Pwa Setup

Overview

Guides the complete conversion of a web app into a Progressive Web App: creating a Web App Manifest, implementing a service worker with caching strategies (Cache First, Network First, Stale-While-Revalidate), offline fallback page, install prompt handling, and push notification setup using the Push API + VAPID keys.

When to Use This Skill

• The app should feel like a native app (installable from browser).
• Users need to use core features offline (read content, draft forms, view dashboards).
• Adding push notifications for re-engagement.
• The user says "make this a PWA", "add offline support", "installable web app".

Prerequisites

• HTTPS (required for service workers and push in production; localhost works for dev).
• Modern browser support (all current evergreen browsers).
• For push: a push service (Firebase Cloud Messaging, VAPID + web-push library on server).

Steps

1. Create Web App Manifest (app/manifest.ts or public/manifest.json):

   • name, short_name, start_url, display ("standalone"), background_color, theme_color, icons (192x192, 512x512, maskable).
   • Screenshots for install prompt (optional but powerful).

2. Implement Service Worker:

   • Lifecycle: install → activate → fetch.
   • Caching strategies per asset type:
     • App shell (HTML, CSS, JS critical): Cache First or Stale-While-Revalidate.
     • API/data: Network First with cache fallback.
     • Images: Cache First with long TTL.
   • Use Workbox (recommended) or write a small custom SW.

3. Offline fallback:

   • A dedicated offline.html page.
   • In fetch handler, return it when network fails for navigation requests.

4. Install prompt:

   • Listen for beforeinstallprompt.
   • Show a custom "Install" button.
   • Call prompt() on user gesture.
   • Handle appinstalled event.

5. Push notifications:

   • Request permission.
   • Subscribe to push using VAPID public key.
   • Send subscription to your server.
   • Server sends push using web-push library.
   • Handle push event in SW and show Notification.

6. Next.js specific:

   • Use next-pwa plugin or manual setup with public/sw.js.
   • Register SW in a client component or layout.

7. Output:

   • Full manifest.
   • Service worker code (or Workbox config).
   • React hook or component for install prompt.
   • Push subscription example.
   • VAPID key generation instructions.
   • Testing checklist.

Examples

Complete manifest.ts, a production-ready service worker with multiple strategies, install prompt component, and a minimal push notification flow (client + server) are included.

Edge Cases & Error Handling

• Permission denied for notifications: Graceful UI, never nag.
• SW update: Proper skipWaiting + clients.claim, with update UI prompt.
• Large offline assets: Be selective about what goes in the cache.
• Background sync: For form submissions when offline (using Background Sync API).

Verification

1. npm run build && npm run start — serve over HTTPS (use serve or Vercel).
2. Open in Chrome — "Install" button or + icon in address bar appears.
3. Click install — app installs to home screen / apps list.
4. Go offline (DevTools → Network → Offline) — core pages still load.
5. Trigger a push notification from server — it arrives even when app is closed.
6. Lighthouse PWA category = 100.
7. Success: App is installable, works offline for key flows, and can receive push.

References

• Web App Manifest
• Service Worker API
• Workbox
• Push API + Notifications
• next-pwa or manual setup