Acknowledge unsubscribes, and nothing re-rings after a restart

Two field reports, one chain: a dismissed alarm came back. Measured on the
emulator, three separate causes, all fixed here.

1. The alarm-clock entry launched an activity. On Android 14+ that launch is
   refused from the background and then *deferred*, so the window surfaced
   later — after the alarm had been acknowledged — and the siren played again
   for a delivered alert. The entry is now a broadcast to AlarmWakeReceiver,
   which only wakes the process and re-posts the takeover notification, and
   ignores an entry that outlived its arming. The one activity PendingIntent
   left is the alarm-clock show intent, which only the user can invoke.

2. A dismissal could be lost. `acknowledgeAlarm` returned early when the
   device identity had not loaded, and the queue's entry required a deviceId,
   so the ack was silently dropped and the ledger still owed the alarm. The
   queue accepts an entry without one (measured: the service takes a
   device-token ack with no deviceId) and the flush resolves the identity.
   Nothing raises — and the armed service does not start listening — until the
   queued dismissals have been read, so a restart cannot ring before the seed.

3. Acknowledging now unsubscribes the device (owner ruling: a dismissal is
   leaving). The ack settles the ledger first, then the subscription row goes;
   the takeover closes itself and Home reports "Acknowledged — this device
   unsubscribed". A leftover subscription was a live address that kept ringing
   on every launch.

Also: an alarm is only sounded for an alert this device still follows (or a
trigger event that actually arrived), and the takeover never renders the raw
alert id as its headline — that fallback is what made a stale launch look like
an alarm for "dbf1a4c2-…".

Verified on the emulator: join → trigger → acknowledge → subscription row gone,
alert delivered, app returns Home by itself; force-stop and reopen is silent
for the whole session (no audio, no notification, no takeover).

__tests__/dismissalReplay.test.ts

@@ -56,11 +56,14 @@ describe('dismissal memory', () => {
     expect(d.suppress('a', undefined, false)).toBe(true);
   });
 
-  it('lets a live socket frame clear the memory — a new trigger must ring', () => {
+  it('does not let a live socket frame undo a dismissal', () => {
+    // Measured: after dismissing, a queued native takeover replayed the trigger
+    // down the socket and the siren came back. The alert is triggered once, so
+    // a second "live" frame for a dismissed alert is the same alarm.
     const d = createDismissals();
     d.mark('a', EVENT);
-    expect(d.suppress('a', EVENT, true)).toBe(false);
-    expect(d.suppress('a', EVENT, false)).toBe(false);
+    expect(d.suppress('a', EVENT, true)).toBe(true);
+    expect(d.suppress('a', EVENT, false)).toBe(true);
   });
 
   it('seeds from the durable ack queue so a replay before the flush is silent', () => {
@@ -74,6 +77,65 @@ describe('dismissal memory', () => {
   });
 });
 
+describe('a dismissal must survive the app being killed', () => {
+  it('queues the ack even before the device identity is loaded', () => {
+    // Measured against the service: a device-token ack with no deviceId is
+    // accepted (the credential identifies the subscription). `acknowledgeAlarm`
+    // used to `return` when `deviceId` was still null, silently dropping the
+    // dismissal — the alarm then owed the ledger again and rang on reopen.
+    const context = fs.readFileSync(
+      path.join(__dirname, '..', 'src', 'state', 'AlarmContext.tsx'),
+      'utf8',
+    );
+    const at = context.indexOf('const acknowledgeAlarm = useCallback');
+    const body = context.slice(at, at + 1600);
+    expect(body).not.toContain('if (!deviceId) return;');
+    expect(body).toContain('enqueueAck(');
+    expect(body).toContain('deviceId: deviceId ?? undefined');
+  });
+
+  it('does not raise an alarm before the queued dismissals are known', () => {
+    const context = fs.readFileSync(
+      path.join(__dirname, '..', 'src', 'state', 'AlarmContext.tsx'),
+      'utf8',
+    );
+    const at = context.indexOf('const handleTrigger = useCallback');
+    const body = context.slice(at, at + 900);
+    expect(body).toContain('dismissalsReadyRef.current');
+    // …and the armed service must not start listening before that either.
+    const armAt = context.indexOf('const armedAttemptRef');
+    const arm = context.slice(armAt, armAt + 900);
+    expect(arm).toContain('if (!dismissalsReady) return;');
+  });
+
+  it('unsubscribes the device as part of acknowledging', () => {
+    // Owner ruling: a subscriber that acknowledged is done with the alarm, so
+    // the acknowledgement drops the subscription instead of leaving a live
+    // address that rings again on the next launch.
+    const context = fs.readFileSync(
+      path.join(__dirname, '..', 'src', 'state', 'AlarmContext.tsx'),
+      'utf8',
+    );
+    const at = context.indexOf('const acknowledgeAlarm = useCallback');
+    const body = context.slice(at, at + 2600);
+    expect(body).toContain('api.removeSubscription(');
+    expect(body).toContain("markEnded(alertId, 'left')");
+    // The ack settles the ledger *before* the row goes, so a failed removal can
+    // never leave the debt behind.
+    expect(body.indexOf('flushAcks(')).toBeLessThan(body.indexOf('api.removeSubscription('));
+  });
+
+  it('flushes a queued ack that has no device id of its own', () => {
+    const source = fs.readFileSync(
+      path.join(__dirname, '..', 'src', 'services', 'pendingAcks.ts'),
+      'utf8',
+    );
+    expect(source).toContain('deviceId?: string;');
+    expect(source).toContain('flushAcks(fallbackDeviceId?: string)');
+    expect(source).toContain('ack.deviceId ?? fallbackDeviceId');
+  });
+});
+
 describe('dismissal reaches the service', () => {
   const screen = fs.readFileSync(
     path.join(__dirname, '..', 'src', 'screens', 'LiveAlarmScreen.tsx'),