# Person 1: UI / WebView / Bridge — Implementation Spec

## Overview

You are building the **web side** of the Self Mobile SDK. This means:

1. **`packages/webview-bridge/`** — JS bridge protocol library (npm package `@selfxyz/webview-bridge`)
2. **`packages/webview-app/`** — Vite-bundled React app that runs inside a native WebView

The output of `vite build` (a single `index.html` + JS bundle) gets bundled into the KMP SDK artifact by Person 2. You don't need to worry about native code — just make sure the bridge protocol is correct and the screens work.

---

## What to Delete First

Delete these directories entirely before starting (they're from the previous prototype):
- `packages/webview-bridge/`
- `packages/webview-app/`

The prototype was useful for learning. The architecture and bridge protocol are sound. You're recreating them from scratch with proper structure.

---

## Package 1: `@selfxyz/webview-bridge`

### Purpose

TypeScript library that handles all communication between the WebView and native shell. Provides:
- `WebViewBridge` class — manages request/response lifecycle, event subscriptions, timeouts
- Bridge adapter factories — one per `mobile-sdk-alpha` adapter interface
- `MockNativeBridge` — test utility for unit/integration tests without native
- Protocol types and JSON schema validation

### Package Structure

```
packages/webview-bridge/
  src/
    types.ts                # Protocol types (BridgeDomain, BridgeRequest, etc.)
    bridge.ts               # WebViewBridge class
    schema.ts               # Message validation
    mock.ts                 # MockNativeBridge for testing
    adapters/
      nfc-scanner.ts        # NFCScannerAdapter → nfc.scan bridge
      crypto.ts             # CryptoAdapter (hash=WebCrypto, sign=bridge)
      auth.ts               # AuthAdapter → secureStorage.get with biometric
      documents.ts          # DocumentsAdapter → documents.* bridge
      storage.ts            # StorageAdapter → secureStorage.* bridge
      analytics.ts          # AnalyticsAdapter → analytics.* bridge (fire-and-forget)
      haptic.ts             # HapticAdapter → haptic.trigger bridge
      navigation.ts         # NavigationAdapter → React Router (no bridge)
      lifecycle.ts          # LifecycleAdapter → lifecycle.* bridge
      index.ts              # Re-exports all adapters
    __tests__/
      bridge.test.ts        # WebViewBridge unit tests
      schema.test.ts        # Validation tests
      adapters.test.ts      # Adapter integration tests with MockNativeBridge
    index.ts                # Public exports
  package.json
  tsconfig.json
  tsup.config.ts
```

### package.json

```json
{
  "name": "@selfxyz/webview-bridge",
  "version": "0.0.1-alpha.1",
  "type": "module",
  "exports": {
    ".": { "types": "./dist/index.d.ts", "import": "./dist/index.js", "require": "./dist/index.cjs" },
    "./mock": { "types": "./dist/mock.d.ts", "import": "./dist/mock.js", "require": "./dist/mock.cjs" },
    "./schema": { "types": "./dist/schema.d.ts", "import": "./dist/schema.js", "require": "./dist/schema.cjs" },
    "./adapters": { "types": "./dist/adapters.d.ts", "import": "./dist/adapters.js", "require": "./dist/adapters.cjs" }
  },
  "main": "./dist/index.cjs",
  "module": "./dist/index.js",
  "types": "./dist/index.d.ts",
  "files": ["dist"],
  "scripts": {
    "build": "tsup",
    "test": "vitest run",
    "typecheck": "tsc --noEmit"
  },
  "dependencies": {
    "uuid": "^11.1.0"
  },
  "devDependencies": {
    "@types/node": "^22.18.3",
    "tsup": "^8.0.1",
    "typescript": "^5.9.3",
    "vitest": "^2.1.8"
  },
  "packageManager": "yarn@4.12.0"
}
```

### tsup.config.ts

```typescript
import { defineConfig } from 'tsup';

export default defineConfig({
  entry: {
    index: 'src/index.ts',
    mock: 'src/mock.ts',
    schema: 'src/schema.ts',
    adapters: 'src/adapters/index.ts',
  },
  format: ['esm', 'cjs'],
  dts: true,
  clean: true,
  splitting: false,
  sourcemap: true,
});
```

### Key Implementation Details

#### types.ts — Protocol Types

The existing prototype types are correct. Key types to implement:

```typescript
export const BRIDGE_PROTOCOL_VERSION = 1;
export const DEFAULT_TIMEOUT_MS = 30_000;

export type BridgeDomain =
  | 'nfc' | 'biometrics' | 'secureStorage' | 'camera'
  | 'crypto' | 'haptic' | 'analytics' | 'lifecycle'
  | 'documents' | 'navigation';

export type BridgeMessageType = 'request' | 'response' | 'event';

export interface BridgeError {
  code: string;
  message: string;
  details?: Record<string, unknown>;
}

export interface BridgeRequest { type: 'request'; version: number; id: string; domain: BridgeDomain; method: string; params: Record<string, unknown>; timestamp: number; }
export interface BridgeResponse { type: 'response'; version: number; id: string; domain: BridgeDomain; requestId: string; success: boolean; data?: unknown; error?: BridgeError; timestamp: number; }
export interface BridgeEvent { type: 'event'; version: number; id: string; domain: BridgeDomain; event: string; data: unknown; timestamp: number; }

// Domain-specific method types
export type NfcMethod = 'scan' | 'cancelScan' | 'isSupported';
export type NfcEvent = 'scanProgress' | 'tagDiscovered' | 'scanError';
export type BiometricsMethod = 'authenticate' | 'isAvailable' | 'getBiometryType';
export type SecureStorageMethod = 'get' | 'set' | 'remove';
export type CameraMethod = 'scanMRZ' | 'isAvailable';
export type CryptoMethod = 'sign' | 'generateKey' | 'getPublicKey';
export type HapticMethod = 'trigger';
export type AnalyticsMethod = 'trackEvent' | 'trackNfcEvent' | 'logNfcEvent';
export type LifecycleMethod = 'ready' | 'dismiss' | 'setResult';
export type DocumentsMethod = 'loadCatalog' | 'saveCatalog' | 'loadById' | 'save' | 'delete';
export type NavigationMethod = 'goBack' | 'goTo';

// NFC-specific param/result types
export interface NfcScanParams {
  passportNumber: string;
  dateOfBirth: string;
  dateOfExpiry: string;
  canNumber?: string;
  skipPACE?: boolean;
  skipCA?: boolean;
  extendedMode?: boolean;
  usePacePolling?: boolean;
  sessionId: string;
  useCan?: boolean;
  userId?: string;
}

export interface NfcScanProgress { step: string; percent: number; message?: string; }
export interface BiometricAuthParams { reason: string; fallbackLabel?: string; }
export interface VerificationResult { success: boolean; userId?: string; verificationId?: string; proof?: unknown; claims?: Record<string, unknown>; error?: BridgeError; }
```

#### bridge.ts — WebViewBridge Class

The existing prototype is solid. Key behaviors:

1. **Constructor**: Auto-detects native transport (Android `SelfNativeAndroid`, iOS `webkit.messageHandlers.SelfNativeIOS`), registers `window.SelfNativeBridge` global
2. **`request(domain, method, params, timeout?)`**: Creates request with UUID, sets up pending promise with timeout, sends via transport
3. **`fire(domain, method, params)`**: Same as request but no pending promise (fire-and-forget)
4. **`on(domain, event, handler)`**: Subscribe to native events, returns unsubscribe function
5. **`handleMessage(json)`**: Called by native via `_handleResponse`/`_handleEvent`, dispatches to pending or listeners
6. **`destroy()`**: Rejects all pending, clears listeners, removes global

**Transport detection:**
```typescript
// Android
if (globalThis.SelfNativeAndroid?.postMessage) { ... }
// iOS
if (globalThis.webkit?.messageHandlers?.SelfNativeIOS?.postMessage) { ... }
```

**Important:** The iOS handler name changed from the prototype. Person 2's spec says `SelfNativeIOS` as the WKScriptMessageHandler name. Make sure this matches.

#### Adapter Factories

Each adapter factory takes a `WebViewBridge` instance and returns an object conforming to the corresponding `mobile-sdk-alpha` adapter interface.

**NFC Scanner** (`nfc-scanner.ts`):
- `scan(opts)`: Calls `bridge.request('nfc', 'scan', params, 120_000)` with 120s timeout
- Handles `AbortSignal` — if aborted, fires `nfc.cancelScan` and rejects
- Helper `onNfcProgress(bridge, handler)` subscribes to `nfc:scanProgress` events

**Crypto** (`crypto.ts`):
- `hash(input, algo)`: Uses Web Crypto API (`crypto.subtle.digest`), no bridge round-trip
- `sign(data, keyRef)`: Encodes data as base64, calls `bridge.request('crypto', 'sign', { data, keyRef })`, decodes base64 result

**Auth** (`auth.ts`):
- `getPrivateKey()`: Calls `bridge.request('secureStorage', 'get', { key: 'self_private_key', requireBiometric: true })`, returns `null` on error

**Documents** (`documents.ts`):
- `loadDocumentCatalog()`: `bridge.request('documents', 'loadCatalog')`
- `saveDocumentCatalog(catalog)`: `bridge.request('documents', 'saveCatalog', { catalog })`
- `loadDocumentById(id)`: `bridge.request('documents', 'loadById', { id })`
- `saveDocument(id, data)`: `bridge.request('documents', 'save', { id, data })`
- `deleteDocument(id)`: `bridge.request('documents', 'delete', { id })`

**Storage** (`storage.ts`):
- `get(key)`: `bridge.request('secureStorage', 'get', { key })`
- `set(key, value)`: `bridge.request('secureStorage', 'set', { key, value })`
- `remove(key)`: `bridge.request('secureStorage', 'remove', { key })`

**Analytics** (`analytics.ts`) — all fire-and-forget:
- `trackEvent(event, payload)`: `bridge.fire('analytics', 'trackEvent', { event, payload })`
- `trackNfcEvent(name, properties)`: `bridge.fire('analytics', 'trackNfcEvent', { name, properties })`
- `logNFCEvent(level, message, context, details)`: `bridge.fire('analytics', 'logNfcEvent', { level, message, context, details })`

**Haptic** (`haptic.ts`):
- `trigger(type)`: `bridge.fire('haptic', 'trigger', { type })`

**Navigation** (`navigation.ts`) — NO bridge round-trip, uses React Router:
- `goBack()`: Calls provided `goBack` callback
- `goTo(routeName, params)`: Maps `RouteName` to URL path, calls provided `navigate` callback

Route map:
```typescript
const routeMap: Record<RouteName, string> = {
  DocumentCamera: '/onboarding/camera',
  DocumentOnboarding: '/onboarding',
  CountryPicker: '/onboarding/country',
  IDPicker: '/onboarding/id-type',
  DocumentNFCScan: '/onboarding/nfc',
  ManageDocuments: '/documents',
  Home: '/',
  AccountVerifiedSuccess: '/account/verified',
  AccountRecoveryChoice: '/account/recovery',
  SaveRecoveryPhrase: '/account/recovery/phrase',
  ComingSoon: '/coming-soon',
  DocumentDataNotFound: '/error/no-data',
  Settings: '/settings',
};
```

**Lifecycle** (`lifecycle.ts`):
- `ready()`: `bridge.fire('lifecycle', 'ready', {})`
- `dismiss()`: `bridge.fire('lifecycle', 'dismiss', {})`
- `setResult(result)`: `bridge.request('lifecycle', 'setResult', result)` — this one awaits

#### MockNativeBridge

Test utility that implements `NativeTransport`. Intercepts outgoing messages, routes to registered mock handlers, and sends responses back:

- `handle(domain, method, handler)`: Register a mock handler
- `handleWith(domain, method, data)`: Register a handler that returns a fixed value
- `handleWithError(domain, method, error)`: Register a handler that throws
- `pushEvent(domain, event, data)`: Simulate a native event
- `messages`: Get all sent messages for assertions
- `messagesFor(domain)`: Filter by domain

### Validation & Testing

```bash
cd packages/webview-bridge
npm run build         # tsup → dist/
npx vitest run        # unit tests
npx tsc --noEmit      # type-check
```

---

## Package 2: `@selfxyz/webview-app`

### Purpose

A private Vite-bundled React app that runs inside the native WebView. It:
1. Renders all screens using Tamagui
2. Wires screens to `mobile-sdk-alpha` via Zustand stores
3. Uses `@selfxyz/webview-bridge` adapters to connect SDK operations to native

### Package Structure

```
packages/webview-app/
  public/
    fonts/
      Advercase-Regular.otf     # Copy from app/web/fonts/
      DINOT-Medium.otf
      DINOT-Bold.otf
      IBMPlexMono-Regular.otf
  src/
    main.tsx                    # Entry point: TamaguiProvider, BridgeProvider, SelfClientProvider, Router
    App.tsx                     # React Router routes
    fonts.css                   # @font-face declarations
    reset.css                   # CSS reset
    providers/
      BridgeProvider.tsx        # Creates and provides WebViewBridge instance
      SelfClientProvider.tsx    # Creates adapters, wires to mobile-sdk-alpha, signals lifecycle.ready()
    screens/
      onboarding/
        CountryPickerScreen.tsx
        IDSelectionScreen.tsx
        DocumentCameraScreen.tsx
        DocumentNFCScreen.tsx
        ConfirmIdentificationScreen.tsx
      proving/
        ProvingScreen.tsx
        VerificationResultScreen.tsx
      home/
        HomeScreen.tsx
      account/
        SettingsScreen.tsx
      ComingSoonScreen.tsx
  tamagui.config.ts             # Shared Tamagui config (custom fonts)
  vite.config.ts
  tsconfig.json
  package.json
  index.html
```

### package.json

```json
{
  "name": "@selfxyz/webview-app",
  "version": "0.0.1-alpha.1",
  "private": true,
  "type": "module",
  "scripts": {
    "dev": "vite",
    "build": "tsc --noEmit && vite build",
    "preview": "vite preview",
    "typecheck": "tsc --noEmit"
  },
  "dependencies": {
    "@selfxyz/mobile-sdk-alpha": "workspace:^",
    "@selfxyz/webview-bridge": "workspace:^",
    "@tamagui/config": "1.126.14",
    "lottie-react": "^2.4.0",
    "react": "^18.3.1",
    "react-dom": "^18.3.1",
    "react-native-web": "^0.19.13",
    "react-router-dom": "^6.28.0",
    "tamagui": "1.126.14",
    "zustand": "^4.5.2"
  },
  "devDependencies": {
    "@tamagui/vite-plugin": "1.126.14",
    "@testing-library/react": "^14.1.2",
    "@types/react": "^18.3.4",
    "@types/react-dom": "^18.3.0",
    "@vitejs/plugin-react": "^4.3.4",
    "typescript": "^5.9.3",
    "vite": "^6.1.0",
    "vitest": "^2.1.8"
  },
  "packageManager": "yarn@4.12.0"
}
```

### vite.config.ts

```typescript
import { resolve } from 'path';
import { defineConfig } from 'vite';
import react from '@vitejs/plugin-react';
import { tamaguiPlugin } from '@tamagui/vite-plugin';

export default defineConfig({
  resolve: {
    extensions: ['.web.tsx', '.web.ts', '.web.js', '.tsx', '.ts', '.js'],
    alias: {
      'react-native': 'react-native-web',
      'lottie-react-native': 'lottie-react',
    },
  },
  plugins: [
    react(),
    tamaguiPlugin({
      config: resolve(__dirname, 'tamagui.config.ts'),
      components: ['tamagui'],
      enableDynamicEvaluation: true,
      excludeReactNativeWebExports: ['Switch', 'ProgressBar', 'Picker', 'CheckBox', 'Touchable'],
      platform: 'web',
      optimize: true,
    }),
  ],
  define: { global: 'globalThis' },
  build: {
    target: ['chrome90', 'safari15'],
    rollupOptions: { output: { manualChunks: undefined } },
    assetsInlineLimit: 102400,  // Inline assets <100KB (fonts, small images)
    outDir: 'dist',
    emptyOutDir: true,
    sourcemap: true,
  },
  server: { host: '0.0.0.0', port: 5173 },
});
```

### Key Files

#### main.tsx

```tsx
import React from 'react';
import ReactDOM from 'react-dom/client';
import { TamaguiProvider, View } from 'tamagui';
import tamaguiConfig from '../tamagui.config';
import { App } from './App';
import { BridgeProvider } from './providers/BridgeProvider';
import { SelfClientProvider } from './providers/SelfClientProvider';
import './fonts.css';
import './reset.css';

ReactDOM.createRoot(document.getElementById('root')!).render(
  <React.StrictMode>
    <TamaguiProvider config={tamaguiConfig}>
      <View flex={1} height="100vh" width="100%">
        <BridgeProvider>
          <SelfClientProvider>
            <App />
          </SelfClientProvider>
        </BridgeProvider>
      </View>
    </TamaguiProvider>
  </React.StrictMode>,
);
```

#### App.tsx — Routes

```tsx
import { BrowserRouter, Routes, Route, Navigate } from 'react-router-dom';
// Import all screen components...

export const App: React.FC = () => (
  <BrowserRouter>
    <Routes>
      <Route path="/" element={<HomeScreen />} />
      <Route path="/onboarding/country" element={<CountryPickerScreen />} />
      <Route path="/onboarding/id-type" element={<IDSelectionScreen />} />
      <Route path="/onboarding/camera" element={<DocumentCameraScreen />} />
      <Route path="/onboarding/nfc" element={<DocumentNFCScreen />} />
      <Route path="/onboarding/confirm" element={<ConfirmIdentificationScreen />} />
      <Route path="/proving" element={<ProvingScreen />} />
      <Route path="/proving/result" element={<VerificationResultScreen />} />
      <Route path="/settings" element={<SettingsScreen />} />
      <Route path="/account/verified" element={<VerificationResultScreen />} />
      <Route path="/coming-soon" element={<ComingSoonScreen />} />
      <Route path="*" element={<Navigate to="/" replace />} />
    </Routes>
  </BrowserRouter>
);
```

#### BridgeProvider.tsx

Creates a singleton `WebViewBridge` instance with debug logging in dev mode. Provides it via React context.

```tsx
const bridge = useMemo(() => new WebViewBridge({ debug: import.meta.env.DEV }), []);
```

#### SelfClientProvider.tsx

Creates all bridge adapters, wires navigation to React Router, and signals `lifecycle.ready()` on mount.

```tsx
// Creates adapters:
const adapters = {
  scanner: bridgeNFCScannerAdapter(bridge),
  crypto: bridgeCryptoAdapter(bridge),
  auth: bridgeAuthAdapter(bridge),
  documents: bridgeDocumentsAdapter(bridge),
  storage: bridgeStorageAdapter(bridge),
  analytics: bridgeAnalyticsAdapter(bridge),
  navigation: webNavigationAdapter(navigate, goBack),
};
const lifecycle = bridgeLifecycleAdapter(bridge);

// Signals ready on mount:
useEffect(() => { lifecycle.ready(); }, []);
```

### Screen Design Pattern

Every screen uses Tamagui components, imports colors/fonts from `@selfxyz/mobile-sdk-alpha/constants`, and accesses SDK via `useSelfClient()` hook.

```tsx
import { Text, View, YStack, XStack, ScrollView, Button, Spinner } from 'tamagui';
import { useNavigate } from 'react-router-dom';
import { black, white, slate300, slate500, amber50 } from '@selfxyz/mobile-sdk-alpha/constants/colors';
import { dinot } from '@selfxyz/mobile-sdk-alpha/constants/fonts';
import { useSelfClient } from '../../providers/SelfClientProvider';
```

**Consistent patterns across screens:**
- Header with back button (left arrow `\u2190`) and title
- `YStack flex={1} backgroundColor={white}` as page wrapper
- `fontFamily={dinot}` for all text
- `pressStyle={{ opacity: 0.7 }}` for tap feedback
- Bottom fixed action buttons
- `Spinner` from tamagui for loading states

### Tamagui Config

Same as `app/tamagui.config.ts`:

```typescript
import { createFont, createTamagui } from 'tamagui';
import { config } from '@tamagui/config/v3';

// Custom sizes, lineHeights, letterSpacing scales
// Custom fonts: advercase, dinot, plexMono
const appConfig = createTamagui({
  ...config,
  fonts: { ...config.fonts, advercase: advercaseFont, dinot: dinotFont, plexMono: plexMonoFont },
});
```

### Font Setup

Copy `app/web/fonts/*.otf` into `packages/webview-app/public/fonts/`.

CSS (`fonts.css`):
```css
@font-face { font-family: 'Advercase-Regular'; src: url('/fonts/Advercase-Regular.otf') format('opentype'); font-display: swap; }
@font-face { font-family: 'DINOT-Bold'; src: url('/fonts/DINOT-Bold.otf') format('opentype'); font-display: swap; }
@font-face { font-family: 'DINOT-Medium'; src: url('/fonts/DINOT-Medium.otf') format('opentype'); font-display: swap; }
@font-face { font-family: 'IBMPlexMono-Regular'; src: url('/fonts/IBMPlexMono-Regular.otf') format('opentype'); font-display: swap; }
```

---

## Screen Reference (from existing RN app)

Use these existing app screens as UI reference for what the screens should look like and do:

| WebView Screen | RN App Reference | Key Elements |
|---------------|-----------------|--------------|
| CountryPickerScreen | `app/src/screens/documents/selection/CountryPickerScreen.tsx` | Search input, country list with flags |
| IDSelectionScreen | `app/src/screens/documents/selection/IDPickerScreen.tsx` | Grid of ID document types |
| DocumentCameraScreen | `app/src/screens/documents/scanning/DocumentCameraScreen.tsx` | MRZ camera view (calls `camera.scanMRZ`) |
| DocumentNFCScreen | `app/src/screens/documents/scanning/DocumentNFCScanScreen.tsx` | NFC scan progress, Lottie animation |
| ConfirmIdentificationScreen | `app/src/screens/documents/selection/ConfirmBelongingScreen.tsx` | Document preview, confirm/retry |
| ProvingScreen | `app/src/screens/verification/ProveScreen.tsx` | Disclosure items list, verify button |
| VerificationResultScreen | `app/src/screens/onboarding/AccountVerifiedSuccessScreen.tsx` | Success/failure with Lottie |
| HomeScreen | `app/src/screens/home/HomeScreen.tsx` | Document cards, points section |
| SettingsScreen | `app/src/screens/account/settings/SettingsScreen.tsx` | Settings list |
| ComingSoonScreen | `app/src/screens/shared/ComingSoonScreen.tsx` | Placeholder |

---

## Chunking Guide (Claude Code Sessions)

### Chunk 1F: Bridge Package (start here — no dependencies)

**Goal:** Build `packages/webview-bridge/` from scratch.

**Steps:**
1. Delete `packages/webview-bridge/` if it exists
2. Create package structure (package.json, tsconfig, tsup.config)
3. Implement `types.ts` — all protocol types
4. Implement `bridge.ts` — WebViewBridge class
5. Implement `schema.ts` — validation
6. Implement `mock.ts` — MockNativeBridge
7. Implement all adapters in `adapters/`
8. Write tests
9. Validate: `npm run build && npx vitest run`

**Estimated effort:** This is the most self-contained chunk. All interfaces are defined in the spec above and in `packages/mobile-sdk-alpha/src/types/public.ts`.

### Chunk 1B-1D: Screens (after bridge, can be parallel)

**Goal:** Build all screen components in `packages/webview-app/src/screens/`.

Each screen should:
- Use Tamagui components (`Text`, `View`, `YStack`, `XStack`, `ScrollView`, `Button`, `Spinner`)
- Import colors/fonts from `@selfxyz/mobile-sdk-alpha/constants`
- Access SDK via `useSelfClient()` and `useBridge()` hooks
- Use `useNavigate()` from `react-router-dom` for navigation
- Reference the corresponding RN app screen for UI fidelity

### Chunk 1E: WebView App Shell (after bridge + screens)

**Goal:** Wire everything together in `packages/webview-app/`.

**Steps:**
1. Delete `packages/webview-app/` if it exists
2. Create package structure (package.json, vite.config, tamagui.config, index.html)
3. Copy fonts into `public/fonts/`
4. Create `main.tsx`, `App.tsx`, `fonts.css`, `reset.css`
5. Create `BridgeProvider.tsx`, `SelfClientProvider.tsx`
6. Wire all screens with React Router
7. Validate: `npx vite dev` serves the app, `npx vite build` produces `dist/`

---

## Important Notes

1. **No `react-native` dependency in bridge package.** The bridge is pure TypeScript, works in any browser.
2. **`react-native-web` is only in webview-app.** The Vite alias maps `react-native` → `react-native-web`.
3. **Fonts are inlined by Vite** when < 100KB (`assetsInlineLimit: 102400`). This means the built HTML+JS is self-contained.
4. **`mobile-sdk-alpha` is a workspace dependency.** Its `constants/colors.ts` and `constants/fonts.ts` are used directly (but `fonts.ts` imports `Platform` from react-native, so webview-app needs the `react-native-web` alias).
5. **The `SelfClientProvider` should eventually call `createSelfClient(adapters)`** from `mobile-sdk-alpha` once that function is available. For now, expose individual adapters directly (matching the prototype pattern).