diff --git a/src/tasks/task-registry.maintenance.ts b/src/tasks/task-registry.maintenance.ts
index 4bfb4187a55..55f80ab321d 100644
--- a/src/tasks/task-registry.maintenance.ts
+++ b/src/tasks/task-registry.maintenance.ts
@@ -205,6 +205,16 @@ function yieldToEventLoop(): Promise<void> {
   return new Promise((resolve) => setImmediate(resolve));
 }
 
+function startScheduledSweep() {
+  if (sweepInProgress) {
+    return;
+  }
+  sweepInProgress = true;
+  void sweepTaskRegistry().finally(() => {
+    sweepInProgress = false;
+  });
+}
+
 export async function runTaskRegistryMaintenance(): Promise<TaskRegistryMaintenanceSummary> {
   ensureTaskRegistryReady();
   const now = Date.now();
@@ -256,32 +266,15 @@ export async function sweepTaskRegistry(): Promise<TaskRegistryMaintenanceSummar
 
 export function startTaskRegistryMaintenance() {
   ensureTaskRegistryReady();
-  // Defer the first sweep to avoid blocking the critical startup window.
-  // Use setTimeout instead of running synchronously at startup.
   deferredSweep = setTimeout(() => {
     deferredSweep = null;
-    if (sweepInProgress) {
-      return;
-    }
-    sweepInProgress = true;
-    void sweepTaskRegistry().finally(() => {
-      sweepInProgress = false;
-    });
+    startScheduledSweep();
   }, 5_000);
+  deferredSweep.unref?.();
   if (sweeper) {
     return;
   }
-  sweeper = setInterval(() => {
-    // Prevent overlapping sweeps — if a previous async sweep is still
-    // running, skip this tick entirely.
-    if (sweepInProgress) {
-      return;
-    }
-    sweepInProgress = true;
-    void sweepTaskRegistry().finally(() => {
-      sweepInProgress = false;
-    });
-  }, TASK_SWEEP_INTERVAL_MS);
+  sweeper = setInterval(startScheduledSweep, TASK_SWEEP_INTERVAL_MS);
   sweeper.unref?.();
 }
 
diff --git a/src/tasks/task-registry.test.ts b/src/tasks/task-registry.test.ts
index f7759020993..6d9a6b14704 100644
--- a/src/tasks/task-registry.test.ts
+++ b/src/tasks/task-registry.test.ts
@@ -36,6 +36,8 @@ import {
   previewTaskRegistryMaintenance,
   reconcileInspectableTasks,
   runTaskRegistryMaintenance,
+  startTaskRegistryMaintenance,
+  stopTaskRegistryMaintenanceForTests,
   sweepTaskRegistry,
 } from "./task-registry.maintenance.js";
 import { configureTaskRegistryRuntime } from "./task-registry.store.js";
@@ -1119,6 +1121,40 @@ describe("task-registry", () => {
     });
   });
 
+  it("cancels the deferred maintenance sweep during test teardown", async () => {
+    await withTaskRegistryTempDir(async (root) => {
+      vi.useFakeTimers();
+      process.env.OPENCLAW_STATE_DIR = root;
+      resetTaskRegistryForTests();
+      const now = Date.now();
+
+      const task = createTaskRecord({
+        runtime: "acp",
+        ownerKey: "agent:main:main",
+        scopeKind: "session",
+        childSessionKey: "agent:main:acp:missing",
+        runId: "run-deferred-maintenance-stop",
+        task: "Missing child",
+        status: "running",
+        deliveryStatus: "pending",
+      });
+      setTaskTimingById({
+        taskId: task.taskId,
+        lastEventAt: now - 10 * 60_000,
+      });
+
+      startTaskRegistryMaintenance();
+      stopTaskRegistryMaintenanceForTests();
+
+      await vi.advanceTimersByTimeAsync(5_000);
+      await flushAsyncWork();
+
+      expect(getTaskById(task.taskId)).toMatchObject({
+        status: "running",
+      });
+    });
+  });
+
   it("summarizes inspectable task audit findings", async () => {
     await withTaskRegistryTempDir(async (root) => {
       process.env.OPENCLAW_STATE_DIR = root;