Main 8d3b061121; Linux x64 fs-39; web development server; Claude Opus 5.5; CLI 2.1.303.
Synthetic reproduction: P background sleeps30 then foreground nested C sleeps90; S background sleeps210. Root returns. User turn sleeps75 over C completion. S finishes idle and wakes continuation.
[2026-10-22T10:27:42.614Z] {"subtype": "task_started", "task_id": "ae3bdec4539e92046", "is_backgrounded": true, "spawn_depth": 1}
[2026-10-22T10:27:43.506Z] {"subtype": "task_started", "task_id": "af5f8890a47c82041", "is_backgrounded": true, "spawn_depth": 1}
[2026-10-22T10:28:23.526Z] {"subtype": "task_started", "task_id": "a4395b942e49da334", "is_backgrounded": false, "spawn_depth": 2, "parent_task_id": "ae3bdec4539e92046"}
[2026-10-22T10:28:30.220Z] {"subtype": "task_progress", "task_id": "a4395b942e49da334"}
[2026-10-22T10:30:03.372Z] {"subtype": "task_notification", "task_id": "a4395b942e49da334", "status": "completed", "summary": "CHILD_DONE"}
Run (1, 'interrupted', '2026-10-22T10:27:03.279Z', '2026-10-22T10:27:22.374Z')
Run (2, 'completed', '2026-10-22T10:27:34.159Z', '2026-10-22T10:27:45.639Z')
Run (3, 'completed', '2026-10-22T10:29:21.328Z', '2026-10-22T10:30:43.148Z')
Run (4, 'completed', '2026-10-22T10:31:19.518Z', '2026-10-22T10:31:21.914Z')
Nested child ('node:provider:claudeAgent:native-item:task%3Aa4395b942e49da334', 'running', '2026-10-22T10:31:19.927Z', None)
UI: Lineage · 1 running; Waiting on subagent Sleep 90 then report; root says both background agents are now done.