P0: reject register() after close_all() with RuntimeError.
P1: catch CancelledError in close_all(), use WeakKeyDictionary for
cancellation_reasons to prevent memory leak, guard StateManager
update_state/reset/load_checkpoint/time_travel after close().
P2: contextlib.suppress in __del__ for partial construction, re-cancel
pending tasks in cleanup_tasks_async, handle late tasks added during
await window, guard AcpEventQueue.publish() after close with _is_closed
flag and is_closed property, fix ASV TimeRegisterBatch crash.
Tests: 5 new Behave scenarios (T1-T4 + is_closed), log handler and
event loop cleanup in after_scenario (T5-T6).
Docs: async_safety.md updated for register-after-close and state
mutation guards.
ISSUES CLOSED: #321
khyari hamza
c406781b86