Root cause of "completed/failed/unverified don't show during a running
batch, only after it ends" (F5 didn't help): build_unified_downloads_response
sorted live tasks active-first (downloading/searching/queued = priority 0-3,
completed/failed = 4-7) then truncated the whole array at items[:limit] (300).
During a busy batch the active+queued tasks filled the limit and pushed every
terminal task off the end, so /api/downloads/all never returned them — the
Completed/Failed/Unverified tabs filter client-side and had nothing to show.
Fix: `limit` now bounds only the persistent-history tail. Live in-memory
tasks are always returned in full — they're already bounded by the 5-min
cleanup automation, and array order is presentation-only since the page
filters per tab client-side.
Verified with a repro (320 queued + 1 completed + 1 failed → terminal rows
were absent at limit=300; now present).
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>