join_pending_inputs slots are normally cleared when the join fires;
partial slots whose inputs never all arrive (upstream removed/renamed,
one-off dynamic partition key, permanent skew) would otherwise leak.
windmill_queue::asset_dispatch::reap_stale_join_slots, called from the
monitor's delete_expired_items loop, deletes a (workspace, subscriber,
partition) slot only when its MOST RECENT row is older than
JOIN_SLOT_TTL_SECS (60d) — per-slot, never per-row, so a legitimately
slow join is not corrupted mid-accumulation. Conservative default;
per-join configurable TTL via the annotation is a planned follow-up.
Test covers stale-reaped / fresh-kept / mixed-slot-kept.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>