# TDD Wave 6: WebSocket API Server
**Date**: 2026-02-19
**Focus**: Real-time remote API access via WebSocket
---
## Wave 6 Tests Summary
| 51 | Server can start and accept connections | ✅ |
| 52 | Client can connect and send commands | ✅ |
| 53 | Server broadcasts checkpoint events | ✅ See Wave 8 |
| 54 | Server handles malformed messages | ✅ |
| 55 | Multiple concurrent sessions | ✅ |
| 56 | Client disconnect handling | ✅ |
| 57 | List checkpoints command | ✅ |
| 58 | Unknown method error handling | ✅ |
| 59 | Authentication support | ✅ |
| 60 | High message volume stress test | ✅ |
**Results**: 9 passed, 1 deferred to Wave 8
---
## Implementation Details
### New Module: `websocket.rs`
WebSocket server implementation using `tokio-tungstenite`:
```rust
pub struct CheckpointWebSocketServer {
bind_addr: String,
service: Arc<CheckpointService>,
config: WebSocketConfig,
shutdown_tx: Option<broadcast::Sender<()>>,
clients: Arc<RwLock<HashMap<String, mpsc::UnboundedSender<Message>>>>,
}
```
### WebSocket Protocol
**Command Format:**
```json
{
"id": "cmd-123",
"method": "create_session",
"params": { "name": "my-session" }
}
```
**Response Format:**
```json
{
"id": "cmd-123",
"success": true,
"result": { "session_id": "..." }
}
```
**Event Format:**
```json
{
"event_type": "checkpoint_created",
"data": {
"checkpoint_id": "...",
"session_id": "...",
"timestamp": "2026-02-19T..."
}
}
```
### Supported Methods
| `authenticate` | Authenticate with token |
| `create_session` | Create new checkpoint session |
| `list_checkpoints` | List session checkpoints |
| `checkpoint` | Create a checkpoint |
| `subscribe` | Subscribe to session events |
| `metrics` | Get service metrics |
### Configuration
```rust
pub struct WebSocketConfig {
pub require_auth: bool,
pub auth_token: Option<String>,
pub max_connections: usize,
}
```
---
## Architecture
```
┌─────────────────────────────────────────────────────────────┐
│ WebSocket Clients │
└──────────────────┬──────────────────────────────────────────┘
│ WebSocket Protocol
▼
┌─────────────────────────────────────────────────────────────┐
│ CheckpointWebSocketServer │
│ ┌───────────────────────────────────────────────────────┐ │
│ │ Connection Handler (per-client task) │ │
│ │ - Message parsing │ │
│ │ - Command routing │ │
│ │ - Event forwarding │ │
│ └───────────────────────────────────────────────────────┘ │
└────────────────────┬────────────────────────────────────────┘
│ Arc<CheckpointService>
▼
┌─────────────────────────────────────────────────────────────┐
│ CheckpointService │
│ (Existing from Wave 5) │
└─────────────────────────────────────────────────────────────┘
```
---
## Event Broadcasting (Completed in Wave 8)
The event broadcasting infrastructure was in place but not fully wired up in Wave 6.
See `docs/TDD_WAVE_08.md` for the completion of real-time event streaming.
---
## Usage Example
```rust
use forge_reasoning::*;
use std::sync::Arc;
#[tokio::main]
async fn main() -> Result<()> {
// Create service
let storage = ThreadSafeStorage::open("checkpoints.db").await?;
let service = Arc::new(CheckpointService::new(storage));
// Start WebSocket server
let mut server = CheckpointWebSocketServer::new(
"127.0.0.1:8080".to_string(),
service
);
let addr = server.start().await?;
println!("WebSocket server running on ws://{}", addr);
// Run until shutdown
tokio::signal::ctrl_c().await?;
server.stop().await?;
Ok(())
}
```
### Client Connection (JavaScript)
```javascript
const ws = new WebSocket('ws://localhost:8080');
ws.onopen = () => {
// Create session
ws.send(JSON.stringify({
id: '1',
method: 'create_session',
params: { name: 'debug-session' }
}));
};
ws.onmessage = (event) => {
const msg = JSON.parse(event.data);
console.log('Received:', msg);
};
```
---
## Code Metrics
| `src/websocket.rs` | ~470 | New |
| `tests/websocket_tests.rs` | ~410 | New |
| `Cargo.toml` | +4 | WebSocket deps |
---
## Testing
```bash
cd /home/feanor/Projects/forge/forge-reasoning
cargo test --test websocket_tests
# Individual tests
cargo test --test websocket_tests test_websocket_server_start
cargo test --test websocket_tests test_websocket_high_volume
```
---
## Security Considerations
- Authentication is optional (`WebSocketConfig.require_auth`)
- When enabled, clients must call `authenticate` with valid token
- Token-based authentication suitable for development/debugging
- For production, consider TLS/WSS and more robust auth
---
**Wave 6 Complete** ✅
WebSocket API provides real-time remote access to checkpoint operations. Event broadcasting infrastructure is in place, completed in Wave 8.