tasks/external.py drives the external_link ledger:
- fetch_external_link(link_id): atomic claim (pending/failed→downloading, so a
duplicate enqueue no-ops), per-host Redis serialize lock (#720 pattern;
requeue-with-countdown if busy), fetch via external_fetch into the artist
library tree, then route each file through importer.attach_in_place via a
synthesized sidecar so it links to the SAME post (archive→ImageRecords,
else→PostAttachment; on-disk original removed for captured files, art stays);
thumbnail+ML enqueue for new images; status downloaded | failed | dead with
attempts/last_error/completed_at/duration.
- sweep_external_links(): enqueue a bounded batch of actionable links.
- recover_external_links() + prune_external_links(): recovery + retention (#89).
- per-host enable read via getattr (forward-compatible; Settings UI adds the
columns in 4d — defaults on, rule #26).
Wiring: celery include + route (download lane) + beat (sweep 10m, recover +
prune daily); download_service phase 3 enqueues a sweep after recording links.
Integration tests: download+attach, failure, dead-letter, non-claimable, sweep.
mega still needs the MEGAcmd binary in the runtime image (Phase 4c). Refs #830.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
