[LuciferYang]

Closes #10824.

LanceNamespaceExternalManifestStore::get now returns Error::NotFound when the namespace reports the table, branch, or version as missing. ExternalManifestCommitHandler reads Error::NotFound from the store as "no record" in version_exists, is_manifest_path_authoritative and the object-store fallback of resolve_version_location, so cleanup now deletes a staging manifest that no namespace record points to. Other namespace errors still propagate unchanged, and get_latest_version keeps its separate chain-missing None contract.

Checking out a version the namespace has no record of now goes through the same object-store fallback as other external manifest stores, so it fails with Lance's NotFound error (ValueError in Python) instead of the namespace's TableVersionNotFound error.

How was this patch tested

test_cleanup_removes_staging_manifest_without_version_record uses a DirectoryNamespace with version tracking and injects one create_table_version failure during an append, so the staging manifest stays behind. It asserts the append fails with an unknown commit status, the loaded dataset remains at version 1, exactly one staging manifest remains, and has_successor_version is false. Cleanup with delete_unverified then removes that manifest, and count_rows(None) on the already-loaded dataset returns 3. The test covers namespace-record classification and cleanup; count_rows on that loaded handle may use manifest metadata and does not prove a fresh reopen, full scan, or data-file readability.

test_error_classification replaces test_get_latest_version_error_classification and covers both get and get_latest_version: a missing table, branch or version reads as absent, and internal, throttling and IO errors propagate with their original variant.

The branch was merged with current main and revalidated:

• cargo test --profile ci --locked -p lance --lib io::commit::namespace_manifest::tests::test_error_classification
• cargo test --profile ci --locked -p lance-namespace-impls --lib dir::tests::e2e_table_version_tracking::test_cleanup_removes_staging_manifest_without_version_record
• cargo test --profile ci --locked -p lance-namespace-impls --lib 'dir::tests::e2e_table_version_tracking::' (44 passed)
• cargo test --profile ci --locked -p lance --lib 'io::commit::external_manifest::test::' (14 passed)
• cargo fmt --all
• cargo clippy --profile ci --locked --all --tests --benches -- -D warnings

[claude]

Claude Code Review

This pull request is from a fork — automated review is disabled. A repository maintainer can comment @claude review to run a one-time review.

[lance-gatekeeper]

✅ Gate recommendation: approve.

This restores cleanup after failed namespace commits while preserving operational errors. No blocking issues found.