fix(tasks): avoid leaking scheduled sweep failures

src/tasks/task-registry.maintenance.ts

@@ -286,9 +286,10 @@ function startScheduledSweep() {
     return;
   }
   sweepInProgress = true;
-  void sweepTaskRegistry().finally(() => {
+  const clearSweepInProgress = () => {
     sweepInProgress = false;
-  });
+  };
+  sweepTaskRegistry().then(clearSweepInProgress, clearSweepInProgress);
 }
 
 export async function runTaskRegistryMaintenance(): Promise<TaskRegistryMaintenanceSummary> {

src/tasks/task-registry.test.ts

@@ -1453,6 +1453,55 @@ describe("task-registry", () => {
     });
   });
 
+  it("does not leak unhandled rejections when the scheduled maintenance sweep fails", async () => {
+    await withTaskRegistryTempDir(async (root) => {
+      vi.useFakeTimers();
+      process.env.OPENCLAW_STATE_DIR = root;
+      resetTaskRegistryForTests();
+
+      const unhandled: unknown[] = [];
+      const onUnhandledRejection = (reason: unknown) => {
+        unhandled.push(reason);
+      };
+      process.on("unhandledRejection", onUnhandledRejection);
+
+      setTaskRegistryMaintenanceRuntimeForTests({
+        readAcpSessionEntry: () => ({
+          cfg: {} as never,
+          storePath: "",
+          sessionKey: "",
+          storeSessionKey: "",
+          entry: undefined,
+          storeReadFailed: false,
+        }),
+        loadSessionStore: () => ({}),
+        resolveStorePath: () => "",
+        parseAgentSessionKey: () => null,
+        isCronJobActive: () => false,
+        getAgentRunContext: () => undefined,
+        deleteTaskRecordById: () => false,
+        ensureTaskRegistryReady: () => {},
+        getTaskById: () => undefined,
+        listTaskRecords: () => {
+          throw new Error("maintenance boom");
+        },
+        markTaskLostById: () => null,
+        maybeDeliverTaskTerminalUpdate: async () => null,
+        resolveTaskForLookupToken: () => undefined,
+        setTaskCleanupAfterById: () => null,
+      });
+
+      try {
+        startTaskRegistryMaintenance();
+        await vi.advanceTimersByTimeAsync(5_000);
+        await flushAsyncWork();
+        expect(unhandled).toEqual([]);
+      } finally {
+        process.off("unhandledRejection", onUnhandledRejection);
+      }
+    });
+  });
+
   it("rechecks current task state before marking a task lost", async () => {
     const now = Date.now();
     const snapshotTask = createTaskRecord({