feat: send bounded push digests for update bursts (Closes #569)

frontend/service-worker.js

@@ -278,6 +278,21 @@ self.addEventListener('push', event => {
   const route = String(payload.route || '');
   const tag = String(payload.tag || '');
   const notificationId = Number(payload.notification_id);
+  const updateCount = Number(payload.update_count);
+  if (
+    route === '#/my-work/updates'
+    && tag === 'stackchain-update-digest'
+    && Number.isSafeInteger(updateCount)
+    && updateCount > 0
+    && updateCount <= 50
+  ) {
+    event.waitUntil(self.registration.showNotification(updateCount + ' new work updates', {
+      body: 'Tap to review them in Stackchain.',
+      tag,
+      data: {route},
+    }));
+    return;
+  }
   if (!/^#\/my-work\/update\/\d+$/.test(route) || !/^stackchain-update-\d+$/.test(tag)) return;
   const options = {
     body: 'Tap to review it in Stackchain.',