[BUG] v2.1.85 breaks syntax highlighting on MacOS 26

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 diff, syntax highlighting is broken after upgrading. the markdown diff view is completely colourless. In python the docstrings are not highlighted and the colours are off compared to previous version.

What Should Happen?

Markdown files diff view should have syntax highlighting. Python files should have proper syntax highlighting.

Error Messages/Logs

Steps to Reproduce

• Ask claude code to create/update a markdown file
• The diff preview does not have any syntax highlighting

Claude Model

Opus

Is this a regression?

Yes, this worked in a previous version

Last Working Version

2.1.84

Claude Code Version

2.1.197 (Claude Code)

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Other

Additional Information

• I am using latest version of kitty terminal
• Reopening #39805 #63373