diff --git a/src/infra/warning-filter.test.ts b/src/infra/warning-filter.test.ts
index 8220037d95..bd3ff1247c 100644
--- a/src/infra/warning-filter.test.ts
+++ b/src/infra/warning-filter.test.ts
@@ -2,12 +2,14 @@ import { afterEach, beforeEach, describe, expect, it, vi } from "vitest";
 import { installProcessWarningFilter, shouldIgnoreWarning } from "./warning-filter.js";
 
 const warningFilterKey = Symbol.for("openclaw.warning-filter");
+const baseEmitWarning = process.emitWarning.bind(process) as typeof process.emitWarning;
 
 function resetWarningFilterInstallState(): void {
   const globalState = globalThis as typeof globalThis & {
     [warningFilterKey]?: { installed: boolean };
   };
   delete globalState[warningFilterKey];
+  process.emitWarning = baseEmitWarning;
 }
 
 describe("warning filter", () => {
@@ -53,37 +55,29 @@ describe("warning filter", () => {
     ).toBe(false);
   });
 
-  it("installs once and only writes unsuppressed warnings", () => {
-    let warningHandler: ((warning: Error & { code?: string; message?: string }) => void) | null =
-      null;
-    const onSpy = vi.spyOn(process, "on").mockImplementation(((event, handler) => {
-      if (event === "warning") {
-        warningHandler = handler as (warning: Error & { code?: string; message?: string }) => void;
-      }
-      return process;
-    }) as typeof process.on);
+  it("installs once and suppresses known warnings at emit time", async () => {
     const writeSpy = vi.spyOn(process.stderr, "write").mockImplementation(() => true);
 
     installProcessWarningFilter();
     installProcessWarningFilter();
+    installProcessWarningFilter();
+    const emitWarning = (...args: unknown[]) =>
+      (process.emitWarning as unknown as (...warningArgs: unknown[]) => void)(...args);
 
-    expect(onSpy).toHaveBeenCalledTimes(1);
-    expect(warningHandler).not.toBeNull();
-
-    warningHandler?.({
-      name: "DeprecationWarning",
+    emitWarning(
+      "The `util._extend` API is deprecated. Please use Object.assign() instead.",
+      "DeprecationWarning",
+      "DEP0060",
+    );
+    emitWarning("The `util._extend` API is deprecated. Please use Object.assign() instead.", {
+      type: "DeprecationWarning",
       code: "DEP0060",
-      message: "The `util._extend` API is deprecated.",
-      toString: () => "suppressed",
-    } as Error & { code?: string; message?: string });
+    });
+    await new Promise((resolve) => setImmediate(resolve));
     expect(writeSpy).not.toHaveBeenCalled();
 
-    warningHandler?.({
-      name: "Warning",
-      message: "Visible warning",
-      stack: "Warning: visible",
-      toString: () => "visible",
-    } as Error & { code?: string; message?: string });
-    expect(writeSpy).toHaveBeenCalledWith("Warning: visible\n");
+    emitWarning("Visible warning", { type: "Warning", code: "OPENCLAW_TEST_WARNING" });
+    await new Promise((resolve) => setImmediate(resolve));
+    expect(writeSpy).toHaveBeenCalled();
   });
 });
diff --git a/src/infra/warning-filter.ts b/src/infra/warning-filter.ts
index 68af7ad5d3..4086322288 100644
--- a/src/infra/warning-filter.ts
+++ b/src/infra/warning-filter.ts
@@ -1,11 +1,15 @@
 const warningFilterKey = Symbol.for("openclaw.warning-filter");
 
-export type ProcessWarning = Error & {
+export type ProcessWarning = {
   code?: string;
   name?: string;
   message?: string;
 };
 
+type ProcessWarningInstallState = {
+  installed: boolean;
+};
+
 export function shouldIgnoreWarning(warning: ProcessWarning): boolean {
   if (warning.code === "DEP0040" && warning.message?.includes("punycode")) {
     return true;
@@ -22,19 +26,60 @@ export function shouldIgnoreWarning(warning: ProcessWarning): boolean {
   return false;
 }
 
+function normalizeWarningArgs(args: unknown[]): ProcessWarning {
+  const warningArg = args[0];
+  const secondArg = args[1];
+  const thirdArg = args[2];
+  let name: string | undefined;
+  let code: string | undefined;
+  let message: string | undefined;
+
+  if (warningArg instanceof Error) {
+    name = warningArg.name;
+    message = warningArg.message;
+    code = (warningArg as Error & { code?: string }).code;
+  } else if (typeof warningArg === "string") {
+    message = warningArg;
+  }
+
+  if (secondArg && typeof secondArg === "object" && !Array.isArray(secondArg)) {
+    const options = secondArg as { type?: unknown; code?: unknown };
+    if (typeof options.type === "string") {
+      name = options.type;
+    }
+    if (typeof options.code === "string") {
+      code = options.code;
+    }
+  } else {
+    if (typeof secondArg === "string") {
+      name = secondArg;
+    }
+    if (typeof thirdArg === "string") {
+      code = thirdArg;
+    }
+  }
+
+  return { name, code, message };
+}
+
 export function installProcessWarningFilter(): void {
   const globalState = globalThis as typeof globalThis & {
-    [warningFilterKey]?: { installed: boolean };
+    [warningFilterKey]?: ProcessWarningInstallState;
   };
   if (globalState[warningFilterKey]?.installed) {
     return;
   }
-  globalState[warningFilterKey] = { installed: true };
 
-  process.on("warning", (warning: ProcessWarning) => {
-    if (shouldIgnoreWarning(warning)) {
+  const originalEmitWarning = process.emitWarning.bind(process);
+  const wrappedEmitWarning: typeof process.emitWarning = ((...args: unknown[]) => {
+    if (shouldIgnoreWarning(normalizeWarningArgs(args))) {
       return;
     }
-    process.stderr.write(`${warning.stack ?? warning.toString()}\n`);
-  });
+    return Reflect.apply(originalEmitWarning, process, args);
+  }) as typeof process.emitWarning;
+
+  process.emitWarning = wrappedEmitWarning;
+  globalState[warningFilterKey] = {
+    installed: true,
+  };
 }