Diff context text color too dark on dark terminal themes

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?

Problem

The unchanged context lines in diff/edit previews are rendered with a hardcoded
truecolor value of approximately RGB(61, 61, 61) / #3d3d3d. On dark terminal
themes (e.g. GruvboxDark with background #282828), this creates insufficient
contrast and makes context lines nearly unreadable.

## Environment

• OS: macOS 25.3.0
• Terminal: WezTerm
• Color scheme: GruvboxDark
• Claude Code version: 2.1.72 (Claude Code)

## Steps to reproduce

1. Use any dark terminal theme with a background darker than ~#383838
2. Trigger an edit proposal that shows a diff with context lines
3. Context lines (unchanged code around the edit) are barely readable

## Expected behavior

Context text should either use a relative color (e.g. ANSI bright black from
the terminal palette) that adapts to the user's color scheme, or the hardcoded
value should provide sufficient contrast on both light and dark backgrounds.

## Notes

Since the color is set as a true 24-bit RGB value, it cannot be overridden
via terminal palette or WezTerm color configuration. A fix needs to come from
Claude Code itself.

What Should Happen?

Context text should either use a relative color (e.g. ANSI bright black from
the terminal palette) that adapts to the user's color scheme, or the hardcoded
value should provide sufficient contrast on both light and dark backgrounds.

Error Messages/Logs

Steps to Reproduce

1. Use any dark terminal theme with a background darker than ~#383838
2. Trigger an edit proposal that shows a diff with context lines
3. Context lines (unchanged code around the edit) are barely readable

Claude Model

Sonnet (default)

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

2.1.72 (Claude Code)

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Other

Additional Information

_No response_