Co-Authored-By is the wrong trailer for your coding agent

Your coding agent just committed a fix, and the commit ends with Co-Authored-By: Claude <noreply@anthropic.com>. GitLab and GitHub parse that trailer and render the model as an author of your work, avatar and all. If you'd rather disclose the tool without promoting it to co-author, this post is the two-setting fix, plus the reasoning you'll want handy when a colleague asks why you bothered.

The authorship claim

Co-Authored-By: makes a claim your forge acts on, and for a tool that claim is false. It predates agents; it exists so pairing humans both get credit, and forges treat it as data: the named party shows up in the commit UI and the contribution graph. Authorship, though, is a loaded status. An author can answer for a change in review, certify its provenance (the whole point of the kernel's Developer Certificate of Origin and its Signed-off-by: line) and hold copyright, which the US Copyright Office says an AI can't. A tool that helped you isn't any of that, any more than a compiler is. The trailer asserts something false in a field machines treat as true.

There's a softer cost too: reviewers who know the trailer is auto-appended read it as "didn't proofread their own commit message". Ask me how I know.

What the kernel does instead

The Linux kernel's coding-assistants policy lands on the format worth copying: AI agents never add Signed-off-by: (that certification is a human act), and assistance is recorded as an inert trailer:

Assisted-by: Claude Code (writing, merge-request)

No forge parses it. It claims nothing. It sits in the message body, greppable by anyone auditing later (git log --grep=Assisted-by), and it can name the skills or tools that actually ran, which doubles as a pointer for the colleague who wants to steal your setup. Think of it as a nutrition label rather than a name tag. Fedora adopted the same trailer; OpenTofu went further and banned the co-author form for tools outright.

Disclosure itself is worth doing even though it isn't free: labeled AI text takes a small, wording-insensitive credibility penalty in controlled studies, but among colleagues who already know you run agents, text that smells generated with no acknowledgment costs more; suspicion lands on you instead of the artifact. A trailer discloses without opening every commit with the one line proven to lower its reception.

The switch

Two pieces: stop the default, state the convention. In Claude Code, blanking the attribution settings removes both the commit trailer and the PR footer:

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

The positive half is one rule in your agent instructions (AGENTS.md, CLAUDE.md, whichever your tools read):

End every agent-drafted commit message with an
`Assisted-by: <tool> (<skills used>)` trailer, e.g.
`Assisted-by: Claude Code (writing, merge-request)`; never add
`Co-Authored-By` for a tool, since forges parse that as an
authorship claim.

On Dotfiles Pro machines both halves ship as settings, not files: the claude role blanks claude_code_settings.attribution, and the agents role renders the trailer rule into the generated AGENTS.md, so every machine and every tool gets the same convention on the next dotpro apply.

Already in a terminal with an agent? Hand it the whole job:

Set up AI-commit attribution my way: disable your default Co-Authored-By
attribution in your settings, and add a rule to my agent
instructions file that every agent-drafted commit ends with an
`Assisted-by: <tool> (<skills used>)` trailer instead. Show me both
changes before saving.

Where this stops working

Honest limits, because trailers are convention, not enforcement. Agents follow instruction files most of the time, not always, and a factorial study of 1,650 Claude Code sessions found compliance falling as a session runs longer, around 5.6% lower odds per generated function, so expect to amend the odd commit. Nothing renders Assisted-by: in a forge UI, which is the point, but it also means the disclosure is invisible until someone looks; if your team wants visible disclosure on merge requests, that's a one-line footer on the MR description, a different decision with its own trade-offs. And a trailer doesn't make the work reviewable: the only attribution that matters in review is that you can explain every line, whoever drafted it.

Co-Authored-By answers "who wrote this", and answers it wrongly. Assisted-by answers "what helped", and answers it truthfully.