[Bug] Anthropic API Error: Content flagged by safeguards on Claude 3.5 Opus

**Bug Description**
API Error: Opus 5 (1M context)'s safeguards flagged this message (https://www.anthropic.com/legal/aup). This sometimes happens with safe, normal conversations. Claude Code can't respond to this message with Opus 5 (1M context).

Double press esc to edit your last message, or try a different model with /model.

Send feedback with /feedback or learn more: https://support.claude.com/en/articles/16049681

Details: `[reasoning_extraction]`

Request ID: req_011Cf1pd6i978C7GHgtvWoyd

**Environment Info**
- Platform: darwin
- Terminal: ghostty
- Version: 2.1.268
- Feedback ID: de712a25-43dd-44b5-bb52-303e97e08cad

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

No file, test, or entry point is named in the report. Start by reproducing the safeguard response with the reported Claude 3.5 Opus 1M-context setup and inspect how Claude Code handles the [reasoning_extraction] response; completion requires a reproducible safe-message case and an agreed behavior for the error.

索引モデルが issue の本文から書いたものです。