PWA & Offline-First Expert (2026 Edition)

English | Bahasa Indonesia

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<a name="english"></a>

English

Description

Expert guide for building enterprise-grade Local-First and Progressive Web Applications (PWA). Eliminates loading spinners by reading and writing to local databases (OPFS SQLite, RxDB, IndexedDB) first, replicating seamlessly in the background with zero conflict (CRDTs, ElectricSQL, PowerSync), and packaging to native stores via PWABuilder.

Trigger Conditions

• Applications requiring full offline functionality (field operations, mobile dashboards, transit apps).
• User experience demands 0ms local read/write latency without loading spinners.
• Multi-device sync architecture with automatic conflict resolution.
• Packaging web apps for distribution on Google Play Store, iOS Safari PWA, or Microsoft Store.

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1. The Local-First Principles (2026 Standard)

1. No Spinners for Local Data: UI reads and writes to local storage (OPFS / IndexedDB) synchronously. Latency is always 0ms.
2. Multi-Device Conflict-Free Replication: Changes replicate in the background using CRDTs or central event logs (ElectricSQL / PowerSync).
3. Network is an Enhancement: App is 100% functional on an airplane or subway without internet.
4. User Owns Their Data: Data persists on client hardware first; cloud server is a backup/sync relay.

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2. Production Recipe: Service Worker Caching (Workbox v7 / Native SW)

// sw.ts - Production Service Worker with Stale-While-Revalidate
/// <reference lib="webworker" />
declare const self: ServiceWorkerGlobalScope;

const CACHE_NAME = 'app-v2.11.0-cache';
const STATIC_ASSETS = [
  '/',
  '/index.html',
  '/manifest.json',
  '/styles/global.css',
  '/icons/icon-512x512.png',
];

// 1. Install & Pre-cache critical application shell
self.addEventListener('install', (event) => {
  event.waitUntil(
    caches.open(CACHE_NAME).then((cache) => cache.addAll(STATIC_ASSETS))
  );
  self.skipWaiting();
});

// 2. Activate & Clean stale caches
self.addEventListener('activate', (event) => {
  event.waitUntil(
    caches.keys().then((keys) =>
      Promise.all(
        keys.filter((k) => k !== CACHE_NAME).map((k) => caches.delete(k))
      )
    )
  );
  self.clients.claim();
});

// 3. Stale-While-Revalidate Strategy for Navigation & API GETs
self.addEventListener('fetch', (event) => {
  const { request } = event;

  // Ignore POST/PUT/DELETE mutations (handled by offline sync queues)
  if (request.method !== 'GET') return;

  event.respondWith(
    caches.open(CACHE_NAME).then(async (cache) => {
      const cachedResponse = await cache.match(request);
      
      const fetchPromise = fetch(request)
        .then((networkResponse) => {
          if (networkResponse.status === 200) {
            cache.put(request, networkResponse.clone());
          }
          return networkResponse;
        })
        .catch(() => cachedResponse || Response.error());

      return cachedResponse || fetchPromise;
    })
  );
});

// 4. Background Sync for offline mutations
self.addEventListener('sync', (event: any) => {
  if (event.tag === 'sync-mutations') {
    event.waitUntil(flushOfflineMutationQueue());
  }
});

async function flushOfflineMutationQueue() {
  // Read pending mutations from IndexedDB and POST to backend
}

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3. Production Recipe: Local-First Database Sync with RxDB (TypeScript)

// local-db.ts - Reactive Offline-First Database with Background Replication
import { createRxDatabase, addRxPlugin } from 'rxdb';
import { getRxStorageDexie } from 'rxdb/plugins/storage-dexie';
import { replicateGraphQL } from 'rxdb/plugins/replication-graphql';

export interface TaskDocType {
  id: string;
  title: string;
  isCompleted: boolean;
  updatedAt: string;
}

const taskSchema = {
  version: 0,
  primaryKey: 'id',
  type: 'object',
  properties: {
    id: { type: 'string', maxLength: 100 },
    title: { type: 'string' },
    isCompleted: { type: 'boolean' },
    updatedAt: { type: 'string', format: 'date-time' },
  },
  required: ['id', 'title', 'isCompleted', 'updatedAt'],
};

export async function initLocalDB() {
  const db = await createRxDatabase({
    name: 'app_local_db',
    storage: getRxStorageDexie(),
  });

  await db.addCollections({
    tasks: { schema: taskSchema },
  });

  // Background Replication with Server (GraphQL / REST Sync)
  replicateGraphQL({
    collection: db.tasks,
    url: 'https://api.myapp.com/graphql',
    pull: {
      queryBuilder: (doc) => ({
        query: `query { syncTasks(since: "${doc ? doc.updatedAt : 0}") { id title isCompleted updatedAt } }`,
        variables: {},
      }),
      modifier: (doc) => doc,
    },
    push: {
      queryBuilder: (doc) => ({
        query: `mutation { pushTask(task: ${JSON.stringify(doc)}) { id } }`,
        variables: {},
      }),
      batchSize: 10,
    },
    live: true,
    retryTime: 1000 * 5, // Auto-retry on network reconnection
  });

  return db;
}

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4. App Store Distribution: PWABuilder Standard

To distribute your web application on Google Play Store (TWA - Trusted Web Activity) and Microsoft Windows Store:

1. Ensure Web App Manifest has:
   • display: "standalone"
   • id: "/?source=pwa"
   • icons: At least 192x192 and 512x512 maskable PNGs.
   • shortcuts for rapid action launching.
2. Generate signed Android APK/AAB or Windows MSIX packages using:

   npx @pwabuilder/cli https://myapp.com
   

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Orchestration & Integration

• senior-frontend: For UI integration with offline state bars and optimistic mutation hooks.
• state-management-expert: For connecting RxDB / local stores with Zustand or TanStack Store.
• database-orm-expert: For designing compatible backend schemas with ElectricSQL / Postgres.
• email-notification-expert: For Web Push Notification subscription handling.

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<a name="bahasa-indonesia"></a>

Bahasa Indonesia

Deskripsi

Panduan ahli untuk membangun aplikasi web Local-First dan Progressive Web Applications (PWA) kelas enterprise. Menghilangkan ketergantungan loading spinner dengan membaca dan menulis langsung ke database lokal (OPFS SQLite, RxDB, IndexedDB) terlebih dahulu, sinkronisasi otomatis di latar belakang tanpa bentrok data (CRDTs, ElectricSQL, PowerSync), dan packaging ke toko aplikasi native melalui PWABuilder.

Kondisi Pemicu

• Aplikasi yang memerlukan fungsionalitas offline penuh (pekerjaan lapangan, dashboard mobile, aplikasi transit).
• Tuntutan pengalaman pengguna dengan latensi baca/tulis lokal 0ms tanpa loading spinner.
• Arsitektur sinkronisasi multi-perangkat dengan resolusi konflik data otomatis.
• Kebutuhan rilis aplikasi web ke Google Play Store, iOS Safari PWA, atau Microsoft Store.

Ringkasan Prinsip Local-First & PWA

1. 0ms Latensi Lokal: Komponen membaca dan menulis ke IndexedDB / OPFS lokal secara instan.
2. Sinkronisasi Reaktif Latar Belakang: Replikasi data berjalan di background worker; mutasi offline dicatat dalam antrean IndexedDB dan di-flush saat jaringan online.
3. Pola Service Worker: Stale-While-Revalidate untuk asset statis dan rute shell utama menggunakan Service Worker v3.
4. Distribusi Native: Menggunakan PWABuilder CLI untuk menghasilkan APK Android TWA dan paket MSIX Windows.

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Integrasi Orkestrasi

• senior-frontend: Integrasi UI indikator status offline dan hook mutasi optimistik.
• state-management-expert: Menghubungkan RxDB / local storage ke Zustand atau TanStack Store.
• database-orm-expert: Perancangan skema backend PostgreSQL yang kompatibel dengan replikasi CRDT / ElectricSQL.
• email-notification-expert: Penanganan registrasi dan subscription Web Push Notification.