observability-silent-thread-death-an-unhandled-exception-e-g-assert-failure-in-the-i-d66456ae

THEN Wrap the cache retrieval logic (e.g., around `assert mm_item is not None`) in a try-except block that logs the full exception and optionally restarts the thread or gracefully degrades. Also add a watchdog to detect stalled input threads.

try:
    mm_item = cache.get(hash)
    assert mm_item is not None, f"Expected a cached item for {mm_hash=}"
except Exception:
    logger.exception("Cache lookup failed; input thread terminating.")
    # Optionally restart the thread or set a health flag.