fix(runtime): avoid leaking detached cleanup promises

extensions/whatsapp/src/auto-reply/monitor/last-route.test.ts

@@ -0,0 +1,37 @@
+import { afterEach, describe, expect, it } from "vitest";
+import { trackBackgroundTask } from "./last-route.js";
+
+const waitForAsyncCallbacks = async () => {
+  await Promise.resolve();
+  await new Promise((resolve) => setTimeout(resolve, 0));
+};
+
+describe("trackBackgroundTask", () => {
+  const unhandledRejections: unknown[] = [];
+  const onUnhandledRejection = (reason: unknown) => {
+    unhandledRejections.push(reason);
+  };
+
+  afterEach(() => {
+    process.off("unhandledRejection", onUnhandledRejection);
+    unhandledRejections.length = 0;
+  });
+
+  it("does not leak unhandled rejections when a tracked task fails", async () => {
+    process.on("unhandledRejection", onUnhandledRejection);
+    const backgroundTasks = new Set<Promise<unknown>>();
+    let rejectTask!: (reason?: unknown) => void;
+    const task = new Promise<void>((_resolve, reject) => {
+      rejectTask = reject;
+    });
+
+    trackBackgroundTask(backgroundTasks, task);
+    expect(backgroundTasks.size).toBe(1);
+
+    rejectTask(new Error("boom"));
+    await waitForAsyncCallbacks();
+
+    expect(backgroundTasks.size).toBe(0);
+    expect(unhandledRejections).toEqual([]);
+  });
+});

extensions/whatsapp/src/auto-reply/monitor/last-route.ts

@@ -9,9 +9,10 @@ export function trackBackgroundTask(
   task: Promise<unknown>,
 ) {
   backgroundTasks.add(task);
-  void task.finally(() => {
+  const cleanup = () => {
     backgroundTasks.delete(task);
-  });
+  };
+  task.then(cleanup, cleanup);
 }
 
 export function updateLastRouteInBackground(params: {