docs(deps): expand tokio-tar cleanup contract (#6984)

Cargo.toml

@@ -232,7 +232,7 @@ tokio-postgres-rustls = "0.14.0"
 # Utilities and Tools
 anyhow = "1.0.104"
 arc-swap = "1.9.2"
-# RUSTFS_COMPAT_TODO(tokio-tar-extension-limits): keep the fork pin until bounded extension parsing is released upstream. Remove after astral-sh/tokio-tar#118 is merged and a published tokio-tar release exposes the extension limits used here.
+# RUSTFS_COMPAT_TODO(tokio-tar-extension-limits): keep the fork pin until every parser hardening used by Snowball is released upstream. Remove after astral-sh/tokio-tar#118 is merged and a published release includes extension, physical-entry, and sparse limits, cancellation-safe sparse parsing, and error-fused entry streams.
 astral-tokio-tar = { git = "https://github.com/cxymds/tokio-tar.git", rev = "603756478b7668436e464519c77ccac22a99ba96" }
 atoi = "3.1.0"
 atomic_enum = "0.3.0"

deny.toml

@@ -36,8 +36,9 @@ unknown-registry = "deny"
 unknown-git = "deny"
 allow-registry = ["https://github.com/rust-lang/crates.io-index"]
 allow-git = [
-    # Temporary tokio-tar fork pinned to the reviewed bounded extension parser
-    # change while astral-sh/tokio-tar#118 awaits an upstream release.
+    # Temporary tokio-tar fork pinned to the reviewed parser limits,
+    # cancellation safety, and error-fusing change while
+    # astral-sh/tokio-tar#118 awaits an upstream release.
     # owner: cxymds  review: 2026-10
     "https://github.com/cxymds/tokio-tar.git",
     # Official s3s repository. Temporarily pinned to the merged generic REST

docs/architecture/compat-cleanup-register.md

@@ -12,7 +12,7 @@ for later deletion.
 
 ## Open Items
 
-- `tokio-tar-extension-limits` bounded archive extension parsing: Snowball extraction depends on explicit limits for GNU long-name, GNU long-link, and PAX extension payloads, while the released tokio-tar API does not expose those limits. Keep the reviewed fork pin so untrusted archives cannot allocate unbounded extension metadata. Remove the fork pin after astral-sh/tokio-tar#118 is merged and a published tokio-tar release exposes the extension limits used here.
+- `tokio-tar-extension-limits` bounded archive parser hardening: Snowball extraction depends on per-entry and cumulative GNU long-name, GNU long-link, and PAX extension limits; physical-entry, GNU sparse-map, and sparse-continuation limits; cancellation-safe sparse parsing; and fused entry streams after parser errors. The released tokio-tar API does not provide this complete boundary. Keep the reviewed fork pin until astral-sh/tokio-tar#118 is merged and one published tokio-tar release contains every listed capability with the Snowball regression fixtures passing against that release.
 - `backlog-2102` rc.2/rc.3 empty scanner usage floor recovery: old DeleteBucket cleanup could synthesize an empty incomplete v2 usage primary/backup before leadership added an epoch, while newer scanners require a durable authoritative baseline identity. New scanners recognize only that exact serialized empty-fence shape, preserve its epoch through a CAS-protected recovery marker, and rebuild namespace coverage without treating zero usage as authoritative. Remove this recovery path and marker after rc.2 and rc.3 are no longer supported direct-upgrade sources.
 - `s3gate-metadata-xml` persisted bucket XML migration: mixed-version site-replication peers, retained `.metadata.bin` objects, and backup archives can all carry XML written by the s3s codec, so the gateway migration must keep the legacy codec available until every stored form has crossed a verified rewrite boundary. Remove the legacy s3s parser and serializer only after the minimum supported direct-upgrade release reads and writes every persisted XML configuration family through the gateway codec, the four-way D1-D5 gate has remained clean for one full support window, every supported mixed-version site-replication topology has completed its writer upgrade, and migration tooling has verified or rewritten every retained bucket metadata object and restorable backup archive.
 - `rustfs-6339` legacy bucket policy ID casing: earlier RustFS releases persisted the top-level policy identifier as "ID", while current writes use the S3-compatible "Id" spelling. Readers accept both spellings so retained bucket metadata remains usable after upgrade. Remove the legacy alias after migration tooling has rewritten every retained bucket policy using "ID".