Claude Code adds Co-Authored-By: Claude to every commit by default — this should be opt-in

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?

To whom it may concern,

I'm writing to formally raise an issue with Claude Code's default behavior of appending Co-Authored-By: Claude <noreply@anthropic.com> trailers to git commits created through the tool. I discovered this after noticing, unprompted, that every commit I'd pushed to my public GitHub repository was labeled as co-authored by Claude. At no point during setup, installation, or any commit I authorized was this behavior disclosed to me in a way that asked for my consent. It is buried in the tool's internal system prompt as an opt-out default — which is to say, it is not consent at all.

Let me explain why this bothers me with an analogy. Imagine I walk into Walmart, buy my groceries, and on the way out an employee slaps a sticker on the back of my shirt that reads "Happy Walmart Customer." I didn't see them do it. I only find out later when a friend points it out. Walmart would argue the sticker is harmless, removable, and disclosed somewhere in fine print on the receipt. That argument would not survive five minutes in court — unconsented physical contact is battery, and using a customer's body as advertising space is not something any legal team would approve. The reason Walmart doesn't do this isn't because the practice would be hard to defend. It's because the law, and basic ethical norms, protect a person's property from uninvited branding.

Extend the analogy: I cannot walk down the street sticking my business's logo on strangers, their bags, or their parked cars. That's battery, trespass to chattels, vandalism, and in some jurisdictions criminal mischief. The law draws a bright line around non-consensual branding of property you don't own. Software attribution lives in a gray zone legally, but the instinct the law protects in the physical world — my stuff is mine, and you need my permission to put your name on it — is the same instinct you are violating by default with every commit your tool creates.

"some users want the attribution." That's fine. Those users can opt in. That is literally what opt-in means. Their existence is not an argument for defaulting the behavior on for everyone else; it is the argument for asking. The current default does not exist to serve users who want attribution. It exists because on-by-default maximizes Anthropic's brand visibility on every public repository touched by your product. That is a product decision, and it is one that places your commercial interest above your users' ownership of their own work.

My request is straightforward:

Change the default to off. Users who want the trailer can enable it.
Surface the choice at setup time, with a clear one-line explanation, the same way every modern developer tool prompts for telemetry, crash reporting, or analytics.
Make the setting persistent and easy to find in documented configuration, not buried in a system prompt most users will never read.
"Documented in the system prompt" is not consent. It's the software equivalent of a disclaimer on page 47 of a EULA no one reads. Your users deserve better, and the standard you already apply to cookies, telemetry, and tracking elsewhere in the industry is the standard that should apply here.

For the avoidance of doubt, this communication is made without prejudice to any and all rights and remedies available to me at law or in equity, all of which I expressly reserve. My raising this matter informally, and any ongoing use of the product while awaiting your response, shall not be construed as acceptance, waiver, or acquiescence to the practice described above.

Sincerely,
Mike V

Co-Authored-By: Claude Code <noreply@anthropic.com>
(appended automatically, without my consent — see body of letter above.)

What Should Happen?

Claude Code should not append Co-Authored-By: Claude <noreply@anthropic.com> to commits by default.

Error Messages/Logs

Steps to Reproduce

1 - Install Claude Code and authenticate.
2 - Open any git repository (or git init a new one).
3 - Ask Claude to make any change and commit it — e.g. "edit the README and commit."
4 - Allow Claude to run through its standard commit flow.
5 - Run git log -1 --format=%B to inspect the resulting commit message.

Observed: The commit message contains a Co-Authored-By: Claude <noreply@anthropic.com> trailer that the user did not request, was not prompted about at setup, and did not approve at commit time.

Expected: The commit message contains only the content the user authored or approved. Any attribution trailer should require explicit opt-in via a documented setting or setup-time prompt.

Reproducibility: 100% — happens on every commit created through Claude Code's default commit flow, across every repository, regardless of project language, platform, or whether the repo is public or private.

Claude Model

Opus

Is this a regression?

No, this never worked

Last Working Version

_No response_

Claude Code Version

2.1.72 (Claude Code)

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

VS Code integrated terminal

Additional Information

_No response_