Component Spec: nats-broker

Responsibilities

• Provide broker-based pub/sub for backend services.
• Provide websocket-compatible endpoint for browser streaming clients.
• Support subject wildcard subscriptions for account-scoped updates.

Covered Flows

• F2 trade submission to processing event chain.
• F4 real-time update streaming to UI.
• STARTUP runtime readiness dependency for event-producing services.

Requirement Coverage

• FR-701, FR-702, FR-703, FR-705
• NFR-701, NFR-702, NFR-703, NFR-704

Interfaces

• NATS client: 4222
• Monitoring: 8222 (optional debug)
• Browser websocket (proxied): /nats-ws

Verification

• scripts/test-state-005-messaging-nats-replacement.sh (to be implemented)