[BUG] Entire UI is monochrome — no colors, syntax highlighting, or selection indicators

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?

After updating Claude Code, the entire UI renders in black and white with no colors at all. Specifically:

• No syntax highlighting in diff previews or code blocks
• No colored cursor on the text input line
• No visible "current selection" highlight in menus (e.g., /config theme picker) — only the > indicator and checkmark are visible, but no color differentiation
• No color differentiation for added/removed lines in diffs

The UI is completely monochrome despite the terminal fully supporting colors (TERM=xterm-256color, COLORTERM=truecolor).

What Should Happen?

The UI should display with full colors: syntax highlighting in code/diffs, colored diff markers (red for removed, green for added lines), visible colored selection highlight in menus, and a visible cursor on the text input line.

Error Messages/Logs

No error messages — the application runs normally, it just has no colors.

Steps to Reproduce

1. Update Claude Code to v2.1.52
2. Launch claude in any terminal (Warp, Ghostty, or default macOS zsh terminal)
3. Run /config and navigate to the Theme picker
4. Observe: the entire UI is monochrome black-and-white — no syntax highlighting in the diff preview, no colored selection indicator on the theme list, no colors anywhere

Claude Model

Opus

Is this a regression?

Yes, this worked in a previous version

Last Working Version

2.1.50

Claude Code Version

2.1.52 (Claude Code)

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Warp/Ghostty/Zsh

Additional Information

• Reproduced on multiple terminals: Warp, Ghostty, and default zsh terminal — all exhibit the same monochrome issue
• NO_COLOR is not set
• FORCE_COLOR is not set
• COLORTERM=truecolor
• TERM=xterm-256color
• macOS 15.7.1 (Darwin 24.6.0)
• Issue started after a Claude Code update, not a macOS or terminal update

<img width="663" height="613" alt="Image" src="https://github.com/user-attachments/assets/370100f7-2779-44c8-8810-bc35158c8423" />

<img width="711" height="474" alt="Image" src="https://github.com/user-attachments/assets/3d7c4b14-0400-4851-8d39-a4665aad103c" />