- queue: the lease-expiry sweep waited on the workers' `Notify`. `notify_one`
stores a permit, so a sweep wakeup could consume the one meant for a worker,
which then blocked on `notified()` (it only waits when the table looked
empty, i.e. indefinitely) with a due row sitting there. The sweep now has
its own notify, woken only by stop.
- x-media: split fetch's retry loop into `fetch` (3 attempts, unchanged) and
`fetch_once` (1 attempt); inline queries use the latter — the 800ms debounce
plus 1s/2s backoffs were outlasting the answer window of the query.
- send: chunk_media_items now moves items out of the input Vec instead of
requiring `T: Clone` and copying every payload.
fmt/clippy clean, 55 + 69 tests pass.
- send: the PHOTO_INVALID_DIMENSIONS marker never matched (the description is
lower-cased, the marker was not), so oversized photos sent by URL were
classified Permanent instead of taking the download-and-downscale fallback.
- inline: the debounce state was one global slot, so a second user's query
cancelled the first user's pending answer entirely; it is now per user.
- state: prune_expired wrote back a stale snapshot without the per-chat lock,
clobbering a concurrent update() (lost edit-message record -> "Expired");
it now re-reads and prunes under the same lock update() uses.
- send/queue: a task dead-lettered on retry exhaustion kept its keep-alive
temp media (ugoira MP4) alive until process exit; dead_letter_notify now
releases it, and enqueue_retry releases when the enqueue itself fails.
Also folds the duplicated retry enqueue in post_send_actions into
send::enqueue_retry (single clock source, single place that releases).
Tests: +6 (marker, per-user debounce x3, keep-alive release, prune contract
x2); the marker and keep-alive cases were verified to fail before the fix.
cargo fmt/clippy clean, 52 + 69 tests pass.