Plan #693. Large-catalog backfill (Anduo) no longer sprints to the timeout
wall and dies as an error each run. Builds on the cursor checkpoint (#689).
- Time-boxed chunks: BACKFILL_TIMEOUT_SECONDS(1170)→BACKFILL_CHUNK_SECONDS(600),
far under the 1350 soft limit. Hitting it = normal chunk boundary (the
TimeoutExpired path already captures partial output + the cursor), not a
near-wall death.
- Run-until-done state machine driven by config_overrides[_backfill_state]
(running/complete/stalled). A running backfill auto-continues in chunks
across ticks until gallery-dl exits cleanly (rc=0 = reached the bottom →
'complete'); a safety-cap (BACKFILL_MAX_CHUNKS=200) + the #689 stall-guard
pause a pathological walk as 'stalled'. Replaces the N-runs counter
(backfill_runs_remaining repurposed as the cap countdown).
- Progress, not error: a chunk that timed out but advanced (cursor moved
and/or files written) is reclassified TIMEOUT→PARTIAL (status 'ok').
- Retry storm tamed: gallery-dl retries 3→2, downloader timeout 120→60s, so
one stuck CDN file fails in ~1-2 min not ~10 (Anduo #40838).
- API: POST /sources/{id}/backfill now takes {action: start|stop}; service
start_backfill/stop_backfill; new enabled sources auto-arm run-until-done;
source dict exposes backfill_state + backfill_chunks.
Frontend (Start/Stop control + state badge) lands in the next push.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
bvandeusen
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