Documents the recovery procedure for the chromadb index-metadata corruption
shape filed at chroma-core/chroma#6949 and reproduced by mempalace's
rebuild_index code path (#1492).
Symptom: mempalace integrity gate quarantines a segment dir with
"labels present but dimensionality is missing or invalid (None)" at
startup, vector search drops to BM25-only fallback, recall gap appears.
Recovery: patch the dimensionality field back into the index metadata
file (the rest of the segment state is intact). ~90 seconds end-to-end
on a 183k-drawer palace; restored 99.97% of recall.
The "delete the metadata file entirely" workaround from chroma-core/chroma#6949
loses the id_to_label and label_to_id mappings; the patch approach
documented here preserves them.
Companion content:
- docs/recovery/index-metadata-recovery.md (this file)
- Related issues #1492 (producer-side fix) and #1493 (auto-recover
proposal for the integrity gate)
- External: jphein/palace-daemon docs/recovery/chromadb-metadata-dict-patch.md
has the same procedure from a palace-daemon HTTP operator's
perspective, plus tests/test_chromadb_metadata_recovery.py with a
regression test that builds a real palace + corrupts + recovers.
Igor Lins e Silva