CONTRIBUTING.md names the branch pull requests target, describes the
quality checks they must pass, points security reports to private
vulnerability reporting, and sets out the policy for AI-assisted
contributions: the human contributor stays accountable, and AI help is
disclosed with Assisted-by trailers rather than Co-Authored-By. The
pull request template asks for the same disclosure.

Assisted-by: Google Antigravity (gemini-4-argon, initial draft)
Assisted-by: Claude Code (claude-opus-5-5, review & corrections)

The first section of the AI-assisted contributions policy made the
contributor bear 100% responsibility for the submitted code and asked
them to understand every line of it. It now keeps the contributor as the
author, accountable for the change, and asks for what code review can
check: that they reviewed, tested and understood it, and can explain or
revise it. Security care and licensing get points of their own; the
licensing point names the MIT License contributions are accepted under,
and says why AI help makes compatibility worth checking.

Assisted-by: Claude Code (claude-opus-5-5, wording review & corrections)