- Decouple WebSocket connection from session lifecycle: workflows continue running after disconnect
- Message buffering with ring buffer (max 1000) for chat history replay on reconnect
- Session garbage collection: 24-hour TTL for terminal sessions via background asyncio task
- Multi-tab support: last tab wins, old WebSocket closed on new connection for same session
- Cancel now sends explicit WebSocket message instead of relying on disconnect detection
- Replace hardcoded API keys and BASE_URL with ${API_KEY}/${BASE_URL} placeholders in yaml configs
