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Execution Engine

The Execution Engine is the backend module responsible for translating trading group decisions into actual exchange orders.

Architecture​

The engine uses an adapter pattern to support multiple exchanges:

  • Execution Gateway Interface: Defines abstract methods for create_market_order, create_limit_order, fetch_positions, etc.
  • Concrete Adapters: BinanceGateway, OandaGateway, etc.

The Execution Flow​

  1. A trading group reaches a decision and sends a post_trade event via WebSocket.
  2. The WebSocket gateway receives the event. If condition.domain == "trade_decision", it passes the payload to the Execution Engine.
  3. The Execution Engine maps the payload to an OrderRequest.
  4. It checks the linked Trade Account to see what mode is active:
    • Simulated: Skips the exchange entirely; simulates a successful fill.
    • Sandbox / Live: Calls the relevant Exchange Adapter to place the order.
  5. The order status is saved to the database.

Position Sync Loop​

Because exchanges do not push all state changes instantly via WebSocket to our current adapter implementation, the backend runs a background polling loop to synchronize state.

  • Loop interval: Defined by ORDER_SYNC_INTERVAL_S in .env.
  • Order sync: Checks the exchange for fills on pending limit orders and records them in the database.
  • Position sync: Compares local database positions against the exchange's position snapshot.
  • Unrealized PnL: Calculated on the fly using the latest 1-minute close prices from the exchange and stored in the database.

If a position is closed manually on the exchange (outside of AITradingSystem), the sync loop detects this drop in net size and updates the local position status to closed, calculating the final realized PnL.