The hourly catalog-backfill scan had gone effectively dead on prod: its
job sat behind a ~430k-deep wait list and, even when it ran, self-skipped
because the queue backlog (431k) was far over the maxBacklog ceiling
(1000). Net result: newly-decoded / zero-parts vehicles were never
onboarded — they starved behind the deep-drill backlog (ic stuck at 28
for days, 0 backfill-scan jobs ever completed).
Root constraint (verified against bullmq 5.68 lua): moveToActive drains
the `wait` list (RPOPLPUSH from the tail) BEFORE the `prioritized` ZSET,
so a `priority` job is starved behind an already-deep wait queue — the
opposite of what's wanted. The lever that works is `lifo`: it RPUSHes to
the tail, where the very next RPOPLPUSH picks it, ahead of the FIFO
backlog. addJobFromScheduler honours lifo too, so the scan job itself can
jump the queue.
Changes:
- Thread a `fast` flag through the init→children→parts chain; fast jobs
are enqueued with `lifo:true` so the whole chain jumps the backlog.
- Backfill scan: Phase-1 (zero-parts vehicles) now runs every wave in the
fast lane even when the backlog is over the ceiling; only Phase-2 (the
rolling rescan that piles on) is suspended while the queue is deep.
- Register the hourly scan job with `lifo:true` so it fires on the next
tick instead of being buried for days.
Tested: new prefetch-worker.service.spec (lifo wiring + Phase-1/Phase-2
gating), full api suite green (248 passed), typecheck + biome clean.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
