fix(storage): resolve erasure parity per pool (#4977)

* fix(filemeta): add state-aware file info validation

* fix(filemeta): validate shard arithmetic and delete paths

* fix(ecstore): add fallible erasure construction

* fix(ecstore): resolve storage parity per pool

* fix(storage): report heterogeneous erasure layouts

* fix(admin): publish prepared storage config atomically

* fix(storage): harden per-pool parity boundaries

* fix(storage): address pre-PR validation findings

* test(ci): fix strict-topology validation fixtures

* fix(heal): preserve delete markers during repair

* refactor(filemeta): drop unused ValidatedFileInfo witness

ValidatedFileInfo wrapped an unread `_file_info` reference alongside an `Option<ValidatedErasureLayout>`, but only the layout was ever consumed. Return the layout directly from `FileInfo::validate` so the sole production consumer (`LocalDisk::check_parts`) and the two unit tests read it without the extra witness type and lifetime.

No behavior change.

* fix(filemeta): keep compressed and MinIO-migrated tiered objects readable

The new decode-path validation rejected several legitimate on-disk shapes that older RustFS and MinIO-migrated data carry, turning readable objects into FileCorrupt:

- Compressed objects written with an unknown upload size persist a negative per-part actual_size (the documented "unknown size" sentinel that ObjectInfo::get_actual_size already tolerates). validate_collection_contents rejected it via usize::try_from; now a negative actual_size skips shard validation and only real, non-negative sizes are checked.
- MinIO-migrated objects transitioned to a versioned remote tier store the tier version id as a UUID string, not 16 raw bytes. MetaObject::into_fileinfo returned FileCorrupt (main tolerated it as None), making all versions of the object unreadable; MetaDeleteMarker free-version records took a Some(nil) sentinel path with the same effect, which also breaks free-version expiry (remote-tier leak). Both now decode through a shared transitioned_version_id_from_meta_sys helper: 16 raw bytes or a UUID string are accepted, anything else is tolerated as None instead of failing the read.

Regression tests updated to assert the readable/compat behavior, with new tests covering MinIO string-form recovery.

* fix(scanner): build the delete-marker test fixture without erasure geometry

get_size_counts_delete_markers_separately_from_versions built its delete marker with `FileInfo::new(object, 1, 1)`, which attaches erasure geometry (data=1/parity=1/distribution). This PR classifies versions by shape via `is_storage_delete_marker()` (no geometry) rather than the raw `deleted` flag, so a geometry-bearing "delete marker" is correctly serialized as a purge-pending payload Object and counted as a version — CI saw summary.versions=3, expected 2.

Real delete markers carry no erasure geometry (delete paths build them as `FileInfo { deleted: true, ..Default::default() }`), so construct the fixture the same way. It then classifies as a storage delete marker and the counts (versions=2, delete_markers=1) hold. This keeps the PR's more-correct classification, which prevents a purge-pending object's geometry from being dropped when serialized as a bare delete marker.

* docs(changelog): note per-pool parity fix and storage-class startup upgrade caveat

Records the #4801 per-pool erasure parity fix under Fixed, and documents the upgrade behavior where a persisted storage class that a small or heterogeneous pool cannot satisfy now fails startup — with the RUSTFS_STORAGE_CLASS_STANDARD recovery steps. Docs-only; covers R4 from the on-disk compatibility audit.

* fix(heal): report parity from erasure geometry, not is_valid()

heal_object set HealResultItem.parity_blocks via `if lfi.is_valid()`, which was missed by the migration of the other quorum/metadata predicates. With the new `is_valid()` semantics (full payload validation; delete markers now return false), a delete marker or a geometry-bearing version with a benign collection quirk would misreport parity as the pool default instead of its own. Use `has_valid_erasure_geometry()` — the narrow "does this carry erasure geometry" predicate the rest of the migration uses — so reporting matches the object's actual layout. Reporting-only; no data-path change.

* fix(filemeta): do not silently serialize a non-canonical deleted FileInfo as an Object

`From<FileInfo> for FileMetaVersion` classifies by `is_storage_delete_marker()` (shape), which correctly routes canonical delete markers to Delete and purge-pending payloads (deleted=true with real erasure geometry) to Object. But a `deleted` FileInfo that is neither a canonical marker nor a valid erasure payload would silently serialize as a zero-geometry MetaObject that later fails `validate_for_metadata_read`. Write paths validate first (`validate_for_erasure_write` / `validate_for_metadata_read`), so this is a caller bug; `From` is infallible, so surface it with a structured `warn!` on the malformed branch instead of writing corrupt metadata silently. Legitimate purge-pending objects (valid geometry) are unaffected — the guard only fires for `deleted && !has_valid_erasure_geometry()`.

* test(filemeta): assert real historical xl.meta versions pass metadata-read validation

Empirical companion to the code-reasoned decode-tolerance invariants (docs/architecture/erasure-coding.md §11) and the rolling-upgrade / MinIO-migration compatibility concern: the tightened `validate_for_metadata_read` runs on every local disk read and peer-RPC-decoded FileInfo, so it must accept every version of real historically-written xl.meta, never reject it as FileCorrupt.

Loads five real fixtures — MinIO small-inline, MinIO versioned (two object versions + a delete marker), MinIO large multipart, a legacy V1 (xl.json-derived) object, and a legacy meta_ver 2 object — decodes every version with parts materialized, and asserts validate_for_metadata_read() is Ok for each. Reverting the tolerant handling (delete-marker shape, legacy per-part checksums, string/short transitioned-versionID, negative actual_size) turns this red.

* fix(ci): remove duplicate storage test re-exports

---------

Co-authored-by: overtrue <anzhengchao@gmail.com>

CHANGELOG.md

@@ -9,6 +9,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Fixed
 - **Helm Ingress**: `customAnnotations` are now merged with class-specific annotations (nginx/traefik) instead of being ignored when `ingress.className` is set.
+- **Per-pool erasure parity**: Erasure parity (STANDARD and reduced-redundancy) is now resolved independently for every pool instead of reusing the first pool's value. A heterogeneous topology — for example a 4-drive pool plus a 2-drive pool created during expansion — previously inherited the first pool's parity and could resolve to zero data shards in the smaller pool, panicking Reed-Solomon construction on write. Automatic parity now resolves per pool (for example `2+2` in the 4-drive pool and `1+1` in the 2-drive pool). Fixes #4801.
 
 ### Added
 - **NATS JetStream Publish Path**: Opt-in at-least-once delivery for the NATS notify and audit targets. A NATS Core publish flushes to the connection without awaiting a broker acknowledgement, so an event can be lost across a broker restart or a reconnect after the send queue has already cleared it. A queued event now clears only after the JetStream `PublishAck`, so bucket notifications survive those interruptions. Off by default and byte-identical to the NATS Core path when disabled.
@@ -38,6 +39,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Changed
 - **HTTP Server Stack**: Integrated `KeystoneAuthLayer` middleware from `rustfs-keystone` crate into service stack (positioned after ReadinessGateLayer)
+- **Storage-class validation on startup (upgrade note)**: A persisted explicit storage class (`RUSTFS_STORAGE_CLASS_STANDARD` / `RUSTFS_STORAGE_CLASS_RRS`, for example `EC:2`) is now validated against the actual per-pool drive counts at startup and rejected when a pool cannot satisfy it. This is fail-closed and correct, but a cluster that persisted a storage class larger than a small or heterogeneous pool can hold (for example `EC:2` alongside a 2-drive pool), which earlier releases accepted and silently resolved to an invalid layout, will now refuse to start after upgrade. To recover, unset `RUSTFS_STORAGE_CLASS_STANDARD` so the server derives a valid per-pool default automatically, or set it to a value every pool can satisfy.
 - **IAMAuth**: Enhanced `get_secret_key()` to return empty secret for Keystone credentials (bypasses signature validation)
 - **Auth Module**: Modified `check_key_valid()` to retrieve Keystone credentials from task-local storage and determine admin status
 - **`StorageBackend` trait**: extended with multipart upload methods (`create_multipart_upload`, `upload_part`, `complete_multipart_upload`, `abort_multipart_upload`) plus `upload_part_copy`. Streaming-upload code path is now available to FTPS, WebDAV, and Swift drivers as well.