feat: add gasestimator helper for soroban transactions

packages/sdk/src/__tests__/GasEstimator.test.ts

@@ -0,0 +1,128 @@
+import { describe, expect, it, vi } from "vitest";
+import {
+  GasEstimator,
+  estimateSorobanGas,
+  type GasEstimatorRpc,
+} from "../utils/GasEstimator";
+
+function createRpc(overrides: Partial<GasEstimatorRpc> = {}): GasEstimatorRpc {
+  return {
+    simulateTransaction: vi.fn().mockResolvedValue({
+      minResourceFee: "1000",
+    }),
+    getFeeStats: vi.fn().mockResolvedValue({
+      inclusionFee: {
+        p50: "100",
+        p90: "120",
+        p95: "140",
+        p99: "200",
+        transactionCount: "5",
+      },
+    }),
+    ...overrides,
+  } as GasEstimatorRpc;
+}
+
+describe("GasEstimator", () => {
+  it("combines simulation resource fees with low congestion fee stats", async () => {
+    const rpc = createRpc();
+    const estimator = new GasEstimator({ rpc });
+
+    const estimate = await estimator.estimate({} as any);
+
+    expect(rpc.simulateTransaction).toHaveBeenCalled();
+    expect(rpc.getFeeStats).toHaveBeenCalled();
+    expect(estimate.minResourceFee).toBe("1000");
+    expect(estimate.resourceFee).toBe("1200");
+    expect(estimate.inclusionFee).toBe("110");
+    expect(estimate.recommendedFee).toBe("1310");
+    expect(estimate.congestionLevel).toBe("low");
+  });
+
+  it("uses higher percentiles and a larger buffer during high congestion", async () => {
+    const rpc = createRpc({
+      getFeeStats: vi.fn().mockResolvedValue({
+        inclusionFee: {
+          p50: "200",
+          p90: "450",
+          p95: "700",
+          p99: "1200",
+          transactionCount: "520",
+        },
+      }),
+    });
+    const estimator = new GasEstimator({ rpc });
+
+    const estimate = await estimator.estimate({} as any);
+
+    expect(estimate.congestionLevel).toBe("high");
+    expect(estimate.inclusionFee).toBe("945");
+    expect(estimate.recommendedFee).toBe("2145");
+  });
+
+  it("falls back to the configured base fee when fee stats are unavailable", async () => {
+    const rpc = createRpc({
+      getFeeStats: vi.fn().mockRejectedValue(new Error("method not found")),
+    });
+    const estimator = new GasEstimator({ rpc, baseFee: "250" });
+
+    const estimate = await estimator.estimate({} as any);
+
+    expect(estimate.congestionLevel).toBe("unknown");
+    expect(estimate.inclusionFee).toBe("275");
+    expect(estimate.recommendedFee).toBe("1475");
+  });
+
+  it("buffers resource limits parsed from Soroban transaction data", async () => {
+    const resources = {
+      instructions: () => 10,
+      readBytes: () => 20,
+      writeBytes: () => 30,
+      footprint: () => ({
+        readOnly: () => ["a", "b"],
+        readWrite: () => ["c"],
+      }),
+    };
+    const transactionData = {
+      resources: () => resources,
+    };
+    const rpc = createRpc({
+      simulateTransaction: vi.fn().mockResolvedValue({
+        minResourceFee: "1000",
+        transactionData,
+      }),
+    });
+    const estimator = new GasEstimator({ rpc, resourceBuffer: 1.5 });
+
+    const estimate = await estimator.estimate({} as any);
+
+    expect(estimate.resourceLimits).toEqual({
+      instructions: 15,
+      readBytes: 30,
+      writeBytes: 45,
+      readEntries: 3,
+      writeEntries: 2,
+    });
+  });
+
+  it("throws when simulation returns an error response", async () => {
+    const rpc = createRpc({
+      simulateTransaction: vi
+        .fn()
+        .mockResolvedValue({ error: "host function failed" }),
+    });
+    const estimator = new GasEstimator({ rpc });
+
+    await expect(estimator.estimate({} as any)).rejects.toThrow(
+      "Gas estimation simulation failed: host function failed"
+    );
+  });
+
+  it("provides a function helper for one-off estimates", async () => {
+    const rpc = createRpc();
+
+    const estimate = await estimateSorobanGas({} as any, { rpc });
+
+    expect(estimate.recommendedFee).toBe("1310");
+  });
+});

packages/sdk/src/index.ts

@@ -37,6 +37,7 @@ export * from "./utils/networkDetection";
 export * from "./utils/streamHistory";
 export * from "./utils/BalanceWatcher";
 export * from "./utils/transactions";
+export * from "./utils/GasEstimator";
 
 // Export error handling utilities
 export {