PR #310226 changed git.addAICoAuthor default from "off" to "all" in VS Code’s Git extension, silently appending Co-authored-by: Copilot trailers to commits.
Key Takeaways
The change is in extensions/git/package.json; the config schema default was flipped to "all" but the runtime fallback in extensions/git/src/repository.ts still hardcodes 'off', creating a sync bug.
Default was later walked back to "chatAndAgent" in PR #312880, so the sequence is off -> all -> chatAndAgent.
The trailer is appended without appearing in the commit message UI, meaning developers never see it before it lands in history.
No user notification or opt-in prompt was added alongside the default change.
Hacker News Comment Review
The MS engineer who approved the PR publicly apologized and called it a mistake; commenters largely rejected “no ill intent” framing given the silent default-on behavior and lack of validation.
Copilot’s own automated review on the PR flagged the repository.ts sync bug and suggested reverting, but the comment was ignored before merge – a detail commenters found darkly ironic.
Security and compliance teams face immediate practical fallout: Co-authored-by: Copilot in commit history can conflict with “approved AI” or data-security policies, and the trailer length alone violates short-commit-message linting rules.
Notable Comments
@dmitriv: The approving engineer, not an anonymous critic, confirmed the mistake and that “it should not be on by default.”
@tln: “Co-authored-by: NEVER appears in the commit message UI – it is added without the user even seeing it.”
