fix: complete private outbox purge before sign-out (#293)

frontend/background-issue-sync.js

@@ -8,7 +8,14 @@ function createIndexedDbTransaction(indexedDB, dbName = 'stackchain-background-o
           request.result.createObjectStore('issues', { keyPath: 'id' });
         }
       };
-      request.onsuccess = () => resolve(request.result);
+      request.onsuccess = () => {
+        const db = request.result;
+        db.onversionchange = () => {
+          db.close();
+          databasePromise = undefined;
+        };
+        resolve(db);
+      };
       request.onerror = () => reject(request.error);
     });
     return databasePromise;
@@ -17,7 +24,7 @@ function createIndexedDbTransaction(indexedDB, dbName = 'stackchain-background-o
     request.onsuccess = () => resolve(request.result);
     request.onerror = () => reject(request.error);
   });
-  return async work => {
+  const transact = async work => {
     const db = await database();
     return new Promise((resolve, reject) => {
       const transaction = db.transaction('issues', 'readwrite');
@@ -38,6 +45,13 @@ function createIndexedDbTransaction(indexedDB, dbName = 'stackchain-background-o
       });
     });
   };
+  transact.close = async () => {
+    if (!databasePromise) return;
+    const db = await databasePromise;
+    db.close();
+    databasePromise = undefined;
+  };
+  return transact;
 }
 
 function createIssueSyncStore({ transaction, indexedDB = globalThis.indexedDB, now = () => Date.now(), claimMs = 30000 } = {}) {
@@ -149,10 +163,13 @@ function createIssueSyncStore({ transaction, indexedDB = globalThis.indexedDB, n
         item.status !== 'sent' && item.ownerLogin !== ownerLogin).length),
     setReceiptPreference,
     getReceiptPreference,
+    close: () => transact.close?.(),
   };
 }
 
 function createBackgroundIssueSync({ store, fetchJson, base = '' }) {
+  let purgeRequested = false;
+  let activeFlush = null;
   function receiptFor(item, status, delivered = {}) {
     if (status === 'attention') {
       return { id: item.id, status, kind: item.kind ? 'message' : 'issue', route: '#/my-work/drafts' };
@@ -238,6 +255,7 @@ function createBackgroundIssueSync({ store, fetchJson, base = '' }) {
   }
 
   async function send(item, currentLogin) {
+    if (purgeRequested) return { blocked: true };
     if (!currentLogin || item.ownerLogin !== currentLogin) return { blocked: true };
     await store.upsert(item);
     const claimed = await store.claim(item.id, currentLogin);
@@ -245,7 +263,7 @@ function createBackgroundIssueSync({ store, fetchJson, base = '' }) {
     return deliver(claimed);
   }
 
-  async function flush() {
+  async function runFlush() {
     const identity = await fetchJson(base + 'api/v1/background-identity', {
       headers: { Accept: 'application/json' }, cache: 'no-store',
     });
@@ -267,8 +285,21 @@ function createBackgroundIssueSync({ store, fetchJson, base = '' }) {
     return { confirmed, blocked, attention, login, receipts };
   }
 
+  function flush() {
+    if (purgeRequested) return Promise.resolve({ confirmed: [], blocked: 0, attention: 0, login: '', receipts: [] });
+    if (activeFlush) return activeFlush;
+    activeFlush = runFlush().finally(() => { activeFlush = null; });
+    return activeFlush;
+  }
+
+  async function purge() {
+    purgeRequested = true;
+    if (activeFlush) await activeFlush.catch(() => {});
+    await store.close?.();
+  }
+
   return {
-    flush, send,
+    flush, send, purge,
     reconcile: (items, outboxLane) => store.reconcile(items, outboxLane),
     snapshot: () => store.snapshot(),
     setReceiptPreference: (ownerLogin, enabled) => store.setReceiptPreference(ownerLogin, enabled),

frontend/service-worker.js

@@ -1,6 +1,6 @@
 const BASE = new URL('./', self.location.href).pathname;
 importScripts(BASE + 'static/background-issue-sync.js');
-const CACHE = 'stackchain-dashboard-shell-v24';
+const CACHE = 'stackchain-dashboard-shell-v25';
 const OUTAGE_STATUSES = new Set([500, 502, 503, 504]);
 const SHELL = [
   BASE,
@@ -100,6 +100,14 @@ self.addEventListener('sync', event => {
 
 self.addEventListener('message', event => {
   if (event.data?.type === 'stackchain-resume-outbox') event.waitUntil(flushAndNotify());
+  if (event.data?.type === 'stackchain-purge-outbox') event.waitUntil((async () => {
+    try {
+      await issueSync.purge();
+      event.ports?.[0]?.postMessage({ ok: true });
+    } catch (error) {
+      event.ports?.[0]?.postMessage({ ok: false, error: String(error?.message || 'Outbox purge failed.') });
+    }
+  })());
 });
 
 self.addEventListener('notificationclick', event => {

frontend/session.js

@@ -13,9 +13,14 @@
       indexedDB: root.indexedDB,
       caches: root.caches,
       serviceWorker: root.navigator?.serviceWorker,
+      MessageChannel: root.MessageChannel,
       location: root.location,
       confirmAction: message => root.confirm(message),
       onExpired: () => root.dispatchEvent(new CustomEvent('stackchain:session-expired')),
+      onClearError: error => {
+        root.dispatchEvent(new CustomEvent('stackchain:device-clear-failed', { detail: error.message }));
+        root.alert('Signed out, but private queued work could not be cleared. Close other Stackchain tabs and clear this site’s data.');
+      },
     });
     root.fetch = boundary.fetch;
     const attach = () => {
@@ -30,8 +35,9 @@
     root.stackchainSession = boundary;
   }
 })(typeof window !== 'undefined' ? window : this, function createSessionBoundary({
-  cookie, origin, base, fetchImpl, localStorage, sessionStorage, indexedDB, caches, serviceWorker, location, confirmAction,
+  cookie, origin, base, fetchImpl, localStorage, sessionStorage, indexedDB, caches, serviceWorker, MessageChannel, location, confirmAction,
   onExpired = () => {},
+  onClearError = () => {},
 }) {
   const SAFE_METHODS = new Set(['GET', 'HEAD', 'OPTIONS']);
 
@@ -73,11 +79,44 @@
     } catch (_error) { /* Cookie invalidation still protects server data. */ }
   }
 
+  async function stopWorkerOutbox() {
+    const registration = await serviceWorker?.ready;
+    if (!registration?.active || !MessageChannel) return;
+    await new Promise((resolve, reject) => {
+      const channel = new MessageChannel();
+      const timeout = setTimeout(() => reject(new Error('Background outbox purge timed out.')), 3000);
+      channel.port1.onmessage = event => {
+        clearTimeout(timeout);
+        if (event.data?.ok) resolve();
+        else reject(new Error(event.data?.error || 'Background outbox purge failed.'));
+      };
+      registration.active.postMessage({ type: 'stackchain-purge-outbox' }, [channel.port2]);
+    });
+  }
+
+  function deletePrivateOutbox() {
+    if (!indexedDB) return Promise.resolve();
+    return new Promise((resolve, reject) => {
+      let request;
+      try { request = indexedDB.deleteDatabase('stackchain-background-outbox-v1'); }
+      catch (error) { reject(error); return; }
+      request.onsuccess = () => resolve();
+      request.onerror = () => reject(request.error || new Error('IndexedDB deletion failed.'));
+      request.onblocked = () => reject(new Error('IndexedDB deletion was blocked.'));
+    });
+  }
+
   async function clearPrivateDeviceData() {
     removeDashboardStorage(localStorage);
     if (sessionStorage !== localStorage) removeDashboardStorage(sessionStorage);
-    try { indexedDB?.deleteDatabase('stackchain-background-outbox-v1'); }
-    catch (_error) { /* Continue clearing other dashboard state. */ }
+    try {
+      await stopWorkerOutbox();
+      await deletePrivateOutbox();
+    } catch (_error) {
+      const error = new Error('Could not clear private queued work from this device.');
+      onClearError(error);
+      throw error;
+    }
     try {
       const keys = await caches?.keys?.() || [];
       await Promise.all(keys.filter(key => key.startsWith('stackchain-dashboard-')).map(key => caches.delete(key)));