feat: exempt matching bots from PR description check

.github/scripts/validate-pr-description.js

@@ -2,14 +2,29 @@
  * Validate that a PR description has a filled Overview section.
  * Intended for use with actions/github-script.
  *
+ * Revert PRs and bot authors whose login matches EXEMPT_BOT_LOGIN_PATTERN are
+ * exempt; detection lives here rather than in a caller/workflow `if` condition
+ * so the job still completes successfully instead of showing as skipped, which
+ * can block merges when this check is required.
+ *
  * @param {{ core: import('@actions/core'), context: import('@actions/github').Context }} params
  * @param {{ minOverviewLength?: number }} options
  */
-/**
- * Revert PRs are exempt from description validation. Detection lives here rather than
- * in a workflow `if` condition so the job still completes successfully instead of
- * showing as skipped, which can block merges when this check is required.
- */
+
+/** Case-insensitive: "alloy" anywhere, or "ai" as a hyphen/underscore-delimited token. */
+const EXEMPT_BOT_LOGIN_PATTERN = /alloy|(?:^|[-_])ai(?:[-_]|$)/i;
+
+function normalizeBotLogin(login) {
+  return (login ?? '').toLowerCase().replace(/\[bot\]$/, '');
+}
+
+function isExemptBotPr(pr) {
+  if (pr?.user?.type !== 'Bot') {
+    return false;
+  }
+  return EXEMPT_BOT_LOGIN_PATTERN.test(normalizeBotLogin(pr?.user?.login));
+}
+
 function isRevertPr(pr) {
   const title = pr?.title ?? '';
   const headRef = pr?.head?.ref ?? '';
@@ -20,6 +35,11 @@ module.exports = async function validatePrDescription({ core, context }, options
   const minOverviewLength = Number(options.minOverviewLength) || 40;
   const pr = context.payload.pull_request;
 
+  if (isExemptBotPr(pr)) {
+    core.info('Skipping PR description check for exempt bot-authored PR.');
+    return;
+  }
+
   if (isRevertPr(pr)) {
     core.info('Skipping PR description check for revert PR.');
     return;

.github/workflows/callable.pr-description-check.yaml

@@ -11,6 +11,16 @@ on:
       GH_TOKEN:
         required: true
 
+# The actual use of the workflow should have the following:
+#on:
+#  pull_request:
+#    types: [opened, edited, reopened]
+#
+# Exempt bot and revert PRs are handled in validate-pr-description.js so this job
+# still passes. Other bot PRs must fill Overview. Callers must always invoke this
+# workflow — do not add a job-level if on the caller, or the required check stays
+# pending for bot-authored PRs.
+
 jobs:
   pr-description-check:
     name: PR description check
@@ -37,7 +47,7 @@ jobs:
             const script = require('${{ github.workspace }}/.github/scripts/validate-pr-description.js');
             // github, context, and core are injected by github-script from this
             // job's runtime context (the caller's workflow run / PR payload).
-            // Revert PRs (title "Revert ..." or revert-* branch) are exempt — see validate-pr-description.js.
+            // Exempt bot and revert PRs are handled in validate-pr-description.js.
             await script(
               { github, context, core },
               { minOverviewLength: Number(process.env.MIN_OVERVIEW_LENGTH) }