Guard service worker cache refresh listener wiring

Agent-Logs-Url: https://github.com/frostaura/fa.lifeos/sessions/8570f3e6-1dfd-4519-8939-c252040f6a12

Co-authored-by: frostaura <8956241+frostaura@users.noreply.github.com>

Author: Copilot

src/frontend/src/hooks/__tests__/useServiceWorkerCacheRefresh.test.tsx

@@ -120,4 +120,22 @@ describe('useServiceWorkerCacheRefresh', () => {
 
     expect(removeEventListenerMock).toHaveBeenCalledWith('message', expect.any(Function));
   });
+
+  it('stays idle when the service worker container does not expose event listeners', () => {
+    Object.defineProperty(globalThis.navigator, 'serviceWorker', {
+      configurable: true,
+      value: {
+        getRegistration: vi.fn(),
+      },
+    });
+
+    const { result, unmount } = renderHook(() => useServiceWorkerCacheRefresh());
+
+    expect(result.current.phase).toBe('idle');
+    expect(addEventListenerMock).not.toHaveBeenCalled();
+
+    unmount();
+
+    expect(removeEventListenerMock).not.toHaveBeenCalled();
+  });
 });

src/frontend/src/hooks/useServiceWorkerCacheRefresh.ts

@@ -42,6 +42,15 @@ export function useServiceWorkerCacheRefresh(enabled = true): ServiceWorkerCache
       return;
     }
 
+    const serviceWorkerContainer = navigator.serviceWorker;
+    if (
+      !serviceWorkerContainer
+      || typeof serviceWorkerContainer.addEventListener !== 'function'
+      || typeof serviceWorkerContainer.removeEventListener !== 'function'
+    ) {
+      return;
+    }
+
     const invalidateSubscribedQueries = () => {
       dispatch(apiSlice.util.invalidateTags(apiSliceTagTypes.map((type) => ({ type }))));
       dispatch(identityApi.util.invalidateTags(identityApiTagTypes.map((type) => ({ type }))));
@@ -95,10 +104,10 @@ export function useServiceWorkerCacheRefresh(enabled = true): ServiceWorkerCache
       }, INVALIDATION_DEBOUNCE_MS);
     };
 
-    navigator.serviceWorker.addEventListener('message', handleMessage);
+    serviceWorkerContainer.addEventListener('message', handleMessage);
 
     return () => {
-      navigator.serviceWorker.removeEventListener('message', handleMessage);
+      serviceWorkerContainer.removeEventListener('message', handleMessage);
       activeRequestKeysRef.current.clear();
       if (invalidateTimerRef.current) {
         window.clearTimeout(invalidateTimerRef.current);