[Bug] Agent loses context and makes repeated mistakes during extended sessions

**Bug Description**
This was an unusually poor session where the agent felt lost for long portions of the back and forth. There are numerous mistakes, a lack of record keeping. This is one of the few times that I've had this experience which makes it feel so unusualk.

**Environment Info**
- Platform: darwin
- Terminal: ghostty
- Version: 2.1.265
- Feedback ID: 8f3840f4-333c-42ee-9e02-ca2238bff107

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

No files, tests, or reproduction steps are named. Start from the reported environment and Feedback ID 8f3840f4-333c-42ee-9e02-ca2238bff107 on version 2.1.265, and look for enough session detail to make the context-loss behavior reproducible. Done would require a confirmed root cause or a minimal repro with a regression check.

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