Add Binance exchange support

- Updated the environment configuration to include Binance as a selectable exchange option.
- Enhanced the README documentation to reflect the addition of Binance.
- Implemented the Binance exchange adapter and integrated it into the existing exchange framework.
- Modified the basis arbitrage strategy to support Binance alongside existing exchanges.
- Added tests to ensure proper functionality and integration of Binance within the trading system.

tests/basis-arb-engine.test.ts

@@ -71,6 +71,13 @@ describe("BasisArbEngine", () => {
         time: 2_000,
       }),
     };
+    const futuresClient = {
+      getPremiumIndex: vi.fn().mockResolvedValue({
+        fundingRate: "0.0001",
+        nextFundingTime: 3_600_000,
+        time: 2_000,
+      }),
+    };
 
     const engine = new BasisArbEngine(
       {
@@ -79,10 +86,12 @@ describe("BasisArbEngine", () => {
         refreshIntervalMs: 1_000,
         maxLogEntries: 10,
         takerFeeRate: 0.0004,
+        arbAmount: 1,
       },
       adapter,
       {
         spotClient,
+        futuresClient,
         now: () => 1_000,
       }
     );
@@ -111,7 +120,7 @@ describe("BasisArbEngine", () => {
     const expectedNet = 1.04 * (1 - effectiveFee) - 1.05 * (1 + effectiveFee);
     expect(snapshot.netSpread).toBeCloseTo(expectedNet, 6);
     expect(snapshot.netSpreadBps).toBeCloseTo((expectedNet / 1.05) * 10_000, 6);
-    expect(snapshot.feedStatus).toEqual({ futures: true, spot: true });
+    expect(snapshot.feedStatus).toEqual({ futures: true, spot: true, funding: true });
     expect(snapshot.opportunity).toBe(expectedNet >= 0);
 
     engine.stop();

tests/config.test.ts

@@ -49,4 +49,11 @@ describe("resolveSymbolFromEnv", () => {
 
     expect(resolveSymbolFromEnv("standx")).toBe("ETH-USD");
   });
+
+  it("supports binance symbol defaults when explicit exchange id is provided", () => {
+    delete process.env.EXCHANGE;
+    process.env.BINANCE_SYMBOL = "ETHUSDT";
+
+    expect(resolveSymbolFromEnv("binance")).toBe("ETHUSDT");
+  });
 });

tests/exchange-factory.test.ts

@@ -5,6 +5,7 @@ import { GrvtExchangeAdapter } from "../src/exchanges/grvt/adapter";
 import { BackpackExchangeAdapter } from "../src/exchanges/backpack/adapter";
 import { ParadexExchangeAdapter } from "../src/exchanges/paradex/adapter";
 import { StandxExchangeAdapter } from "../src/exchanges/standx/adapter";
+import { BinanceExchangeAdapter } from "../src/exchanges/binance/adapter";
 
 const ORIGINAL_ENV = { ...process.env };
 
@@ -32,6 +33,7 @@ describe("exchange factory", () => {
     expect(resolveExchangeId("BACKPACK")).toBe("backpack");
     expect(resolveExchangeId("PaRaDeX")).toBe("paradex");
     expect(resolveExchangeId("StandX")).toBe("standx");
+    expect(resolveExchangeId("BiNaNcE")).toBe("binance");
   });
 
   it("creates grvt adapter when EXCHANGE=grvt", () => {
@@ -79,4 +81,15 @@ describe("exchange factory", () => {
     expect(adapter).toBeInstanceOf(StandxExchangeAdapter);
     expect(adapter.id).toBe("standx");
   });
+
+  it("creates binance adapter when EXCHANGE=binance", () => {
+    process.env.EXCHANGE = "binance";
+    process.env.BINANCE_API_KEY = "api-key";
+    process.env.BINANCE_API_SECRET = "api-secret";
+    process.env.BINANCE_SYMBOL = "BTCUSDT";
+
+    const adapter = createExchangeAdapter({ symbol: "BTCUSDT" });
+    expect(adapter).toBeInstanceOf(BinanceExchangeAdapter);
+    expect(adapter.id).toBe("binance");
+  });
 });