angular-pwa-offline

Standard IDs

ID	Severity	What it checks
PWA-001	P1	@angular/service-worker not configured despite an offline requirement
PWA-002	P2	No offline fallback page/shell shown when the network is unreachable
PWA-003	P2	Caching strategy doesn't distinguish static app-shell assets from dynamic API data
PWA-004	P1	No conflict-resolution story for data edited offline and synced later

---

Check A — Service worker not configured (PWA-001)

Detection

For an app with a stated offline requirement (field technicians, warehouse scanning apps), check whether @angular/service-worker is added (ng add @angular/pwa) and registered in app.config.ts. Without it, the app simply fails to load with no cached shell the moment connectivity drops.

BAD — no service worker despite an offline requirement

export const appConfig: ApplicationConfig = {
  providers: [provideHttpClient(), provideRouter(routes)],
  // No provideServiceWorker() — the app is unusable the moment the network drops.
};

GOOD — service worker registered, enabled only in production

export const appConfig: ApplicationConfig = {
  providers: [
    provideServiceWorker('ngsw-worker.js', {
      enabled: !isDevMode(),
      registrationStrategy: 'registerWhenStable:30000',
    }),
  ],
};

---

Check B — No offline fallback UI (PWA-002)

Detection

Check whether the app shows a dedicated "you're offline" state (via SwUpdate/navigator.onLine + a connectivity service) versus letting failed HTTP calls surface as generic errors indistinguishable from a server-side failure (overlaps angular-error-handling AEH-004's recoverable-vs-crash distinction — offline is a third, distinct state).

BAD — offline looks identical to a generic server error

this.http.get('/api/orders').pipe(
  catchError(() => { this.toast.show('Something went wrong'); return of([]); })
).subscribe();