diff --git a/extensions/signal/src/client-adapter.test.ts b/extensions/signal/src/client-adapter.test.ts
index 4701bdf8c77..27eec13003f 100644
--- a/extensions/signal/src/client-adapter.test.ts
+++ b/extensions/signal/src/client-adapter.test.ts
@@ -1,4 +1,4 @@
-import { describe, expect, it, vi, beforeEach } from "vitest";
+import { afterEach, beforeEach, describe, expect, it, vi } from "vitest";
 import {
   signalRpcRequest as signalRpcRequestImpl,
   detectSignalApiMode,
@@ -37,6 +37,11 @@ beforeEach(() => {
   );
 });
 
+afterEach(() => {
+  vi.restoreAllMocks();
+  vi.useRealTimers();
+});
+
 function setApiMode(mode: SignalApiMode) {
   currentApiMode = mode;
 }
@@ -378,6 +383,44 @@ describe("signalCheck", () => {
       error: "Signal API not reachable at http://localhost:8080",
     });
   });
+
+  it("drops cached auto mode when the current clock is not a valid date timestamp", async () => {
+    setApiMode("auto");
+    vi.spyOn(Date, "now").mockReturnValueOnce(1_700_000_000_000).mockReturnValueOnce(Number.NaN);
+    mockNativeCheck.mockResolvedValue({ ok: true, status: 200 });
+    mockContainerCheck.mockResolvedValue({ ok: false, status: 404 });
+
+    await expect(signalCheck("http://auto-invalid-clock.local:8080")).resolves.toEqual({
+      ok: true,
+      status: 200,
+    });
+    await expect(signalCheck("http://auto-invalid-clock.local:8080")).resolves.toEqual({
+      ok: true,
+      status: 200,
+    });
+
+    expect(mockNativeCheck).toHaveBeenCalledTimes(4);
+    expect(mockContainerCheck).toHaveBeenCalledTimes(2);
+  });
+
+  it("does not cache auto mode when the expiry timestamp would exceed the valid date range", async () => {
+    setApiMode("auto");
+    vi.spyOn(Date, "now").mockReturnValue(8_640_000_000_000_000);
+    mockNativeCheck.mockResolvedValue({ ok: true, status: 200 });
+    mockContainerCheck.mockResolvedValue({ ok: false, status: 404 });
+
+    await expect(signalCheck("http://auto-overflow-clock.local:8080")).resolves.toEqual({
+      ok: true,
+      status: 200,
+    });
+    await expect(signalCheck("http://auto-overflow-clock.local:8080")).resolves.toEqual({
+      ok: true,
+      status: 200,
+    });
+
+    expect(mockNativeCheck).toHaveBeenCalledTimes(4);
+    expect(mockContainerCheck).toHaveBeenCalledTimes(2);
+  });
 });
 
 describe("streamSignalEvents", () => {
diff --git a/extensions/signal/src/client-adapter.ts b/extensions/signal/src/client-adapter.ts
index 94778bdb944..13ad59b5e78 100644
--- a/extensions/signal/src/client-adapter.ts
+++ b/extensions/signal/src/client-adapter.ts
@@ -6,6 +6,10 @@
  * only need to change their import path.
  */
 
+import {
+  asDateTimestampMs,
+  resolveExpiresAtMsFromDurationMs,
+} from "openclaw/plugin-sdk/number-runtime";
 import {
   containerCheck,
   containerRpcRequest,
@@ -74,24 +78,33 @@ async function resolveAutoApiMode(
   timeoutMs = DEFAULT_TIMEOUT_MS,
   options: { account?: string; requireContainerReceive?: boolean } = {},
 ): Promise<"native" | "container"> {
+  const rawNow = Date.now();
+  const now = asDateTimestampMs(rawNow);
   const cached = detectedModeCache.get(baseUrl);
-  if (cached && cached.expiresAt > Date.now()) {
-    if (
-      cached.mode !== "container" ||
-      !options.requireContainerReceive ||
-      (Boolean(options.account?.trim()) && cached.receiveAccount === options.account?.trim())
-    ) {
-      return cached.mode;
+  if (cached) {
+    if (now !== undefined && cached.expiresAt > now) {
+      if (
+        cached.mode !== "container" ||
+        !options.requireContainerReceive ||
+        (Boolean(options.account?.trim()) && cached.receiveAccount === options.account?.trim())
+      ) {
+        return cached.mode;
+      }
+    } else {
+      detectedModeCache.delete(baseUrl);
     }
   }
   const detected = await detectSignalApiMode(baseUrl, timeoutMs, options);
-  detectedModeCache.set(baseUrl, {
-    mode: detected,
-    expiresAt: Date.now() + MODE_CACHE_TTL_MS,
-    ...(detected === "container" && options.requireContainerReceive && options.account
-      ? { receiveAccount: options.account }
-      : {}),
-  });
+  const expiresAt = resolveExpiresAtMsFromDurationMs(MODE_CACHE_TTL_MS, { nowMs: rawNow });
+  if (expiresAt !== undefined) {
+    detectedModeCache.set(baseUrl, {
+      mode: detected,
+      expiresAt,
+      ...(detected === "container" && options.requireContainerReceive && options.account
+        ? { receiveAccount: options.account }
+        : {}),
+    });
+  }
   return detected;
 }