Deduplication GC (garbage_collect, Phase 2):
- Add an orphan grace period before a ref_count=0 blob's backing file is
physically deleted, mirroring git's gc.pruneExpire. New
storage.blobs.orphaned_at records when a blob last reached ref_count 0;
the delete trigger and every decrement / 0-ref insert path stamp it,
every re-reference clears it.
- Cross-check that no manifest lists the chunk and no file points at the
blob before deleting it (mirrors Phase 1's file check), so a stale
ref_count can only delay collection, never delete live content.
- Unlink the backing files with bounded parallel fan-out.
Together these close a TOCTOU where a concurrent upload of identical
content could re-reference a chunk in the window between the GC row
delete committing and the backing file being unlinked. Individual file
deletes still reclaim eagerly; only bulk empty-trash and the periodic
sweep observe the grace window.
Trash: match ErrorKind::NotFound instead of substring-matching the error
message when treating an already-deleted item as success.
Content-index worker: supervise the drain loop and restart it with
backoff after a panic, instead of letting a panic silently freeze the
search index while the dirty queue grows unbounded.
Adds migration 20260802000000_blob_gc_grace.sql and an integration test
covering the grace window and reference cross-checks.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_0172rsVwzTwD216R9HXT2aU4
Claude