[Bug] Anthropic API Error: Opus 5 safeguards triggered on benign input

**Bug Description**
▐▛███▛█ Claude Code v2.1.247
▝▜██████▀ Opus 4.8 with max effort · Claude Pro
▝▝ ▝▝ C:\Users\minzhan

❯ /status
⎿ Set Fast mode to ON

❯ HI

● Opus 5's safeguards flagged this message. Our intentionally broad safeguards allow us to deliver more capabilities faster, but can sometimes flag legitimate coding, cybersecurity, and biology tasks. Switched to Opus 4.8. Send feedback with /feedback or learn more

Details: `[cyber]`
⎿ Tip: You can configure model switch behavior in /config

Hey! What are you working on today?

✻ Cooked for 7s · done 1:00 AM

**Environment Info**
- Platform: win32
- Terminal: windows-terminal
- Version: 2.1.247
- Feedback ID: 3fccd952-61b6-4a9e-b190-2bef72ce6545

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

Reproduce the report in Claude Code v2.1.247 on Windows by sending “HI” after enabling Fast mode and observe the Opus 5 safeguard response and fallback to Opus 4.8. No source files or tests are identified in the issue, so the work is complete only when this benign input no longer triggers the safeguard unexpectedly.

索引モデルが issue の本文から書いたものです。