[BUG] attribution.commit setting in settings.json is ignored — system prompt Co-Authored-By trailer always wins

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?

The attribution.commit field in .claude/settings.json has no effect on commit messages produced by Claude Code. Regardless of what value is set, commits always end with the hardcoded trailer:

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

What Should Happen?

The attribution.commit string should be used as the attribution appended to commit messages, as described in the documentation.

Actual behaviour

The system prompt instruction to append Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com> takes precedence and the settings.json value is never applied.

Environment

• Platform: Windows 11
• Shell: PowerShell

Error Messages/Logs

Steps to Reproduce

1. Set .claude/settings.json to:

{
"attribution": {
"commit": "<",
"pr": ""
}
}

1. Ask Claude Code to make a commit.
2. Observe the commit message — the configured value (<) does not appear. The hardcoded Co-Authored-By trailer appears instead.

Claude Model

Sonnet (default)

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

2.1.165

Platform

Other

Operating System

Windows

Terminal/Shell

PowerShell

Additional Information

_No response_