sqlite_stat1 was last gathered by a migration while image_exif had 402
rows and an all-NULL content_hash, so the planner treated the hash index
as non-selective and scanned it for every row in the back-ref refresh's
correlated subqueries. The face_detections pass took ~20s per watcher
tick while holding the write lock, so chat/persona-chat persistence blew
past busy_timeout and returned 500s. With fresh stats the three
refreshes drop from ~22s to ~0.1s.
- library_maintenance: add refresh_planner_stats (plain ANALYZE;
PRAGMA optimize doesn't catch this on SQLite 3.45), run on full-scan
ticks ahead of reconcile / back-ref refresh.
- utils: retry backoff used 1_u32.pow(..), a flat ~100ms; make it the
documented exponential 100/200/400ms.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Cameron CordesandClaude Opus 5.5
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