chore: Add PR review reminder workflow

.github/workflows/pr-review-reminder.yml

@@ -0,0 +1,155 @@
+name: 'PR: Review Reminder'
+
+on:
+  workflow_dispatch:
+  schedule:
+    # Run every day at 10:00 AM UTC
+    - cron: '0 10 * * *'
+
+permissions:
+  pull-requests: write
+  issues: write
+
+concurrency:
+  group: ${{ github.workflow }}
+  cancel-in-progress: false
+
+jobs:
+  remind-reviewers:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Remind pending reviewers
+        uses: actions/github-script@v7
+        with:
+          script: |
+            const { owner, repo } = context.repo;
+            const now = new Date();
+            const THRESHOLD_MS = 48 * 60 * 60 * 1000; // 48 hours
+
+            // Returns a unique HTML comment marker for a reviewer key (login or "team:slug").
+            // Used for precise per-reviewer deduplication in existing comments.
+            function reminderMarker(key) {
+              return `<!-- review-reminder:${key} -->`;
+            }
+
+            // Fetch all open PRs
+            const prs = await github.paginate(github.rest.pulls.list, {
+              owner,
+              repo,
+              state: 'open',
+              per_page: 100,
+            });
+
+            core.info(`Found ${prs.length} open PRs`);
+
+            for (const pr of prs) {
+              // Skip draft PRs and PRs opened by bots
+              if (pr.draft) continue;
+              if (pr.user?.type === 'Bot') continue;
+
+              // Get currently requested reviewers (only those who haven't reviewed yet —
+              // GitHub automatically removes a reviewer from this list once they submit a review)
+              const { data: requested } = await github.rest.pulls.listRequestedReviewers({
+                owner,
+                repo,
+                pull_number: pr.number,
+              });
+
+              const pendingReviewers = requested.reviewers; // individual users
+              const pendingTeams = requested.teams; // team reviewers
+              if (pendingReviewers.length === 0 && pendingTeams.length === 0) continue;
+
+              // Fetch the PR timeline to determine when each review was (last) requested
+              const timeline = await github.paginate(github.rest.issues.listEventsForTimeline, {
+                owner,
+                repo,
+                issue_number: pr.number,
+                per_page: 100,
+              });
+
+              // Fetch existing comments so we can suppress duplicate reminders
+              const comments = await github.paginate(github.rest.issues.listComments, {
+                owner,
+                repo,
+                issue_number: pr.number,
+                per_page: 100,
+              });
+
+              const botComments = comments.filter(c => c.user?.login === 'github-actions[bot]');
+
+              // Returns the date of the most recent reminder comment that contains the given marker,
+              // or null if no such comment exists.
+              function latestReminderDate(key) {
+                const marker = reminderMarker(key);
+                const matches = botComments
+                  .filter(c => c.body.includes(marker))
+                  .sort((a, b) => new Date(b.created_at) - new Date(a.created_at));
+                return matches.length > 0 ? new Date(matches[0].created_at) : null;
+              }
+
+              // Returns true if a reminder is due for a reviewer/team:
+              // - The review was requested more than 48 hours ago, AND
+              // - No reminder has been posted since the most recent review_requested event
+              //   (this correctly resets the reminder when a new push re-requests the review)
+              function needsReminder(requestedAt, key) {
+                if (now - requestedAt < THRESHOLD_MS) return false;
+                const lastReminded = latestReminderDate(key);
+                if (lastReminded && lastReminded >= requestedAt) return false;
+                return true;
+              }
+
+              // Collect overdue individual reviewers
+              const toRemind = []; // { key, mention }
+
+              for (const reviewer of pendingReviewers) {
+                const requestEvents = timeline
+                  .filter(
+                    e =>
+                      e.event === 'review_requested' &&
+                      e.requested_reviewer?.login === reviewer.login,
+                  )
+                  .sort((a, b) => new Date(b.created_at) - new Date(a.created_at));
+
+                if (requestEvents.length === 0) continue;
+
+                const requestedAt = new Date(requestEvents[0].created_at);
+                if (!needsReminder(requestedAt, reviewer.login)) continue;
+
+                toRemind.push({ key: reviewer.login, mention: `@${reviewer.login}` });
+              }
+
+              // Collect overdue team reviewers
+              for (const team of pendingTeams) {
+                const requestEvents = timeline
+                  .filter(
+                    e =>
+                      e.event === 'review_requested' && e.requested_team?.slug === team.slug,
+                  )
+                  .sort((a, b) => new Date(b.created_at) - new Date(a.created_at));
+
+                if (requestEvents.length === 0) continue;
+
+                const requestedAt = new Date(requestEvents[0].created_at);
+                const key = `team:${team.slug}`;
+                if (!needsReminder(requestedAt, key)) continue;
+
+                toRemind.push({ key, mention: `@${owner}/${team.slug}` });
+              }
+
+              if (toRemind.length === 0) continue;
+
+              // Build a single comment that includes per-reviewer markers (for precise dedup
+              // on subsequent runs) and @-mentions all overdue reviewers/teams.
+              const markers = toRemind.map(({ key }) => reminderMarker(key)).join('\n');
+              const mentions = toRemind.map(({ mention }) => mention).join(', ');
+              const body = `${markers}\n👋 ${mentions} — you were requested to review this PR more than 48 hours ago. Could you please take a look when you get a chance? Thank you!`;
+
+              await github.rest.issues.createComment({
+                owner,
+                repo,
+                issue_number: pr.number,
+                body,
+              });
+
+              core.info(`Posted review reminder on PR #${pr.number} for: ${mentions}`);
+            }