sp3-test-1770368381/.sdlc/features/websocket-chat/spec.md

WebSocket Chat - Feature Specification

Overview

Add WebSocket support to the chat-api service. GET /ws upgrades to a WebSocket connection. Incoming messages are published to a Redis Pub/Sub channel. A Redis subscriber broadcasts received messages to all connected WebSocket clients.

Requirements

Functional Requirements

1. WebSocket Endpoint: GET /api/chat-api/ws upgrades HTTP connections to WebSocket
2. Message Publishing: Incoming WebSocket messages are published to Redis Pub/Sub channels
3. Message Broadcasting: A Redis subscriber receives messages and broadcasts them to all connected WebSocket clients
4. Room Support: Optional room-based messaging via GET /api/chat-api/ws/{room} or ?room= query parameter

Non-Functional Requirements

1. Uses existing pkg/realtime package (Hub, WSClient, RedisBroadcaster)
2. Follows existing chat-api handler and routing patterns
3. Redis connection configured via REDIS_URL environment variable
4. Graceful shutdown of hub and Redis broadcaster on SIGTERM

Acceptance Criteria

• GET /api/chat-api/ws upgrades to WebSocket
• Messages sent by a client are published to Redis
• Messages from Redis are broadcast to all connected clients
• Hub and Redis broadcaster shut down gracefully
• Configuration via REDIS_URL environment variable
• OpenAPI spec updated with WebSocket endpoint documentation