How should a project credit AI in commit metadata — and what wording is right for open-source vs commercial projects? This repo is a primary-source-cited research report on that question.
Drop Co-authored-by: for AI. Use Assisted-by: <tool>:<model> for open-source (escalate to Generated-by: when the AI wrote substantial chunks), keep a human Signed-off-by: where the project uses the DCO, and for commercial/proprietary code prefer Assisted-by: or an internal provenance field so the public author line stays human. Always follow the specific project's policy if it has one — a few projects (Kubernetes) ban trailers entirely and want prose disclosure instead.
| Context | Use | Avoid |
|---|---|---|
OSS — DCO / Signed-off-by project |
Assisted-by: <tool>:<model> (→ Generated-by: for big chunks) + a human Signed-off-by: |
Co-authored-by:/Co-developed-by: for AI; any AI Signed-off-by: |
| OSS — casual GitHub project | Assisted-by: or a plain body-note disclosure |
reflexive Co-authored-by: tool default |
| Commercial / proprietary | Assisted-by: or an internal provenance field; keep the public author line human |
Co-authored-by: <AI> (muddies CLA / indemnity accountability) |
Co-authored-by: asserts authorship, and that is exactly the problem for AI. Under U.S. law an author must be human, AI-only output isn't copyrightable, and in DCO/Signed-off-by projects co-authorship implies a rights certification an AI legally cannot make. The open-source ecosystem has converged on a non-authorial pair of trailers instead — Assisted-by: for light help, escalating to Generated-by: for substantial AI output — which record tool use honestly while keeping the human as the sole author and signer.
Two myths the research retires: AI trailers do not pollute anyone's contribution graph (they use synthetic emails matching no account), and the popular alternative phrasings (Partly-generated-with, Co-developed-with, Written-with) are valid but have zero adoption and don't beat the standard pair. The friction driver is that coding tools (Claude Code, Copilot, Cursor, aider) still default to Co-authored-by: for AI — all toggleable off.
- REPORT.md — executive summary, full wording-options catalog, OSS-vs-commercial recommendation matrix, and copy-paste commit examples.
- GLOSSARY.md — plain-language definitions of the less-common terms (DCO, CLA, SLSA, kernel trailers, the case law).
- sources/ — six numbered, independently-cited primary-source notes (git/GitHub trailer mechanics, the DCO & sign-off, AI-tool defaults, real project policies, copyright/legal, and the wording catalog).
Every claim in the report traces to a primary source with a URL.
This report is AI-generated content: ordered by the repository owner and executed by an automated Claude research workflow — Claude Opus 4.8 (claude-opus-4-8) via Claude Code — under human direction and review. Published 2026-07-08 12:05 UTC+00:00. In keeping with its own recommendation, its commits are labeled with a Generated-by: trailer rather than Co-authored-by:. See the full Provenance note in the report.