fix(runtime): expose errno in fetch-failed JSON cause.code

Author: hopelynd

packages/runtime/src/error-handler.ts

@@ -78,11 +78,12 @@ function fromFetchFailed(err: TypeError): BailianError {
   if (causeMsg && causeMsg !== code) detailParts.push(causeMsg);
   const detail = detailParts.length > 0 ? detailParts.join(": ") : "unknown cause";
 
+  // Prefer the errno (ENOTFOUND, …) so JSON toJSON() exposes cause.code for agents.
   return new BailianError(
     `Network request failed: ${detail}`,
     ExitCode.NETWORK,
     pickNetworkHint(code),
-    { cause: err },
+    { cause: cause ?? err },
   );
 }
 

packages/runtime/tests/error-handler.test.ts

@@ -0,0 +1,85 @@
+import { ExitCode } from "bailian-cli-core";
+import { expect, test } from "vite-plus/test";
+import { handleError } from "../src/error-handler.ts";
+
+test("handleError: fetch failed JSON includes cause.code from errno", () => {
+  const previousOutput = process.env.DASHSCOPE_OUTPUT;
+  process.env.DASHSCOPE_OUTPUT = "json";
+
+  let stderr = "";
+  const originalWrite = process.stderr.write.bind(process.stderr);
+  const originalExit = process.exit;
+  process.stderr.write = ((chunk: string | Uint8Array) => {
+    stderr += String(chunk);
+    return true;
+  }) as typeof process.stderr.write;
+  process.exit = ((code?: number) => {
+    throw new Error(`process.exit:${code ?? 0}`);
+  }) as typeof process.exit;
+
+  const root = Object.assign(new Error("getaddrinfo ENOTFOUND example.invalid"), {
+    code: "ENOTFOUND",
+  });
+  const fetchFailed = new TypeError("fetch failed", { cause: root });
+
+  try {
+    expect(() => handleError(fetchFailed, "bl")).toThrow(
+      new RegExp(`process\\.exit:${ExitCode.NETWORK}`),
+    );
+    const payload = JSON.parse(stderr.trim()) as {
+      error: { code: number; message: string; cause?: { message: string; code?: string } };
+    };
+    expect(payload.error.code).toBe(ExitCode.NETWORK);
+    expect(payload.error.message).toMatch(/ENOTFOUND/);
+    expect(payload.error.cause).toEqual({
+      message: root.message,
+      code: "ENOTFOUND",
+    });
+  } finally {
+    process.stderr.write = originalWrite;
+    process.exit = originalExit;
+    if (previousOutput === undefined) {
+      delete process.env.DASHSCOPE_OUTPUT;
+    } else {
+      process.env.DASHSCOPE_OUTPUT = previousOutput;
+    }
+  }
+});
+
+test("handleError: fetch failed without nested cause still maps to NETWORK", () => {
+  const previousOutput = process.env.DASHSCOPE_OUTPUT;
+  process.env.DASHSCOPE_OUTPUT = "json";
+
+  let stderr = "";
+  const originalWrite = process.stderr.write.bind(process.stderr);
+  const originalExit = process.exit;
+  process.stderr.write = ((chunk: string | Uint8Array) => {
+    stderr += String(chunk);
+    return true;
+  }) as typeof process.stderr.write;
+  process.exit = ((code?: number) => {
+    throw new Error(`process.exit:${code ?? 0}`);
+  }) as typeof process.exit;
+
+  const fetchFailed = new TypeError("fetch failed");
+
+  try {
+    expect(() => handleError(fetchFailed, "bl")).toThrow(
+      new RegExp(`process\\.exit:${ExitCode.NETWORK}`),
+    );
+    const payload = JSON.parse(stderr.trim()) as {
+      error: { code: number; message: string; cause?: { message: string; code?: string } };
+    };
+    expect(payload.error.code).toBe(ExitCode.NETWORK);
+    expect(payload.error.message).toMatch(/unknown cause/);
+    expect(payload.error.cause).toEqual({ message: "fetch failed" });
+  } finally {
+    process.stderr.write = originalWrite;
+    process.exit = originalExit;
+    if (previousOutput === undefined) {
+      delete process.env.DASHSCOPE_OUTPUT;
+    } else {
+      process.env.DASHSCOPE_OUTPUT = previousOutput;
+    }
+  }
+});