ci: block invalid pull requests (#2010)

.github/workflows/pr-filter.yml

@@ -0,0 +1,22 @@
+name: Block Invalid PR
+
+on:
+  pull_request_target:
+    types: [opened, reopened, edited]
+
+jobs:
+  check-template:
+    runs-on: ubuntu-latest
+    permissions:
+      pull-requests: write
+    steps:
+      - name: Checkout Code
+        uses: actions/checkout@v4
+
+      - name: Check PR Content
+        uses: actions/github-script@v7
+        with:
+          github-token: ${{ secrets.GITHUB_TOKEN }}
+          script: |
+            const script = require('.github/workflows/scripts/pr-filter.js');
+            await script({ github, context });

.github/workflows/scripts/pr-filter.js

@@ -0,0 +1,40 @@
+function noTypes(markdown) {
+  if (/## Type of change/.test(markdown) && /- \[x\]/i.test(markdown)) {
+    return false;
+  }
+  return true;
+}
+
+function noDescription(markdown) {
+  return (
+    /## Description/.test(markdown) === false ||
+    /## Description\s*\n\s*## \w+/.test(markdown) ||
+    /## Description\s*\n\s*$/.test(markdown)
+  );
+}
+
+module.exports = async ({ github, context }) => {
+  const pr = context.payload.pull_request;
+
+  if (pr.labels.length > 0) {
+    // Skip if the PR is already labeled (typically created by a deps-bot.)
+    return;
+  }
+
+  const body = pr.body === null ? '' : pr.body.trim();
+  const markdown = body.replace(/<!--[\s\S]*?-->/g, '');
+
+  if (body === '' || noTypes(markdown) || noDescription(markdown)) {
+    await github.rest.pulls.update({
+      ...context.repo,
+      pull_number: pr.number,
+      state: 'closed'
+    });
+
+    await github.rest.issues.createComment({
+      ...context.repo,
+      issue_number: pr.number,
+      body: "Oops, it seems you've submitted an invalid pull request. No worries, we'll close it for you."
+    });
+  }
+};