refactor: extract shared order handler factory, deduplicate 8 order.ts files

Created src/exchanges/order-handlers.ts with createOrderHandlers() factory.
All 8 exchange order.ts files now use config-driven delegation instead of
duplicated ~80-line implementations. Shared applyCommonFields() logic
consolidated into the factory module.

src/exchanges/order-handlers.ts

@@ -0,0 +1,144 @@
+import type { Order, CreateOrderParams, TimeInForce } from "./types";
+import type {
+  BaseOrderIntent,
+  ClosePositionIntent,
+  LimitOrderIntent,
+  MarketOrderIntent,
+  StopOrderIntent,
+  TrailingStopOrderIntent,
+} from "./order-schema";
+import { toStringBoolean } from "./order-schema";
+
+export interface OrderHandlerConfig {
+  exchangeName: string;
+  defaultLimitTimeInForce: TimeInForce | "GTX";
+  defaultMarketTimeInForce?: TimeInForce;
+  defaultCloseTimeInForce?: TimeInForce;
+  defaultStopTimeInForce?: TimeInForce;
+  defaultStopTriggerType?: "UNSPECIFIED" | "TAKE_PROFIT" | "STOP_LOSS";
+  supportsTrailingStop: boolean;
+  supportsTriggerType: boolean;
+  stopDefaultReduceOnly?: boolean;
+  stopDefaultClosePosition?: boolean;
+  closeDefaultClosePosition?: boolean;
+  stopPriceAsPrice?: boolean;
+}
+
+export interface OrderHandlers {
+  createLimitOrder(intent: LimitOrderIntent): Promise<Order>;
+  createMarketOrder(intent: MarketOrderIntent): Promise<Order>;
+  createStopOrder(intent: StopOrderIntent): Promise<Order>;
+  createTrailingStopOrder(intent: TrailingStopOrderIntent): Promise<Order>;
+  createClosePositionOrder(intent: ClosePositionIntent): Promise<Order>;
+}
+
+function applyCommonFields(params: CreateOrderParams, intent: BaseOrderIntent): CreateOrderParams {
+  if (params.quantity === undefined) {
+    params.quantity = intent.quantity;
+  }
+  if (params.timeInForce === undefined && intent.timeInForce) {
+    params.timeInForce = intent.timeInForce;
+  }
+  if (intent.reduceOnly !== undefined) {
+    params.reduceOnly = toStringBoolean(intent.reduceOnly);
+  }
+  if (intent.closePosition !== undefined) {
+    params.closePosition = toStringBoolean(intent.closePosition);
+  }
+  return params;
+}
+
+export function createOrderHandlers(config: OrderHandlerConfig): OrderHandlers {
+  return {
+    async createLimitOrder(intent: LimitOrderIntent): Promise<Order> {
+      const params: CreateOrderParams = applyCommonFields(
+        {
+          symbol: intent.symbol,
+          side: intent.side,
+          type: "LIMIT",
+          quantity: intent.quantity,
+          price: intent.price,
+          timeInForce: intent.timeInForce ?? config.defaultLimitTimeInForce,
+          slPrice: intent.slPrice,
+          tpPrice: intent.tpPrice,
+        },
+        intent,
+      );
+      return intent.adapter.createOrder(params);
+    },
+
+    async createMarketOrder(intent: MarketOrderIntent): Promise<Order> {
+      const params: CreateOrderParams = applyCommonFields(
+        {
+          symbol: intent.symbol,
+          side: intent.side,
+          type: "MARKET",
+          quantity: intent.quantity,
+          timeInForce: intent.timeInForce ?? config.defaultMarketTimeInForce,
+        },
+        intent,
+      );
+      return intent.adapter.createOrder(params);
+    },
+
+    async createStopOrder(intent: StopOrderIntent): Promise<Order> {
+      const params: CreateOrderParams = applyCommonFields(
+        {
+          symbol: intent.symbol,
+          side: intent.side,
+          type: "STOP_MARKET",
+          quantity: intent.quantity,
+          stopPrice: intent.stopPrice,
+          timeInForce: intent.timeInForce ?? (config.defaultStopTimeInForce ?? "GTC"),
+          triggerType: config.supportsTriggerType ? (intent.triggerType ?? config.defaultStopTriggerType) : undefined,
+          price: config.stopPriceAsPrice ? intent.stopPrice : undefined,
+        },
+        intent,
+      );
+      if (config.stopDefaultReduceOnly && intent.reduceOnly === undefined) {
+        params.reduceOnly = "true";
+      }
+      if (config.stopDefaultClosePosition && intent.closePosition === undefined) {
+        params.closePosition = "true";
+      }
+      return intent.adapter.createOrder(params);
+    },
+
+    async createTrailingStopOrder(intent: TrailingStopOrderIntent): Promise<Order> {
+      if (!config.supportsTrailingStop) {
+        throw new Error(`${config.exchangeName} does not support trailing stop orders`);
+      }
+      const params: CreateOrderParams = applyCommonFields(
+        {
+          symbol: intent.symbol,
+          side: intent.side,
+          type: "TRAILING_STOP_MARKET",
+          quantity: intent.quantity,
+          activationPrice: intent.activationPrice,
+          callbackRate: intent.callbackRate,
+          timeInForce: intent.timeInForce ?? "GTC",
+        },
+        intent,
+      );
+      return intent.adapter.createOrder(params);
+    },
+
+    async createClosePositionOrder(intent: ClosePositionIntent): Promise<Order> {
+      const params: CreateOrderParams = applyCommonFields(
+        {
+          symbol: intent.symbol,
+          side: intent.side,
+          type: "MARKET",
+          quantity: intent.quantity,
+          reduceOnly: "true",
+          timeInForce: intent.timeInForce ?? config.defaultCloseTimeInForce,
+        },
+        intent,
+      );
+      if (config.closeDefaultClosePosition && intent.closePosition === undefined) {
+        params.closePosition = "true";
+      }
+      return intent.adapter.createOrder(params);
+    },
+  };
+}