Unexpected 'Output blocked by content filtering policy' error during normal session

Bug Description

During a normal Claude Code session (working on open-source repo setup tasks — creating community health files, CI config, etc.), I received:

API Error: 400 {"type":"error","error":{"type":"invalid_request_error","message":"Output blocked by content filtering policy"},"request_id":"req_011CYAA2MrK6wR2VZer6SCJ5"}

Context

• The session involved standard software engineering tasks (creating GitHub issue templates, CONTRIBUTING.md, CHANGELOG, etc.)
• No sensitive or policy-violating content was being generated
• The error appeared to come from the Anthropic API content filtering layer
• Model: Claude Opus 4.6

Expected Behavior

The response should not be blocked by content filtering for standard code/project scaffolding tasks.

Environment

• Claude Code CLI
• macOS (Darwin 24.6.0)
• Date: 2026-02-15

Additional Notes

• The error is non-deterministic — retrying may or may not reproduce it
• No hooks or local configuration are responsible (verified by inspecting all configured hooks)
• Request ID: req_011CYAA2MrK6wR2VZer6SCJ5