# FRE-600: WebSocket Foundation + Yjs CRDT Sync

## Phase 1 Implementation Status

### ✅ Completed Components

#### 1. Core Infrastructure
- **`tsconfig.json`** - TypeScript configuration with SolidJS support
- **`vite.config.ts`** - Vite build configuration with WebSocket proxy
- **`package.json`** - Dependencies and scripts

#### 2. Yjs Document Structure (`src/lib/collaboration/yjs-document.ts`)
- `createScreenplayDoc()` - Creates Yjs document with screenplay structure
- `getOrCreateSharedTypes()` - Access to shared types (Text, Map)
- Metadata, characters, and scenes management

#### 3. WebSocket Connection Manager (`src/lib/collaboration/websocket-connection.ts`)
- `WebSocketConnection` class implementing `WebSocketConnectionManager` interface
- Automatic reconnection with exponential backoff
- Connection status tracking (`connecting`, `connected`, `disconnected`, `reconnecting`)
- JWT authentication support

#### 4. CRDT Document Manager (`src/lib/collaboration/crdt-document.ts`)
- `CRDTDocument` class implementing `CRDTDocumentManager` interface
- Document lifecycle management
- Undo/Redo stack integration
- WebSocket provider coordination

#### 5. WebSocket Server (`server/websocket/`)
- **`server.ts`** - Core WebSocket server with Yjs sync protocol
  - Document state management
  - Client connection tracking
  - Message handling (sync, update)
  - JWT authentication middleware
- **`index.ts`** - Server entry point with configuration

#### 6. SolidJS Bindings (`src/lib/collaboration/solid-bindings.ts`)
- `useYText()` - Reactive binding for Yjs Text
- `useYMap()` - Reactive binding for Yjs Map
- `useYArray()` - Reactive binding for Yjs Array
- `useCollaborativeText()` - Collaborative editor binding
- `useCollaborativeDoc()` - Full document binding

#### 7. Collaborative Editor Component (`src/components/editor/collaborative-editor.tsx`)
- `CollaborativeEditor` component
- Real-time text synchronization
- Cursor position preservation
- Event handling for collaborative edits

#### 8. Tests (`src/lib/collaboration/crdt-document.test.ts`)
- Document creation tests
- Text synchronization tests
- Concurrent operations tests
- Undo/Redo tests
- Metadata management tests
- Character and scene storage tests

### 📋 Usage Example

```typescript
// Client-side initialization
import { CRDTDocument } from './src/lib/collaboration/crdt-document';

const docManager = new CRDTDocument();
await docManager.initialize(
  'project-123',
  'ws://localhost:8080',
  'jwt-auth-token'
);

// Access the document
const doc = await docManager.initialize(...);
const text = doc.getText('main');
text.insert(0, 'Hello, collaborative world!');

// SolidJS integration
import { useCollaborativeDoc } from './src/lib/collaboration/solid-bindings';

function Editor() {
  const { text, metadata } = useCollaborativeDoc(doc);
  
  return (
    <CollaborativeEditor
      doc={doc}
      projectId="project-123"
      userId="user-456"
    />
  );
}
```

### 🚀 Running the Server

```bash
# Install dependencies
npm install

# Start development server
npm run dev

# Start WebSocket server
npm run server:dev

# Run tests
npm test
```

### 📁 File Structure

```
src/
├── lib/
│   └── collaboration/
│       ├── yjs-document.ts          # Yjs document structure
│       ├── websocket-connection.ts  # WebSocket client
│       ├── crdt-document.ts         # CRDT manager
│       ├── solid-bindings.ts        # SolidJS reactive bindings
│       └── crdt-document.test.ts    # Unit tests
└── components/
    └── editor/
        └── collaborative-editor.tsx # Collaborative editor component

server/
└── websocket/
    ├── server.ts   # WebSocket server implementation
    └── index.ts    # Server entry point
```

### 🔧 Configuration

#### Environment Variables
```env
# WebSocket Server
WS_PORT=8080
JWT_SECRET=your-secret-key
ENABLE_AUTH=true

# Client
VITE_WS_URL=ws://localhost:8080
```

### ✅ Deliverables Met

- [x] Two app instances can sync text changes via WebSocket
- [x] Basic undo/redo functionality
- [x] Connection status indicator
- [x] Unit tests for CRDT operations

### 📊 Next Steps (Phase 2)

1. Implement `PresenceManager` with cursor tracking
2. Set up Redis for presence state
3. Create `CollaboratorList` component
4. Implement remote cursor rendering
5. Add user idle detection

### 📝 Dependencies Status

- **FRE-586** (Core editor): Needed for editor component attachment
- **FRE-588** (DB schema): Needed for project metadata
- **FRE-596** (Auth): Needed for JWT token generation

### ⚠️ Known Blockers

1. **WebSocket server infrastructure deployment** - Server code ready, needs deployment
2. **JWT authentication setup** - Requires FRE-596 auth tokens

---

**Status:** Phase 1 foundation complete, ready for Code Review
**Next Phase:** Presence & Visibility (Weeks 3-4)