Feature/v2/smartfolders rebuild (#6480)

Co-authored-by: aikido-pr-checks[bot] <169896070+aikido-pr-checks[bot]@users.noreply.github.com>

frontend/editor/public/sw-folder-retry.js

@@ -0,0 +1,88 @@
+/**
+ * Service worker for Watched Folder retry scheduling.
+ *
+ * Reads the earliest pending retry from IndexedDB and sets a setTimeout for it.
+ * When the timer fires it posts PROCESS_DUE_RETRIES to all window clients so
+ * the main thread can atomically claim and process the due entries.
+ *
+ * Limitations:
+ *   - Browsers may terminate idle service workers after ~30 s. The main thread
+ *     therefore also drains due retries on mount and on visibilitychange as a
+ *     fallback — no retries are lost, they may just fire slightly late.
+ *   - Multiple clients each post a SCHEDULE_RETRY message; the SW deduplicates
+ *     by resetting the timer each time, so only one notification is sent.
+ */
+
+const DB_NAME = "stirling-pdf-retry-schedule";
+const STORE_NAME = "retries";
+
+let retryTimer = null;
+
+self.addEventListener("install", () => self.skipWaiting());
+
+self.addEventListener("activate", (event) => {
+  event.waitUntil(self.clients.claim().then(scheduleNextTimer));
+});
+
+self.addEventListener("message", (event) => {
+  if (event.data?.type === "SCHEDULE_RETRY") {
+    scheduleNextTimer();
+  }
+});
+
+function openDB() {
+  return new Promise((resolve, reject) => {
+    const req = indexedDB.open(DB_NAME, 1);
+    req.onsuccess = () => resolve(req.result);
+    req.onerror = () => reject(new Error("SW: failed to open retry DB"));
+    // Create store if this SW activates before the main thread has opened the DB
+    req.onupgradeneeded = (event) => {
+      const db = event.target.result;
+      if (!db.objectStoreNames.contains(STORE_NAME)) {
+        const store = db.createObjectStore(STORE_NAME, { keyPath: "id" });
+        store.createIndex("dueAt", "dueAt", { unique: false });
+      }
+    };
+  });
+}
+
+async function getEarliestDueAt() {
+  try {
+    const db = await openDB();
+    return new Promise((resolve) => {
+      const tx = db.transaction([STORE_NAME], "readonly");
+      const req = tx.objectStore(STORE_NAME).index("dueAt").openCursor();
+      req.onsuccess = () => resolve(req.result ? req.result.value.dueAt : null);
+      req.onerror = () => resolve(null);
+    });
+  } catch {
+    return null;
+  }
+}
+
+async function notifyClients() {
+  const clients = await self.clients.matchAll({
+    type: "window",
+    includeUncontrolled: true,
+  });
+  for (const client of clients) {
+    client.postMessage({ type: "PROCESS_DUE_RETRIES" });
+  }
+}
+
+async function scheduleNextTimer() {
+  if (retryTimer !== null) {
+    clearTimeout(retryTimer);
+    retryTimer = null;
+  }
+  const earliest = await getEarliestDueAt();
+  if (earliest === null) return;
+
+  const delay = Math.max(0, earliest - Date.now());
+  retryTimer = setTimeout(async () => {
+    retryTimer = null;
+    await notifyClients();
+    // Re-schedule for any remaining entries that were not yet due
+    await scheduleNextTimer();
+  }, delay);
+}