Add option to disable automatic Co-authored-by: Copilot trailer in commits generated by Copilot CLI

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🏷️ Discussion Type

Product Feedback

💬 Feature/Topic Area

Copilot CLI

Body

Summary

Please add a configuration option to disable the automatic injection of the Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com> trailer in commit messages generated by GitHub Copilot CLI.

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Current Behavior

When GitHub Copilot CLI generates or amends commits on behalf of the user, it automatically appends the following trailer to every commit message:

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

There is currently no configuration option, CLI flag, or project-level setting to opt out of this behavior.

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Expected / Desired Behavior

Users should be able to opt out of the automatic Co-authored-by trailer injection via one or more of the following mechanisms:

1. A CLI flag — e.g., --no-copilot-trailer or --no-co-authored-by
2. A global user config — e.g., in ~/.config/gh/config.yml or a dedicated Copilot settings file
3. A per-repository config — e.g., via .github/copilot-config.yml or a recognized key in AGENTS.md / COPILOT-INSTRUCTIONS.md

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Use Cases

• Clean commit history requirements: Some teams or open source projects enforce strict commit message formats (e.g., Conventional Commits) and reject commits with unexpected trailers.
• CI/CD pipeline validation: Automated pipelines that lint commit messages may fail when unexpected trailers are present.
• Personal preference: Some users prefer to maintain full ownership of their commit history without automated attribution from tooling.

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Why This Matters

While AI attribution is valuable for transparency in many contexts, it should be opt-in or at least opt-out — not forced on every commit without a way to disable it. Providing a configuration option respects user autonomy while still allowing those who want the trailer to keep it enabled by default.

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Workaround (Current)

The only current workaround is to manually amend each commit after the fact:

git commit --amend -m "$(git log -1 --pretty=%B | grep -v 'Co-authored-by')"

This is tedious and error-prone, especially in automated or high-frequency commit workflows.

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Related: Creating a commit with multiple authors

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