Backfill downloads stranded with empty logs + a generic "stranded by
recovery sweep" error. Root cause: the backfill gallery-dl subprocess
timeout (1170s) exceeded download_source's Celery soft_time_limit (900s),
so SoftTimeLimitExceeded preempted subprocess.TimeoutExpired. The
TimeoutExpired path (which captures partial stdout/stderr and finalizes
the event) never ran, the event was left 'running', and phase 3 never
decremented backfill_runs_remaining — so the source re-ran and
re-stranded every tick (Anduo #39912).
Two layers:
1. Raise download_source limits (soft 900→1350, hard 1200→1500) so both
subprocess budgets (870 tick / 1170 backfill) sit below the soft
limit with phase-3 persist headroom. Promote to module constants and
guard the invariant with a test.
2. Catch SoftTimeLimitExceeded in download_source and finalize the
in-flight event with a real reason, mirror phase-3 source-health, and
decrement backfill so a chronically-slow source self-heals to tick
mode. The existing celery_signals handler only covered TaskRun, not
DownloadEvent — that was the gap.
Updates stale 900/1200 references in gallery_dl.py + maintenance.py.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
bvandeusen