Skill: Prove a PR

Verify the tree that will land

• Run every check on the PR head after its final rebase or cherry-pick. Re-run and re-publish after any history rewrite; test runs are bound to a commit SHA.
• Before merging a stacked PR, inspect gh pr view <n> --json baseRefName,headRefName,headRefOid. If its base PR merged first, the stack can merge into the feature branch instead of dev; GitHub then recreates commits with new SHAs and orphans their test evidence.
• Detect stray commits with git log --oneline <branch> ^origin/dev. Remedy a bad stack by cherry-picking only the intended commits onto current dev, then re-run every check and re-publish every test run.

Produce the agent-first verdict