[Bug] Anthropic API Error: False positive cyber safeguard block on tool completion messages

**Bug Description**
False positive from cyber safeguards. Context: I run behavioral QA on my own
CLI agent - 200 test cases covering tone, refusals, emotional scenarios,
conversation handling. No security, exploits, malware or third-party systems
involved. The block fired three times in a row at 2:18 PM, each time right
after a background command reported "completed (exit code 0)", not on any
user prompt. Details: [cyber]. Request IDs: req_011Cf8gYXufBQNVVNTmBSy7F,
req_011Cf8gYzbX8YdFZAveqLqdg, req_011Cf8gb6yoR83zDoVkYMHtw. Session context
was ~485k tokens with prior error messages accumulated in history, which
looks like it amplified the classifier.

**Environment Info**
- Platform: linux
- Terminal: xterm-256color
- Version: 2.1.273
- Feedback ID: 7ce20eb5-78de-436e-aa93-23fe70edc670

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

No repository file or test is identified. Start by reviewing the reported request IDs, version 2.1.273, and the reproduction context around completed background commands and the long session history. Done means determining whether the safeguard block can be reproduced and documenting or fixing the cause.

Written by the indexing model from the issue text.