name: External PR Scope Guard

# Required status check that constrains what a NON-MEMBER pull request may change.
# Members (write/admin) are unrestricted and skip this check. For a non-member PR this
# fails unless the PR is an in-scope external contribution per .github/scripts/external-pr-scope.js:
# it changes ONLY .claude-plugin/marketplace.json, the delta is additions-only (no existing
# entry modified or removed), and every ADDED entry's source.url is a repo that ALREADY backs
# a live plugin in this marketplace (the allowed set is derived from the live marketplace —
# there is no maintained allowlist).
#
# Add the scope-guard job as a REQUIRED status check in branch protection for it to block merge.
#
# Security: runs on pull_request_target but checks out only the BASE repo (trusted) for the
# shared script; the head marketplace.json is fetched as DATA via the API and parsed, never executed.

on:
  pull_request_target:
    types: [opened, synchronize, reopened]

permissions:
  contents: read
  pull-requests: read

jobs:
  scope-guard:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4   # base repo (trusted)
      - uses: actions/github-script@v7
        with:
          script: |
            const author = context.payload.pull_request.user.login;

            const { data: perm } = await github.rest.repos.getCollaboratorPermissionLevel({
              owner: context.repo.owner, repo: context.repo.repo, username: author,
            });
            if (['admin', 'write'].includes(perm.permission)) {
              console.log(`${author} is ${perm.permission} (member) — scope guard not applicable.`);
              return;
            }

            const { evaluate } = require(`${process.env.GITHUB_WORKSPACE}/.github/scripts/external-pr-scope.js`);
            const result = await evaluate({ github, context });

            if (!result.ok) {
              core.setFailed(
                `Scope guard: a non-member PR may only ADD marketplace.json entries whose source repo already backs a live plugin here.\n - ` +
                result.problems.join('\n - ')
              );
              return;
            }
            console.log(`Scope guard passed: adds ${result.added.join(', ') || 'none'}, all from repos already live here.`);