Issue 20348 runtime reproduction
Commit: 70e5e384da
Environment: Linux x86_64; real web dev app; Codex gpt-6.1-sol; browser 1280x800
Steps: delegate same Codex child -> READY -> parent PARENT_DONE -> Settle parent -> open child -> Reply PONG

2026-10-21T22:36:48.771Z outgoing thread/unsubscribe {"threadId": "01a1609b-aa7f-7750-971b-2a1211df7aba"}
2026-10-21T22:36:48.778Z outgoing thread/unsubscribe {"threadId": "01a1609b-8ee3-70e0-96f9-10d88744feff"}
2026-10-21T22:37:08.186Z outgoing turn/start child=01a1609b-aa7f-7750-971b-2a1211df7aba input=Reply exactly PONG, no tools.
2026-10-21T22:37:08.227Z {"method": "thread/status/changed", "params": {"threadId": "01a1609b-aa7f-7750-971b-2a1211df7aba", "status": {"type": "active", "activeFlags": []}}, "emittedAtMs": 1792622228225}
2026-10-21T22:37:09.911Z {"method": "thread/status/changed", "params": {"threadId": "01a1609b-aa7f-7750-971b-2a1211df7aba", "status": {"type": "idle"}}, "emittedAtMs": 1792622229910}
Codex saved: {"timestamp": "2026-10-21T22:37:09.904Z", "ordinal": 32, "type": "event_msg", "payload": {"type": "task_complete", "root_turn_id": "01a1609c-72e2-7013-9b8c-cb48932be3de", "turn_id": "01a1609c-72e2-7013-9b8c-cb48932be3de", "last_agent_message": "PONG", "started_at": 1792622228, "completed_at": 1792622229, "duration_ms": 1695, "time_to_first_token_ms": 1610}}
Observed: no child thread/resume before follow-up turn/start; no child item/completion notifications after start. Browser remained Working without PONG.