WebSocket API - PitchMarket

Connect to GET /ws on the API server (same origin as REST, default :8080). The hub broadcasts the six event types pinned in interface contract §5; slow clients are dropped rather than allowed to back-pressure the exchange.

Events

Event	Emitted when	Typical consumer use
`book_update`	The book changes at any level (new order, fill, cancel, expiry)	Re-render the ladder
`fill`	A match settles (or mirrors) a fill	Fill feed, position refresh
`order_update`	An order’s state changes — including the revert → reconcile path when an on-chain settle loses a race and the soft-lock is unwound	Portfolio open-orders list
`combo_quote`	An MM posts a quote on an open RFQ	Combo builder quote countdown
`match_state`	Live fixture state changes (score, minute, kickoff, full-time)	Market header
`oneliner`	A new AI one-liner is generated (~2-minute ticker)	Rotating commentary strip

Client behavior

The reference client is frontend/lib/useLiveMarket.ts (ported to mobile/src/lib/useLiveMarket.ts with an AppState foreground-refetch, since mobile OSes freeze sockets in the background). Pattern: load a REST snapshot first, then apply WS events on top; on disconnect, reconnect with backoff and re-snapshot.

Events are broadcast to all connected clients; filtering by market happens client-side. The exchange core (backend/internal/exchange) is the single emitter — every order path (API and MM bot) produces the same events.