Actions on Gromacs files triggers false "Usage Policy Violation" error in Opus

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report (please file separate reports for different bugs)
• [x] I am using the latest version of Claude Code

What's Wrong?

When working with Gromacs files, such as checkpoint *.cpt files or umbrella sampling pullx.xvg files, Opus very often triggers false error on user policy violation. pullx.xvg files are particularly nasty - they trigger this error on almost any operation involving them. The files themselves are absolutely innocent - just columns of numbers, not even remotely resembling anything suspicios in cybersecurity domain or such.

When error appears the only way to continue the session is to switch to Sonnet, which works with these files with no problems.

What Should Happen?

Gromacs files such as *.cpt and pullx.xvg should not trigger cybersecurity violation error - they are innocent.

Error Messages/Logs

API Error: Claude Code is unable to respond to this request, which appears to violate our Usage Policy
     (https://www.anthropic.com/legal/aup). This request triggered restrictions on violative cyber content and was blocked under
     Anthropic's Usage Policy. To request an adjustment pursuant to our Cyber Verification Program based on how you use Claude, fill
     out https://claude.com/form/cyber-use-case?token=-Ihw5635pD-KXgVm7wzJx0bjtCkPUNRXSZt5FzOHRQ39wZO52rRqmksCm2dJeU3ZQ2fq5gY43gCl3
     3q7tnRgUYYbs8JxdoVHEzJoAgX3wOGUi5t24DH3dJUlU9tOG0HncDRi-ioLKA… Please double press esc to edit your last message or start a new
     session for Claude Code to assist with a different task.

     Request ID: req_011CbYn9hCmvMTRr8Eg8Cu98

Steps to Reproduce

Some prompts that trigger the error:

• "download all pullx files"
• "find this rotation coordinate in pullx.xvg"
• "convert checkpoint in each window to gro files and download them"
• "convert all checkpoints to gro on the cluster"

Claude Model

Opus

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

2.1.158 (Claude Code)

Platform

Anthropic API

Operating System

Other Linux

Terminal/Shell

Other

Additional Information

_No response_