[BUG] Corruption happens to Unicode English during `/copy` resulting in mojibake (yet, `/export` works fine)

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?

Corruption happens to Unicode English text:

If I use /copy, em dashes and paragraph signs, emojis, and other special characters turn into â^@, â, etc.
If I use /export, the text is clean and proper.

Something seems to be affecting the clipboard helper specifically.
I even made sure to set env locales explicitly. Didn't help.

Running in a Linux dev container on Mac host.

What Should Happen?

Clean text copied.

Error Messages/Logs

Steps to Reproduce

1. Have a chat session in VS Code extension
2. Go to claude -c in CLI and do /copy (since the extension UI does not support basic copying)
3. Observe garbled up characters when you paste
4. Yet if you try /export - it all looks fine.

Claude Model

Opus

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

2.1.168 (Claude Code)

Platform

Anthropic API

Operating System

Ubuntu/Debian Linux

Terminal/Shell

VS Code integrated terminal

Additional Information

VS Code container (so, Debian) over Mac host