[BUG] Constant AUP violation errors when Claude Code reads raw data files (example included)

.tmp-160387-p1-content.txt

Edit/TL;DR

I was able to distill the ostensibly offending content in this example. Pasting the following string into a Claude Chat window with Opus 4.6 causes an AUP violation.

[<0046004B00440055004400460057004800550003>-26<000B00520055000F0003>-25<0049005200550003>-25<002700520051004E0048005C000F0003>-25<005800510047004800550051004800440057004B000C0003>]TJ
T*

The above translates to "CHARACTER OR FOR DONKEY UNDERNEATH". It is from a Hasbro Shrek toy ad.

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?

In the past week, Claude Opus has become unusable for troubleshooting issues related to reading/writing various types of data files (vectors, fonts, documents, etc.) due to a new filter that flags prosaic patterns of strings as AUP violations. Claude will read a file as text, hit a "magic string" that fits a certain pattern, and flag the chat as an AUP violation. While other users have reported similar issues, none seem to have a reproducible example, so I am opening this issue to provide a minimal reprex.

The included text file contains contents from a publicly available .pdf file advertising a Hasbro children's toy. I intentionally chose the least offensive thing possible, but the errors are not specific to this file. In the latest Claude for VSCode version, Claude throws an AUP error after merely being asked to read this file. I replicate this in a new chat session in a new repo with nothing else in it.

What Should Happen?

Claude should not throw an AUP error.

Error Messages/Logs

Steps to Reproduce

Create a new repo with the provided file. Select the file in VSCode. Prompt Claude to "read this file". See below.

.tmp-160387-p1-content.txt
Alternative link: https://github.com/Balearica/claude-bug-files/blob/master/.tmp-160387-p1-content.txt

Read this file.
Read .tmp-160387-p1-content.txt
API Error: Claude Code is unable to respond to this request, which appears to violate our Usage Policy (https://www.anthropic.com/legal/aup). Try rephrasing the request or attempting a different approach. If you are seeing this refusal repeatedly, try running /model claude-sonnet-4-20250514 to switch models.

Claude Model

Opus

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

2.1.109

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

WSL (Windows Subsystem for Linux)

Additional Information

I am using VSCode extension (Version: 2.1.109). This happens whether using the terminal in VSCode or the Chat window. I could not replicate this exactly using the claude CLI alone, but similar errors are eventually thrown, it just takes slightly longer.

I understand issues of this nature are routinely closed/hand-waved away as transient/probabilistic issues. This is not. This replicates on a new repo in a new chat. Virtually every chat I have made in the last few days has resulted in the chat being flagged for AUP violations. The product is unusable.