pr-triage.yml

name: PR Triage

# Runs on pull_request_target, not pull_request: fork PRs get a read-only
# GITHUB_TOKEN under pull_request regardless of the permissions below, so the
# label/comment writes 403. This job never checks out or runs PR head code (it
# only reads context.payload and the files API), so pull_request_target is safe.
on:
  pull_request_target:
    types: [opened, edited, synchronize, reopened]

permissions:
  contents: read
  pull-requests: write
  issues: write

concurrency:
  group: pr-triage-${{ github.event.pull_request.number }}
  cancel-in-progress: true

jobs:
  triage:
    name: Quality-signal triage
    runs-on: ubuntu-latest
    timeout-minutes: 10
    steps:
      - name: Label and guide
        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8.0.0
        with:
          script: |
            const pr = context.payload.pull_request;
            const { owner, repo } = context.repo;
            const prNumber = pr.number;

            // Trusted authors bypass triage entirely.
            const trusted = ["OWNER", "MEMBER", "COLLABORATOR"];
            if (trusted.includes(pr.author_association)) {
              core.info(`Author association ${pr.author_association} is trusted; skipping triage.`);
              return;
            }

            // Labels this workflow owns. Anything here may be added or removed each run.
            const MANAGED = ["needs-issue", "needs-description", "needs-tests", "workflow-change"];
            const want = new Set();

            const body = pr.body || "";

            // Linked issue: look for "closes/fixes/resolves #N" or any bare #N reference.
            const hasLinkedIssue =
              /\b(close[sd]?|fix(e[sd])?|resolve[sd]?)\b[^\n]*#\d+/i.test(body) ||
              /#\d+/.test(body);
            if (!hasLinkedIssue) want.add("needs-issue");

            // Description substance: strip HTML comments and markdown headings, then measure.
            const stripped = body
              .replace(/<!--[\s\S]*?-->/g, "")
              .replace(/^#+.*$/gm, "")
              .trim();
            if (stripped.length < 50) want.add("needs-description");

            // File-based signals.
            const files = await github.paginate(github.rest.pulls.listFiles, {
              owner, repo, pull_number: prNumber, per_page: 100,
            });
            const names = files.map(f => f.filename);

            const isFork = pr.head.repo && pr.head.repo.full_name !== pr.base.repo.full_name;
            const touchesWorkflows = names.some(n => n.startsWith(".github/workflows/"));
            if (isFork && touchesWorkflows) want.add("workflow-change");

            const changedRust = names.some(n => n.startsWith("crates/") && n.endsWith(".rs"));
            // A test can live in a tests/ dir, a *_test.rs file, or (the common Rust
            // pattern) an inline #[test] / #[cfg(test)] block added inside the source file.
            // Async tests use a namespaced attribute (#[tokio::test], #[async_std::test],
            // possibly with args like #[tokio::test(flavor = ...)]) rather than the bare
            // #[test]. Match only on added lines, with the attribute at the start of the
            // line after horizontal whitespace, covering bare, cfg(test), namespaced,
            // optional leading ::, and raw-identifier (r#test) forms. No head-file fetch
            // or lexer: needs-tests is advisory, not a merge gate.
            const addsInlineTest = files.some(f =>
              f.filename.endsWith(".rs") && f.patch &&
              /^\+[ \t]*#\[[ \t]*(?:cfg[ \t]*\([ \t]*test[ \t]*\)|(?:::[ \t]*)?(?:[\w-]+[ \t]*::[ \t]*)*(?:r#)?test\b)/m.test(f.patch));
            const touchedTests =
              names.some(n => n.includes("/tests/") || n.endsWith("_test.rs")) || addsInlineTest;
            if (changedRust && !touchedTests) want.add("needs-tests");

            // Reconcile labels: add wanted managed labels, remove managed labels no longer wanted.
            const current = (await github.rest.issues.listLabelsOnIssue({
              owner, repo, issue_number: prNumber,
            })).data.map(l => l.name);

            const toAdd = [...want].filter(l => !current.includes(l));
            const toRemove = MANAGED.filter(l => current.includes(l) && !want.has(l));

            if (toAdd.length) {
              await github.rest.issues.addLabels({ owner, repo, issue_number: prNumber, labels: toAdd });
            }
            for (const name of toRemove) {
              await github.rest.issues.removeLabel({ owner, repo, issue_number: prNumber, name })
                .catch(() => {}); // ignore if already gone
            }

            // Guidance comment: only for advisory signals, and only once.
            const advisory = ["needs-issue", "needs-description", "needs-tests"].filter(l => want.has(l));
            if (!advisory.length) return;

            const MARKER = "<!-- gitlawb-triage -->";
            const comments = await github.paginate(github.rest.issues.listComments, {
              owner, repo, issue_number: prNumber, per_page: 100,
            });
            if (comments.some(c => c.body && c.body.includes(MARKER))) {
              core.info("Guidance comment already present; not reposting.");
              return;
            }

            const reasons = {
              "needs-issue": "Link the issue this addresses (`Closes #123`). For protocol changes, open an issue first.",
              "needs-description": "Add a short summary of what changes and why: the template's Summary and Motivation sections.",
              "needs-tests": "This changes Rust source but no tests changed. Tests are required for fixes and strongly encouraged for features.",
            };
            const lines = advisory.map(l => `- ${reasons[l]}`).join("\n");
            const comment = [
              MARKER,
              "Thanks for the contribution. A couple of things will help us review this faster:",
              "",
              lines,
              "",
              "See [CONTRIBUTING.md](https://github.com/Gitlawb/node/blob/main/CONTRIBUTING.md). Update the PR and these notes will clear automatically.",
            ].join("\n");

            await github.rest.issues.createComment({ owner, repo, issue_number: prNumber, body: comment });