[Bug] Subagent closes without user confirmation before exit

**Bug Description**
I'm pretty sure the subagent was interacting with me and confirmed with me before closing, the parent agent got very confused about this and thought that the subagent had gone rogue.

**Environment Info**
- Platform: darwin
- Terminal: iTerm.app
- Version: 2.1.251
- Feedback ID: a2c060e5-cbb6-4572-9477-7b0fcd0a3386

**Errors**
```json
[]
```

Start by reproducing the subagent exit on darwin using iTerm.app, then trace the subagent lifecycle and its interaction with the parent agent. Done means the subagent does not close before user confirmation and the parent agent receives an accurate exit state.

Written by the indexing model from the issue text.