Both sync scripts had their own retry loop, each broken differently.
update_danbooru retried a failed page three times, then `break` -- no message,
no exit code, no record. Those 200 posts were simply never archived, and since
incremental mode restarts from the database max id, nothing ever goes back for
them. A hole in an archive is invisible in the finished dataset; it only turns
up years later when someone queries a range and gets less than they should.
Failures are now collected, printed, and force a non-zero exit.
Neither honoured Retry-After, and both throttled per thread. The quota is per
account, so sixteen independently-limited workers overshoot sixteenfold; the
producer's sleep(0.1) then pinned the total at 10 req/s, exactly Danbooru's
documented ceiling, so any jitter tripped a 429. The shared limiter starts at
5 req/s, halves on a 429 and pauses *every* worker -- punishing only the thread
that happened to lose leaves the other fifteen to exhaust the quota again, so
the ag…
