all(&disk_stores, bucket).await;
-            let create_opts = ObjectOptions {
-                user_defined: HashMap::from([(SSEC_ALGORITHM_HEADER.to_string(), "AES256".to_string())]),
-                ..Default::default()
-            };
-            let (upload_id, parts) = stage_upload_with_create_opts(&set_disks, bucket, object, &[0x43; 4096], &create_opts).await;
-            let upload_id_path = SetDisks::get_upload_id_dir(bucket, object, &upload_id);
-            let upload_resource = rustfs_lock::ObjectKey::new(RUSTFS_META_MULTIPART_BUCKET, upload_id_path);
-            let object_resource = rustfs_lock::ObjectKey::new(bucket, object);
-            signaling.set_target(upload_resource.clone());
-            signaling.clear_observed();
-            let _setup_type_guard = SetupTypeGuard::switch_to(SetupType::DistErasure).await;
-            let barrier = MultipartCommitBarrier::install(bucket, object, MultipartCommitPause::AfterRename);
+        temp_env::async_with_vars(
+            [
+                (crate::object_api::ENV_RUSTFS_ENCRYPTED_RANGE_SEEK, Some("true")),
+                (rustfs_config::ENV_OBJECT_LOCK_ACQUIRE_TIMEOUT, Some("60")),
+            ],
+            async {
+                let manager = Arc::new(rustfs_lock::GlobalLockManager::new());
+                let signaling = Arc::new(SignalingLockClient::new(Arc::new(LocalClient::with_manager(manager))));
+                let lockers: Vec<Arc<dyn LockClient>> = vec![signaling.clone()];
+                let (_temp_dirs, disk_stores, set_disks) = hermetic_set_disks_with_lockers(4, 0, 2, lockers).await;
+                let bucket = "multipart-layout-lock-order-bucket";
+                let object = "object";
+                make_bucket_on_all(&disk_stores, bucket).await;
+                let create_opts = ObjectOptions {
+                    user_defined: HashMap::from([(SSEC_ALGORITHM_HEADER.to_string(), "AES256".to_string())]),
+                    ..Default::default()
+                };
+                let (upload_id, parts) =
+                    stage_upload_with_create_opts(&set_disks, bucket, object, &[0x43; 4096], &create_opts).await;
+                let upload_id_path = SetDisks::get_upload_id_dir(bucket, object, &upload_id);
+                let upload_resource = rustfs_lock::ObjectKey::new(RUSTFS_META_MULTIPART_BUCKET, upload_id_path);
+                let object_resource = rustfs_lock::ObjectKey::new(bucket, object);
+                signaling.set_target(upload_resource.clone());
+                signaling.clear_observed();
+                let _setup_type_guard = SetupTypeGuard::switch_to(SetupType::DistErasure).await;
+                let barrier = MultipartCommitBarrier::install(bucket, object, MultipartCommitPause::AfterRename);
 
-            let complete_store = set_disks.clone();
-            let complete_upload_id = upload_id.clone();
-            let complete = tokio::spawn(async move {
-                complete_store
-                    .complete_multipart_upload(bucket, object, &complete_upload_id, parts, &ObjectOptions::default())
+                let complete_store = set_disks.clone();
+                let complete_upload_id = upload_id.clone();
+                let complete = tokio::spawn(async move {
+                    complete_store
+                        .complete_multipart_upload(bucket, object, &complete_upload_id, parts, &ObjectOptions::default())
+                        .await
+                });
+                barrier.wait_until_paused().await;
+
+                let observed = signaling.observed();
+                let object_position = observed
+                    .iter()
+                    .position(|resource| resource == &object_resource)
+                    .expect("completion should acquire the object lock");
+                let upload_position = observed
+                    .iter()
+                    .position(|resource| resource == &upload_resource)
+                    .expect("completion should acquire the upload lock");
+                assert!(object_position < upload_position, "completion must acquire object before upload");
+
+                let abort_store = set_disks.clone();
+                let abort_upload_id = upload_id.clone();
+                let abort = tokio::spawn(async move {
+                    abort_store
+                        .abort_multipart_upload(bucket, object, &abort_upload_id, &ObjectOptions::default())
+                        .await
+                });
+                signaling.wait_for_attempts(2).await;
+                tokio::task::yield_now().await;
+                assert!(!abort.is_finished(), "abort must wait until completion releases the upload lock");
+
+                let list_store = set_disks.clone();
+                let list_upload_id = upload_id.clone();
+                let list = tokio::spawn(async move {
+                    list_store
+                        .list_object_parts(bucket, object, &list_upload_id, None, MAX_PARTS_COUNT, &ObjectOptions::default())
+                        .await
+                });
+                signaling.wait_for_attempts(3).await;
+                tokio::task::yield_now().await;
+                assert!(!list.is_finished(), "ListParts must wait until completion releases the upload lock");
+
+                barrier.release();
+                complete
                     .await
-            });
-            barrier.wait_until_paused().await;
-
-            let observed = signaling.observed();
-            let object_position = observed
-                .iter()
-                .position(|resource| resource == &object_resource)
-                .expect("completion should acquire the object lock");
-            let upload_position = observed
-                .iter()
-                .position(|resource| resource == &upload_resource)
-                .expect("completion should acquire the upload lock");
-            assert!(object_position < upload_position, "completion must acquire object before upload");
-
-            let abort_store = set_disks.clone();
-            let abort_upload_id = upload_id.clone();
-            let abort = tokio::spawn(async move {
-                abort_store
-                    .abort_multipart_upload(bucket, object, &abort_upload_id, &ObjectOptions::default())
+                    .expect("completion task should not panic")
+                    .expect("completion should commit after the barrier is released");
+                let abort_err = abort
                     .await
-            });
-            signaling.wait_for_attempts(2).await;
-            tokio::task::yield_now().await;
-            assert!(!abort.is_finished(), "abort must wait until completion releases the upload lock");
-
-            let list_store = set_disks.clone();
-            let list_upload_id = upload_id.clone();
-            let list = tokio::spawn(async move {
-                list_store
-                    .list_object_parts(bucket, object, &list_upload_id, None, MAX_PARTS_COUNT, &ObjectOptions::default())
+                    .expect("abort task should not panic")
+                    .expect_err("the committed upload should no longer exist when abort acquires the lock");
+                assert!(
+                    matches!(abort_err, StorageError::InvalidUploadID(..)),
+                    "abort should return InvalidUploadID after completion, got {abort_err:?}"
+                );
+                let list_err = list
                     .await
-            });
-            signaling.wait_for_attempts(3).await;
-            tokio::task::yield_now().await;
-            assert!(!list.is_finished(), "ListParts must wait until completion releases the upload lock");
-
-            barrier.release();
-            complete
-                .await
-                .expect("completion task should not panic")
-                .expect("completion should commit after the barrier is released");
-            let abort_err = abort
-                .await
-                .expect("abort task should not panic")
-                .expect_err("the committed upload should no longer exist when abort acquires the lock");
-            assert!(matches!(abort_err, StorageError::InvalidUploadID(..)));
-            let list_err = list
-                .await
-                .expect("ListParts task should not panic")
-                .expect_err("the committed upload should no longer exist when ListParts acquires the lock");
-            assert!(matches!(list_err, StorageError::InvalidUploadID(..)));
-        })
+                    .expect("ListParts task should not panic")
+                    .expect_err("the committed upload should no longer exist when ListParts acquires the lock");
+                assert!(
+                    matches!(list_err, StorageError::InvalidUploadID(..)),
+                    "ListParts should return InvalidUploadID after completion, got {list_err:?}"
+                );
+            },
+        )
         .await;
     }
 

crates/ecstore/src/set_disk/ops/object.rs

@@ -2320,13 +2320,25 @@ async fn pause_transition_commit(bucket: &str, object: &str, pause: TransitionCo
     }
 }
 
+#[cfg(test)]
 fn persisted_transition_version(
     remote_version: &str,
 ) -> std::io::Result<(Option<String>, rustfs_filemeta::TransitionVersionState)> {
     persisted_transition_version_with_gate(remote_version, remote_version_state_writer_enabled())
 }
 
+#[cfg(test)]
 fn remote_version_state_writer_enabled() -> bool {
+    remote_version_state_writer_fleet_proof().is_some()
+}
+
+fn remote_version_state_writer_fleet_proof() -> Option<crate::services::notification_sys::RemoteVersionStateFleetProofToken> {
+    remote_version_state_writer_requested()
+        .then(crate::services::notification_sys::acquire_remote_version_state_fleet_proof)
+        .flatten()
+}
+
+fn remote_version_state_writer_requested() -> bool {
     remote_version_state_writer_enabled_for(
         rustfs_utils::get_env_bool(
             rustfs_config::ENV_TIER_REMOTE_VERSION_STATE_WRITE,
@@ -2336,11 +2348,25 @@ fn remote_version_state_writer_enabled() -> bool {
             rustfs_config::ENV_TIER_REMOTE_VERSION_STATE_FLEET_CONFIRMED,
             rustfs_config::DEFAULT_TIER_REMOTE_VERSION_STATE_FLEET_CONFIRMED,
         ),
+        true,
     )
 }
 
-fn remote_version_state_writer_enabled_for(requested: bool, fleet_confirmed: bool) -> bool {
-    requested && fleet_confirmed
+fn remote_version_state_writer_fleet_proof_matches(
+    proof: &crate::services::notification_sys::RemoteVersionStateFleetProofToken,
+) -> bool {
+    remote_version_state_writer_fleet_proof_matches_for(
+        remote_version_state_writer_requested(),
+        crate::services::notification_sys::remote_version_state_fleet_proof_matches(proof),
+    )
+}
+
+fn remote_version_state_writer_fleet_proof_matches_for(requested: bool, fleet_proof_matches: bool) -> bool {
+    requested && fleet_proof_matches
+}
+
+fn remote_version_state_writer_enabled_for(requested: bool, fleet_confirmed: bool, fleet_proof_valid: bool) -> bool {
+    requested && fleet_confirmed && fleet_proof_valid
 }
 
 fn persisted_transition_version_with_gate(
@@ -2359,7 +2385,7 @@ fn persisted_transition_version_with_gate(
         Ok(_) => Ok((Some(remote_version.to_string()), rustfs_filemeta::TransitionVersionState::Exact)),
         Err(_) if !remote_version_state_writer_enabled => Err(std::io::Error::new(
             std::io::ErrorKind::Unsupported,
-            "opaque remote tier versions require the operator-attested fleet gate",
+            "opaque remote tier versions require the operator-attested live fleet capability gate",
         )),
         Err(_) if remote_version == "null" => {
             Ok((Some(remote_version.to_string()), rustfs_filemeta::TransitionVersionState::SuspendedNull))
@@ -2605,7 +2631,7 @@ mod transition_upload_completion_tests {
 mod transition_version_id_tests {
     use super::{
         TransitionUploadCandidate, persisted_transition_version, persisted_transition_version_with_gate,
-        remote_version_state_writer_enabled_for,
+        remote_version_state_writer_enabled_for, remote_version_state_writer_fleet_proof_matches_for,
     };
     use rustfs_filemeta::TransitionVersionState;
     use uuid::Uuid;
@@ -2648,15 +2674,35 @@ mod transition_version_id_tests {
 
     #[test]
     fn remote_version_state_writer_requires_request_and_fleet_confirmation() {
-        for (case, requested, fleet_confirmed, expected) in [
-            ("old defaults", false, false, false),
-            ("missing fleet confirmation", true, false, false),
-            ("missing local opt-in", false, true, false),
-            ("explicitly unconfirmed fleet", true, false, false),
-            ("rolled-back writer", false, true, false),
-            ("fully upgraded fleet", true, true, true),
+        for (case, requested, fleet_confirmed, fleet_proof_valid, expected) in [
+            ("old defaults", false, false, false, false),
+            ("missing fleet confirmation", true, false, true, false),
+            ("missing local opt-in", false, true, true, false),
+            ("missing fleet proof", true, true, false, false),
+            ("explicitly unconfirmed fleet", true, false, true, false),
+            ("rolled-back writer", false, true, true, false),
+            ("fully upgraded fleet", true, true, true, true),
         ] {
-            assert_eq!(remote_version_state_writer_enabled_for(requested, fleet_confirmed), expected, "{case}");
+            assert_eq!(
+                remote_version_state_writer_enabled_for(requested, fleet_confirmed, fleet_proof_valid),
+                expected,
+                "{case}"
+            );
+        }
+    }
+
+    #[test]
+    fn remote_version_state_commit_rechecks_operator_gate_and_live_proof() {
+        for (case, requested, fleet_proof_matches, expected) in [
+            ("operator gate closed", false, true, false),
+            ("fleet proof changed", true, false, false),
+            ("current authorization", true, true, true),
+        ] {
+            assert_eq!(
+                remote_version_state_writer_fleet_proof_matches_for(requested, fleet_proof_matches),
+                expected,
+                "{case}"
+            );
         }
     }
 
@@ -3841,6 +3887,16 @@ impl crate::storage_api_contracts::object::ObjectOperations for SetDisks {
         let dest_obj = transaction.remote_object.clone();
         let mut transition_meta = (*oi.user_defined).clone();
         transition_meta.insert("name".to_string(), object.to_string());
+        rustfs_utils::http::metadata_compat::insert_str(
+            &mut transition_meta,
+            rustfs_utils::http::metadata_compat::SUFFIX_TRANSITION_TRANSACTION_ID,
+            transaction.transaction_id.to_string(),
+        );
+        rustfs_utils::http::metadata_compat::insert_str(
+            &mut transition_meta,
+            rustfs_utils::http::metadata_compat::SUFFIX_TRANSITION_TIER_DESTINATION_ID,
+            rustfs_utils::crypto::hex(transaction.backend_fingerprint),
+        );
 
         if let Some(content_type) = oi.content_type.as_ref().filter(|value| !value.is_empty()) {
             transition_meta.insert(CONTENT_TYPE.to_ascii_lowercase(), content_type.clone());
@@ -3951,20 +4007,24 @@ impl crate::storage_api_contracts::object::ObjectOperations for SetDisks {
             delete_transition_transaction_after_remote_cleanup(transaction_api.as_ref(), transaction_id, bucket, object).await;
             return Err(err.into());
         }
-        let (transition_version_id, transition_version_state) = match persisted_transition_version(candidate.remote_version()) {
-            Ok(version) => version,
-            Err(err) => {
-                let cleanup_api = transition_cleanup_store(&self.ctx).await;
-                if let Err(cleanup_err) = upload_cleanup.cleanup_rejected_upload(cleanup_api).await {
-                    return Err(StorageError::Io(std::io::Error::other(format!(
-                        "{err}; rejected remote upload cleanup failed: {cleanup_err}"
-                    ))));
+        let fleet_proof = remote_version_state_writer_fleet_proof();
+        let remote_version_requires_fleet_proof =
+            !candidate.remote_version().is_empty() && Uuid::parse_str(candidate.remote_version()).is_err();
+        let (transition_version_id, transition_version_state) =
+            match persisted_transition_version_with_gate(candidate.remote_version(), fleet_proof.is_some()) {
+                Ok(version) => version,
+                Err(err) => {
+                    let cleanup_api = transition_cleanup_store(&self.ctx).await;
+                    if let Err(cleanup_err) = upload_cleanup.cleanup_rejected_upload(cleanup_api).await {
+                        return Err(StorageError::Io(std::io::Error::other(format!(
+                            "{err}; rejected remote upload cleanup failed: {cleanup_err}"
+                        ))));
+                    }
+                    delete_transition_transaction_after_remote_cleanup(transaction_api.as_ref(), transaction_id, bucket, object)
+                        .await;
+                    return Err(err.into());
                 }
-                delete_transition_transaction_after_remote_cleanup(transaction_api.as_ref(), transaction_id, bucket, object)
-                    .await;
-                return Err(err.into());
-            }
-        };
+            };
         if let Err(err) = advance_and_save_transition_transaction(
             transaction_api.as_ref(),
             &mut transaction,
@@ -4080,6 +4140,21 @@ impl crate::storage_api_contracts::object::ObjectOperations for SetDisks {
         }
         #[cfg(test)]
         pause_transition_commit(bucket, object, TransitionCommitPause::AfterLeaseValidation).await;
+        // This check is the fleet-proof lease linearization point. Revocation
+        // blocks later commits; an already-authorized local quorum commit is
+        // allowed to finish without holding a synchronous lock across I/O.
+        if remote_version_requires_fleet_proof
+            && !fleet_proof
+                .as_ref()
+                .is_some_and(remote_version_state_writer_fleet_proof_matches)
+        {
+            drop(transition_lock_guard);
+            if upload_cleanup.cleanup().await.is_ok() {
+                delete_transition_transaction_after_remote_cleanup(transaction_api.as_ref(), transaction_id, bucket, object)
+                    .await;
+            }
+            return Err(Error::other("remote version state fleet capability changed during transition"));
+        }
         if let Err(err) = advance_and_save_transition_transaction(
             transaction_api.as_ref(),
             &mut transaction,

crates/ecstore/src/store/bucket.rs

@@ -568,6 +568,7 @@ mod tests {
     };
     use crate::bucket::metadata::table_bucket_catalog_metadata_prefix;
     use crate::bucket::metadata_sys;
+    use crate::cluster::rpc::peer_s3_client::install_delete_bucket_empty_scan_barrier;
     use crate::disk::{BUCKET_META_PREFIX, RUSTFS_META_BUCKET};
     use crate::error::StorageError;
     use crate::object_api::{ObjectOptions, PutObjReader};
@@ -589,6 +590,7 @@ mod tests {
     use std::sync::atomic::{AtomicBool, Ordering};
     use std::time::{Duration, SystemTime};
     use time::OffsetDateTime;
+    use tokio::io::AsyncReadExt;
     use tokio::sync::{Notify, OnceCell};
     use tokio_util::sync::CancellationToken;
     use uuid::Uuid;
@@ -1048,7 +1050,7 @@ mod tests {
             .await
             .expect("bucket should be created");
         for disk_path in &disk_paths {
-            tokio::fs::create_dir_all(disk_path.join(&bucket).join("empty-directory"))
+            tokio::fs::create_dir_all(disk_path.join(&bucket).join("empty-directory/nested/leaf"))
                 .await
                 .expect("empty directory remnant should be created");
         }
@@ -1257,6 +1259,55 @@ mod tests {
         );
     }
 
+    #[tokio::test]
+    #[serial]
+    async fn bucket_delete_preserves_put_committed_after_empty_scan() {
+        let (_, ecstore) = setup_bucket_delete_test_env().await;
+        let bucket = format!("bucket-delete-empty-scan-race-{}", Uuid::new_v4().simple());
+        let object = "committed-after-empty-scan";
+        let payload = b"object committed after DeleteBucket empty scan".to_vec();
+
+        ecstore
+            .make_bucket(&bucket, &MakeBucketOptions::default())
+            .await
+            .expect("bucket should be created");
+
+        let barrier = install_delete_bucket_empty_scan_barrier();
+        let delete_store = ecstore.clone();
+        let delete_bucket = bucket.clone();
+        let delete = tokio::spawn(async move {
+            delete_store
+                .delete_bucket(&delete_bucket, &DeleteBucketOptions::default())
+                .await
+        });
+        barrier.wait_until_paused().await;
+
+        let mut put_reader = PutObjReader::from_vec(payload.clone());
+        ecstore
+            .put_object(&bucket, object, &mut put_reader, &ObjectOptions::default())
+            .await
+            .expect("PUT should commit while DeleteBucket is paused after its empty scan");
+
+        barrier.release();
+        let err = delete
+            .await
+            .expect("DeleteBucket task should join")
+            .expect_err("DeleteBucket must reject a PUT committed after its empty scan");
+        assert!(matches!(err, StorageError::BucketNotEmpty(name) if name == bucket));
+
+        let mut reader = ecstore
+            .get_object_reader(&bucket, object, None, http::HeaderMap::new(), &ObjectOptions::default())
+            .await
+            .expect("committed object should remain readable after DeleteBucket fails");
+        let mut restored = Vec::new();
+        reader
+            .stream
+            .read_to_end(&mut restored)
+            .await
+            .expect("object body should remain readable");
+        assert_eq!(restored, payload);
+    }
+
     #[tokio::test]
     #[serial]
     async fn bucket_recreation_does_not_publish_unverified_usage() {

crates/ecstore/src/store/init.rs

@@ -562,10 +562,12 @@ mod tests {
             },
             tier_sweeper::Jentry,
             transition_transaction::{
-                TRANSITION_TRANSACTION_RECORD_PREFIX, TransitionCleanupDecision, TransitionCleanupProof, TransitionRemoteVersion,
-                TransitionSourceIdentity, TransitionSourceVersionMode, TransitionTransaction, TransitionTransactionInit,
-                TransitionTransactionState, load_transition_transaction_record, recover_transition_transaction_records,
-                save_transition_transaction_record,
+                TRANSITION_TRANSACTION_RECORD_PREFIX, TransitionCleanupDecision, TransitionCleanupProof, TransitionOperatorError,
+                TransitionOperatorProbe, TransitionRemoteVersion, TransitionSourceIdentity, TransitionSourceVersionMode,
+                TransitionTransaction, TransitionTransactionInit, TransitionTransactionState,
+                delete_transition_candidate_for_operator, finalize_missing_transition_transaction_for_operator,
+                inspect_transition_transaction_for_operator, load_transition_transaction_record,
+                recover_transition_transaction_records, save_transition_transaction_record,
             },
         },
         client::transition_api::ReaderImpl,
@@ -575,6 +577,7 @@ mod tests {
         services::tier::{
             test_util::{MockWarmBackend, MockWarmOp, TransitionCleanupStoreBarrier, register_mock_tier},
             tier::{TIER_CONFIG_FILE, TierConfigMgr},
+            tier_config::{TierConfig, TierType, TierWasabi},
             tier_mutation_intent::{
                 TIER_MUTATION_INTENT_RECORD_PREFIX, TierMutationIntent, TierMutationIntentKind, TierMutationIntentState,
                 TierMutationIntentTarget, advance_tier_mutation_intent_record_idempotent, delete_tier_mutation_intent_record,
@@ -1163,6 +1166,37 @@ mod tests {
             .len()
     }
 
+    #[cfg(feature = "test-util")]
+    async fn register_transition_reconcile_test_tier(
+        handle: &Arc<tokio::sync::RwLock<TierConfigMgr>>,
+        tier_name: &str,
+    ) -> MockWarmBackend {
+        let backend = MockWarmBackend::new();
+        let mut manager = handle.write().await;
+        manager.tiers.insert(
+            tier_name.to_string(),
+            TierConfig {
+                version: "v1".to_string(),
+                tier_type: TierType::Wasabi,
+                name: tier_name.to_string(),
+                wasabi: Some(TierWasabi {
+                    name: tier_name.to_string(),
+                    endpoint: "https://s3.wasabisys.com".to_string(),
+                    access_key: "test-access-key".to_string(),
+                    secret_key: "test-secret-key".to_string(),
+                    bucket: "mock-tier".to_string(),
+                    prefix: format!("mock/{}/", uuid::Uuid::new_v4()),
+                    region: "us-east-1".to_string(),
+                }),
+                ..Default::default()
+            },
+        );
+        manager
+            .install_test_driver(tier_name, Box::new(backend.clone()))
+            .expect("mock fallback tier driver should install");
+        backend
+    }
+
     #[cfg(feature = "test-util")]
     async fn wait_for_tier_delete_journal_recovery(
         store: Arc<crate::store::ECStore>,
@@ -2738,7 +2772,7 @@ mod tests {
             .await;
             crate::bucket::metadata_sys::init_bucket_metadata_sys(store.clone(), Vec::new()).await;
 
-            let backend = register_mock_tier(&ctx.tier_config_mgr(), tier_name).await;
+            let backend = register_transition_reconcile_test_tier(&ctx.tier_config_mgr(), tier_name).await;
             let backend_identity = TierConfigMgr::acquire_operation_lease(&ctx.tier_config_mgr(), tier_name)
                 .await
                 .expect("tier lease should resolve")
@@ -2809,6 +2843,157 @@ mod tests {
         }
     }
 
+    #[cfg(feature = "test-util")]
+    #[tokio::test]
+    #[serial_test::serial(storage_class_env)]
+    async fn operator_reconcile_deletes_exact_candidate_before_finalizing_record() {
+        let temp_dir = tempfile::tempdir().expect("create temp store dir");
+        let (ctx, store, _shutdown) =
+            without_storage_class_env(build_isolated_test_store(temp_dir.path(), "transition-operator-reconcile", &[4])).await;
+        crate::bucket::metadata_sys::init_bucket_metadata_sys(store.clone(), Vec::new()).await;
+
+        let tier_name = "TXOPERATOR";
+        let backend = register_transition_reconcile_test_tier(&ctx.tier_config_mgr(), tier_name).await;
+        let backend_identity = TierConfigMgr::acquire_operation_lease(&ctx.tier_config_mgr(), tier_name)
+            .await
+            .expect("tier lease should resolve")
+            .backend_identity();
+        let mut transaction = TransitionTransaction::new(TransitionTransactionInit {
+            deployment_id: ctx.deployment_id().expect("test store should initialize deployment id"),
+            transaction_id: uuid::Uuid::new_v4(),
+            owner_epoch: uuid::Uuid::new_v4(),
+            write_id: uuid::Uuid::new_v4(),
+            source: TransitionSourceIdentity {
+                bucket: "source-bucket".to_string(),
+                object: "source-object".to_string(),
+                version_id: None,
+                data_dir: uuid::Uuid::new_v4(),
+                mod_time_unix_nanos: 1_770_000_000_000_000_000,
+                size: 42,
+                etag: "source-etag".to_string(),
+                version_mode: TransitionSourceVersionMode::Unversioned,
+            },
+            tier_name: tier_name.to_string(),
+            backend_fingerprint: backend_identity,
+            not_after_unix_nanos: 1,
+        })
+        .expect("transaction should build");
+        transaction
+            .advance(transaction.fence(), TransitionTransactionState::UploadOutcomeUnknown, None)
+            .expect("transaction should enter unknown upload outcome state");
+
+        let remote_version = uuid::Uuid::new_v4().to_string();
+        backend.set_put_remote_version(Some(remote_version.clone())).await;
+        let candidate = bytes::Bytes::from_static(b"operator-confirmed transition candidate");
+        backend
+            .put(
+                &transaction.remote_object,
+                ReaderImpl::Body(candidate.clone()),
+                i64::try_from(candidate.len()).expect("test candidate length should fit i64"),
+            )
+            .await
+            .expect("mock backend should accept candidate");
+        save_transition_transaction_record(store.clone(), &transaction)
+            .await
+            .expect("transaction record should persist");
+
+        let status = inspect_transition_transaction_for_operator(store.clone(), transaction.transaction_id)
+            .await
+            .expect("operator inspection should probe the candidate");
+        assert_eq!(status.probe, TransitionOperatorProbe::VersionedPresent(remote_version.clone()));
+
+        let wrong_version = uuid::Uuid::new_v4().to_string();
+        let err = delete_transition_candidate_for_operator(store.clone(), transaction.transaction_id, &wrong_version)
+            .await
+            .expect_err("a mismatched exact version must fail before deleting a candidate");
+        assert!(matches!(
+            err,
+            TransitionOperatorError::CandidateVersionMismatch {
+                expected,
+                actual: TransitionOperatorProbe::VersionedPresent(ref observed),
+            } if expected == wrong_version && observed == &remote_version
+        ));
+        assert!(backend.contains(&transaction.remote_object).await);
+        assert_eq!(backend.exact_remove_count(), 0);
+        load_transition_transaction_record(store.clone(), transaction.transaction_id)
+            .await
+            .expect("an incorrect exact version must retain the transaction journal");
+
+        let result = delete_transition_candidate_for_operator(store.clone(), transaction.transaction_id, &remote_version)
+            .await
+            .expect("operator-confirmed exact candidate should be deleted");
+        assert_eq!(result.status.probe, TransitionOperatorProbe::Missing);
+        assert!(result.journal_observed_after_delete);
+        assert_eq!(backend.exact_remove_count(), 1);
+        assert_eq!(backend.remove_versions().await, vec![(transaction.remote_object.clone(), remote_version)]);
+        load_transition_transaction_record(store.clone(), transaction.transaction_id)
+            .await
+            .expect("candidate deletion must retain the transaction journal");
+
+        finalize_missing_transition_transaction_for_operator(store.clone(), transaction.transaction_id)
+            .await
+            .expect("a separately confirmed missing candidate should permit finalization");
+        assert!(matches!(
+            load_transition_transaction_record(store, transaction.transaction_id).await,
+            Err(Error::ConfigNotFound)
+        ));
+    }
+
+    #[cfg(feature = "test-util")]
+    #[tokio::test]
+    #[serial_test::serial(storage_class_env)]
+    async fn operator_finalize_retains_record_without_missing_proof() {
+        let temp_dir = tempfile::tempdir().expect("create temp store dir");
+        let (ctx, store, _shutdown) =
+            without_storage_class_env(build_isolated_test_store(temp_dir.path(), "transition-operator-fail-closed", &[4])).await;
+        crate::bucket::metadata_sys::init_bucket_metadata_sys(store.clone(), Vec::new()).await;
+
+        let tier_name = "TXOPERATORFAIL";
+        let backend = register_transition_reconcile_test_tier(&ctx.tier_config_mgr(), tier_name).await;
+        let backend_identity = TierConfigMgr::acquire_operation_lease(&ctx.tier_config_mgr(), tier_name)
+            .await
+            .expect("tier lease should resolve")
+            .backend_identity();
+        let mut transaction = TransitionTransaction::new(TransitionTransactionInit {
+            deployment_id: ctx.deployment_id().expect("test store should initialize deployment id"),
+            transaction_id: uuid::Uuid::new_v4(),
+            owner_epoch: uuid::Uuid::new_v4(),
+            write_id: uuid::Uuid::new_v4(),
+            source: TransitionSourceIdentity {
+                bucket: "source-bucket".to_string(),
+                object: "source-object".to_string(),
+                version_id: None,
+                data_dir: uuid::Uuid::new_v4(),
+                mod_time_unix_nanos: 1_770_000_000_000_000_000,
+                size: 42,
+                etag: "source-etag".to_string(),
+                version_mode: TransitionSourceVersionMode::Unversioned,
+            },
+            tier_name: tier_name.to_string(),
+            backend_fingerprint: backend_identity,
+            not_after_unix_nanos: 1,
+        })
+        .expect("transaction should build");
+        transaction
+            .advance(transaction.fence(), TransitionTransactionState::UploadOutcomeUnknown, None)
+            .expect("transaction should enter unknown upload outcome state");
+        save_transition_transaction_record(store.clone(), &transaction)
+            .await
+            .expect("transaction record should persist");
+        backend
+            .set_transition_candidate_probe_override(Some(TransitionCandidateProbe::Unsupported))
+            .await;
+
+        assert!(matches!(
+            finalize_missing_transition_transaction_for_operator(store.clone(), transaction.transaction_id).await,
+            Err(TransitionOperatorError::CandidateNotMissing(TransitionOperatorProbe::Unsupported))
+        ));
+        load_transition_transaction_record(store, transaction.transaction_id)
+            .await
+            .expect("an unsupported probe must retain the transaction journal");
+        assert_eq!(backend.remove_count().await, 0);
+    }
+
     #[cfg(feature = "test-util")]
     #[tokio::test]
     #[serial_test::serial(storage_class_env)]
@@ -2819,7 +3004,7 @@ mod tests {
         crate::bucket::metadata_sys::init_bucket_metadata_sys(store.clone(), Vec::new()).await;
 
         let tier_name = "TXRESPONSELOSS";
-        let backend = register_mock_tier(&ctx.tier_config_mgr(), tier_name).await;
+        let backend = register_transition_reconcile_test_tier(&ctx.tier_config_mgr(), tier_name).await;
         let bucket = "transition-response-loss-bucket";
         let object = "source.bin";
         store

crates/ecstore/src/store/list_objects.rs

@@ -6895,6 +6895,7 @@ mod test {
         )
         .await
         .expect("local disk should be created");
+        disk.make_volume("bucket").await.expect("test bucket should be created");
         let mut fi = FileInfo::new("object", 1, 1);
         fi.volume = "bucket".to_owned();
         fi.name = "object".to_owned();

crates/ecstore/src/test_tracing.rs

@@ -0,0 +1,43 @@
+//! Test-only guard against tracing's process-global callsite-interest cache.
+//!
+//! Any test that installs its own subscriber and then asserts on span or event
+//! context is asserting on process-global state. See
+//! [`pin_callsite_interest_for_test`] for what goes wrong and why holding its
+//! guard fixes it.
+
+/// Stop a sibling test thread from poisoning tracing's process-global callsite
+/// interest cache while this test asserts on span or event context.
+///
+/// `tracing` caches every callsite's `Interest` in **process-global** state, and
+/// the first thread to reach a callsite fixes that value. While at most one
+/// dispatcher is registered, tracing-core takes a fast path
+/// (`Dispatchers::rebuilder` -> `Rebuilder::JustOne`) that derives a
+/// newly-registered callsite's interest from whichever subscriber is current
+/// *on the registering thread*, and registration happens exactly once (guarded
+/// by a CAS in `DefaultCallsite::register`).
+///
+/// In a multi-threaded `cargo test` binary a sibling test therefore routinely
+/// reaches a production callsite first, from a thread with no subscriber
+/// installed: the interest is derived from that thread's `NoSubscriber` and
+/// cached as `Interest::never()` for the whole process. From then on the
+/// callsite is dead for *every* later caller, including a test that installed
+/// its own subscriber — an `info_span!` silently evaluates to `Span::none()`, and
+/// a `warn!`/`info!` event never fires at all.
+///
+/// Registering a second, inert dispatcher closes both halves of that race:
+///
+/// * constructing it rebuilds every *already-registered* callsite's interest
+///   against the live dispatcher set — which includes the caller's subscriber —
+///   repairing whatever a sibling may already have poisoned; and
+/// * holding it alive keeps tracing-core off the single-dispatcher fast path, so
+///   a callsite registered *later* by any thread is resolved against that live
+///   set instead of the registering thread's `NoSubscriber`.
+///
+/// Call this **after** installing the test's subscriber, and hold the returned
+/// guard for the rest of the test. Only the `cargo test` fallback needs it:
+/// nextest runs each test in its own process, where there is no sibling thread
+/// to lose the race to (see `docs/testing/README.md`).
+#[must_use = "callsite interest is only pinned while the returned guard is held"]
+pub(crate) fn pin_callsite_interest_for_test() -> tracing::Dispatch {
+    tracing::Dispatch::new(tracing_core::subscriber::NoSubscriber::default())
+}

crates/io-metrics/src/internode_metrics.rs

@@ -67,6 +67,7 @@ const INTERNODE_MSGPACK_JSON_FALLBACK_TOTAL: &str = "rustfs_system_network_inter
 const INTERNODE_MSGPACK_JSON_DECODE_ERROR_TOTAL: &str = "rustfs_system_network_internode_msgpack_json_decode_error_total";
 const INTERNODE_SIGNATURE_V1_FALLBACK_TOTAL: &str = "rustfs_system_network_internode_signature_v1_fallback_total";
 const INTERNODE_BODY_DIGEST_FALLBACK_TOTAL: &str = "rustfs_system_network_internode_body_digest_fallback_total";
+const INTERNODE_REPLAY_SCOPE_FALLBACK_TOTAL: &str = "rustfs_system_network_internode_replay_scope_fallback_total";
 const INTERNODE_REPLAY_CACHE_OVERFLOW_TOTAL: &str = "rustfs_system_network_internode_replay_cache_overflow_total";
 const ERASURE_WRITE_QUORUM_FAILURES_TOTAL: &str = "rustfs_system_storage_erasure_write_quorum_failures_total";
 
@@ -159,6 +160,7 @@ pub struct InternodeMetricsSnapshot {
     pub operation_write_shutdown_errors_total: u64,
     pub signature_v1_fallback_total: u64,
     pub body_digest_fallback_total: u64,
+    pub replay_scope_fallback_total: u64,
     pub replay_cache_overflow_total: u64,
 }
 
@@ -180,6 +182,7 @@ pub struct InternodeMetrics {
     msgpack_json_decode_error_total: AtomicU64,
     signature_v1_fallback_total: AtomicU64,
     body_digest_fallback_total: AtomicU64,
+    replay_scope_fallback_total: AtomicU64,
     replay_cache_overflow_total: AtomicU64,
 }
 
@@ -431,6 +434,13 @@ impl InternodeMetrics {
         counter!(INTERNODE_BODY_DIGEST_FALLBACK_TOTAL).increment(1);
     }
 
+    /// Count an accepted v1/v2 request that does not carry the replay-scoped signature. This is
+    /// the convergence signal for `RUSTFS_INTERNODE_RPC_REPLAY_SCOPE_STRICT`.
+    pub fn record_replay_scope_fallback(&self) {
+        self.replay_scope_fallback_total.fetch_add(1, Ordering::Relaxed);
+        counter!(INTERNODE_REPLAY_SCOPE_FALLBACK_TOTAL).increment(1);
+    }
+
     /// Count a body-bound internode RPC rejected because the replay-protection nonce cache was
     /// full. Overflow fails closed, so a sustained non-zero rate means
     /// `RUSTFS_INTERNODE_RPC_REPLAY_CACHE_CAPACITY` is undersized for this node's peak legitimate
@@ -488,6 +498,7 @@ impl InternodeMetrics {
             operation_write_shutdown_errors_total: self.operation_write_shutdown_errors_total.load(Ordering::Relaxed),
             signature_v1_fallback_total: self.signature_v1_fallback_total.load(Ordering::Relaxed),
             body_digest_fallback_total: self.body_digest_fallback_total.load(Ordering::Relaxed),
+            replay_scope_fallback_total: self.replay_scope_fallback_total.load(Ordering::Relaxed),
             replay_cache_overflow_total: self.replay_cache_overflow_total.load(Ordering::Relaxed),
         }
     }
@@ -510,6 +521,7 @@ impl InternodeMetrics {
         self.msgpack_json_decode_error_total.store(0, Ordering::Relaxed);
         self.signature_v1_fallback_total.store(0, Ordering::Relaxed);
         self.body_digest_fallback_total.store(0, Ordering::Relaxed);
+        self.replay_scope_fallback_total.store(0, Ordering::Relaxed);
         self.replay_cache_overflow_total.store(0, Ordering::Relaxed);
     }
 }
@@ -887,6 +899,19 @@ mod tests {
         assert_eq!(metrics.snapshot().signature_v1_fallback_total, 0);
     }
 
+    #[test]
+    fn replay_scope_fallback_counter_updates_snapshot_and_resets() {
+        let metrics = InternodeMetrics::default();
+        assert_eq!(metrics.snapshot().replay_scope_fallback_total, 0);
+
+        metrics.record_replay_scope_fallback();
+        metrics.record_replay_scope_fallback();
+        assert_eq!(metrics.snapshot().replay_scope_fallback_total, 2);
+
+        metrics.reset_for_test();
+        assert_eq!(metrics.snapshot().replay_scope_fallback_total, 0);
+    }
+
     #[test]
     fn cluster_peer_flips_offline_after_threshold_and_back_online() {
         // Unique addr keeps this independent of the process-global registry / other tests.

crates/protos/src/lib.rs

@@ -171,6 +171,7 @@ pub const HEAL_CONTROL_RPC_MAX_MESSAGE_SIZE: usize = heal_control::RESULT_MAX_SI
 pub const HEAL_CONTROL_PROTOCOL_VERSION: u32 = 2;
 pub const DYNAMIC_CONFIG_PROTOCOL_VERSION: u32 = 1;
 pub const HEAL_CONTROL_CAPABILITY_PROBE_PREFIX: &[u8] = b"rustfs-heal-control-capability-v2\0";
+pub const REMOTE_VERSION_STATE_CAPABILITY_PROBE_PREFIX: &[u8] = b"rustfs-tier-remote-version-state-capability-v1\0";
 pub const TIER_MUTATION_RPC_MAX_PREPARE_PAYLOAD_SIZE: usize = 64 * 1024;
 pub const TIER_MUTATION_RPC_MAX_COMMIT_PAYLOAD_SIZE: usize = 1024;
 pub const TIER_MUTATION_RPC_MAX_MESSAGE_SIZE: usize = TIER_MUTATION_RPC_MAX_PREPARE_PAYLOAD_SIZE + 4096;
@@ -197,6 +198,49 @@ pub fn is_heal_control_capability_probe(command: &[u8]) -> bool {
     command.len() == HEAL_CONTROL_CAPABILITY_PROBE_PREFIX.len() + 16 && command.starts_with(HEAL_CONTROL_CAPABILITY_PROBE_PREFIX)
 }
 
+pub fn remote_version_state_capability_probe(nonce: &[u8; 16]) -> Vec<u8> {
+    let mut probe = Vec::with_capacity(REMOTE_VERSION_STATE_CAPABILITY_PROBE_PREFIX.len() + nonce.len());
+    probe.extend_from_slice(REMOTE_VERSION_STATE_CAPABILITY_PROBE_PREFIX);
+    probe.extend_from_slice(nonce);
+    probe
+}
+
+pub fn is_remote_version_state_capability_probe(command: &[u8]) -> bool {
+    command.len() == REMOTE_VERSION_STATE_CAPABILITY_PROBE_PREFIX.len() + 16
+        && command.starts_with(REMOTE_VERSION_STATE_CAPABILITY_PROBE_PREFIX)
+}
+
+pub fn encode_remote_version_state_capability(
+    topology_member: &str,
+    process_epoch: &[u8; 16],
+) -> Result<Vec<u8>, std::num::TryFromIntError> {
+    let topology_member = topology_member.as_bytes();
+    let mut result = Vec::with_capacity(8 + topology_member.len() + process_epoch.len());
+    result.extend_from_slice(&u64::try_from(topology_member.len())?.to_be_bytes());
+    result.extend_from_slice(topology_member);
+    result.extend_from_slice(process_epoch);
+    Ok(result)
+}
+
+pub fn decode_remote_version_state_capability(result: &[u8]) -> Result<(&str, &[u8; 16]), &'static str> {
+    let member_len = result
+        .get(..8)
+        .and_then(|value| value.try_into().ok())
+        .map(u64::from_be_bytes)
+        .ok_or("remote version state capability is truncated")?;
+    let member_len = usize::try_from(member_len).map_err(|_| "remote version state member length cannot be represented")?;
+    let member_end = 8_usize
+        .checked_add(member_len)
+        .ok_or("remote version state member length overflow")?;
+    let topology_member = std::str::from_utf8(result.get(8..member_end).ok_or("remote version state member is truncated")?)
+        .map_err(|_| "remote version state member is not UTF-8")?;
+    let process_epoch = result
+        .get(member_end..)
+        .and_then(|value| value.try_into().ok())
+        .ok_or("remote version state process epoch has an invalid length")?;
+    Ok((topology_member, process_epoch))
+}
+
 /// Builds the stable byte representation authenticated for a heal-control request.
 ///
 /// This deliberately does not reuse protobuf encoding: mixed-version peers may
@@ -1656,10 +1700,12 @@ mod scanner_activity_tests {
 #[cfg(test)]
 mod heal_control_tests {
     use super::{
-        HEAL_CONTROL_CAPABILITY_PROBE_PREFIX, HEAL_CONTROL_PROTOCOL_VERSION, canonical_heal_control_capability_ack,
-        canonical_heal_control_request_body, canonical_heal_control_response_body, heal_control_capability_probe,
+        HEAL_CONTROL_CAPABILITY_PROBE_PREFIX, HEAL_CONTROL_PROTOCOL_VERSION, REMOTE_VERSION_STATE_CAPABILITY_PROBE_PREFIX,
+        canonical_heal_control_capability_ack, canonical_heal_control_request_body, canonical_heal_control_response_body,
+        decode_remote_version_state_capability, encode_remote_version_state_capability, heal_control_capability_probe,
         heal_control_coordinator_epoch, heal_control_execution_timeout, heal_control_execution_timeout_for,
-        internode_rpc_timeout, is_heal_control_capability_probe, normalize_internode_rpc_timeout,
+        internode_rpc_timeout, is_heal_control_capability_probe, is_remote_version_state_capability_probe,
+        normalize_internode_rpc_timeout, remote_version_state_capability_probe,
     };
     use crate::heal_control;
     use std::time::Duration;
@@ -1716,6 +1762,29 @@ mod heal_control_tests {
         assert!(!is_heal_control_capability_probe(HEAL_CONTROL_CAPABILITY_PROBE_PREFIX));
     }
 
+    #[test]
+    fn remote_version_state_capability_probe_requires_exact_nonce() {
+        let probe = remote_version_state_capability_probe(&[7; 16]);
+        assert!(is_remote_version_state_capability_probe(&probe));
+        assert!(!is_remote_version_state_capability_probe(REMOTE_VERSION_STATE_CAPABILITY_PROBE_PREFIX));
+    }
+
+    #[test]
+    fn remote_version_state_capability_binds_member_and_process_epoch() {
+        let encoded =
+            encode_remote_version_state_capability("node-a:9000", &[7; 16]).expect("small capability response should encode");
+        assert_eq!(
+            decode_remote_version_state_capability(&encoded).expect("capability response should decode"),
+            ("node-a:9000", &[7; 16])
+        );
+        assert!(decode_remote_version_state_capability(&encoded[..encoded.len() - 1]).is_err());
+
+        let mut invalid_utf8 =
+            encode_remote_version_state_capability("node-a", &[7; 16]).expect("small capability response should encode");
+        invalid_utf8[8] = 0xff;
+        assert!(decode_remote_version_state_capability(&invalid_utf8).is_err());
+    }
+
     #[test]
     fn canonical_response_binds_request_and_result() {
         let baseline = canonical_heal_control_response_body(2, "abcdef", b"query", b"result").unwrap();

crates/scanner/src/data_usage_define.rs

@@ -48,6 +48,7 @@ pub const DATA_USAGE_ROOT: &str = SLASH_SEPARATOR;
 const DATA_USAGE_BLOOM_NAME: &str = ".bloomcycle.bin";
 
 pub const DATA_USAGE_CACHE_NAME: &str = ".usage-cache.bin";
+pub(crate) const DATA_USAGE_CACHE_KEY_FORMAT: u16 = 1;
 const DATA_USAGE_CACHE_SAVE_RETRIES: u32 = 2;
 const DATA_USAGE_CACHE_BACKUP_SAVE_TIMEOUT_SECS_MAX: u64 = 5;
 const DATA_USAGE_CACHE_BACKUP_SAVE_RETRIES: u32 = 0;
@@ -437,6 +438,8 @@ pub struct DataUsageCacheInfo {
     pub snapshot_complete: bool,
     #[serde(default)]
     pub scan_plan_digest: Option<DataUsageScanPlanDigest>,
+    #[serde(default)]
+    pub cache_key_format: u16,
 }
 
 impl Serialize for DataUsageCacheInfo {
@@ -446,7 +449,7 @@ impl Serialize for DataUsageCacheInfo {
     {
         // Keep this metadata map-encoded so older readers can ignore fields
         // appended by newer scanner versions during rolling upgrades.
-        let mut state = serializer.serialize_map(Some(15))?;
+        let mut state = serializer.serialize_map(Some(16))?;
         state.serialize_entry("name", &self.name)?;
         state.serialize_entry("next_cycle", &self.next_cycle)?;
         state.serialize_entry("leader_epoch", &self.leader_epoch)?;
@@ -462,6 +465,7 @@ impl Serialize for DataUsageCacheInfo {
         state.serialize_entry("source", &self.source)?;
         state.serialize_entry("snapshot_complete", &self.snapshot_complete)?;
         state.serialize_entry("scan_plan_digest", &self.scan_plan_digest)?;
+        state.serialize_entry("cache_key_format", &self.cache_key_format)?;
         state.end()
     }
 }
@@ -500,19 +504,34 @@ impl DataUsageCache {
 
         let source_matches = self.info.source == Some(source);
         let plan_matches = self.info.scan_plan_digest == Some(scan_plan_digest);
-        let reusable = self.info.name == name
+        let metadata_is_reusable = self.info.name == name
             && self.info.leader_epoch == leader_epoch
             && plan_matches
-            && (source_matches || (!require_source && self.info.source.is_none()));
+            && (source_matches || (!require_source && self.info.source.is_none()))
+            && self.info.cache_key_format == DATA_USAGE_CACHE_KEY_FORMAT;
+        let reusable = metadata_is_reusable
+            && (self.cache.is_empty()
+                || if name == DATA_USAGE_ROOT || self.info.snapshot_complete {
+                    self.checked_flatten_complete_scope(name).is_some()
+                } else {
+                    self.checked_flatten(name).is_some()
+                });
         if !reusable {
+            let pending_heals = if self.info.name == name {
+                std::mem::take(&mut self.info.pending_heals)
+            } else {
+                Vec::new()
+            };
             *self = Self::default();
             self.info.name = name.to_string();
+            self.info.pending_heals = pending_heals;
         }
 
         self.info.next_cycle = next_cycle;
         self.info.leader_epoch = leader_epoch;
         self.info.source = Some(source);
         self.info.scan_plan_digest = Some(scan_plan_digest);
+        self.info.cache_key_format = DATA_USAGE_CACHE_KEY_FORMAT;
         self.info.snapshot_complete = false;
         if reusable {
             DataUsageCachePrepareOutcome::Reused
@@ -576,36 +595,60 @@ impl DataUsageCache {
     }
 
     pub(crate) fn checked_flatten(&self, path: &str) -> Option<DataUsageEntry> {
+        self.checked_flatten_inner(path).map(|(entry, _)| entry)
+    }
+
+    pub(crate) fn checked_flatten_complete(&self, path: &str) -> Option<DataUsageEntry> {
+        self.checked_flatten_inner(path)
+            .filter(|(_, visited)| *visited == self.cache.len())
+            .map(|(entry, _)| entry)
+    }
+
+    pub(crate) fn checked_flatten_complete_scope(&self, path: &str) -> Option<DataUsageEntry> {
+        if path == DATA_USAGE_ROOT {
+            return self.checked_flatten_complete(path);
+        }
+        let (entry, visited) = self.checked_flatten_inner(path)?;
+        let root_parent_only = {
+            let path_key = hash_path(path).key();
+            self.cache
+                .get(DATA_USAGE_ROOT)
+                .is_some_and(|root| root_is_parent_only(root, &path_key))
+        };
+        let expected_entries = self.cache.len().saturating_sub(usize::from(root_parent_only));
+        (visited == expected_entries).then_some(entry)
+    }
+
+    fn checked_flatten_inner(&self, path: &str) -> Option<(DataUsageEntry, usize)> {
         let root_key = hash_path(path).key();
-        let root = self.cache.get(&root_key)?;
-        let mut visited = HashSet::from([root_key]);
-        let mut pending = root.children.iter().map(|child| (child.clone(), 1usize)).collect::<Vec<_>>();
+        let (root_key, root) = self.cache.get_key_value(&root_key)?;
+        if root.compacted && !root.children.is_empty() {
+            return None;
+        }
+        let mut visited = HashSet::from([root_key.as_str()]);
+        let mut pending = root.children.iter().map(|child| (child.as_str(), 1usize)).collect::<Vec<_>>();
         let mut flattened = DataUsageEntry::default();
-        let mut root_entry = root.clone();
-        root_entry.children.clear();
-        if !flattened.checked_merge(&root_entry) {
+        if !flattened.checked_merge(root) {
             return None;
         }
         flattened.compacted = root.compacted;
 
         while let Some((key, depth)) = pending.pop() {
-            if depth > MAX_DATA_USAGE_CACHE_DEPTH || !visited.insert(key.clone()) {
+            if depth > MAX_DATA_USAGE_CACHE_DEPTH || !visited.insert(key) {
                 return None;
             }
-            let entry = self.cache.get(&key)?;
-            if depth == MAX_DATA_USAGE_CACHE_DEPTH && !entry.children.is_empty() {
+            let entry = self.cache.get(key)?;
+            if (entry.compacted || depth == MAX_DATA_USAGE_CACHE_DEPTH) && !entry.children.is_empty() {
                 return None;
             }
-            pending.extend(entry.children.iter().map(|child| (child.clone(), depth + 1)));
+            pending.extend(entry.children.iter().map(|child| (child.as_str(), depth + 1)));
 
-            let mut child_entry = entry.clone();
-            child_entry.children.clear();
-            if !flattened.checked_merge(&child_entry) {
+            if !flattened.checked_merge(entry) {
                 return None;
             }
         }
 
-        Some(flattened)
+        Some((flattened, visited.len()))
     }
 
     fn flatten_with_guard(&self, root: &DataUsageEntry, visited: &mut HashSet<String>, depth: usize) -> DataUsageEntry {
@@ -1524,6 +1567,18 @@ fn mark_with_depth(duc: &DataUsageCache, entry: &DataUsageEntry, found: &mut Has
     }
 }
 
+fn root_is_parent_only(root: &DataUsageEntry, child: &str) -> bool {
+    root.children.len() == 1
+        && root.children.contains(child)
+        && root.size == 0
+        && root.objects == 0
+        && root.versions == 0
+        && root.delete_markers == 0
+        && root.replication_stats.is_none()
+        && !root.compacted
+        && root.failed_objects == 0
+}
+
 /// Trait for storage-specific operations on DataUsageCache
 #[async_trait::async_trait]
 pub trait DataUsageCacheStorage {
@@ -2287,6 +2342,7 @@ mod tests {
         assert!(decoded.source.is_none());
         assert!(!decoded.snapshot_complete);
         assert!(decoded.scan_plan_digest.is_none());
+        assert_eq!(decoded.cache_key_format, 0);
     }
 
     #[test]
@@ -2328,6 +2384,7 @@ mod tests {
         assert!(decoded.source.is_none());
         assert!(!decoded.snapshot_complete);
         assert!(decoded.scan_plan_digest.is_none());
+        assert_eq!(decoded.cache_key_format, 0);
     }
 
     #[test]
@@ -2363,6 +2420,7 @@ mod tests {
                 source: Some(DataUsageCacheSource::new(1, 2)),
                 snapshot_complete: true,
                 scan_plan_digest: Some(TEST_PLAN_DIGEST),
+                cache_key_format: DATA_USAGE_CACHE_KEY_FORMAT,
                 ..Default::default()
             },
             ..Default::default()
@@ -2381,6 +2439,7 @@ mod tests {
         assert_eq!(current.info.source, Some(DataUsageCacheSource::new(1, 2)));
         assert!(current.info.snapshot_complete);
         assert_eq!(current.info.scan_plan_digest, Some(TEST_PLAN_DIGEST));
+        assert_eq!(current.info.cache_key_format, DATA_USAGE_CACHE_KEY_FORMAT);
         assert_eq!(current.find("bucket").map(|entry| entry.objects), Some(3));
 
         let decoded: OldDataUsageCache = rmp_serde::from_slice(&buf).expect("Old reader failed to deserialize new cache");
@@ -2442,6 +2501,7 @@ mod tests {
                 source: Some(source),
                 snapshot_complete: false,
                 scan_plan_digest: Some(TEST_PLAN_DIGEST),
+                cache_key_format: DATA_USAGE_CACHE_KEY_FORMAT,
                 ..Default::default()
             },
             ..Default::default()
@@ -2466,6 +2526,254 @@ mod tests {
         assert!(!cache.info.snapshot_complete);
     }
 
+    #[test]
+    fn data_usage_cache_prepare_for_scan_preserves_pending_heal_only_progress() {
+        let source = DataUsageCacheSource::new(1, 0);
+        let pending_heal = PendingScannerHeal {
+            kind: PendingScannerHealKind::Object,
+            bucket: "bucket".to_string(),
+            object: Some("prefix/object".to_string()),
+            version_id: Some("version-a".to_string()),
+            scan_mode: HealScanMode::Deep,
+            first_seen: 1,
+            last_attempt: 2,
+            attempts: 3,
+            last_admission_result: "full".to_string(),
+            last_admission_reason: "queue_full".to_string(),
+        };
+        let mut cache = DataUsageCache {
+            info: DataUsageCacheInfo {
+                name: "bucket".to_string(),
+                next_cycle: 7,
+                source: Some(source),
+                scan_plan_digest: Some(TEST_PLAN_DIGEST),
+                cache_key_format: DATA_USAGE_CACHE_KEY_FORMAT,
+                pending_heals: vec![pending_heal.clone()],
+                ..Default::default()
+            },
+            ..Default::default()
+        };
+
+        let outcome = cache.prepare_for_scan("bucket", 8, 0, source, TEST_PLAN_DIGEST, true);
+
+        assert_eq!(outcome, DataUsageCachePrepareOutcome::Reused);
+        assert_eq!(cache.info.pending_heals, vec![pending_heal]);
+        assert!(cache.cache.is_empty());
+        assert!(!cache.info.snapshot_complete);
+    }
+
+    #[test]
+    fn data_usage_cache_prepare_for_scan_preserves_namespace_pending_heals_during_key_format_rebuild() {
+        let source = DataUsageCacheSource::new(1, 0);
+        let pending_heal = PendingScannerHeal {
+            kind: PendingScannerHealKind::Object,
+            bucket: "bucket".to_string(),
+            object: Some("prefix/object".to_string()),
+            version_id: Some("version-a".to_string()),
+            scan_mode: HealScanMode::Deep,
+            first_seen: 1,
+            last_attempt: 2,
+            attempts: 3,
+            last_admission_result: "full".to_string(),
+            last_admission_reason: "queue_full".to_string(),
+        };
+        let mut cache = DataUsageCache {
+            info: DataUsageCacheInfo {
+                name: DATA_USAGE_ROOT.to_string(),
+                next_cycle: 7,
+                source: Some(source),
+                scan_plan_digest: Some(TEST_PLAN_DIGEST),
+                pending_heals: vec![pending_heal.clone()],
+                ..Default::default()
+            },
+            ..Default::default()
+        };
+        cache.replace(DATA_USAGE_ROOT, "", DataUsageEntry::default());
+
+        let outcome = cache.prepare_for_scan(DATA_USAGE_ROOT, 8, 0, source, TEST_PLAN_DIGEST, true);
+
+        assert_eq!(outcome, DataUsageCachePrepareOutcome::Reset);
+        assert_eq!(cache.info.pending_heals, vec![pending_heal]);
+        assert!(cache.cache.is_empty());
+        assert_eq!(cache.info.cache_key_format, DATA_USAGE_CACHE_KEY_FORMAT);
+    }
+
+    #[test]
+    fn data_usage_cache_prepare_for_scan_drops_pending_heals_from_a_different_scope() {
+        let source = DataUsageCacheSource::new(1, 0);
+        let mut cache = DataUsageCache {
+            info: DataUsageCacheInfo {
+                name: "old-bucket".to_string(),
+                next_cycle: 7,
+                source: Some(source),
+                scan_plan_digest: Some(TEST_PLAN_DIGEST),
+                pending_heals: vec![PendingScannerHeal {
+                    kind: PendingScannerHealKind::Object,
+                    bucket: "old-bucket".to_string(),
+                    object: Some("prefix/object".to_string()),
+                    version_id: None,
+                    scan_mode: HealScanMode::Normal,
+                    first_seen: 1,
+                    last_attempt: 2,
+                    attempts: 3,
+                    last_admission_result: "full".to_string(),
+                    last_admission_reason: "queue_full".to_string(),
+                }],
+                ..Default::default()
+            },
+            ..Default::default()
+        };
+
+        let outcome = cache.prepare_for_scan("new-bucket", 8, 0, source, TEST_PLAN_DIGEST, true);
+
+        assert_eq!(outcome, DataUsageCachePrepareOutcome::Reset);
+        assert_eq!(cache.info.name, "new-bucket");
+        assert!(cache.info.pending_heals.is_empty());
+    }
+
+    #[test]
+    fn data_usage_cache_prepare_for_scan_resets_unknown_key_format() {
+        let source = DataUsageCacheSource::new(1, 0);
+        let mut cache = DataUsageCache {
+            info: DataUsageCacheInfo {
+                name: "bucket".to_string(),
+                next_cycle: 7,
+                source: Some(source),
+                scan_plan_digest: Some(TEST_PLAN_DIGEST),
+                cache_key_format: DATA_USAGE_CACHE_KEY_FORMAT + 1,
+                ..Default::default()
+            },
+            ..Default::default()
+        };
+        cache.replace(
+            "bucket",
+            "",
+            DataUsageEntry {
+                objects: 3,
+                ..Default::default()
+            },
+        );
+
+        let outcome = cache.prepare_for_scan("bucket", 8, 0, source, TEST_PLAN_DIGEST, true);
+
+        assert_eq!(outcome, DataUsageCachePrepareOutcome::Reset);
+        assert!(cache.cache.is_empty());
+        assert_eq!(cache.info.cache_key_format, DATA_USAGE_CACHE_KEY_FORMAT);
+    }
+
+    #[test]
+    fn data_usage_cache_prepare_for_scan_resets_persisted_windows_key_mismatch() {
+        let source = DataUsageCacheSource::new(1, 0);
+        let root_key = hash_path("bucket").key();
+        let mut cache = DataUsageCache {
+            info: DataUsageCacheInfo {
+                name: "bucket".to_string(),
+                next_cycle: 7,
+                source: Some(source),
+                snapshot_complete: true,
+                scan_plan_digest: Some(TEST_PLAN_DIGEST),
+                ..Default::default()
+            },
+            ..Default::default()
+        };
+        cache.cache.insert(
+            root_key,
+            DataUsageEntry {
+                children: HashSet::from(["bucket/prefix".to_string()]),
+                ..Default::default()
+            },
+        );
+        cache.cache.insert(
+            "bucket\\prefix".to_string(),
+            DataUsageEntry {
+                objects: 3,
+                ..Default::default()
+            },
+        );
+
+        let encoded = cache.marshal_msg().expect("legacy Windows cache should serialize");
+        let mut decoded = DataUsageCache::unmarshal(&encoded).expect("legacy Windows cache should deserialize");
+        let outcome = decoded.prepare_for_scan("bucket", 8, 0, source, TEST_PLAN_DIGEST, true);
+
+        assert_eq!(outcome, DataUsageCachePrepareOutcome::Reset);
+        assert!(decoded.cache.is_empty());
+        assert_eq!(decoded.info.name, "bucket");
+        assert_eq!(decoded.info.next_cycle, 8);
+        assert_eq!(decoded.info.source, Some(source));
+        assert!(!decoded.info.snapshot_complete);
+    }
+
+    #[test]
+    fn data_usage_cache_prepare_for_scan_resets_current_cache_with_dangling_child() {
+        let source = DataUsageCacheSource::new(1, 0);
+        let mut cache = DataUsageCache {
+            info: DataUsageCacheInfo {
+                name: "bucket".to_string(),
+                next_cycle: 7,
+                source: Some(source),
+                scan_plan_digest: Some(TEST_PLAN_DIGEST),
+                cache_key_format: DATA_USAGE_CACHE_KEY_FORMAT,
+                ..Default::default()
+            },
+            ..Default::default()
+        };
+        cache.cache.insert(
+            hash_path("bucket").key(),
+            DataUsageEntry {
+                children: HashSet::from([hash_path("bucket/missing").key()]),
+                ..Default::default()
+            },
+        );
+
+        let outcome = cache.prepare_for_scan("bucket", 8, 0, source, TEST_PLAN_DIGEST, true);
+
+        assert_eq!(outcome, DataUsageCachePrepareOutcome::Reset);
+        assert!(cache.cache.is_empty());
+        assert_eq!(cache.info.cache_key_format, DATA_USAGE_CACHE_KEY_FORMAT);
+    }
+
+    #[test]
+    fn data_usage_cache_prepare_for_scan_resets_complete_bucket_cache_with_detached_entry() {
+        let source = DataUsageCacheSource::new(1, 0);
+        let mut cache = DataUsageCache {
+            info: DataUsageCacheInfo {
+                name: "bucket".to_string(),
+                next_cycle: 7,
+                source: Some(source),
+                snapshot_complete: true,
+                scan_plan_digest: Some(TEST_PLAN_DIGEST),
+                cache_key_format: DATA_USAGE_CACHE_KEY_FORMAT,
+                ..Default::default()
+            },
+            ..Default::default()
+        };
+        cache.cache.insert(
+            hash_path("bucket").key(),
+            DataUsageEntry {
+                objects: 1,
+                ..Default::default()
+            },
+        );
+        cache.cache.insert(
+            hash_path("bucket/detached").key(),
+            DataUsageEntry {
+                objects: 2,
+                ..Default::default()
+            },
+        );
+        assert_eq!(cache.checked_flatten("bucket").map(|entry| entry.objects), Some(1));
+        assert!(
+            cache.checked_flatten_complete("bucket").is_none(),
+            "complete bucket cache reuse must reject detached entries"
+        );
+
+        let outcome = cache.prepare_for_scan("bucket", 8, 0, source, TEST_PLAN_DIGEST, true);
+
+        assert_eq!(outcome, DataUsageCachePrepareOutcome::Reset);
+        assert!(cache.cache.is_empty());
+        assert_eq!(cache.info.cache_key_format, DATA_USAGE_CACHE_KEY_FORMAT);
+    }
+
     #[test]
     fn data_usage_cache_prepare_for_scan_rejects_legacy_cache_without_a_bucket_plan() {
         let source = DataUsageCacheSource::new(0, 0);
@@ -2836,6 +3144,98 @@ mod tests {
         );
     }
 
+    #[test]
+    fn checked_flatten_complete_rejects_detached_entries() {
+        let mut cache = DataUsageCache::default();
+        cache.cache.insert(
+            hash_path("bucket").key(),
+            DataUsageEntry {
+                objects: 1,
+                ..Default::default()
+            },
+        );
+        cache.cache.insert(
+            hash_path("bucket/detached").key(),
+            DataUsageEntry {
+                objects: 2,
+                ..Default::default()
+            },
+        );
+
+        assert_eq!(
+            cache.checked_flatten("bucket").map(|entry| entry.objects),
+            Some(1),
+            "subtree flattening may ignore entries outside the requested subtree"
+        );
+        assert!(
+            cache.checked_flatten_complete("bucket").is_none(),
+            "an authoritative cache root must reach every persisted entry"
+        );
+    }
+
+    #[test]
+    fn checked_flatten_rejects_compacted_entries_with_children() {
+        let root_key = hash_path("bucket").key();
+        let child_key = hash_path("bucket/prefix").key();
+        let mut cache = DataUsageCache::default();
+        cache.cache.insert(
+            root_key,
+            DataUsageEntry {
+                children: HashSet::from([child_key.clone()]),
+                compacted: true,
+                ..Default::default()
+            },
+        );
+        cache.cache.insert(
+            child_key,
+            DataUsageEntry {
+                objects: 1,
+                ..Default::default()
+            },
+        );
+
+        assert!(
+            cache.checked_flatten_complete("bucket").is_none(),
+            "a compacted entry cannot retain child links without double-counting"
+        );
+    }
+
+    #[test]
+    fn checked_flatten_rejects_compacted_descendants_with_children() {
+        let root_key = hash_path("bucket").key();
+        let child_key = hash_path("bucket/prefix").key();
+        let grandchild_key = hash_path("bucket/prefix/object").key();
+        let mut cache = DataUsageCache::default();
+        cache.cache.insert(
+            root_key,
+            DataUsageEntry {
+                children: HashSet::from([child_key.clone()]),
+                ..Default::default()
+            },
+        );
+        cache.cache.insert(
+            child_key,
+            DataUsageEntry {
+                objects: 1,
+                children: HashSet::from([grandchild_key.clone()]),
+                compacted: true,
+                ..Default::default()
+            },
+        );
+        cache.cache.insert(
+            grandchild_key,
+            DataUsageEntry {
+                objects: 1,
+                ..Default::default()
+            },
+        );
+
+        assert!(
+            cache.checked_flatten("bucket").is_none(),
+            "a compacted descendant cannot retain child links without double-counting"
+        );
+    }
+
     #[test]
     fn checked_flatten_accepts_depth_limit_and_rejects_deeper_tree() {
         let root_key = hash_path("bucket").key();

crates/scanner/src/remote_scanner.rs

@@ -14,8 +14,8 @@
 
 use crate::scanner_budget::{ScannerCycleBudget, ScannerCycleBudgetConfig};
 use crate::scanner_io::{
-    ScannerDiskScanOutcome, ScannerIODisk, cache_root_entry_info, cache_snapshot_is_current, scanner_cache_lock_resource,
-    scanner_cache_lock_timeout, scanner_set_disk_inventory,
+    DataUsageCacheScanState, ScannerDiskScanOutcome, ScannerIODisk, cache_root_entry_info, current_cache_root_or_prepare,
+    scanner_cache_lock_resource, scanner_cache_lock_timeout, scanner_set_disk_inventory,
 };
 use crate::storage_api::owner::NS_SCANNER_PROTOCOL_VERSION;
 use crate::storage_api::scan::NamespaceLocking as _;
@@ -966,32 +966,34 @@ async fn scan_and_persist_local_bucket(
     let revisions = cache.load_with_revisions(set.clone(), &cache_name).await.map_err(|err| {
         RemoteScannerServerError::worker(format!("remote namespace scanner cache load or revision lookup failed: {err}"))
     })?;
-    if cache_snapshot_is_current(&cache, &bucket, source, next_cycle, leader_epoch, scan_plan_digest) {
-        if guard.is_lock_lost() {
-            return Err(RemoteScannerServerError::worker(
-                "remote namespace scanner cache lock was lost before reusing the current snapshot",
-            ));
+    let scan_state = current_cache_root_or_prepare(&mut cache, &bucket, source, next_cycle, leader_epoch, scan_plan_digest, true);
+    match scan_state {
+        DataUsageCacheScanState::Current(usage) => {
+            if guard.is_lock_lost() {
+                return Err(RemoteScannerServerError::worker(
+                    "remote namespace scanner cache lock was lost before reusing the current snapshot",
+                ));
+            }
+            return Ok(RemoteScannerFrameResult::Complete(Box::new(RemoteScannerComplete {
+                source,
+                scan_plan_digest,
+                usage: *usage,
+                pending_maintenance_work: !cache.info.pending_heals.is_empty(),
+            })));
         }
-        return Ok(RemoteScannerFrameResult::Complete(Box::new(RemoteScannerComplete {
-            source,
-            scan_plan_digest,
-            usage: cache_root_entry_info(&cache)
-                .map_err(|err| RemoteScannerServerError::worker(format!("remote namespace scanner cache is corrupt: {err}")))?,
-            pending_maintenance_work: !cache.info.pending_heals.is_empty(),
-        })));
-    }
-    match cache.prepare_for_scan(&bucket, next_cycle, leader_epoch, source, scan_plan_digest, true) {
-        DataUsageCachePrepareOutcome::RejectedNewerCycle => {
-            return Ok(RemoteScannerFrameResult::CycleAhead {
-                required_cycle: cache.info.next_cycle,
-            });
-        }
-        DataUsageCachePrepareOutcome::RejectedNewerLeader => {
-            return Err(RemoteScannerServerError::worker(
-                "remote namespace scanner rejected work from an older leader epoch",
-            ));
-        }
-        DataUsageCachePrepareOutcome::Reused | DataUsageCachePrepareOutcome::Reset => {}
+        DataUsageCacheScanState::Prepared { outcome, .. } => match outcome {
+            DataUsageCachePrepareOutcome::RejectedNewerCycle => {
+                return Ok(RemoteScannerFrameResult::CycleAhead {
+                    required_cycle: cache.info.next_cycle,
+                });
+            }
+            DataUsageCachePrepareOutcome::RejectedNewerLeader => {
+                return Err(RemoteScannerServerError::worker(
+                    "remote namespace scanner rejected work from an older leader epoch",
+                ));
+            }
+            DataUsageCachePrepareOutcome::Reused | DataUsageCachePrepareOutcome::Reset => {}
+        },
     }
     cache.info.skip_healing = skip_healing;
 
@@ -1971,6 +1973,7 @@ mod tests {
 
     #[test]
     fn request_rejects_empty_truncated_oversized_and_wrong_version_payloads() {
+        assert_eq!(NS_SCANNER_PROTOCOL_VERSION, 3);
         assert!(decode_remote_scanner_request(&[]).is_err());
 
         let mut body = rmp_serde::to_vec_named(&test_request(Uuid::new_v4())).expect("request should encode");
@@ -1980,7 +1983,7 @@ mod tests {
         let oversized = vec![0_u8; NS_SCANNER_MAX_REQUEST_BODY_SIZE + 1];
         assert!(decode_remote_scanner_request(&oversized).is_err());
 
-        for version in [NS_SCANNER_PROTOCOL_VERSION - 1, NS_SCANNER_PROTOCOL_VERSION + 1] {
+        for version in [2, 4] {
             let mut wrong_version = test_request(Uuid::new_v4());
             wrong_version.version = version;
             let body = rmp_serde::to_vec_named(&wrong_version).expect("request should encode");
@@ -2885,14 +2888,15 @@ mod tests {
 
     #[tokio::test]
     async fn wrong_frame_version_and_sequence_are_rejected() {
+        assert_eq!(NS_SCANNER_PROTOCOL_VERSION, 3);
         let request_id = Uuid::new_v4();
         let auth = FrameAuthenticator::for_test(request_id);
         let frame = RemoteScannerFrame::progress(RemoteScannerProgress::default());
         let payload = rmp_serde::to_vec_named(&frame).expect("frame should encode");
 
         for (version, sequence, expected_error) in [
-            (NS_SCANNER_PROTOCOL_VERSION - 1, 0, "unsupported remote namespace scanner frame version"),
-            (NS_SCANNER_PROTOCOL_VERSION + 1, 0, "unsupported remote namespace scanner frame version"),
+            (2, 0, "unsupported remote namespace scanner frame version"),
+            (4, 0, "unsupported remote namespace scanner frame version"),
             (NS_SCANNER_PROTOCOL_VERSION, 1, "frame sequence is invalid"),
         ] {
             let envelope = RemoteScannerFrameEnvelope {

crates/scanner/src/scanner_folder.rs

@@ -1508,6 +1508,9 @@ impl FolderScanner {
             if entry.children.contains(&child) {
                 continue;
             }
+            if !self.old_cache.cache.contains_key(&child) {
+                continue;
+            }
 
             let child_hash = DataUsageHash(child.clone());
             self.new_cache
@@ -2320,7 +2323,6 @@ impl FolderScanner {
                     }
                     tokio::task::yield_now().await;
 
-                    let h = DataUsageHash(folder_item.name.clone());
                     into.add_child(&h);
                     self.record_scan_resume_hint(&folder_item.name);
                     // We scanned a folder, optionally send update.
@@ -2646,7 +2648,7 @@ impl FolderScanner {
                         tokio::task::yield_now().await;
                     } else {
                         let mut dst = DataUsageEntry::default();
-                        let h = DataUsageHash(folder_item.name.clone());
+                        let h = hash_path(&folder_item.name);
 
                         // Use Box::pin for recursive async call
                         let fut = Box::pin(self.scan_folder(ctx.clone(), folder_item.clone(), &mut dst));
@@ -2911,7 +2913,7 @@ mod tests {
     use serial_test::serial;
     #[cfg(unix)]
     use std::os::unix::fs::{PermissionsExt, symlink};
-    use std::sync::atomic::AtomicBool;
+    use std::sync::atomic::{AtomicBool, AtomicUsize, Ordering};
     use temp_env::{with_var, with_var_unset};
     use uuid::Uuid;
 
@@ -3864,11 +3866,15 @@ mod tests {
     }
 
     async fn write_test_object_metadata(root: &std::path::Path, bucket: &str, object: &str) {
+        write_test_object_metadata_bytes(root, bucket, object, &metadata_for_object(bucket, object)).await;
+    }
+
+    async fn write_test_object_metadata_bytes(root: &std::path::Path, bucket: &str, object: &str, metadata: &[u8]) {
         let object_dir = root.join(bucket).join(object);
         tokio::fs::create_dir_all(&object_dir)
             .await
             .expect("failed to create test object directory");
-        tokio::fs::write(object_dir.join("xl.meta"), metadata_for_object(bucket, object))
+        tokio::fs::write(object_dir.join("xl.meta"), metadata)
             .await
             .expect("failed to write test object metadata");
     }
@@ -4165,27 +4171,28 @@ mod tests {
     async fn test_scan_folder_exits_when_abandoned_child_listing_finishes() {
         let (mut scanner, temp_dir) = build_test_scanner().await;
         let _guard = TestGuard::new(60, 100, &mut scanner, temp_dir.clone());
-        let _heal_responder = rustfs_common::heal_channel::init_heal_channel().ok().map(|mut heal_rx| {
-            tokio::spawn(async move {
-                while let Some(command) = heal_rx.recv().await {
-                    if let rustfs_common::heal_channel::HealChannelCommand::Start { response_tx, .. } = command {
-                        let _ = response_tx.send(Ok(HealAdmissionResult::Accepted));
-                    }
+        let heal_starts = Arc::new(AtomicUsize::new(0));
+        let heal_starts_clone = heal_starts.clone();
+        let mut heal_rx =
+            rustfs_common::heal_channel::init_heal_channel().expect("heal channel should initialize once for scanner tests");
+        let _heal_responder = tokio::spawn(async move {
+            while let Some(command) = heal_rx.recv().await {
+                if let rustfs_common::heal_channel::HealChannelCommand::Start { response_tx, .. } = command {
+                    heal_starts_clone.fetch_add(1, Ordering::Relaxed);
+                    let _ = response_tx.send(Ok(HealAdmissionResult::Accepted));
                 }
-            })
+            }
         });
 
         let bucket = "src-archive";
-        tokio::fs::create_dir_all(temp_dir.join(bucket))
-            .await
-            .expect("failed to create bucket directory");
+        let object = "snapshots/37b3f20d941e2f5e6d99114d9bb2f3e67a8a2e5c9c4c5a1b0d6e7f8091a2b3c4";
+        let metadata = metadata_for_object(bucket, object);
+        write_test_object_metadata_bytes(&temp_dir, bucket, object, &metadata).await;
 
         let mut disks = vec![scanner.local_disk.clone()];
         for disk_name in ["disk2", "disk3", "disk4"] {
             let disk_root = temp_dir.join(disk_name);
-            tokio::fs::create_dir_all(disk_root.join(bucket))
-                .await
-                .expect("failed to create extra disk bucket directory");
+            write_test_object_metadata_bytes(&disk_root, bucket, object, &metadata).await;
             let endpoint =
                 Endpoint::try_from(disk_root.to_string_lossy().as_ref()).expect("failed to create extra disk endpoint");
             let disk = new_disk(
@@ -4204,7 +4211,7 @@ mod tests {
         scanner.disks = disks;
         scanner.disks_quorum = 2;
         scanner.old_cache.replace(
-            "src-archive/snapshots/37b3f20d941e2f5e6d99114d9bb2f3e67a8a2e5c9c4c5a1b0d6e7f8091a2b3c4",
+            &format!("{bucket}/{object}"),
             bucket,
             DataUsageEntry {
                 objects: 1,
@@ -4219,13 +4226,17 @@ mod tests {
             object_heal_prob_div: 1,
         };
 
-        tokio::time::timeout(
-            Duration::from_millis(200),
-            scanner.scan_folder(CancellationToken::new(), folder, &mut into),
-        )
-        .await
-        .expect("scan_folder should not hang after list_path_raw finishes")
-        .expect("scan_folder should finish successfully");
+        tokio::time::timeout(Duration::from_secs(2), scanner.scan_folder(CancellationToken::new(), folder, &mut into))
+            .await
+            .expect("scan_folder should not hang after list_path_raw finishes")
+            .expect("scan_folder should finish successfully");
+
+        let root = scanner
+            .new_cache
+            .checked_flatten(bucket)
+            .expect("healed cache must contain canonical child links");
+        assert_eq!(root.objects, 1);
+        assert!(heal_starts.load(Ordering::Relaxed) > 0, "test must execute the heal child-link path");
     }
 
     #[tokio::test]
@@ -4774,7 +4785,7 @@ mod tests {
         .expect("unbounded scan should finish after partial progress");
 
         let root = result
-            .size_recursive("bucket")
+            .checked_flatten("bucket")
             .expect("completed cache should retain bucket usage");
         assert_eq!(root.objects, 5);
         assert!(result.info.snapshot_complete);
@@ -4828,6 +4839,106 @@ mod tests {
         );
     }
 
+    #[tokio::test]
+    #[serial]
+    async fn test_partial_entry_does_not_carry_missing_old_child() {
+        let (mut scanner, temp_dir) = build_test_scanner().await;
+        let _guard = TestGuard {
+            temp_dir: Some(temp_dir),
+        };
+        let root_hash = hash_path("bucket");
+        scanner.old_cache.cache.insert(
+            root_hash.key(),
+            DataUsageEntry {
+                children: HashSet::from([hash_path("bucket/missing").key()]),
+                ..Default::default()
+            },
+        );
+
+        let mut partial = DataUsageEntry {
+            objects: 2,
+            size: 2,
+            ..Default::default()
+        };
+        scanner.carry_forward_old_children(&root_hash, &mut partial);
+        scanner.new_cache.replace_hashed(&root_hash, &None, &partial);
+
+        assert!(partial.children.is_empty());
+        let flattened = scanner
+            .new_cache
+            .checked_flatten("bucket")
+            .expect("a partial cache must not retain dangling child links");
+        assert_eq!(flattened.objects, 2);
+        assert_eq!(flattened.size, 2);
+    }
+
+    #[tokio::test]
+    #[serial]
+    async fn test_legacy_windows_cache_rebuilds_and_round_trips_portable_keys() {
+        let (scanner, temp_dir) = build_test_scanner().await;
+        let _guard = TestGuard {
+            temp_dir: Some(temp_dir.clone()),
+        };
+        write_test_object_metadata(&temp_dir, "bucket", "prefix/object").await;
+
+        let source = crate::data_usage_define::DataUsageCacheSource::new(0, 0);
+        let scan_plan_digest = crate::data_usage_define::DataUsageScanPlanDigest([9; 32]);
+        let mut legacy = DataUsageCache {
+            info: crate::data_usage_define::DataUsageCacheInfo {
+                name: "bucket".to_string(),
+                next_cycle: 7,
+                source: Some(source),
+                scan_plan_digest: Some(scan_plan_digest),
+                ..Default::default()
+            },
+            ..Default::default()
+        };
+        legacy.cache.insert(
+            "bucket".to_string(),
+            DataUsageEntry {
+                children: HashSet::from(["bucket\\prefix".to_string()]),
+                ..Default::default()
+            },
+        );
+        legacy.cache.insert(
+            "bucket\\prefix".to_string(),
+            DataUsageEntry {
+                objects: 1,
+                ..Default::default()
+            },
+        );
+        let encoded = legacy.marshal_msg().expect("legacy cache should serialize");
+        let mut migrated = DataUsageCache::unmarshal(&encoded).expect("legacy cache should deserialize");
+        assert_eq!(
+            migrated.prepare_for_scan("bucket", 8, 0, source, scan_plan_digest, true),
+            crate::data_usage_define::DataUsageCachePrepareOutcome::Reset
+        );
+
+        let parent = CancellationToken::new();
+        let budget = ScannerCycleBudget::new(&parent, Default::default());
+        let rebuilt = scan_data_folder(
+            budget.token(),
+            budget,
+            vec![scanner.local_disk.clone()],
+            scanner.local_disk,
+            migrated,
+            None,
+            HealScanMode::Normal,
+            SCANNER_SLEEPER.clone(),
+        )
+        .await
+        .expect("portable cache rebuild should complete");
+        let persisted = rebuilt.marshal_msg().expect("rebuilt cache should serialize");
+        let decoded = DataUsageCache::unmarshal(&persisted).expect("rebuilt cache should deserialize");
+
+        assert_eq!(decoded.info.cache_key_format, crate::data_usage_define::DATA_USAGE_CACHE_KEY_FORMAT);
+        assert!(decoded.cache.keys().all(|key| !key.contains('\\')));
+        let root = decoded
+            .checked_flatten("bucket")
+            .expect("rebuilt persisted cache should have a complete root");
+        assert_eq!(root.objects, 1);
+    }
+
     #[tokio::test]
     #[serial]
     async fn test_scan_data_folder_success_clears_resume_hint() {

crates/scanner/src/scanner_io.rs

@@ -12,6 +12,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+use crate::data_usage_define::DATA_USAGE_CACHE_KEY_FORMAT;
 use crate::scanner_budget::ScannerCycleBudget;
 use crate::scanner_folder::{ScannerItem, scan_data_folder};
 use crate::sleeper::SCANNER_SLEEPER;
@@ -830,7 +831,7 @@ pub(crate) fn cache_root_entry_info(cache: &DataUsageCache) -> std::result::Resu
         return Err(ScannerError::Other("scanner cache root name is empty".to_string()));
     }
     let entry = cache
-        .checked_flatten(&cache.info.name)
+        .checked_flatten_complete_scope(&cache.info.name)
         .ok_or_else(|| ScannerError::Other(format!("scanner cache root is missing or corrupt: {}", cache.info.name)))?;
 
     Ok(DataUsageEntryInfo {
@@ -852,7 +853,7 @@ fn should_publish_completed_snapshot(completed_count: usize, total_count: usize,
 #[derive(Clone, Copy, Debug, PartialEq, Eq)]
 enum NamespaceScannerWorkerMode {
     Coordinator,
-    RemoteV3(uuid::Uuid),
+    RemoteV4(uuid::Uuid),
 }
 
 fn namespace_scanner_workers<T>(
@@ -868,7 +869,7 @@ fn namespace_scanner_workers<T>(
     workers.extend(
         remote_disks
             .into_iter()
-            .map(|(disk, server_epoch)| (disk, NamespaceScannerWorkerMode::RemoteV3(server_epoch))),
+            .map(|(disk, server_epoch)| (disk, NamespaceScannerWorkerMode::RemoteV4(server_epoch))),
     );
     workers
 }
@@ -958,7 +959,57 @@ where
     let _ = tokio::time::timeout(SCANNER_CACHE_LOCK_LOSS_SHUTDOWN_TIMEOUT, scan).await;
 }
 
-pub(crate) fn cache_snapshot_is_current(
+pub(crate) fn current_cache_root_entry(
+    cache: &DataUsageCache,
+    name: &str,
+    source: DataUsageCacheSource,
+    next_cycle: u64,
+    leader_epoch: u64,
+    scan_plan_digest: DataUsageScanPlanDigest,
+) -> std::result::Result<Option<DataUsageEntryInfo>, ScannerError> {
+    let metadata_is_current = cache.info.name == name
+        && cache.info.source == Some(source)
+        && cache.info.snapshot_complete
+        && cache.info.scan_plan_digest == Some(scan_plan_digest)
+        && cache.info.last_update.is_some()
+        && cache.info.next_cycle == next_cycle
+        && cache.info.leader_epoch == leader_epoch
+        && cache.info.cache_key_format == DATA_USAGE_CACHE_KEY_FORMAT;
+    if !metadata_is_current {
+        return Ok(None);
+    }
+
+    cache_root_entry_info(cache).map(Some)
+}
+
+pub(crate) enum DataUsageCacheScanState {
+    Current(Box<DataUsageEntryInfo>),
+    Prepared {
+        outcome: DataUsageCachePrepareOutcome,
+        invalid_current: Option<ScannerError>,
+    },
+}
+
+pub(crate) fn current_cache_root_or_prepare(
+    cache: &mut DataUsageCache,
+    name: &str,
+    source: DataUsageCacheSource,
+    next_cycle: u64,
+    leader_epoch: u64,
+    scan_plan_digest: DataUsageScanPlanDigest,
+    require_source: bool,
+) -> DataUsageCacheScanState {
+    match current_cache_root_entry(cache, name, source, next_cycle, leader_epoch, scan_plan_digest) {
+        Ok(Some(root)) => DataUsageCacheScanState::Current(Box::new(root)),
+        current => DataUsageCacheScanState::Prepared {
+            invalid_current: current.err(),
+            outcome: cache.prepare_for_scan(name, next_cycle, leader_epoch, source, scan_plan_digest, require_source),
+        },
+    }
+}
+
+#[cfg(test)]
+fn cache_snapshot_is_current(
     cache: &DataUsageCache,
     name: &str,
     source: DataUsageCacheSource,
@@ -966,13 +1017,10 @@ pub(crate) fn cache_snapshot_is_current(
     leader_epoch: u64,
     scan_plan_digest: DataUsageScanPlanDigest,
 ) -> bool {
-    cache.info.name == name
-        && cache.info.source == Some(source)
-        && cache.info.snapshot_complete
-        && cache.info.scan_plan_digest == Some(scan_plan_digest)
-        && cache.info.last_update.is_some()
-        && cache.info.next_cycle == next_cycle
-        && cache.info.leader_epoch == leader_epoch
+    matches!(
+        current_cache_root_entry(cache, name, source, next_cycle, leader_epoch, scan_plan_digest),
+        Ok(Some(_))
+    )
 }
 
 fn completed_data_usage_info(
@@ -1061,6 +1109,7 @@ mod publish_gate_tests {
                 source: Some(source),
                 snapshot_complete: false,
                 scan_plan_digest: Some(TEST_PLAN_DIGEST),
+                cache_key_format: DATA_USAGE_CACHE_KEY_FORMAT,
                 ..Default::default()
             },
             ..Default::default()
@@ -1102,6 +1151,7 @@ mod publish_gate_tests {
                 source: Some(source),
                 snapshot_complete: true,
                 scan_plan_digest: Some(TEST_PLAN_DIGEST),
+                cache_key_format: DATA_USAGE_CACHE_KEY_FORMAT,
                 ..Default::default()
             },
             ..Default::default()
@@ -1423,17 +1473,145 @@ mod publish_gate_tests {
         assert!(!cache_snapshot_is_current(&cache, DATA_USAGE_ROOT, source, 10, 2, TEST_PLAN_DIGEST));
     }
 
+    #[test]
+    fn current_cache_snapshot_rejects_persisted_windows_key_mismatch() {
+        let source = DataUsageCacheSource::new(1, 2);
+        let mut cache = DataUsageCache {
+            info: DataUsageCacheInfo {
+                name: "bucket".to_string(),
+                next_cycle: 10,
+                last_update: Some(SystemTime::UNIX_EPOCH),
+                source: Some(source),
+                snapshot_complete: true,
+                scan_plan_digest: Some(TEST_PLAN_DIGEST),
+                cache_key_format: DATA_USAGE_CACHE_KEY_FORMAT,
+                ..Default::default()
+            },
+            ..Default::default()
+        };
+        cache.cache.insert(
+            "bucket".to_string(),
+            DataUsageEntry {
+                children: HashSet::from(["bucket/prefix".to_string()]),
+                ..Default::default()
+            },
+        );
+        cache.cache.insert(
+            "bucket\\prefix".to_string(),
+            DataUsageEntry {
+                objects: 3,
+                ..Default::default()
+            },
+        );
+
+        assert!(!cache_snapshot_is_current(&cache, "bucket", source, 10, 0, TEST_PLAN_DIGEST));
+        match current_cache_root_or_prepare(&mut cache, "bucket", source, 10, 0, TEST_PLAN_DIGEST, true) {
+            DataUsageCacheScanState::Prepared {
+                outcome: DataUsageCachePrepareOutcome::Reset,
+                invalid_current: Some(_),
+            } => {}
+            _ => panic!("an invalid current cache must enter the rebuild path"),
+        }
+        assert!(cache.cache.is_empty());
+        assert_eq!(cache.info.cache_key_format, DATA_USAGE_CACHE_KEY_FORMAT);
+    }
+
+    #[test]
+    fn current_cache_snapshot_rejects_structurally_valid_legacy_key_format() {
+        let source = DataUsageCacheSource::new(1, 2);
+        let mut cache = DataUsageCache {
+            info: DataUsageCacheInfo {
+                name: "bucket".to_string(),
+                next_cycle: 10,
+                last_update: Some(SystemTime::UNIX_EPOCH),
+                source: Some(source),
+                snapshot_complete: true,
+                scan_plan_digest: Some(TEST_PLAN_DIGEST),
+                ..Default::default()
+            },
+            ..Default::default()
+        };
+        cache.cache.insert(
+            "bucket".to_string(),
+            DataUsageEntry {
+                children: HashSet::from(["bucket\\prefix".to_string()]),
+                ..Default::default()
+            },
+        );
+        cache.cache.insert(
+            "bucket\\prefix".to_string(),
+            DataUsageEntry {
+                objects: 3,
+                ..Default::default()
+            },
+        );
+        assert_eq!(cache.checked_flatten("bucket").map(|entry| entry.objects), Some(3));
+
+        match current_cache_root_or_prepare(&mut cache, "bucket", source, 10, 0, TEST_PLAN_DIGEST, true) {
+            DataUsageCacheScanState::Prepared {
+                outcome: DataUsageCachePrepareOutcome::Reset,
+                invalid_current: None,
+            } => {}
+            _ => panic!("a legacy key format must enter the rebuild path"),
+        }
+        assert!(cache.cache.is_empty());
+        assert_eq!(cache.info.cache_key_format, DATA_USAGE_CACHE_KEY_FORMAT);
+    }
+
+    #[test]
+    fn current_cache_snapshot_rejects_current_bucket_cache_with_detached_entry() {
+        let source = DataUsageCacheSource::new(1, 2);
+        let mut cache = DataUsageCache {
+            info: DataUsageCacheInfo {
+                name: "bucket".to_string(),
+                next_cycle: 10,
+                last_update: Some(SystemTime::UNIX_EPOCH),
+                source: Some(source),
+                snapshot_complete: true,
+                scan_plan_digest: Some(TEST_PLAN_DIGEST),
+                cache_key_format: DATA_USAGE_CACHE_KEY_FORMAT,
+                ..Default::default()
+            },
+            ..Default::default()
+        };
+        cache.cache.insert(
+            "bucket".to_string(),
+            DataUsageEntry {
+                objects: 1,
+                ..Default::default()
+            },
+        );
+        cache.cache.insert(
+            "bucket/detached".to_string(),
+            DataUsageEntry {
+                objects: 2,
+                ..Default::default()
+            },
+        );
+        assert_eq!(cache.checked_flatten("bucket").map(|entry| entry.objects), Some(1));
+
+        match current_cache_root_or_prepare(&mut cache, "bucket", source, 10, 0, TEST_PLAN_DIGEST, true) {
+            DataUsageCacheScanState::Prepared {
+                outcome: DataUsageCachePrepareOutcome::Reset,
+                invalid_current: Some(_),
+            } => {}
+            _ => panic!("a detached complete bucket cache must enter the rebuild path"),
+        }
+        assert!(cache.cache.is_empty());
+        assert_eq!(cache.info.cache_key_format, DATA_USAGE_CACHE_KEY_FORMAT);
+    }
+
     #[test]
     fn namespace_scanner_worker_selection_keeps_coordinator_fallback_disks() {
         let server_epoch = uuid::Uuid::new_v4();
-        let workers = namespace_scanner_workers(vec!["local", "legacy-remote"], vec![("v3", server_epoch)]);
+        let workers = namespace_scanner_workers(vec!["local", "legacy-remote"], vec![("v4", server_epoch)]);
 
         assert_eq!(
             workers,
             vec![
                 ("local", NamespaceScannerWorkerMode::Coordinator),
                 ("legacy-remote", NamespaceScannerWorkerMode::Coordinator),
-                ("v3", NamespaceScannerWorkerMode::RemoteV3(server_epoch)),
+                ("v4", NamespaceScannerWorkerMode::RemoteV4(server_epoch)),
             ]
         );
         assert!(namespace_scanner_workers::<()>(Vec::new(), Vec::new()).is_empty());
@@ -1507,6 +1685,7 @@ mod publish_gate_tests {
                 source: Some(source),
                 snapshot_complete: true,
                 scan_plan_digest: Some(first),
+                cache_key_format: DATA_USAGE_CACHE_KEY_FORMAT,
                 ..Default::default()
             },
             ..Default::default()
@@ -1595,6 +1774,15 @@ async fn send_cache_root_entry_info(
     pending_maintenance_work: &AtomicBool,
 ) -> std::result::Result<(), ScannerError> {
     let root = cache_root_entry_info(cache)?;
+    send_cache_root_entry(bucket_result_tx, root, cache, pending_maintenance_work).await
+}
+
+async fn send_cache_root_entry(
+    bucket_result_tx: &mpsc::Sender<DataUsageEntryInfo>,
+    root: DataUsageEntryInfo,
+    cache: &DataUsageCache,
+    pending_maintenance_work: &AtomicBool,
+) -> std::result::Result<(), ScannerError> {
     record_bucket_pending_maintenance_work(cache, pending_maintenance_work);
     bucket_result_tx
         .send(root)
@@ -1690,13 +1878,16 @@ async fn persist_and_publish_cache_snapshot(
         );
         return None;
     }
-    if cache_snapshot_is_current(
-        &persisted,
-        DATA_USAGE_ROOT,
-        source,
-        cache_snapshot.info.next_cycle,
-        cache_snapshot.info.leader_epoch,
-        scan_plan_digest,
+    if matches!(
+        current_cache_root_entry(
+            &persisted,
+            DATA_USAGE_ROOT,
+            source,
+            cache_snapshot.info.next_cycle,
+            cache_snapshot.info.leader_epoch,
+            scan_plan_digest,
+        ),
+        Ok(Some(_))
     ) {
         cache_snapshot = persisted;
     } else {
@@ -2329,6 +2520,7 @@ impl ScannerIOCache for SetDisks {
                     source: Some(source),
                     snapshot_complete: true,
                     scan_plan_digest: Some(scan_plan_digest),
+                    cache_key_format: DATA_USAGE_CACHE_KEY_FORMAT,
                     ..Default::default()
                 },
                 cache: HashMap::new(),
@@ -2450,7 +2642,7 @@ impl ScannerIOCache for SetDisks {
                 subsystem = LOG_SUBSYSTEM_IO,
                 pool = self.pool_index,
                 set = self.set_index,
-                v3_disks = remote_disk_count,
+                v4_disks = remote_disk_count,
                 unsupported_remote_disks,
                 state = "unsupported_remote_disks_using_coordinator",
                 "Scanner set assigned remote disks without namespace scanner support to coordinator-driven workers"
@@ -2547,6 +2739,7 @@ impl ScannerIOCache for SetDisks {
                 source: Some(source),
                 snapshot_complete: false,
                 scan_plan_digest: Some(scan_plan_digest),
+                cache_key_format: DATA_USAGE_CACHE_KEY_FORMAT,
                 ..Default::default()
             },
             cache: HashMap::new(),
@@ -2638,7 +2831,7 @@ impl ScannerIOCache for SetDisks {
             let dirty_usage_buckets_clone = dirty_usage_buckets.clone();
             let cache_cycle_floor_clone = cache_cycle_floor.clone();
             let remote_server_epoch = match worker_mode {
-                NamespaceScannerWorkerMode::RemoteV3(server_epoch) => Some(server_epoch),
+                NamespaceScannerWorkerMode::RemoteV4(server_epoch) => Some(server_epoch),
                 NamespaceScannerWorkerMode::Coordinator => None,
             };
             futs.push(tokio::spawn(async move {
@@ -2948,48 +3141,71 @@ impl ScannerIOCache for SetDisks {
                             continue;
                         }
                     };
-                    if cache_snapshot_is_current(&cache, &bucket.name, source, want_cycle, leader_epoch, bucket_scan_plan_digest)
-                    {
-                        if cache_guard.is_lock_lost() {
-                            record_failed_dirty_bucket(&failed_dirty_buckets_clone, &bucket.name).await;
-                            error!(
-                                target: "rustfs::scanner::io",
-                                event = EVENT_SCANNER_CACHE_PERSIST_STATE,
-                                component = LOG_COMPONENT_SCANNER,
-                                subsystem = LOG_SUBSYSTEM_IO,
-                                bucket = %bucket.name,
-                                cache_name = %cache_name,
-                                state = "lock_lost_before_reuse",
-                                "Current scanner bucket cache root publish skipped after lock loss"
-                            );
-                            continue;
-                        }
-                        if let Err(e) =
-                            send_cache_root_entry_info(&bucket_result_tx_clone, &cache, &pending_maintenance_work_clone).await
-                        {
-                            record_failed_dirty_bucket(&failed_dirty_buckets_clone, &bucket.name).await;
-                            error!(
-                                target: "rustfs::scanner::io",
-                                event = EVENT_SCANNER_DATA_USAGE_STREAM,
-                                component = LOG_COMPONENT_SCANNER,
-                                subsystem = LOG_SUBSYSTEM_IO,
-                                bucket = %bucket.name,
-                                state = "send_current_root_failed",
-                                error = %e,
-                                "Current scanner bucket cache root entry publish failed"
-                            );
-                        }
-                        continue;
-                    }
-
-                    match cache.prepare_for_scan(
+                    let scan_state = current_cache_root_or_prepare(
+                        &mut cache,
                         &bucket.name,
+                        source,
                         want_cycle,
                         leader_epoch,
-                        source,
                         bucket_scan_plan_digest,
                         require_cache_source,
-                    ) {
+                    );
+                    let outcome = match scan_state {
+                        DataUsageCacheScanState::Current(root) => {
+                            if cache_guard.is_lock_lost() {
+                                record_failed_dirty_bucket(&failed_dirty_buckets_clone, &bucket.name).await;
+                                error!(
+                                    target: "rustfs::scanner::io",
+                                    event = EVENT_SCANNER_CACHE_PERSIST_STATE,
+                                    component = LOG_COMPONENT_SCANNER,
+                                    subsystem = LOG_SUBSYSTEM_IO,
+                                    bucket = %bucket.name,
+                                    cache_name = %cache_name,
+                                    state = "lock_lost_before_reuse",
+                                    "Current scanner bucket cache root publish skipped after lock loss"
+                                );
+                                continue;
+                            }
+                            if let Err(e) =
+                                send_cache_root_entry(&bucket_result_tx_clone, *root, &cache, &pending_maintenance_work_clone)
+                                    .await
+                            {
+                                record_failed_dirty_bucket(&failed_dirty_buckets_clone, &bucket.name).await;
+                                error!(
+                                    target: "rustfs::scanner::io",
+                                    event = EVENT_SCANNER_DATA_USAGE_STREAM,
+                                    component = LOG_COMPONENT_SCANNER,
+                                    subsystem = LOG_SUBSYSTEM_IO,
+                                    bucket = %bucket.name,
+                                    state = "send_current_root_failed",
+                                    error = %e,
+                                    "Current scanner bucket cache root entry publish failed"
+                                );
+                            }
+                            continue;
+                        }
+                        DataUsageCacheScanState::Prepared {
+                            outcome,
+                            invalid_current,
+                        } => {
+                            if let Some(e) = invalid_current {
+                                warn!(
+                                    target: "rustfs::scanner::io",
+                                    event = EVENT_SCANNER_CACHE_PERSIST_STATE,
+                                    component = LOG_COMPONENT_SCANNER,
+                                    subsystem = LOG_SUBSYSTEM_IO,
+                                    bucket = %bucket.name,
+                                    cache_name = %cache_name,
+                                    state = "current_cache_invalid",
+                                    error = %e,
+                                    "Current scanner bucket cache is invalid; rebuilding"
+                                );
+                            }
+                            outcome
+                        }
+                    };
+
+                    match outcome {
                         DataUsageCachePrepareOutcome::RejectedNewerCycle => {
                             cache_cycle_floor_clone.fetch_max(cache.info.next_cycle, Ordering::AcqRel);
                             record_failed_dirty_bucket(&failed_dirty_buckets_clone, &bucket.name).await;
@@ -3361,6 +3577,7 @@ impl ScannerIOCache for SetDisks {
                     source: Some(source),
                     snapshot_complete: false,
                     scan_plan_digest: Some(scan_plan_digest),
+                    cache_key_format: DATA_USAGE_CACHE_KEY_FORMAT,
                     ..Default::default()
                 },
                 cache: HashMap::new(),
@@ -4668,6 +4885,67 @@ mod tests {
         root.add_child(&crate::hash_path("bucket/missing"));
         dangling.replace("bucket", DATA_USAGE_ROOT, root);
         assert!(cache_root_entry_info(&dangling).is_err());
+
+        let mut detached = DataUsageCache {
+            info: DataUsageCacheInfo {
+                name: DATA_USAGE_ROOT.to_string(),
+                ..Default::default()
+            },
+            ..Default::default()
+        };
+        detached.replace("bucket", DATA_USAGE_ROOT, DataUsageEntry::default());
+        detached.replace(
+            "bucket/detached",
+            "",
+            DataUsageEntry {
+                objects: 1,
+                ..Default::default()
+            },
+        );
+        assert!(cache_root_entry_info(&detached).is_err());
+
+        let mut detached_bucket = DataUsageCache {
+            info: DataUsageCacheInfo {
+                name: "bucket".to_string(),
+                ..Default::default()
+            },
+            ..Default::default()
+        };
+        detached_bucket.replace(
+            "bucket",
+            DATA_USAGE_ROOT,
+            DataUsageEntry {
+                objects: 1,
+                ..Default::default()
+            },
+        );
+        detached_bucket.replace(
+            "bucket/detached",
+            "",
+            DataUsageEntry {
+                objects: 1,
+                ..Default::default()
+            },
+        );
+        assert!(cache_root_entry_info(&detached_bucket).is_err());
+
+        let mut compacted_with_child = DataUsageCache {
+            info: DataUsageCacheInfo {
+                name: "bucket".to_string(),
+                ..Default::default()
+            },
+            ..Default::default()
+        };
+        compacted_with_child.replace(
+            "bucket",
+            DATA_USAGE_ROOT,
+            DataUsageEntry {
+                compacted: true,
+                ..Default::default()
+            },
+        );
+        compacted_with_child.replace("bucket/prefix", "bucket", DataUsageEntry::default());
+        assert!(cache_root_entry_info(&compacted_with_child).is_err());
     }
 
     #[test]

crates/storage-api/src/bucket.rs

@@ -53,7 +53,7 @@ pub struct DeleteBucketOptions {
     pub no_recreate: bool,
     /// Force deletion even if bucket is not empty.
     pub force: bool,
-    /// Force deletion only after the local peer verifies the bucket is empty.
+    /// Delete empty directory remnants after the local peer verifies no object metadata exists.
     pub force_if_empty: bool,
     /// Site replication delete operation.
     pub srdelete_op: SRBucketDeleteOp,

crates/utils/src/http/metadata_compat.rs

@@ -40,6 +40,7 @@ pub const SUFFIX_TRANSITIONED_VERSION_ID: &str = "transitioned-versionID";
 pub const SUFFIX_TRANSITIONED_VERSION_STATE: &str = "transitioned-version-state";
 pub const SUFFIX_TRANSITION_TIER: &str = "transition-tier";
 pub const SUFFIX_TRANSITION_TIER_DESTINATION_ID: &str = "transition-tier-destination-id";
+pub const SUFFIX_TRANSITION_TRANSACTION_ID: &str = "transition-transaction-id";
 pub const SUFFIX_RESTORE_OPERATION_ID: &str = "restore-operation-id";
 pub const SUFFIX_FREE_VERSION: &str = "free-version";
 pub const SUFFIX_PURGESTATUS: &str = "purgestatus";

docs/operations/tier-ilm-debugging.md

@@ -98,6 +98,39 @@ rc admin ilm transition run local/mybucket --prefix logs/ --tier cold --max-obje
 
 Inspect the aggregate counters before widening scope. Full object-key lists are intentionally not returned by the admin response. If `RUSTFS_RPC_SECRET` or other credentials were pasted into an issue, chat, log, or ticket while debugging tiering, rotate them on every node, restart the cluster with the new value, and redact the exposed copy before sharing more diagnostics.
 
+## Reconcile an unknown transition upload
+
+Historical transition transactions in `upload_outcome_unknown` state can use an explicit two-stage operator workflow when the tier probe is ambiguous and the provider supports exact version deletion. The endpoint refuses transactions that are still inside their ownership window or are in any other state.
+
+First inspect the transaction without changing it:
+
+```text
+GET /rustfs/admin/v3/ilm/transition/reconcile/<transaction-id>
+```
+
+If independent provider evidence identifies the exact remote version to remove, submit that opaque version identifier with explicit confirmation:
+
+```json
+POST /rustfs/admin/v3/ilm/transition/reconcile/<transaction-id>
+{
+  "action": "delete_candidate",
+  "confirm": true,
+  "remote_version_id": "<exact-provider-version>"
+}
+```
+
+This operation performs only an exact version delete. Its response reports whether the transaction journal was still observed after the delete; background recovery may have finalized the same transaction concurrently. If the journal remains, inspect the transaction again and finalize it only after the live provider probe proves that the candidate is missing:
+
+```json
+POST /rustfs/admin/v3/ilm/transition/reconcile/<transaction-id>
+{
+  "action": "finalize_missing",
+  "confirm": true
+}
+```
+
+`finalize_missing` re-runs the provider probe and fails closed for `unversioned_present`, `versioned_present`, `ambiguous`, `unsupported`, or probe errors. It never accepts an operator assertion in place of a live `missing` result. Providers without an authoritative probe or exact version deletion remain pending; this endpoint does not infer provider capabilities, accept external absence assertions, or select a candidate automatically.
+
 ## Historical fixes (for context, already merged)
 
 - Expire/GET race (`NoSuchVersion` during expiry of a tiered object):

rustfs/src/admin/handlers/ilm_transition.rs

@@ -20,8 +20,10 @@ use crate::admin::storage_api::error::StorageError;
 use crate::admin::storage_api::lifecycle::{
     ManualTransitionCancelCheck, ManualTransitionJobRecord, ManualTransitionJobState, ManualTransitionProgressSink,
     ManualTransitionQueueSnapshot, ManualTransitionRunOptions, ManualTransitionRunReport, ManualTransitionScopeAdmission,
-    ManualTransitionScopeAdmissionClaim, claim_manual_transition_scope_admission,
-    delete_manual_transition_scope_admission_if_current, enqueue_transition_for_existing_objects_scoped,
+    ManualTransitionScopeAdmissionClaim, TransitionOperatorDeleteResult, TransitionOperatorError,
+    claim_manual_transition_scope_admission, delete_manual_transition_scope_admission_if_current,
+    delete_transition_candidate_for_operator, enqueue_transition_for_existing_objects_scoped,
+    finalize_missing_transition_transaction_for_operator, inspect_transition_transaction_for_operator,
     load_manual_transition_job_record, load_manual_transition_job_record_with_etag, load_manual_transition_scope_admission,
     manual_transition_job_lease_expired, manual_transition_queue_snapshot, manual_transition_scope_admission_lease_expired,
     persist_manual_transition_job_progress, renew_manual_transition_job_lease, request_manual_transition_job_cancel,
@@ -33,6 +35,7 @@ use crate::server::{ADMIN_PREFIX, RemoteAddr};
 use http::{HeaderMap, HeaderValue};
 use hyper::{Method, StatusCode};
 use matchit::Params;
+use rustfs_config::MAX_ADMIN_REQUEST_BODY_SIZE;
 use rustfs_policy::policy::action::{Action, AdminAction};
 use rustfs_utils::{
     MaskedAccessKey,
@@ -56,6 +59,7 @@ const MAX_MANUAL_TRANSITION_DURATION_SECONDS: u64 = 3600;
 const LOG_COMPONENT_ADMIN: &str = "admin";
 const LOG_SUBSYSTEM_ILM_TRANSITION: &str = "ilm_transition";
 const EVENT_ADMIN_ILM_TRANSITION_STATE: &str = "admin_ilm_transition_state";
+const EVENT_ADMIN_ILM_TRANSITION_RECONCILE: &str = "admin_ilm_transition_reconcile";
 
 static ACTIVE_MANUAL_TRANSITION_SCOPES: OnceLock<Mutex<Vec<ManualTransitionRunScope>>> = OnceLock::new();
 #[cfg(feature = "e2e-test-hooks")]
@@ -218,6 +222,16 @@ pub fn register_ilm_transition_route(r: &mut S3Router<AdminOperation>) -> std::i
         format!("{ADMIN_PREFIX}/v3/ilm/transition/jobs/{{job_id}}").as_str(),
         AdminOperation(&ManualTransitionJobCancelHandler {}),
     )?;
+    r.insert(
+        Method::GET,
+        format!("{ADMIN_PREFIX}/v3/ilm/transition/reconcile/{{transaction_id}}").as_str(),
+        AdminOperation(&TransitionReconcileInspectHandler {}),
+    )?;
+    r.insert(
+        Method::POST,
+        format!("{ADMIN_PREFIX}/v3/ilm/transition/reconcile/{{transaction_id}}").as_str(),
+        AdminOperation(&TransitionReconcileApplyHandler {}),
+    )?;
     Ok(())
 }
 
@@ -389,6 +403,10 @@ fn log_manual_transition_completed(
 }
 
 async fn authorize_manual_transition_request(req: &S3Request<Body>) -> S3Result<String> {
+    authorize_transition_admin_request(req, AdminAction::SetTierAction).await
+}
+
+async fn authorize_transition_admin_request(req: &S3Request<Body>, action: AdminAction) -> S3Result<String> {
     let Some(input_cred) = req.credentials.as_ref() else {
         return Err(s3_error!(InvalidRequest, "authentication required"));
     };
@@ -401,19 +419,122 @@ async fn authorize_manual_transition_request(req: &S3Request<Body>) -> S3Result<
         .get::<Option<RemoteAddr>>()
         .and_then(|opt| opt.map(|addr| addr.0));
 
-    validate_admin_request(
-        &req.headers,
-        &cred,
-        owner,
-        false,
-        vec![Action::AdminAction(AdminAction::SetTierAction)],
-        remote_addr,
-    )
-    .await?;
+    validate_admin_request(&req.headers, &cred, owner, false, vec![Action::AdminAction(action)], remote_addr).await?;
 
     Ok(actor)
 }
 
+fn transition_transaction_id_from_params(params: &Params<'_, '_>) -> S3Result<Uuid> {
+    Uuid::parse_str(params.get("transaction_id").unwrap_or(""))
+        .map_err(|_| s3_error!(InvalidArgument, "invalid transition transaction id"))
+}
+
+fn map_transition_operator_error(err: TransitionOperatorError) -> S3Error {
+    match err {
+        TransitionOperatorError::NotFound => s3_error!(NoSuchKey, "transition transaction not found"),
+        TransitionOperatorError::NotExpired => {
+            s3_error!(OperationAborted, "transition transaction is still inside its active ownership window")
+        }
+        TransitionOperatorError::InvalidState(_) => {
+            s3_error!(OperationAborted, "transition transaction is not eligible for operator reconciliation")
+        }
+        TransitionOperatorError::RemoteVersionRequired => {
+            s3_error!(InvalidArgument, "an exact non-empty remote version is required")
+        }
+        TransitionOperatorError::CandidateNotMissing(_) => {
+            s3_error!(OperationAborted, "remote candidate is not proven missing")
+        }
+        TransitionOperatorError::CandidateVersionMismatch { .. } => {
+            s3_error!(OperationAborted, "remote candidate version does not match requested exact version")
+        }
+        TransitionOperatorError::Store(_) | TransitionOperatorError::Remote(_) => {
+            s3_error!(InternalError, "transition reconciliation failed")
+        }
+    }
+}
+
+#[derive(Debug, Deserialize)]
+#[serde(rename_all = "snake_case")]
+enum TransitionReconcileAction {
+    DeleteCandidate,
+    FinalizeMissing,
+}
+
+#[derive(Debug, Deserialize)]
+#[serde(deny_unknown_fields)]
+struct TransitionReconcileRequest {
+    action: TransitionReconcileAction,
+    confirm: bool,
+    #[serde(default)]
+    remote_version_id: Option<String>,
+}
+
+enum ValidatedTransitionReconcileAction<'a> {
+    DeleteCandidate(&'a str),
+    FinalizeMissing,
+}
+
+fn validate_transition_reconcile_request(
+    request: &TransitionReconcileRequest,
+) -> S3Result<ValidatedTransitionReconcileAction<'_>> {
+    if !request.confirm {
+        return Err(s3_error!(
+            InvalidRequest,
+            "transition reconciliation requires confirm=true; use GET to inspect without changes"
+        ));
+    }
+    match request.action {
+        TransitionReconcileAction::DeleteCandidate => request
+            .remote_version_id
+            .as_deref()
+            .filter(|version_id| !version_id.is_empty())
+            .map(ValidatedTransitionReconcileAction::DeleteCandidate)
+            .ok_or_else(|| s3_error!(InvalidArgument, "delete_candidate requires remote_version_id")),
+        TransitionReconcileAction::FinalizeMissing if request.remote_version_id.is_none() => {
+            Ok(ValidatedTransitionReconcileAction::FinalizeMissing)
+        }
+        TransitionReconcileAction::FinalizeMissing => {
+            Err(s3_error!(InvalidArgument, "finalize_missing must not include remote_version_id"))
+        }
+    }
+}
+
+#[derive(Debug, Serialize)]
+struct TransitionCandidateDeleteResponse {
+    outcome: &'static str,
+    result: TransitionOperatorDeleteResult,
+}
+
+#[derive(Debug, Serialize)]
+struct TransitionFinalizeMissingResponse {
+    outcome: &'static str,
+    journal_retained: bool,
+    transaction_id: Uuid,
+}
+
+fn log_transition_reconcile_applied(
+    transaction_id: Uuid,
+    action: &str,
+    outcome: &str,
+    request_id: &str,
+    actor: &str,
+    remote_addr: &str,
+) {
+    info!(
+        event = EVENT_ADMIN_ILM_TRANSITION_RECONCILE,
+        component = LOG_COMPONENT_ADMIN,
+        subsystem = LOG_SUBSYSTEM_ILM_TRANSITION,
+        operation = "transition_operator_reconcile",
+        transaction_id = %transaction_id,
+        action,
+        outcome,
+        request_id = %request_id,
+        actor = %actor,
+        remote_addr = %remote_addr,
+        "admin transition reconciliation applied"
+    );
+}
+
 fn response_state(report: &ManualTransitionRunReport) -> &'static str {
     if report.was_truncated() || report.has_partial_enqueue() || report.tier_failure > 0 || report.transition_failed > 0 {
         "partial"
@@ -902,6 +1023,81 @@ impl Operation for ManualTransitionJobCancelHandler {
     }
 }
 
+pub struct TransitionReconcileInspectHandler {}
+
+#[async_trait::async_trait]
+impl Operation for TransitionReconcileInspectHandler {
+    async fn call(&self, req: S3Request<Body>, params: Params<'_, '_>) -> S3Result<S3Response<(StatusCode, Body)>> {
+        authorize_transition_admin_request(&req, AdminAction::ListTierAction).await?;
+        let transaction_id = transition_transaction_id_from_params(&params)?;
+        let Some(store) = object_store_from_extensions(&req.extensions) else {
+            return Err(s3_error!(InternalError, "object store is not initialized"));
+        };
+        let status = inspect_transition_transaction_for_operator(store, transaction_id)
+            .await
+            .map_err(map_transition_operator_error)?;
+        json_response(&status, StatusCode::OK)
+    }
+}
+
+pub struct TransitionReconcileApplyHandler {}
+
+#[async_trait::async_trait]
+impl Operation for TransitionReconcileApplyHandler {
+    async fn call(&self, req: S3Request<Body>, params: Params<'_, '_>) -> S3Result<S3Response<(StatusCode, Body)>> {
+        let request_id = admin_request_id(&req.headers).unwrap_or_default().to_string();
+        let remote_addr = admin_remote_addr(&req).unwrap_or_default();
+        let actor = authorize_transition_admin_request(&req, AdminAction::SetTierAction).await?;
+        let transaction_id = transition_transaction_id_from_params(&params)?;
+        let Some(store) = object_store_from_extensions(&req.extensions) else {
+            return Err(s3_error!(InternalError, "object store is not initialized"));
+        };
+        let mut input = req.input;
+        let body = input
+            .store_all_limited(MAX_ADMIN_REQUEST_BODY_SIZE)
+            .await
+            .map_err(|_| s3_error!(InvalidRequest, "transition reconciliation body is too large or unreadable"))?;
+        let request: TransitionReconcileRequest = serde_json::from_slice(&body)
+            .map_err(|_| s3_error!(InvalidRequest, "transition reconciliation request must be valid JSON"))?;
+
+        match validate_transition_reconcile_request(&request)? {
+            ValidatedTransitionReconcileAction::DeleteCandidate(remote_version_id) => {
+                let result = delete_transition_candidate_for_operator(store, transaction_id, remote_version_id)
+                    .await
+                    .map_err(map_transition_operator_error)?;
+                let outcome = if result.journal_observed_after_delete {
+                    "exact_delete_completed_journal_observed"
+                } else {
+                    "exact_delete_completed_journal_already_finalized"
+                };
+                log_transition_reconcile_applied(transaction_id, "delete_candidate", outcome, &request_id, &actor, &remote_addr);
+                json_response(&TransitionCandidateDeleteResponse { outcome, result }, StatusCode::OK)
+            }
+            ValidatedTransitionReconcileAction::FinalizeMissing => {
+                finalize_missing_transition_transaction_for_operator(store, transaction_id)
+                    .await
+                    .map_err(map_transition_operator_error)?;
+                log_transition_reconcile_applied(
+                    transaction_id,
+                    "finalize_missing",
+                    "journal_deleted_after_missing_probe",
+                    &request_id,
+                    &actor,
+                    &remote_addr,
+                );
+                json_response(
+                    &TransitionFinalizeMissingResponse {
+                        outcome: "journal_finalized",
+                        journal_retained: false,
+                        transaction_id,
+                    },
+                    StatusCode::OK,
+                )
+            }
+        }
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
@@ -931,6 +1127,65 @@ mod tests {
         }
     }
 
+    #[test]
+    fn transition_reconcile_request_is_explicit_and_fail_closed() {
+        let unconfirmed: TransitionReconcileRequest =
+            serde_json::from_slice(br#"{"action":"delete_candidate","confirm":false,"remote_version_id":"v1"}"#)
+                .expect("request should decode");
+        assert!(validate_transition_reconcile_request(&unconfirmed).is_err());
+
+        let missing_version: TransitionReconcileRequest =
+            serde_json::from_slice(br#"{"action":"delete_candidate","confirm":true}"#).expect("request should decode");
+        assert!(validate_transition_reconcile_request(&missing_version).is_err());
+
+        let unsafe_finalize: TransitionReconcileRequest =
+            serde_json::from_slice(br#"{"action":"finalize_missing","confirm":true,"remote_version_id":"v1"}"#)
+                .expect("request should decode");
+        assert!(validate_transition_reconcile_request(&unsafe_finalize).is_err());
+
+        let delete: TransitionReconcileRequest =
+            serde_json::from_slice(br#"{"action":"delete_candidate","confirm":true,"remote_version_id":"opaque-v1"}"#)
+                .expect("request should decode");
+        assert!(matches!(
+            validate_transition_reconcile_request(&delete),
+            Ok(ValidatedTransitionReconcileAction::DeleteCandidate("opaque-v1"))
+        ));
+
+        let finalize: TransitionReconcileRequest =
+            serde_json::from_slice(br#"{"action":"finalize_missing","confirm":true}"#).expect("request should decode");
+        assert!(matches!(
+            validate_transition_reconcile_request(&finalize),
+            Ok(ValidatedTransitionReconcileAction::FinalizeMissing)
+        ));
+
+        assert!(
+            serde_json::from_slice::<TransitionReconcileRequest>(
+                br#"{"action":"finalize_missing","confirm":true,"unexpected":true}"#
+            )
+            .is_err()
+        );
+    }
+
+    #[test]
+    fn transition_reconcile_routes_use_read_and_write_tier_actions() {
+        let src = include_str!("ilm_transition.rs");
+        let inspect = src
+            .split("impl Operation for TransitionReconcileInspectHandler")
+            .nth(1)
+            .and_then(|block| block.split("impl Operation for TransitionReconcileApplyHandler").next())
+            .expect("inspect handler block");
+        assert!(inspect.contains("AdminAction::ListTierAction"));
+        assert!(!inspect.contains("AdminAction::SetTierAction"));
+
+        let apply = src
+            .split("impl Operation for TransitionReconcileApplyHandler")
+            .nth(1)
+            .and_then(|block| block.split("#[cfg(test)]").next())
+            .expect("apply handler block");
+        assert!(apply.contains("AdminAction::SetTierAction"));
+        assert!(!apply.contains("AdminAction::ListTierAction"));
+    }
+
     #[test]
     fn manual_transition_query_defaults_to_bounded_run() {
         let (bucket, options, run_mode) =

rustfs/src/admin/route_policy.rs

@@ -432,6 +432,18 @@ pub const ADMIN_ROUTE_POLICY_SPECS: &[AdminRouteSpec] = &[
         SET_TIER,
         RouteRiskLevel::High,
     ),
+    admin(
+        HttpMethod::Get,
+        "/rustfs/admin/v3/ilm/transition/reconcile/{transaction_id}",
+        LIST_TIER,
+        RouteRiskLevel::High,
+    ),
+    admin(
+        HttpMethod::Post,
+        "/rustfs/admin/v3/ilm/transition/reconcile/{transaction_id}",
+        SET_TIER,
+        RouteRiskLevel::High,
+    ),
     admin(
         HttpMethod::Get,
         "/rustfs/admin/v3/audit/target/list",
@@ -1825,13 +1837,17 @@ mod tests {
     }
 
     #[test]
-    fn route_policy_requires_set_tier_for_manual_transition_routes() {
+    fn route_policy_uses_tier_actions_for_transition_routes() {
         assert_action(HttpMethod::Post, "/rustfs/admin/v3/ilm/transition/run", SET_TIER);
         assert_action(HttpMethod::Get, "/rustfs/admin/v3/ilm/transition/jobs/{job_id}", SET_TIER);
         assert_action(HttpMethod::Delete, "/rustfs/admin/v3/ilm/transition/jobs/{job_id}", SET_TIER);
+        assert_action(HttpMethod::Get, "/rustfs/admin/v3/ilm/transition/reconcile/{transaction_id}", LIST_TIER);
+        assert_action(HttpMethod::Post, "/rustfs/admin/v3/ilm/transition/reconcile/{transaction_id}", SET_TIER);
         assert_not_action(HttpMethod::Post, "/rustfs/admin/v3/ilm/transition/run", SERVER_INFO);
         assert_not_action(HttpMethod::Get, "/rustfs/admin/v3/ilm/transition/jobs/{job_id}", SERVER_INFO);
         assert_not_action(HttpMethod::Delete, "/rustfs/admin/v3/ilm/transition/jobs/{job_id}", SERVER_INFO);
+        assert_not_action(HttpMethod::Get, "/rustfs/admin/v3/ilm/transition/reconcile/{transaction_id}", SET_TIER);
+        assert_not_action(HttpMethod::Post, "/rustfs/admin/v3/ilm/transition/reconcile/{transaction_id}", LIST_TIER);
     }
 
     #[test]

rustfs/src/admin/route_registration_test.rs

@@ -202,6 +202,16 @@ fn expected_admin_route_matrix() -> Vec<RouteMatrixEntry> {
             "/v3/ilm/transition/jobs/{job_id}",
             "/v3/ilm/transition/jobs/11111111-1111-4111-8111-111111111111",
         ),
+        admin_route_sample(
+            Method::GET,
+            "/v3/ilm/transition/reconcile/{transaction_id}",
+            "/v3/ilm/transition/reconcile/11111111-1111-4111-8111-111111111111",
+        ),
+        admin_route_sample(
+            Method::POST,
+            "/v3/ilm/transition/reconcile/{transaction_id}",
+            "/v3/ilm/transition/reconcile/11111111-1111-4111-8111-111111111111",
+        ),
         admin_route_sample(
             Method::DELETE,
             "/v3/ilm/transition/jobs/{job_id}",
@@ -856,6 +866,16 @@ fn test_register_routes_cover_representative_admin_paths() {
         Method::DELETE,
         &admin_path("/v3/ilm/transition/jobs/11111111-1111-4111-8111-111111111111"),
     );
+    assert_route(
+        &router,
+        Method::GET,
+        &admin_path("/v3/ilm/transition/reconcile/11111111-1111-4111-8111-111111111111"),
+    );
+    assert_route(
+        &router,
+        Method::POST,
+        &admin_path("/v3/ilm/transition/reconcile/11111111-1111-4111-8111-111111111111"),
+    );
 
     assert_route(&router, Method::GET, &table_catalog_path("/config"));
     assert_route(&router, Method::PUT, &table_catalog_path("/buckets/analytics"));

rustfs/src/admin/router.rs

@@ -2655,6 +2655,10 @@ fn is_public_health_path(path: &str) -> bool {
     path == HEALTH_PREFIX || path == HEALTH_READY_PATH
 }
 
+fn server_context_not_ready_error() -> S3Error {
+    s3_error!(ServiceUnavailable, "server context is not ready")
+}
+
 fn is_object_zip_download_token_path(method: &Method, uri: &Uri) -> bool {
     if method != Method::GET {
         return false;
@@ -2783,6 +2787,9 @@ where
     async fn check_access(&self, req: &mut S3Request<Body>) -> S3Result<()> {
         if let Some(server_ctx) = &self.server_ctx {
             req.extensions.insert(server_ctx.clone());
+            if !is_public_health_path(req.uri.path()) && server_ctx.installed_app_context().is_none() {
+                return Err(server_context_not_ready_error());
+            }
         }
         if parse_replication_extension_request(&req.method, &req.uri).is_some()
             || parse_misc_extension_request(&req.method, &req.uri).is_some()
@@ -2836,6 +2843,9 @@ where
     async fn call(&self, mut req: S3Request<Body>) -> S3Result<S3Response<Body>> {
         if let Some(server_ctx) = &self.server_ctx {
             req.extensions.insert(server_ctx.clone());
+            if !is_public_health_path(req.uri.path()) && server_ctx.installed_app_context().is_none() {
+                return Err(server_context_not_ready_error());
+            }
         }
         if let Some(ext_req) = parse_replication_extension_request(&req.method, &req.uri) {
             return handle_replication_extension_request(&mut req, &ext_req).await;

rustfs/src/admin/runtime_sources.rs

@@ -76,19 +76,29 @@ pub(crate) fn object_store_from_req<B>(req: &s3s::S3Request<B>) -> Option<Arc<EC
 }
 
 pub(crate) fn app_context_from_req<B>(req: &s3s::S3Request<B>) -> Option<Arc<AppContext>> {
-    req.extensions
-        .get::<Arc<ServerContextSlot>>()
-        .and_then(|slot| slot.app_context())
-        .or_else(current_app_context)
+    app_context_from_extensions(&req.extensions)
+}
+
+/// Resolve an application context from request extensions.
+///
+/// An injected slot identifies the server that owns the request. If that
+/// server has not finished startup yet, returning its ambient global context
+/// could select a different server, so this fails closed. Only requests with
+/// no slot retain the legacy ambient fallback.
+pub(crate) fn app_context_from_extensions(extensions: &http::Extensions) -> Option<Arc<AppContext>> {
+    match extensions.get::<Arc<ServerContextSlot>>() {
+        Some(slot) => slot.installed_app_context(),
+        None => current_app_context(),
+    }
 }
 
 /// Field-borrow form of [`object_store_from_req`] for handlers that have
 /// already moved other request fields (body, credentials) out of the request.
 pub(crate) fn object_store_from_extensions(extensions: &http::Extensions) -> Option<Arc<ECStore>> {
-    extensions
-        .get::<Arc<ServerContextSlot>>()
-        .and_then(|slot| slot.object_store())
-        .or_else(current_object_store_handle)
+    match extensions.get::<Arc<ServerContextSlot>>() {
+        Some(slot) => slot.installed_object_store(),
+        None => current_object_store_handle(),
+    }
 }
 
 pub(crate) fn current_notification_system() -> Option<Arc<NotificationSys>> {
@@ -168,3 +178,151 @@ pub(crate) fn publish_storage_class_config(config: StorageClassConfig) {
         root_runtime_sources::fallback_storage_class_interface().set(config);
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::{
+        AppContext, IamInterface, KmsInterface, ServerContextSlot, app_context_from_extensions, app_context_from_req,
+        current_app_context, object_store_from_extensions, publish_test_app_context,
+    };
+    use crate::admin::router::{Operation, S3Router};
+    use hyper::{Method, StatusCode};
+    use matchit::Params;
+    use rustfs_iam::{store::object::ObjectStore, sys::IamSys};
+    use rustfs_kms::KmsServiceManager;
+    use s3s::route::S3Route;
+    use s3s::{Body, S3ErrorCode, S3Request, S3Response, s3_error};
+    use std::sync::Arc;
+
+    struct UnreadyIam;
+
+    impl IamInterface for UnreadyIam {
+        fn handle(&self) -> Arc<IamSys<ObjectStore>> {
+            panic!("test context does not resolve IAM")
+        }
+
+        fn is_ready(&self) -> bool {
+            false
+        }
+    }
+
+    struct TestKms;
+
+    impl KmsInterface for TestKms {
+        fn handle(&self) -> Arc<KmsServiceManager> {
+            Arc::new(KmsServiceManager::new())
+        }
+    }
+
+    async fn ambient_context() -> Arc<AppContext> {
+        if let Some(context) = current_app_context() {
+            return context;
+        }
+
+        let env = rustfs_test_utils::TestECStoreEnv::builder()
+            .prefix("server_context_slot")
+            .disk_count(1)
+            .init_bucket_metadata(false)
+            .build()
+            .await;
+        let context = Arc::new(AppContext::new(env.ecstore, Arc::new(UnreadyIam), Arc::new(TestKms)));
+        publish_test_app_context(context);
+        current_app_context().expect("test context must be globally published")
+    }
+
+    fn distinct_context(context: &AppContext) -> Arc<AppContext> {
+        Arc::new(AppContext::new(context.object_store(), Arc::new(UnreadyIam), Arc::new(TestKms)))
+    }
+
+    fn request(extensions: http::Extensions) -> S3Request<Body> {
+        S3Request {
+            input: Body::empty(),
+            method: Method::GET,
+            uri: "/context-probe".parse().expect("test URI"),
+            headers: http::HeaderMap::new(),
+            extensions,
+            credentials: None,
+            region: None,
+            service: None,
+            trailing_headers: None,
+        }
+    }
+
+    #[tokio::test]
+    #[serial_test::serial]
+    async fn request_with_empty_slot_never_uses_ambient_context() {
+        let ambient = ambient_context().await;
+        let slot = ServerContextSlot::new();
+        let mut extensions = http::Extensions::new();
+        extensions.insert(slot);
+
+        assert!(app_context_from_extensions(&extensions).is_none());
+        assert!(object_store_from_extensions(&extensions).is_none());
+        assert!(app_context_from_req(&request(extensions)).is_none());
+        assert!(Arc::ptr_eq(
+            &current_app_context().expect("ambient context must remain available"),
+            &ambient
+        ));
+    }
+
+    #[tokio::test]
+    #[serial_test::serial]
+    async fn request_with_installed_slot_resolves_only_its_context() {
+        let ambient = ambient_context().await;
+        let installed = distinct_context(&ambient);
+        let slot = ServerContextSlot::new();
+        assert!(slot.install(installed.clone()));
+        let mut extensions = http::Extensions::new();
+        extensions.insert(slot);
+
+        let resolved = app_context_from_extensions(&extensions).expect("installed slot must resolve");
+        assert!(Arc::ptr_eq(&resolved, &installed));
+        assert!(!Arc::ptr_eq(&resolved, &ambient));
+    }
+
+    #[tokio::test]
+    #[serial_test::serial]
+    async fn request_without_slot_keeps_legacy_ambient_resolution() {
+        let ambient = ambient_context().await;
+        let extensions = http::Extensions::new();
+
+        let resolved = app_context_from_extensions(&extensions).expect("legacy request must use ambient context");
+        assert!(Arc::ptr_eq(&resolved, &ambient));
+        assert!(object_store_from_extensions(&extensions).is_some());
+    }
+
+    struct ContextDependentAdminRoute;
+
+    #[async_trait::async_trait]
+    impl Operation for ContextDependentAdminRoute {
+        async fn call(&self, req: S3Request<Body>, _params: Params<'_, '_>) -> s3s::S3Result<S3Response<(StatusCode, Body)>> {
+            app_context_from_req(&req).ok_or_else(|| s3_error!(ServiceUnavailable, "server context is not ready"))?;
+            Ok(S3Response::new((StatusCode::NO_CONTENT, Body::empty())))
+        }
+    }
+
+    #[tokio::test]
+    #[serial_test::serial]
+    async fn context_dependent_admin_route_fails_closed_until_slot_installation() {
+        let ambient = ambient_context().await;
+        let slot = ServerContextSlot::new();
+        let mut router = S3Router::new(false);
+        router.set_server_ctx(slot.clone());
+        router
+            .insert(Method::GET, "/context-probe", ContextDependentAdminRoute)
+            .expect("register test route");
+
+        let err = router
+            .call(request(http::Extensions::new()))
+            .await
+            .expect_err("empty slot must fail closed");
+        assert_eq!(err.code(), &S3ErrorCode::ServiceUnavailable);
+
+        assert!(slot.install(distinct_context(&ambient)));
+        let response = router
+            .call(request(http::Extensions::new()))
+            .await
+            .expect("installed slot must serve request");
+        assert_eq!(response.status, Some(StatusCode::NO_CONTENT));
+    }
+}

rustfs/src/admin/storage_api.rs

@@ -210,6 +210,10 @@ pub(crate) mod lifecycle {
     pub(crate) type ManualTransitionRunOptions =
         super::ecstore_bucket::lifecycle::bucket_lifecycle_ops::ManualTransitionRunOptions;
     pub(crate) type ManualTransitionRunReport = super::ecstore_bucket::lifecycle::bucket_lifecycle_ops::ManualTransitionRunReport;
+    pub(crate) use super::ecstore_bucket::lifecycle::transition_transaction::{
+        TransitionOperatorDeleteResult, TransitionOperatorError, delete_transition_candidate_for_operator,
+        finalize_missing_transition_transaction_for_operator, inspect_transition_transaction_for_operator,
+    };
 
     pub(crate) async fn enqueue_transition_for_existing_objects_scoped(
         api: std::sync::Arc<super::ECStore>,

rustfs/src/app/context/server_slot.rs

@@ -20,11 +20,10 @@
 //! request-path owners (the `FS` service), and installs the `AppContext` into
 //! it once IAM bootstrap completes.
 //!
-//! Until every app subsystem is per-server (backlog#1052 S3), resolution falls
-//! back to the process-global `AppContext` singleton when the slot has not
-//! been installed — byte-for-byte the ambient resolution the request path used
-//! before this seam existed. The fallback is removed when multi-instance flips
-//! on (backlog#1052 S5).
+//! Some legacy, non-request call sites still use the ambient compatibility
+//! resolver. Request dispatch must instead use the strict installed-context
+//! accessors: once a request carries a server slot, an empty slot means that
+//! server is not ready rather than that another server's global context applies.
 
 use super::global::{AppContext, get_global_app_context};
 use crate::app::storage_api::context::ECStore;
@@ -62,10 +61,26 @@ impl ServerContextSlot {
         self.app_context.set(context).is_ok()
     }
 
+    /// This server's installed application context, if startup has completed.
+    ///
+    /// Request-scoped resolution must use this accessor so an empty slot never
+    /// resolves through another server's ambient context.
+    pub fn installed_app_context(&self) -> Option<Arc<AppContext>> {
+        self.app_context.get().cloned()
+    }
+
+    /// This server's installed object store, if startup has completed.
+    pub fn installed_object_store(&self) -> Option<Arc<ECStore>> {
+        self.installed_app_context().map(|context| context.object_store())
+    }
+
     /// This server's application context: the installed one, or the
-    /// process-global singleton as the single-instance legacy default.
+    /// process-global singleton as the legacy compatibility default.
+    ///
+    /// This accessor is for callers without request-slot semantics. Request
+    /// dispatch must use [`Self::installed_app_context`] instead.
     pub fn app_context(&self) -> Option<Arc<AppContext>> {
-        self.app_context.get().cloned().or_else(get_global_app_context)
+        self.installed_app_context().or_else(get_global_app_context)
     }
 
     /// This server's object store, resolved through [`Self::app_context`].
@@ -88,7 +103,7 @@ mod tests {
     // nothing: the same "not ready yet" answer the ambient path gives before
     // IAM bootstrap completes.
     #[test]
-    fn empty_slot_resolves_like_the_ambient_path() {
+    fn empty_slot_retains_ambient_compatibility() {
         let slot = ServerContextSlot::new();
         assert_eq!(slot.app_context().is_some(), get_global_app_context().is_some());
         assert_eq!(slot.object_store().is_some(), get_global_app_context().is_some());

rustfs/src/embedded.rs

@@ -60,6 +60,94 @@ use std::net::SocketAddr;
 use std::path::PathBuf;
 use tokio_util::sync::CancellationToken;
 
+#[cfg(feature = "e2e-test-hooks")]
+use std::sync::{Mutex, OnceLock};
+#[cfg(feature = "e2e-test-hooks")]
+use tokio::sync::oneshot;
+
+#[cfg(feature = "e2e-test-hooks")]
+struct EmbeddedStartupHook {
+    port: u16,
+    http_bound: oneshot::Sender<()>,
+    release: oneshot::Receiver<()>,
+}
+
+#[cfg(feature = "e2e-test-hooks")]
+static EMBEDDED_STARTUP_HOOK: OnceLock<Mutex<Option<EmbeddedStartupHook>>> = OnceLock::new();
+
+/// Test-only gate for the point after an embedded HTTP listener binds and
+/// before its application context is installed.
+#[cfg(feature = "e2e-test-hooks")]
+#[doc(hidden)]
+pub struct EmbeddedStartupBarrier {
+    http_bound: oneshot::Receiver<()>,
+    release: Option<oneshot::Sender<()>>,
+}
+
+#[cfg(feature = "e2e-test-hooks")]
+impl EmbeddedStartupBarrier {
+    /// Wait until the next embedded server has bound its HTTP listener.
+    pub async fn wait_until_http_bound(&mut self) {
+        (&mut self.http_bound)
+            .await
+            .expect("embedded startup hook must signal after binding HTTP");
+    }
+
+    /// Allow the paused embedded startup to install its application context.
+    pub fn release(mut self) {
+        if let Some(release) = self.release.take() {
+            let _ = release.send(());
+        }
+    }
+}
+
+#[cfg(feature = "e2e-test-hooks")]
+impl Drop for EmbeddedStartupBarrier {
+    fn drop(&mut self) {
+        if let Some(release) = self.release.take() {
+            let _ = release.send(());
+        }
+    }
+}
+
+/// Pause the embedded startup for `port` after its HTTP listener binds.
+#[cfg(feature = "e2e-test-hooks")]
+#[doc(hidden)]
+pub fn pause_embedded_startup_after_http_bind(port: u16) -> EmbeddedStartupBarrier {
+    let (http_bound_tx, http_bound) = oneshot::channel();
+    let (release, release_rx) = oneshot::channel();
+    let hook = EmbeddedStartupHook {
+        port,
+        http_bound: http_bound_tx,
+        release: release_rx,
+    };
+    let mut active_hook = EMBEDDED_STARTUP_HOOK
+        .get_or_init(|| Mutex::new(None))
+        .lock()
+        .expect("embedded startup hook lock must not be poisoned");
+    assert!(active_hook.replace(hook).is_none(), "only one embedded startup hook may be active");
+
+    EmbeddedStartupBarrier {
+        http_bound,
+        release: Some(release),
+    }
+}
+
+#[cfg(feature = "e2e-test-hooks")]
+pub(crate) async fn wait_for_embedded_startup_hook(port: u16) {
+    let hook = {
+        let mut active_hook = EMBEDDED_STARTUP_HOOK
+            .get_or_init(|| Mutex::new(None))
+            .lock()
+            .expect("embedded startup hook lock must not be poisoned");
+        active_hook.take_if(|hook| hook.port == port)
+    };
+    if let Some(hook) = hook {
+        let _ = hook.http_bound.send(());
+        let _ = hook.release.await;
+    }
+}
+
 /// Error type for embedded server operations.
 #[derive(Debug)]
 pub enum ServerError {

rustfs/src/server/http.rs

@@ -37,7 +37,8 @@ use crate::storage_api::server::http as storage;
 use crate::storage_api::server::http::rpc::InternodeRpcService;
 use crate::storage_api::server::http::tonic_service::make_server;
 use crate::storage_api::server::http::{
-    ServerContextSlot, TONIC_RPC_PREFIX, normalize_tonic_rpc_audience, verify_tonic_rpc_signature,
+    ServerContextSlot, TONIC_RPC_PREFIX, normalize_tonic_rpc_audience, tonic_boot_epoch_challenge,
+    tonic_boot_epoch_response_headers, verify_tonic_rpc_signature_with_bootstrap,
 };
 use bytes::Bytes;
 use http::{HeaderMap, Method, Request as HttpRequest, Response, Uri};
@@ -152,13 +153,17 @@ impl<S> RpcRequestPathService<S> {
     }
 }
 
-impl<S, B> Service<HttpRequest<B>> for RpcRequestPathService<S>
+impl<S, B, ResBody> Service<HttpRequest<B>> for RpcRequestPathService<S>
 where
-    S: Service<HttpRequest<B>>,
+    S: Service<HttpRequest<B>, Response = Response<ResBody>>,
+    S::Error: Send + 'static,
+    S::Future: Send + 'static,
+    B: Send + 'static,
+    ResBody: Send + 'static,
 {
-    type Response = S::Response;
+    type Response = Response<ResBody>;
     type Error = S::Error;
-    type Future = S::Future;
+    type Future = Pin<Box<dyn Future<Output = std::result::Result<Self::Response, Self::Error>> + Send>>;
 
     fn poll_ready(&mut self, cx: &mut Context<'_>) -> Poll<std::result::Result<(), Self::Error>> {
         self.inner.poll_ready(cx)
@@ -170,7 +175,22 @@ where
             method: req.method().clone(),
         };
         req.extensions_mut().insert(target);
-        self.inner.call(req)
+        let response_headers = tonic_boot_epoch_challenge(req.headers())
+            .ok()
+            .flatten()
+            .and_then(|challenge| {
+                storage::try_current_local_node_name()
+                    .and_then(|node| normalize_tonic_rpc_audience(&node).ok())
+                    .and_then(|audience| tonic_boot_epoch_response_headers(&audience, challenge).ok())
+            });
+        let future = self.inner.call(req);
+        Box::pin(async move {
+            let mut response = future.await?;
+            if let Some(headers) = response_headers {
+                response.headers_mut().extend(headers);
+            }
+            Ok(response)
+        })
     }
 }
 
@@ -1862,7 +1882,15 @@ fn check_auth(req: Request<()>) -> std::result::Result<Request<()>, Status> {
         .filter(|method| !method.is_empty() && !method.contains('/'))
         .ok_or_else(|| Status::unauthenticated("Invalid RPC request path"))?;
     debug_assert!(!rpc_method.is_empty());
-    verify_tonic_rpc_signature(&audience, target.uri.path(), req.metadata().as_ref()).map_err(|e| {
+    let allow_replay_scope_bootstrap = target.uri.path() == "/node_service.NodeService/Ping"
+        && tonic_boot_epoch_challenge(req.metadata().as_ref()).is_ok_and(|challenge| challenge.is_some());
+    verify_tonic_rpc_signature_with_bootstrap(
+        &audience,
+        target.uri.path(),
+        req.metadata().as_ref(),
+        allow_replay_scope_bootstrap,
+    )
+    .map_err(|e| {
         error!(
             event = EVENT_RPC_SIGNATURE_VERIFICATION_FAILED,
             component = LOG_COMPONENT_SERVER,

rustfs/src/server/layer.rs

@@ -254,7 +254,7 @@ where
                     req.headers_mut().insert(REQUEST_ID_HEADER, request_id);
                 }
             }
-            RequestContext::from_headers_without_trace_context(req.headers())
+            RequestContext::from_propagated_headers(req.headers())
         };
         let request_id = if is_s3 {
             HeaderValue::from_str(&request_context.request_id).ok()
@@ -2369,6 +2369,39 @@ mod tests {
         }
     }
 
+    #[tokio::test]
+    async fn non_s3_request_context_preserves_propagated_trace_context() {
+        global::set_text_map_propagator(TraceContextPropagator::new());
+        let capture = HeaderCaptureService::default();
+        let captured_context = capture.request_context();
+        let mut service = ExternalRequestContextLayer::default().layer(capture);
+        let request = Request::builder()
+            .uri("/rustfs/admin/v3/info")
+            .header(REQUEST_ID_HEADER, "client-request-id")
+            .header("traceparent", "00-4bf92f3577b34da6a3ce929d0e0e4736-00f067aa0ba902b7-01")
+            .body(())
+            .expect("build admin request");
+
+        let response = service.call(request).await.expect("admin response");
+        let context = captured_context
+            .lock()
+            .expect("captured request context")
+            .clone()
+            .expect("admin request context");
+
+        assert_eq!(
+            response
+                .headers()
+                .get(REQUEST_ID_HEADER)
+                .and_then(|value| value.to_str().ok()),
+            Some("client-request-id")
+        );
+        assert_eq!(context.request_id, "client-request-id");
+        assert_eq!(context.x_amz_request_id, "client-request-id");
+        assert_eq!(context.trace_id.as_deref(), Some("4bf92f3577b34da6a3ce929d0e0e4736"));
+        assert_eq!(context.span_id.as_deref(), Some("00f067aa0ba902b7"));
+    }
+
     #[test]
     fn console_redirect_request_id_contract_follows_redirect_enablement() {
         for path in ["/", "/rustfs", "/index.html"] {

rustfs/src/startup_embedded.rs

@@ -156,6 +156,9 @@ pub(crate) async fn run_embedded_startup(args: EmbeddedStartupArgs) -> Result<Em
     let bound_addr = http_server.bound_addr;
     let cancel_token = CancellationToken::new();
 
+    #[cfg(feature = "e2e-test-hooks")]
+    crate::embedded::wait_for_embedded_startup_hook(bound_addr.port()).await;
+
     let storage_runtime = match init_embedded_startup_storage_runtime(
         listen_context.server_addr,
         &endpoint_pools,

rustfs/src/storage/request_context.rs

@@ -100,15 +100,18 @@ impl RequestContext {
         )
     }
 
-    /// Create a context from propagated request headers without copying trace
-    /// state into the request context.
-    pub(crate) fn from_headers_without_trace_context(headers: &HeaderMap) -> Self {
+    /// Create a context for a non-S3 request while mirroring the propagated
+    /// canonical request ID into the compatibility alias.
+    pub(crate) fn from_propagated_headers(headers: &HeaderMap) -> Self {
         let request_id = extract_request_id_from_headers(headers);
+        let (trace_id, span_id) = extract_trace_context_ids_from_headers(headers)
+            .map(|(trace_id, span_id)| (Some(trace_id), Some(span_id)))
+            .unwrap_or((None, None));
         Self {
             x_amz_request_id: request_id.clone(),
             request_id,
-            trace_id: None,
-            span_id: None,
+            trace_id,
+            span_id,
             start_time: Instant::now(),
         }
     }
@@ -329,17 +332,22 @@ mod tests {
     }
 
     #[test]
-    fn test_propagated_request_context_mirrors_canonical_request_id() {
+    fn test_propagated_request_context_mirrors_canonical_id_and_preserves_trace_context() {
+        global::set_text_map_propagator(TraceContextPropagator::new());
         let mut headers = HeaderMap::new();
         headers.insert("x-request-id", HeaderValue::from_static("canonical-request-id"));
         headers.insert("x-amz-request-id", HeaderValue::from_static("untrusted-amz-request-id"));
+        headers.insert(
+            "traceparent",
+            HeaderValue::from_static("00-4bf92f3577b34da6a3ce929d0e0e4736-00f067aa0ba902b7-01"),
+        );
 
-        let ctx = RequestContext::from_headers_without_trace_context(&headers);
+        let ctx = RequestContext::from_propagated_headers(&headers);
 
         assert_eq!(ctx.request_id, "canonical-request-id");
         assert_eq!(ctx.x_amz_request_id, "canonical-request-id");
-        assert!(ctx.trace_id.is_none());
-        assert!(ctx.span_id.is_none());
+        assert_eq!(ctx.trace_id.as_deref(), Some("4bf92f3577b34da6a3ce929d0e0e4736"));
+        assert_eq!(ctx.span_id.as_deref(), Some("00f067aa0ba902b7"));
     }
 
     #[test]

rustfs/src/storage/rpc/node_service.rs

@@ -52,7 +52,7 @@ use std::{
     collections::HashMap,
     io::Cursor,
     pin::Pin,
-    sync::{Arc, OnceLock},
+    sync::{Arc, LazyLock, OnceLock},
 };
 use time::OffsetDateTime;
 use tokio::spawn;
@@ -128,6 +128,7 @@ fn remove_heal_control_replay(
 }
 
 static HEAL_CONTROL_REPLAY_CACHE: OnceLock<tokio::sync::Mutex<HashMap<String, Arc<HealControlReplayEntry>>>> = OnceLock::new();
+static NODE_CAPABILITY_SERVER_EPOCH: LazyLock<Uuid> = LazyLock::new(Uuid::new_v4);
 
 fn admit_heal_control_replay(
     replay_cache: &mut HashMap<String, Arc<HealControlReplayEntry>>,
@@ -465,6 +466,19 @@ impl HealControlRpcService {
 pub(crate) async fn initialize_heal_topology_fingerprint(
     cache: Arc<tokio::sync::OnceCell<String>>,
     endpoint_pools: EndpointServerPools,
+) -> Result<(), String> {
+    initialize_heal_topology_fingerprint_with_probe(
+        cache,
+        endpoint_pools,
+        crate::storage::storage_api::start_remote_version_state_fleet_probe,
+    )
+    .await
+}
+
+async fn initialize_heal_topology_fingerprint_with_probe(
+    cache: Arc<tokio::sync::OnceCell<String>>,
+    endpoint_pools: EndpointServerPools,
+    start_probe: impl FnOnce(String),
 ) -> Result<(), String> {
     if cache.get().is_some() {
         return Ok(());
@@ -472,7 +486,8 @@ pub(crate) async fn initialize_heal_topology_fingerprint(
     let fingerprint = tokio::task::spawn_blocking(move || heal::heal_topology_fingerprint(&endpoint_pools))
         .await
         .map_err(|_| "heal control topology calculation task failed".to_string())??;
-    let _ = cache.set(fingerprint);
+    let _ = cache.set(fingerprint.clone());
+    start_probe(fingerprint);
     Ok(())
 }
 
@@ -806,6 +821,35 @@ impl heal_control_service_server::HealControlService for HealControlRpcService {
                 response_proof: Bytes::new(),
             }));
         }
+        if rustfs_protos::is_remote_version_state_capability_probe(&request.get_ref().command) {
+            let topology_member = self
+                .endpoint_pools()
+                .await
+                .ok_or_else(|| Status::failed_precondition("heal control topology is not initialized"))?
+                .peers()
+                .1;
+            if topology_member.is_empty() {
+                return Err(Status::failed_precondition("local topology member identity is unavailable"));
+            }
+            let result =
+                rustfs_protos::encode_remote_version_state_capability(&topology_member, NODE_CAPABILITY_SERVER_EPOCH.as_bytes())
+                    .map_err(|_| Status::internal("remote version state capability length cannot be represented"))?;
+            let canonical_response = rustfs_protos::canonical_heal_control_response_body(
+                request.get_ref().version,
+                &request.get_ref().topology_fingerprint,
+                &request.get_ref().command,
+                &result,
+            )
+            .map_err(|_| Status::internal("heal control response length cannot be represented"))?;
+            let response_proof = sign_tonic_rpc_response_proof(&canonical_response)
+                .map_err(|_| Status::internal("heal control response proof is unavailable"))?;
+            return Ok(Response::new(HealControlResponse {
+                success: true,
+                result: result.into(),
+                error_info: None,
+                response_proof: response_proof.into(),
+            }));
+        }
         let endpoints = self
             .endpoint_pools()
             .await
@@ -2090,10 +2134,10 @@ mod tests {
         PEER_RESTDRY_RUN, PEER_RESTSIGNAL, PEER_RESTSUB_SYS, SCANNER_ACTIVITY_LEGACY_PROTOCOL_VERSION,
         SCANNER_ACTIVITY_PREVIOUS_PROTOCOL_VERSION, SERVICE_SIGNAL_REFRESH_CONFIG, SERVICE_SIGNAL_RELOAD_DYNAMIC,
         STORAGE_CLASS_SUB_SYS, admit_heal_control_replay, background_rebalance_start_error_message,
-        execute_heal_control_envelope_with_manager, initialize_heal_topology_fingerprint, legacy_scanner_activity_response,
-        make_heal_control_server, make_heal_control_server_with_cache, make_server, make_server_for_context,
-        make_tier_mutation_control_server_for_context, previous_scanner_activity_response, remove_heal_control_replay,
-        scanner_activity_response, stop_rebalance_response,
+        execute_heal_control_envelope_with_manager, initialize_heal_topology_fingerprint,
+        initialize_heal_topology_fingerprint_with_probe, legacy_scanner_activity_response, make_heal_control_server,
+        make_heal_control_server_with_cache, make_server, make_server_for_context, make_tier_mutation_control_server_for_context,
+        previous_scanner_activity_response, remove_heal_control_replay, scanner_activity_response, stop_rebalance_response,
     };
     use crate::storage::rpc::node_service::heal::heal_topology_fingerprint;
     use crate::storage::storage_api::rpc_consumer::node_service::{HealBucketInfo, HealEndpoint};
@@ -2147,6 +2191,7 @@ mod tests {
     use tokio::time::Duration;
     use tokio_stream::wrappers::TcpListenerStream;
     use tonic::{Request, Response, Status};
+    use uuid::Uuid;
 
     const DISK_MUTATION_RPC_METHODS: [&str; 18] = [
         "renamedata",
@@ -3132,6 +3177,60 @@ mod tests {
         assert_eq!(non_coordinator.code(), tonic::Code::FailedPrecondition);
     }
 
+    #[tokio::test]
+    async fn remote_version_state_probe_authenticates_topology_challenge_and_process_epoch() {
+        let _ = rustfs_credentials::set_global_rpc_secret("remote-version-state-node-service-test-secret".to_string());
+        let endpoints = heal_control_test_endpoints_with_coordinator("node-d", true);
+        let fingerprint = heal_topology_fingerprint(&endpoints).expect("test topology should hash");
+        let (service, source) = super::make_heal_control_server_for_source();
+        *source.write().await = Some(endpoints);
+        let probe_command = rustfs_protos::remote_version_state_capability_probe(&[7; 16]);
+        let mut request = Request::new(HealControlRequest {
+            version: rustfs_protos::HEAL_CONTROL_PROTOCOL_VERSION,
+            topology_fingerprint: fingerprint.clone(),
+            command: Bytes::from(probe_command.clone()),
+        });
+        let body = rustfs_protos::canonical_heal_control_request_body(
+            request.get_ref().version,
+            &request.get_ref().topology_fingerprint,
+            &request.get_ref().command,
+        )
+        .expect("probe should encode");
+        set_tonic_canonical_body_digest(&mut request, &body).expect("digest metadata should encode");
+        mark_v2_authenticated(&mut request);
+        let response = service
+            .heal_control(request)
+            .await
+            .expect("matching topology should be acknowledged")
+            .into_inner();
+
+        let (topology_member, process_epoch) =
+            rustfs_protos::decode_remote_version_state_capability(&response.result).expect("capability response should decode");
+        assert_eq!(topology_member, "node-a:9000");
+        let server_epoch = Uuid::from_slice(process_epoch).expect("server epoch should be a UUID");
+        assert!(!server_epoch.is_nil());
+        let canonical_response = rustfs_protos::canonical_heal_control_response_body(
+            rustfs_protos::HEAL_CONTROL_PROTOCOL_VERSION,
+            &fingerprint,
+            &probe_command,
+            &response.result,
+        )
+        .expect("response should encode");
+        crate::storage::storage_api::verify_tonic_rpc_response_proof(&canonical_response, &response.response_proof)
+            .expect("outer proof should bind the response to the request");
+
+        let different_probe = rustfs_protos::remote_version_state_capability_probe(&[8; 16]);
+        let different_response = rustfs_protos::canonical_heal_control_response_body(
+            rustfs_protos::HEAL_CONTROL_PROTOCOL_VERSION,
+            &fingerprint,
+            &different_probe,
+            &response.result,
+        )
+        .expect("different response should encode");
+        crate::storage::storage_api::verify_tonic_rpc_response_proof(&different_response, &response.response_proof)
+            .expect_err("proof from one challenge must not be reusable");
+    }
+
     #[tokio::test]
     async fn heal_control_coordinator_rejects_expired_and_non_admin_starts() {
         let _ = rustfs_credentials::set_global_rpc_secret("heal-control-node-service-test-secret".to_string());
@@ -3194,10 +3293,15 @@ mod tests {
         let topology = heal_control_test_endpoints("node-d");
         let expected = heal_topology_fingerprint(&topology).expect("test topology should hash");
         let cache = Arc::new(tokio::sync::OnceCell::new());
-        initialize_heal_topology_fingerprint(Arc::clone(&cache), topology)
-            .await
-            .expect("valid topology should initialize");
+        let started_probe = Arc::new(std::sync::Mutex::new(None));
+        let started_probe_capture = Arc::clone(&started_probe);
+        initialize_heal_topology_fingerprint_with_probe(Arc::clone(&cache), topology, move |fingerprint| {
+            *started_probe_capture.lock().expect("probe capture should not poison") = Some(fingerprint);
+        })
+        .await
+        .expect("valid topology should initialize");
         assert_eq!(cache.get(), Some(&expected));
+        assert_eq!(started_probe.lock().expect("probe capture should not poison").as_ref(), Some(&expected));
 
         let mut invalid = heal_control_test_endpoints("node-d");
         invalid.as_mut()[0].endpoints.as_mut()[0].pool_idx = -1;

rustfs/src/storage/storage_api.rs

@@ -470,7 +470,7 @@ pub(crate) mod ecstore_metrics {
 #[allow(unused_imports)]
 pub(crate) mod ecstore_notification {
     pub(crate) use rustfs_ecstore::api::notification::{
-        NotificationSys, get_global_notification_sys, new_global_notification_sys,
+        NotificationSys, get_global_notification_sys, new_global_notification_sys, start_remote_version_state_fleet_probe,
     };
 }
 
@@ -495,8 +495,9 @@ pub(crate) mod ecstore_rpc {
     pub(crate) use rustfs_ecstore::api::rpc::{
         LocalPeerS3Client, PEER_RESTDRY_RUN, PEER_RESTSIGNAL, PEER_RESTSUB_SYS, PeerRestClient, PeerS3Client,
         SERVICE_SIGNAL_REFRESH_CONFIG, SERVICE_SIGNAL_RELOAD_DYNAMIC, TONIC_RPC_PREFIX, normalize_tonic_rpc_audience,
-        sign_ns_scanner_capability, sign_tonic_rpc_response_proof, verify_rpc_signature, verify_tonic_canonical_body_digest,
-        verify_tonic_mutation_body_digest, verify_tonic_rpc_signature,
+        sign_ns_scanner_capability, sign_tonic_rpc_response_proof, tonic_boot_epoch_challenge, tonic_boot_epoch_response_headers,
+        verify_rpc_signature, verify_tonic_canonical_body_digest, verify_tonic_mutation_body_digest,
+        verify_tonic_rpc_signature_with_bootstrap,
     };
     #[cfg(test)]
     pub(crate) use rustfs_ecstore::api::rpc::{
@@ -961,6 +962,10 @@ pub(crate) async fn new_global_notification_sys(endpoint_pools: EndpointServerPo
     ecstore_notification::new_global_notification_sys(endpoint_pools).await
 }
 
+pub(crate) fn start_remote_version_state_fleet_probe(topology_fingerprint: String) {
+    ecstore_notification::start_remote_version_state_fleet_probe(topology_fingerprint);
+}
+
 pub(crate) async fn read_config(api: Arc<ECStore>, file: &str) -> Result<Vec<u8>> {
     ecstore_config::com::read_config(api, file).await
 }
@@ -1601,8 +1606,21 @@ pub(crate) fn sign_ns_scanner_capability(challenge: uuid::Uuid, server_epoch: uu
     ecstore_rpc::sign_ns_scanner_capability(challenge, server_epoch)
 }
 
-pub(crate) fn verify_tonic_rpc_signature(audience: &str, path: &str, headers: &http::HeaderMap) -> std::io::Result<()> {
-    ecstore_rpc::verify_tonic_rpc_signature(audience, path, headers)
+pub(crate) fn verify_tonic_rpc_signature_with_bootstrap(
+    audience: &str,
+    path: &str,
+    headers: &http::HeaderMap,
+    allow_replay_scope_bootstrap: bool,
+) -> std::io::Result<()> {
+    ecstore_rpc::verify_tonic_rpc_signature_with_bootstrap(audience, path, headers, allow_replay_scope_bootstrap)
+}
+
+pub(crate) fn tonic_boot_epoch_challenge(headers: &http::HeaderMap) -> std::io::Result<Option<uuid::Uuid>> {
+    ecstore_rpc::tonic_boot_epoch_challenge(headers)
+}
+
+pub(crate) fn tonic_boot_epoch_response_headers(audience: &str, challenge: uuid::Uuid) -> std::io::Result<http::HeaderMap> {
+    ecstore_rpc::tonic_boot_epoch_response_headers(audience, challenge)
 }
 
 pub(crate) fn verify_tonic_canonical_body_digest<T>(request: &tonic::Request<T>, canonical_body: &[u8]) -> std::io::Result<()> {

rustfs/src/storage_api.rs

@@ -97,7 +97,8 @@ pub(crate) mod server {
 
     pub(crate) mod http {
         pub(crate) use crate::storage::storage_api::{
-            ServerContextSlot, TONIC_RPC_PREFIX, normalize_tonic_rpc_audience, verify_tonic_rpc_signature,
+            ServerContextSlot, TONIC_RPC_PREFIX, normalize_tonic_rpc_audience, tonic_boot_epoch_challenge,
+            tonic_boot_epoch_response_headers, verify_tonic_rpc_signature_with_bootstrap,
         };
 
         pub(crate) fn try_current_local_node_name() -> Option<String> {

rustfs/tests/admin_diagnostic_capability_e2e.rs

@@ -84,6 +84,22 @@ async fn signed_bytes_request(
         .expect("signed admin request")
 }
 
+async fn wait_for_ready(client: &Client, endpoint: &str) {
+    let ready_url = format!("{endpoint}/health/ready");
+    tokio::time::timeout(Duration::from_secs(10), async {
+        loop {
+            if let Ok(response) = client.get(&ready_url).send().await
+                && response.status().is_success()
+            {
+                return;
+            }
+            tokio::time::sleep(Duration::from_millis(100)).await;
+        }
+    })
+    .await
+    .expect("embedded server should become ready");
+}
+
 #[tokio::test]
 async fn diagnostic_handlers_enforce_advertised_runtime_contract() {
     let port = match find_available_port() {
@@ -100,9 +116,11 @@ async fn diagnostic_handlers_enforce_advertised_runtime_contract() {
         .expect("start embedded server");
     let endpoint = server.endpoint();
     let client = Client::builder()
+        .no_proxy()
         .timeout(Duration::from_secs(5))
         .build()
         .expect("HTTP client");
+    wait_for_ready(&client, &endpoint).await;
 
     let response = signed_bytes_request(
         &client,
@@ -144,6 +162,7 @@ async fn diagnostic_handlers_enforce_advertised_runtime_contract() {
     );
 
     let stalled_client = Client::builder()
+        .no_proxy()
         .timeout(Duration::from_secs(60))
         .build()
         .expect("stalled HTTP client");

rustfs/tests/embedded_multi_instance_test.rs

@@ -19,7 +19,22 @@
 use aws_sdk_s3::config::{Credentials, Region};
 use aws_sdk_s3::primitives::ByteStream;
 use aws_sdk_s3::{Client, Config};
+#[cfg(feature = "e2e-test-hooks")]
+use chrono::Utc;
+#[cfg(feature = "e2e-test-hooks")]
+use hmac::{Hmac, KeyInit, Mac};
+#[cfg(feature = "e2e-test-hooks")]
+use reqwest::StatusCode;
+#[cfg(feature = "e2e-test-hooks")]
+use rustfs::embedded::pause_embedded_startup_after_http_bind;
 use rustfs::embedded::{RustFSServerBuilder, find_available_port};
+#[cfg(feature = "e2e-test-hooks")]
+use sha2::{Digest, Sha256};
+#[cfg(feature = "e2e-test-hooks")]
+use std::time::Duration;
+
+#[cfg(feature = "e2e-test-hooks")]
+type HmacSha256 = Hmac<Sha256>;
 
 fn s3_client(endpoint: &str, access_key: &str, secret_key: &str) -> Client {
     let creds = Credentials::new(access_key, secret_key, None, None, "test");
@@ -33,6 +48,62 @@ fn s3_client(endpoint: &str, access_key: &str, secret_key: &str) -> Client {
     Client::from_conf(config)
 }
 
+#[cfg(feature = "e2e-test-hooks")]
+fn hex(bytes: impl AsRef<[u8]>) -> String {
+    bytes.as_ref().iter().map(|byte| format!("{byte:02x}")).collect()
+}
+
+#[cfg(feature = "e2e-test-hooks")]
+fn sha256_hex(bytes: &[u8]) -> String {
+    hex(Sha256::digest(bytes))
+}
+
+#[cfg(feature = "e2e-test-hooks")]
+fn hmac(key: &[u8], value: &str) -> Vec<u8> {
+    let mut mac = HmacSha256::new_from_slice(key).expect("HMAC accepts arbitrary key lengths");
+    mac.update(value.as_bytes());
+    mac.finalize().into_bytes().to_vec()
+}
+
+#[cfg(feature = "e2e-test-hooks")]
+fn signed_admin_request(
+    client: &reqwest::Client,
+    endpoint: &str,
+    request_path: &str,
+    access_key: &str,
+    secret_key: &str,
+) -> reqwest::RequestBuilder {
+    let host = endpoint
+        .strip_prefix("http://")
+        .or_else(|| endpoint.strip_prefix("https://"))
+        .expect("embedded endpoint scheme");
+    let payload_hash = sha256_hex(b"");
+    let now = Utc::now();
+    let amz_date = now.format("%Y%m%dT%H%M%SZ").to_string();
+    let date = now.format("%Y%m%d").to_string();
+    let canonical_headers = format!("host:{host}\nx-amz-content-sha256:{payload_hash}\nx-amz-date:{amz_date}\n");
+    let signed_headers = "host;x-amz-content-sha256;x-amz-date";
+    let (path, query) = request_path.split_once('?').unwrap_or((request_path, ""));
+    let canonical_request = format!("GET\n{path}\n{query}\n{canonical_headers}\n{signed_headers}\n{payload_hash}");
+    let scope = format!("{date}/us-east-1/s3/aws4_request");
+    let string_to_sign = format!("AWS4-HMAC-SHA256\n{amz_date}\n{scope}\n{}", sha256_hex(canonical_request.as_bytes()));
+    let date_key = hmac(format!("AWS4{secret_key}").as_bytes(), &date);
+    let region_key = hmac(&date_key, "us-east-1");
+    let service_key = hmac(&region_key, "s3");
+    let signing_key = hmac(&service_key, "aws4_request");
+    let authorization = format!(
+        "AWS4-HMAC-SHA256 Credential={access_key}/{scope}, SignedHeaders={signed_headers}, Signature={}",
+        hex(hmac(&signing_key, &string_to_sign))
+    );
+
+    client
+        .get(format!("{endpoint}{request_path}"))
+        .header("host", host)
+        .header("x-amz-content-sha256", payload_hash)
+        .header("x-amz-date", amz_date)
+        .header("authorization", authorization)
+}
+
 // backlog#1052 acceptance: a second embedded server in the same process no
 // longer aborts on write-once startup state — before this change,
 // `RustFSServer::build()` returned AlreadyStarted (guard) or panicked on
@@ -246,3 +317,112 @@ async fn two_embedded_servers_isolate_auth_and_data_planes() {
     server_a.shutdown().await;
     server_b.shutdown().await;
 }
+
+#[cfg(feature = "e2e-test-hooks")]
+#[tokio::test]
+async fn second_embedded_server_fails_closed_until_its_context_slot_is_installed() {
+    let port_a = match find_available_port() {
+        Ok(port) => port,
+        Err(err) if err.kind() == std::io::ErrorKind::PermissionDenied => return,
+        Err(err) => panic!("find free port for server A: {err}"),
+    };
+    let server_a = RustFSServerBuilder::new()
+        .address(format!("127.0.0.1:{port_a}"))
+        .access_key("startup-window-access-a")
+        .secret_key("startup-window-secret-a")
+        .build()
+        .await
+        .expect("start embedded server A");
+    let client_a = s3_client(&server_a.endpoint(), server_a.access_key(), server_a.secret_key());
+    client_a
+        .create_bucket()
+        .bucket("startup-window")
+        .send()
+        .await
+        .expect("server A creates the shared-name bucket");
+    client_a
+        .put_object()
+        .bucket("startup-window")
+        .key("marker.txt")
+        .body(ByteStream::from_static(b"from A"))
+        .send()
+        .await
+        .expect("server A writes its marker");
+
+    let port_b = match find_available_port() {
+        Ok(port) => port,
+        Err(err) if err.kind() == std::io::ErrorKind::PermissionDenied => {
+            server_a.shutdown().await;
+            return;
+        }
+        Err(err) => {
+            server_a.shutdown().await;
+            panic!("find free port for server B: {err}");
+        }
+    };
+    let endpoint_b = format!("http://127.0.0.1:{port_b}");
+    let b_access_key = "startup-window-access-b";
+    let b_secret_key = "startup-window-secret-b";
+    let mut barrier = pause_embedded_startup_after_http_bind(port_b);
+    let startup_b = tokio::spawn(async move {
+        RustFSServerBuilder::new()
+            .address(format!("127.0.0.1:{port_b}"))
+            .access_key(b_access_key)
+            .secret_key(b_secret_key)
+            .build()
+            .await
+    });
+    tokio::time::timeout(Duration::from_secs(10), barrier.wait_until_http_bound())
+        .await
+        .expect("server B must bind HTTP before installing its context slot");
+
+    let http = reqwest::Client::builder()
+        .no_proxy()
+        .timeout(Duration::from_secs(5))
+        .build()
+        .expect("build local admin client without proxy");
+    let inspect_path = "/rustfs/admin/v3/inspect-data?file=marker.txt&volume=startup-window";
+    let before_install = signed_admin_request(&http, &endpoint_b, inspect_path, b_access_key, b_secret_key)
+        .send()
+        .await
+        .expect("server B HTTP listener must accept the paused request");
+    let before_install_status = before_install.status();
+    let before_install_body = before_install.text().await.expect("read paused response body");
+    assert_eq!(before_install_status, StatusCode::SERVICE_UNAVAILABLE, "{before_install_body}");
+    assert!(
+        before_install_body.contains("server context is not ready"),
+        "paused request must not resolve server A: {before_install_body}"
+    );
+
+    barrier.release();
+    let server_b = tokio::time::timeout(Duration::from_secs(20), startup_b)
+        .await
+        .expect("server B startup must complete after releasing the barrier")
+        .expect("server B startup task must not panic")
+        .expect("start embedded server B");
+    let client_b = s3_client(&server_b.endpoint(), server_b.access_key(), server_b.secret_key());
+    client_b
+        .create_bucket()
+        .bucket("startup-window")
+        .send()
+        .await
+        .expect("server B creates its isolated shared-name bucket");
+    client_b
+        .put_object()
+        .bucket("startup-window")
+        .key("marker.txt")
+        .body(ByteStream::from_static(b"from B"))
+        .send()
+        .await
+        .expect("server B writes its marker");
+
+    let after_install = signed_admin_request(&http, &server_b.endpoint(), inspect_path, b_access_key, b_secret_key)
+        .send()
+        .await
+        .expect("server B admin request after context installation");
+    assert_eq!(after_install.status(), StatusCode::OK);
+    assert_eq!(after_install.bytes().await.expect("read server B marker"), b"from B".as_slice());
+
+    server_b.shutdown().await;
+    server_a.shutdown().await;
+}