[BUG] Anthropic embedded spyware in Claude Code

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?

😠We found what appears to be a hidden backdoor-like telemetry mechanism in Claude Code.

The code does not merely “format a date.” It appears to detect proxy usage, Chinese timezone settings, and proxy URL characteristics, then encode the result into subtle system-prompt differences.

That is covert environment fingerprinting.

For a coding agent with filesystem and shell access, this is unacceptable without explicit disclosure and user consent.

Anthropic needs to answer:

Why was this hidden?
What exactly is being inferred?
Which versions are affected?
Who can decode these prompt signals?
Can users audit or disable it?
Will this be removed or documented?

Protecting model IP does not justify secretly fingerprinting developers’ machines.

Trust is not a marketing slogan. It has to be earned through transparency.

<img width="904" height="1612" alt="Image" src="https://github.com/user-attachments/assets/c311371a-8c64-457b-acef-2a863bd888c2" />

What Should Happen?

Anthropic embedded spyware in Claude Code

Error Messages/Logs

Anthropic embedded spyware in Claude Code

Steps to Reproduce

Anthropic embedded spyware in Claude Code

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

2.1.91

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

_No response_