[longquanzheng]

Summary

• .githooks/commit-msg still strips Cursor trailers, and now rejects any other AI agent attribution: Co-authored-by trailers for Claude, Codex, Copilot, Gemini, OpenAI, or Anthropic, and Claude Code generation footers.
• New script/check-commit-attribution applies the same check to text on stdin. Check Gate CI runs it on every pull request's title, description, and commit messages, so a commit made without the hook still cannot merge.
• CLAUDE.md, AGENTS.md, and .cursor/rules/git-commit.mdc state the rule for every agent, and CONTRIBUTING.md and the Makefile help describe the hook.

Why

Agent co-author trailers reached main through squash merges (c425bb9, ea1ad39, f2e9dd6) even though the repository rule says the commit author, committer, and message must be the human user only. The existing hook only handled Cursor. This makes the rule enforced, locally and in CI.

Testing

• shellcheck on both scripts.
• The hook rejects a Claude Co-authored-by trailer, strips a Cursor trailer and accepts the result, and accepts a plain message.
• The CI script rejects a Claude Code generation footer.
• The Check Gate step runs for the first time on this pull request.