diff --git a/src/logging/diagnostic-runtime.ts b/src/logging/diagnostic-runtime.ts
new file mode 100644
index 00000000000..e2400df9980
--- /dev/null
+++ b/src/logging/diagnostic-runtime.ts
@@ -0,0 +1,40 @@
+import { emitDiagnosticEvent } from "../infra/diagnostic-events.js";
+import { createSubsystemLogger } from "./subsystem.js";
+
+const diag = createSubsystemLogger("diagnostic");
+let lastActivityAt = 0;
+
+export const diagnosticLogger = diag;
+
+export function markDiagnosticActivity(): void {
+  lastActivityAt = Date.now();
+}
+
+export function getLastDiagnosticActivityAt(): number {
+  return lastActivityAt;
+}
+
+export function resetDiagnosticActivityForTest(): void {
+  lastActivityAt = 0;
+}
+
+export function logLaneEnqueue(lane: string, queueSize: number): void {
+  diag.debug(`lane enqueue: lane=${lane} queueSize=${queueSize}`);
+  emitDiagnosticEvent({
+    type: "queue.lane.enqueue",
+    lane,
+    queueSize,
+  });
+  markDiagnosticActivity();
+}
+
+export function logLaneDequeue(lane: string, waitMs: number, queueSize: number): void {
+  diag.debug(`lane dequeue: lane=${lane} waitMs=${waitMs} queueSize=${queueSize}`);
+  emitDiagnosticEvent({
+    type: "queue.lane.dequeue",
+    lane,
+    queueSize,
+    waitMs,
+  });
+  markDiagnosticActivity();
+}
diff --git a/src/logging/diagnostic.ts b/src/logging/diagnostic.ts
index d9e38d64bb8..ad2f4c3050c 100644
--- a/src/logging/diagnostic.ts
+++ b/src/logging/diagnostic.ts
@@ -1,6 +1,12 @@
 import { getRuntimeConfig } from "../config/config.js";
 import type { OpenClawConfig } from "../config/types.openclaw.js";
 import { emitDiagnosticEvent } from "../infra/diagnostic-events.js";
+import {
+  diagnosticLogger as diag,
+  getLastDiagnosticActivityAt,
+  markDiagnosticActivity as markActivity,
+  resetDiagnosticActivityForTest,
+} from "./diagnostic-runtime.js";
 import {
   diagnosticSessionStates,
   getDiagnosticSessionState,
@@ -10,9 +16,7 @@ import {
   type SessionRef,
   type SessionStateValue,
 } from "./diagnostic-session-state.js";
-import { createSubsystemLogger } from "./subsystem.js";
-
-const diag = createSubsystemLogger("diagnostic");
+export { diagnosticLogger, logLaneDequeue, logLaneEnqueue } from "./diagnostic-runtime.js";
 
 const webhookStats = {
   received: 0,
@@ -21,7 +25,6 @@ const webhookStats = {
   lastReceived: 0,
 };
 
-let lastActivityAt = 0;
 const DEFAULT_STUCK_SESSION_WARN_MS = 120_000;
 const MIN_STUCK_SESSION_WARN_MS = 1_000;
 const MAX_STUCK_SESSION_WARN_MS = 24 * 60 * 60 * 1000;
@@ -34,10 +37,6 @@ function loadCommandPollBackoffRuntime() {
   return commandPollBackoffRuntimePromise;
 }
 
-function markActivity() {
-  lastActivityAt = Date.now();
-}
-
 export function resolveStuckSessionWarnMs(config?: OpenClawConfig): number {
   const raw = config?.diagnostics?.stuckSessionWarnMs;
   if (typeof raw !== "number" || !Number.isFinite(raw)) {
@@ -244,27 +243,6 @@ export function logSessionStuck(params: SessionRef & { state: SessionStateValue;
   markActivity();
 }
 
-export function logLaneEnqueue(lane: string, queueSize: number) {
-  diag.debug(`lane enqueue: lane=${lane} queueSize=${queueSize}`);
-  emitDiagnosticEvent({
-    type: "queue.lane.enqueue",
-    lane,
-    queueSize,
-  });
-  markActivity();
-}
-
-export function logLaneDequeue(lane: string, waitMs: number, queueSize: number) {
-  diag.debug(`lane dequeue: lane=${lane} waitMs=${waitMs} queueSize=${queueSize}`);
-  emitDiagnosticEvent({
-    type: "queue.lane.dequeue",
-    lane,
-    queueSize,
-    waitMs,
-  });
-  markActivity();
-}
-
 export function logRunAttempt(params: SessionRef & { runId: string; attempt: number }) {
   diag.debug(
     `run attempt: sessionId=${params.sessionId ?? "unknown"} sessionKey=${
@@ -360,7 +338,7 @@ export function startDiagnosticHeartbeat(
       0,
     );
     const hasActivity =
-      lastActivityAt > 0 ||
+      getLastDiagnosticActivityAt() > 0 ||
       webhookStats.received > 0 ||
       activeCount > 0 ||
       waitingCount > 0 ||
@@ -368,7 +346,7 @@ export function startDiagnosticHeartbeat(
     if (!hasActivity) {
       return;
     }
-    if (now - lastActivityAt > 120_000 && activeCount === 0 && waitingCount === 0) {
+    if (now - getLastDiagnosticActivityAt() > 120_000 && activeCount === 0 && waitingCount === 0) {
       return;
     }
 
@@ -425,12 +403,10 @@ export function getDiagnosticSessionStateCountForTest(): number {
 
 export function resetDiagnosticStateForTest(): void {
   resetDiagnosticSessionStateForTest();
+  resetDiagnosticActivityForTest();
   webhookStats.received = 0;
   webhookStats.processed = 0;
   webhookStats.errors = 0;
   webhookStats.lastReceived = 0;
-  lastActivityAt = 0;
   stopDiagnosticHeartbeat();
 }
-
-export { diag as diagnosticLogger };
diff --git a/src/process/command-queue.test.ts b/src/process/command-queue.test.ts
index 02e63682af6..fec2d252c88 100644
--- a/src/process/command-queue.test.ts
+++ b/src/process/command-queue.test.ts
@@ -12,7 +12,7 @@ const diagnosticMocks = vi.hoisted(() => ({
   },
 }));
 
-vi.mock("../logging/diagnostic.js", () => ({
+vi.mock("../logging/diagnostic-runtime.js", () => ({
   logLaneEnqueue: diagnosticMocks.logLaneEnqueue,
   logLaneDequeue: diagnosticMocks.logLaneDequeue,
   diagnosticLogger: diagnosticMocks.diag,
diff --git a/src/process/command-queue.ts b/src/process/command-queue.ts
index 12011252725..b35dff84212 100644
--- a/src/process/command-queue.ts
+++ b/src/process/command-queue.ts
@@ -1,4 +1,8 @@
-import { diagnosticLogger as diag, logLaneDequeue, logLaneEnqueue } from "../logging/diagnostic.js";
+import {
+  diagnosticLogger as diag,
+  logLaneDequeue,
+  logLaneEnqueue,
+} from "../logging/diagnostic-runtime.js";
 import { resolveGlobalSingleton } from "../shared/global-singleton.js";
 import { CommandLane } from "./lanes.js";
 /**