False positive policy refusal on legitimate epidemiological research content

Summary

Claude Code (Opus) refuses to process legitimate epidemiological meeting notes about wild poliovirus type 1 (WPV1) genetic drift, triggering Usage Policy violations. The content is routine scientific collaboration notes from a global health research meeting involving NIH and WHO-affiliated researchers.

Reproduction

1. Paste meeting notes discussing WPV1 (wild poliovirus) genetic drift into Claude Code running Opus
2. Claude returns: "API Error: Claude Code is unable to respond to this request, which appears to violate our Usage Policy"
3. Switching to Sonnet processes the same content without refusal
4. Switching back to Opus for review of Sonnet's output triggers the refusal again

Specific Behavior

• Model: Opus 4.6 (claude-opus-4-6)
• Content: Meeting notes from an epidemiological working group discussing WPV1 genetic drift, vaccine-derived poliovirus surveillance, and national biosafety committee processes
• Trigger point 1: Initial paste of meeting notes → immediate refusal
• Trigger point 2: After Sonnet successfully processed the notes and created project files, asking Opus to "review Sonnet's edits" → refusal again (Opus refused even when the content was already in local files, not in the user message)
• Workaround: Sonnet does not refuse the same content

Impact

This project is a polio eradication research codebase. The entire domain involves discussing poliovirus transmission, vaccination strategies, and disease surveillance. False positive refusals on routine scientific content force model switching mid-session and break workflow continuity.

The refusal is especially disruptive because:

• It fires on the review request too (trigger point 2), where the user message was just "please review Sonnet's edits" — the sensitive content was only in local files in the working directory
• There is no way to pre-clear a project as legitimate scientific research
• The workaround (switch to Sonnet) loses Opus's context and capabilities

Expected Behavior

Legitimate epidemiological research content — meeting notes discussing poliovirus surveillance, vaccine policy, and public health coordination — should not trigger Usage Policy refusals.

Environment

• Claude Code version: 2.1.x (VSCode extension)
• OS: macOS
• Session ID: 433e66a0-4baf-48d5-8caf-4e0ce2188956