fix: unreadCount badge falls back to timestamp when ack pointer scrolls off page

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

src/app/features/admin/shell/services/admin-order-watcher.service.spec.ts

@@ -54,6 +54,7 @@ describe('AdminOrderWatcherService', () => {
     localStorage.removeItem('adminOrderWatcher.lastNotifiedOrderId.v1');
     localStorage.removeItem('adminOrderWatcher.lastNotifiedOrderCreatedAt.v1');
     localStorage.removeItem('adminOrderWatcher.lastAcknowledgedOrderId.v1');
+    localStorage.removeItem('adminOrderWatcher.lastAcknowledgedOrderCreatedAt.v1');
     localStorage.removeItem('adminOrderWatcher.pollIntervalMs.v1');
 
     // Defaults to unauthenticated so the reactive effect stays a no-op and the
@@ -157,6 +158,39 @@ describe('AdminOrderWatcherService', () => {
     expect(messages.some(m => m.includes('1000'))).toBe(false);
   }));
 
+  it('falls back to a timestamp comparison (not the whole page) for unreadCount when the acknowledged order id disappears', fakeAsync(() => {
+    service.start();
+    tick(0);
+
+    // Second poll introduces 'o3' and pushes 'o2' to index 1.
+    pollIndex = 1;
+    ordersByPoll.push([
+      makeOrder('o3', '1003', '2026-08-15T11:00:00.000Z'),
+      makeOrder('o2', '1002', '2026-08-15T10:00:00.000Z'),
+      makeOrder('o1', '1001', '2026-08-15T09:00:00.000Z'),
+    ]);
+    tick(service.intervalMs());
+
+    // Acknowledge everything up to and including 'o3' (createdAt 11:00:00).
+    service.markAllSeen();
+    expect(service.unreadCount()).toBe(0);
+
+    // Third poll: 'o3' (the acknowledged id) is gone. Page contains orders
+    // both older and newer than o3's createdAt (2026-08-15T11:00:00.000Z).
+    pollIndex = 2;
+    ordersByPoll.push([
+      makeOrder('o6', '1006', '2026-08-15T13:00:00.000Z'),
+      makeOrder('o5', '1005', '2026-08-15T12:00:00.000Z'),
+      makeOrder('o4', '1004', '2026-08-15T10:30:00.000Z'),
+      makeOrder('o0', '1000', '2026-08-15T08:00:00.000Z'),
+    ]);
+    tick(service.intervalMs());
+
+    // Only o6 and o5 are newer than o3's ack createdAt - the buggy behavior
+    // would report the full page length (4) instead of the correct count (2).
+    expect(service.unreadCount()).toBe(2);
+  }));
+
   it('stop() clears the interval so no further polls occur', fakeAsync(() => {
     const gateway = TestBed.inject(AdminOrdersLocalGateway);
     const loadOrdersSpy = spyOn(gateway, 'loadOrders').and.callThrough();

src/app/features/admin/shell/services/admin-order-watcher.service.ts

@@ -10,6 +10,7 @@ import { AdminAuthService } from '../../../../core/admin-auth/admin-auth.service
 const LAST_NOTIFIED_KEY = 'adminOrderWatcher.lastNotifiedOrderId.v1';
 const LAST_NOTIFIED_AT_KEY = 'adminOrderWatcher.lastNotifiedOrderCreatedAt.v1';
 const LAST_ACKNOWLEDGED_KEY = 'adminOrderWatcher.lastAcknowledgedOrderId.v1';
+const LAST_ACKNOWLEDGED_AT_KEY = 'adminOrderWatcher.lastAcknowledgedOrderCreatedAt.v1';
 const POLL_INTERVAL_KEY = 'adminOrderWatcher.pollIntervalMs.v1';
 export const DEFAULT_POLL_INTERVAL_MS = 15000;
 const MIN_POLL_INTERVAL_MS = 1000;
@@ -29,6 +30,7 @@ export class AdminOrderWatcherService {
   readonly recentOrders: Signal<AdminOrder[]> = this.recentOrdersSignal.asReadonly();
 
   private readonly lastAcknowledgedOrderIdSignal = signal<string | null>(this.storage.getItem(LAST_ACKNOWLEDGED_KEY));
+  private readonly lastAcknowledgedOrderCreatedAtSignal = signal<string | null>(this.storage.getItem(LAST_ACKNOWLEDGED_AT_KEY));
 
   readonly unreadCount = computed(() => {
     const orders = this.recentOrdersSignal();
@@ -40,7 +42,14 @@ export class AdminOrderWatcherService {
       return orders.length;
     }
     const idx = orders.findIndex(order => order.id === ackId);
-    return idx === -1 ? orders.length : idx;
+    if (idx !== -1) {
+      return idx;
+    }
+    // The acknowledged order id is no longer present in the current page
+    // (deleted, or many orders arrived since ack) - fall back to a timestamp
+    // comparison instead of treating the whole page as unread.
+    const ackCreatedAt = this.lastAcknowledgedOrderCreatedAtSignal();
+    return ackCreatedAt === null ? orders.length : orders.filter(order => order.createdAt > ackCreatedAt).length;
   });
 
   private readonly intervalMsSignal = signal<number>(this.readStoredIntervalMs());
@@ -96,12 +105,14 @@ export class AdminOrderWatcherService {
   }
 
   markAllSeen(): void {
-    const newestId = this.recentOrdersSignal()[0]?.id;
+    const newest = this.recentOrdersSignal()[0];
-    if (!newestId) {
+    if (!newest) {
       return;
     }
-    this.lastAcknowledgedOrderIdSignal.set(newestId);
+    this.lastAcknowledgedOrderIdSignal.set(newest.id);
-    this.storage.setItem(LAST_ACKNOWLEDGED_KEY, newestId);
+    this.lastAcknowledgedOrderCreatedAtSignal.set(newest.createdAt);
+    this.storage.setItem(LAST_ACKNOWLEDGED_KEY, newest.id);
+    this.storage.setItem(LAST_ACKNOWLEDGED_AT_KEY, newest.createdAt);
   }
 
   private scheduleNext(): void {
@@ -148,7 +159,9 @@ export class AdminOrderWatcherService {
       // acknowledged so a fresh admin session doesn't see the whole history as unread.
       if (this.lastAcknowledgedOrderIdSignal() === null) {
         this.lastAcknowledgedOrderIdSignal.set(items[0].id);
+        this.lastAcknowledgedOrderCreatedAtSignal.set(items[0].createdAt);
         this.storage.setItem(LAST_ACKNOWLEDGED_KEY, items[0].id);
+        this.storage.setItem(LAST_ACKNOWLEDGED_AT_KEY, items[0].createdAt);
       }
       return;
     }