diff --git a/src/cli/cli-utils.test.ts b/src/cli/cli-utils.test.ts
index 7578b7f84db2..776b4a7b8788 100644
--- a/src/cli/cli-utils.test.ts
+++ b/src/cli/cli-utils.test.ts
@@ -1,6 +1,7 @@
 // CLI utility tests cover shared command helpers, option parsing, and output formatting.
 import { Command } from "commander";
 import { describe, expect, it, vi } from "vitest";
+import { runCommandWithRuntime } from "./cli-utils.js";
 import { registerDnsCli } from "./dns-cli.js";
 import { parseByteSize } from "./parse-bytes.js";
 import { parseDurationMs } from "./parse-duration.js";
@@ -33,6 +34,33 @@ describe("waitForever", () => {
   });
 });
 
+describe("runCommandWithRuntime", () => {
+  it("surfaces cause chains and error codes through the default runtime", async () => {
+    const messages: string[] = [];
+    const exits: number[] = [];
+    const cause = Object.assign(new Error("invalid onRequestStart method"), {
+      code: "UND_ERR_INVALID_ARG",
+    });
+    const fetchError = Object.assign(new TypeError("fetch failed"), { cause });
+
+    await runCommandWithRuntime(
+      {
+        error: (message) => messages.push(message),
+        exit: (code) => exits.push(code),
+      },
+      async () => {
+        throw fetchError;
+      },
+    );
+
+    expect(messages).toHaveLength(1);
+    expect(messages[0]).toContain("TypeError: fetch failed");
+    expect(messages[0]).toContain("invalid onRequestStart method");
+    expect(messages[0]).toContain("UND_ERR_INVALID_ARG");
+    expect(exits).toEqual([1]);
+  });
+});
+
 describe("shouldSkipRespawnForArgv", () => {
   it.each([
     { argv: ["node", "openclaw", "--help"] },
diff --git a/src/cli/cli-utils.ts b/src/cli/cli-utils.ts
index c85e2132622c..f4945746ea12 100644
--- a/src/cli/cli-utils.ts
+++ b/src/cli/cli-utils.ts
@@ -32,6 +32,13 @@ export async function withManager<T>(params: {
   }
 }
 
+function formatCommandRuntimeError(err: unknown): string {
+  if (err instanceof Error) {
+    return formatErrorMessage(new Error(String(err), { cause: err.cause }));
+  }
+  return formatErrorMessage(err);
+}
+
 export async function runCommandWithRuntime(
   runtime: { error: (message: string) => void; exit: (code: number) => void },
   action: () => Promise<void>,
@@ -44,7 +51,7 @@ export async function runCommandWithRuntime(
       onError(err);
       return;
     }
-    runtime.error(String(err));
+    runtime.error(formatCommandRuntimeError(err));
     runtime.exit(1);
   }
 }
diff --git a/src/infra/errors.ts b/src/infra/errors.ts
index e5951c1c489b..1bd0ba49c287 100644
--- a/src/infra/errors.ts
+++ b/src/infra/errors.ts
@@ -86,6 +86,10 @@ export function formatErrorMessage(err: unknown): string {
       seen.add(cause);
       if (cause instanceof Error) {
         appendCauseMessage(cause.message);
+        const code = extractErrorCode(cause);
+        if (code) {
+          appendCauseMessage(code);
+        }
         cause = cause.cause;
       } else if (typeof cause === "string") {
         appendCauseMessage(cause);