[BUG] Markdown code block syntax highlighting uses basic ANSI colors instead of true color
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?
Claude Code's markdown renderer uses ANSI color 4 (\e[34m, dark blue) for keywords in fenced code blocks, making them nearly unreadable on dark terminal backgrounds. However, the Write tool's diff preview for the same code uses correct 24-bit true color (monokai). Both renderers are in the same session, same terminal, proving the terminal supports true color.
I'm using /theme of dark
What Should Happen?
Fenced code blocks use true color like the rest of the UI.
Error Messages/Logs
Steps to Reproduce
Ask Claude Code:
Write a 5-line Go program to /tmp/color-test.go, then also display it in a code block
The Write preview has correct monokai colors, the markdown code block has dark blue keywords.
Claude Model
Sonnet (default)
Is this a regression?
I don't know
Last Working Version
_No response_
Claude Code Version
2.1.170 (Claude Code)
Platform
AWS Bedrock
Operating System
Ubuntu/Debian Linux
Terminal/Shell
Xterm
Additional Information
<img width="800" height="561" alt="Image" src="https://github.com/user-attachments/assets/a330740b-2352-4bff-8b30-343ad366ccf5" />