Improve Trading UX: Implement Async Off-chain Matching (Non-blocking)

Issue #89 | State: OPEN | Created: 2026-01-26T06:46:07Z

Labels: enhancement

Assignees: linked0

Updated: 2026-01-26T07:38:39Z | Closed: N/A

Context Currently, the trading flow is synchronous and blocking.

1. User signs order.
2. API submits transaction to Blockchain.
3. API waits for block confirmation (tx.wait()).
4. API responds to Frontend.

This causes a 2-3 second delay for every trade, creating a sluggish user experience compared to CEXs or Polymarket.

Proposed Solution Implement an Asynchronous Matching Engine pattern:

1. Instant ACK: API receives the Signed Order, validates validity (balance/signature), saves to DB as PENDING, and immediately responds 200 OK.
2. Background Processing: A queue/worker picks up the PENDING order and executes the CTFExchange.matchOrders transaction.
3. Websocket Notification: Once the blockchain confirms the tx, the server pushes a ORDER_CONFIRMED event via WebSocket to update the UI status from 'Pending' to 'Confirmed'.

Tasks

• Refactor POST /api/trade to be non-blocking (return immediately after DB save).
• Implement a Job Queue (e.g., BullMQ or simple in-memory queue) for order processing.
• Nonce Management: Implement a robust local nonce manager (Mutex/Redis) to handle concurrent queue processing without 'nonce too low' errors.
• Stuck Transaction Handling: Add logic to detect and speed up stuck transactions (resubmit with higher gas).
• Update Frontend to handle 'Pending' state optimistically (show 'Order Placed' immediately).
• Add WebSocket event TRADE_CONFIRMED to handle final settlement notification.

Definition of Done

• Trading feels 'instant' to the user (< 200ms response).
• Blockchain matching happens transparently in the background. /
• Failures in background matching are gracefully handled (Undo optimistic update / notify user).