The status-bar notifications only expired the front of the queue, so an
expired newer toast could sit in front of a still-live older one and
hide it from view. The liveness check that drives continuous repaints
also disagreed with what render() actually showed.
- Expired toasts are now pruned wherever they sit in the queue, not just
at the front, so the newest remaining toast is always a live one.
- The visible toast is the newest live entry, skipping an expired newer
one. The liveness check reports active while a toast is visible plus
one trailing frame, so the final faded-out state is painted once and
then repaints stop; it self-expires if render() is skipped.
Tests: pruning removes expired entries from anywhere in the queue, the
visible toast skips an expired newest entry, and liveness tracks it.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>