The one-time backfill that actually shrinks the DB: drops stored
tagger_predictions entries below ml_settings.tagger_store_floor from every
image_record row, and clamps any allowlist min_confidence below the floor up
to it. Keep predicate (confidence >= floor) mirrors Tagger.infer's store gate
so backfilled rows match new imports. Keyset by id ASC, idempotent,
self-resumes on the soft time limit; runs on the maintenance_long lane.
pg_dump copies live data only, so this alone fixes the #739 backup timeout —
the reclaim (VACUUM FULL / pg_repack on image_record) is a separate, optional
disk-return step, brief because post-prune the live data is tiny.
- admin.prune_low_confidence_predictions_task + POST /api/admin/maintenance/prune-predictions
- PrunePredictionsCard in the Maintenance panel (shows the current floor)
- tests: registration + prune-keeps->=floor/drops-<floor + allowlist clamp
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>