PR Visual Explainer

Create a self-contained visual companion to a pull request. Treat it as an evidence-backed explanation of the current PR head, not as decorative release notes.

Establish authority and lifecycle

1. Resolve the repository, PR number, base, head, and current head SHA before writing.
2. Read the committed base-to-head diff, relevant tests, repository instructions, and current PR evidence.
3. Create or refresh the guide when the user asks to explain the PR. Do not run solely because another workflow opened a PR.
4. Keep the generated HTML local, unstaged, uncommitted, and unpushed unless the user explicitly requests publication.
5. Reuse a matching guide rather than creating competing files. Refresh it when the PR head, behavior, risk, or validation evidence changes.
6. Preserve unrelated work and report the guide's exact local path and Git state.

Gather current evidence

Establish: