fix: deduplicate dashboard notification events

dashboard/src/store/eventStore.test.tsx

@@ -8,6 +8,37 @@ import { useEventStore } from '../store/eventStore';
 import { generateMockEvents } from '../utils/eventData';
 
 describe('event store selective subscriptions', () => {
+  it('deduplicates events before rendering notification rows', () => {
+    const [firstEvent, secondEvent] = generateMockEvents(2);
+
+    useEventStore.getState().setEvents([firstEvent, firstEvent, secondEvent]);
+
+    render(
+      <div style={{ height: 600, width: 800 }}>
+        <EventListPanel />
+      </div>
+    );
+
+    expect(screen.getAllByRole('article')).toHaveLength(2);
+    expect(screen.getAllByText(`Ledger ${firstEvent.ledger}`)).toHaveLength(1);
+    expect(screen.getAllByText(`Ledger ${secondEvent.ledger}`)).toHaveLength(1);
+  });
+
+  it('does not append duplicate notifications after repeated refresh data', () => {
+    const [firstEvent, secondEvent] = generateMockEvents(2);
+
+    useEventStore.getState().setEvents([firstEvent]);
+    useEventStore.getState().appendEvents([firstEvent, secondEvent, secondEvent]);
+
+    const storedEvents = useEventStore.getState().events;
+
+    expect(storedEvents).toHaveLength(2);
+    expect(storedEvents.map((event) => event.eventId)).toEqual([
+      firstEvent.eventId,
+      secondEvent.eventId,
+    ]);
+  });
+
   it('filter updates do not require reloading the full event collection', async () => {
     useEventStore.setState({
       events: generateMockEvents(100),

dashboard/src/store/eventStore.ts

@@ -16,6 +16,19 @@ interface EventStoreState {
   setError: (error: string | null) => void;
 }
 
+function dedupeEventsById(events: BlockchainEvent[]): BlockchainEvent[] {
+  const seenEventIds = new Set<string>();
+
+  return events.filter((event) => {
+    if (seenEventIds.has(event.eventId)) {
+      return false;
+    }
+
+    seenEventIds.add(event.eventId);
+    return true;
+  });
+}
+
 export const useEventStore = create<EventStoreState>((set) => ({
   events: [],
   filters: {
@@ -25,10 +38,10 @@ export const useEventStore = create<EventStoreState>((set) => ({
   },
   isLoading: false,
   error: null,
-  setEvents: (events) => set({ events }),
+  setEvents: (events) => set({ events: dedupeEventsById(events) }),
   appendEvents: (events) =>
     set((state) => ({
-      events: [...state.events, ...events],
+      events: dedupeEventsById([...state.events, ...events]),
     })),
   setSearch: (search) =>
     set((state) => ({