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Offline Strategy

The Credence frontend uses a Service Worker implemented via vite-plugin-pwa to cache the application shell and read-only endpoints using a cache-first strategy. Write operations that fail due to network errors are automatically queued in IndexedDB and retried upon reconnection.

What's cached

Service Worker Cache

  • App Shell: HTML, CSS, JavaScript, and static assets are precached by the service worker.
  • Read-only Endpoints: API GET requests are cached using a NetworkFirst strategy to provide fresh data when online and cached data when offline.

localStorage

Key Module What's stored Persists across
credence:settings src/context/SettingsContext.tsx Theme, network preference, display options, toast config Tabs, windows, browser restarts
credence:pendingTransactions src/hooks/useTransactions.ts User-initiated transactions not yet confirmed on chain Page reloads
credence:onboarding:step src/pages/Dashboard.tsx Current onboarding tour step Page reloads
credence:onboarding:onboardedAt src/pages/Dashboard.tsx Completion timestamp Page reloads
credence:changelog:last-seen-id src/hooks/useProductUpdates.ts Last-seen changelog entry ID Page reloads
credence:pinnedWidgets src/hooks/usePinnedWidgets.ts Pinned dashboard widgets configuration Page reloads
credence:recent-lookups src/pages/TrustScore.tsx Recent trust-score address lookups Page reloads

What's queued

Pending transactions queue

When a user initiates a transaction (e.g. creating a bond), the transaction is pushed to localStorage under credence:pendingTransactions immediately so it appears in the UI without waiting for server confirmation.

On the next successful server fetch, pending transactions are reconciled — any that match confirmed server entries are removed from the queue.

Write operations

When API requests (e.g., POST, PATCH, PUT) fail due to a network error, the Service Worker automatically captures the payload and queues it in IndexedDB (credence-offline-db). Upon the online event, the Service Worker attempts to replay these queued operations in order.

What happens on cache miss

Queries (useQuery)

Queries fetch from the network first. If offline, the Service Worker serves the response from the api-cache if available. If neither is available, the request fails, and useQuery handles it as an error state.

API client (apiFetch)

Network errors are still surfaced as ApiError with status 0. The application continues to handle these as before to provide immediate user feedback if necessary, even while the Service Worker attempts background retries.

Summary table

Scenario Behaviour
Page load while offline App loads from Service Worker cache. useQuery falls back to cached data or handles the error. Settings, etc. served from localStorage.
Widget refresh while offline useWidgetCache fetches; if network fails, Service Worker serves cached response.
Auto-save / Write while offline apiFetch fails; Service Worker captures request, queues in IndexedDB, and returns 202 Queued.
Reconnect Service Worker detects online event and automatically replays queued writes from IndexedDB.