fix: clean up slack socket waiters on start hooks

extensions/slack/src/monitor/provider.reconnect.test.ts

@@ -19,6 +19,10 @@ class FakeEmitter {
       listener(...args);
     }
   }
+
+  listenerCount(event: string) {
+    return this.listeners.get(event)?.size ?? 0;
+  }
 }
 
 describe("slack socket reconnect helpers", () => {
@@ -117,6 +121,28 @@ describe("slack socket reconnect helpers", () => {
     expect(onStarted).toHaveBeenCalledTimes(1);
   });
 
+  it("cancels the disconnect waiter when onStarted throws", async () => {
+    const client = new FakeEmitter();
+    const app = {
+      receiver: { client },
+      start: vi.fn().mockResolvedValue(undefined),
+    };
+    const err = new Error("status sink failed");
+
+    await expect(
+      __testing.startSlackSocketAndWaitForDisconnect({
+        app: app as never,
+        onStarted: () => {
+          throw err;
+        },
+      }),
+    ).rejects.toThrow("status sink failed");
+
+    expect(client.listenerCount("disconnected")).toBe(0);
+    expect(client.listenerCount("unable_to_socket_mode_start")).toBe(0);
+    expect(client.listenerCount("error")).toBe(0);
+  });
+
   it("preserves error payload from unable_to_socket_mode_start event", async () => {
     const client = new FakeEmitter();
     const app = { receiver: { client } };

extensions/slack/src/monitor/provider.ts

@@ -245,18 +245,18 @@ async function startSlackSocketAndWaitForDisconnect(params: {
   const disconnectWaiter = createSlackSocketDisconnectWaiter(params.app, params.abortSignal);
   try {
     await Promise.resolve(params.app.start());
+    if (params.abortSignal?.aborted) {
+      disconnectWaiter.cancel();
+      return null;
+    }
+    params.onStarted?.();
+    const disconnect = await disconnectWaiter.promise;
+    disconnectWaiter.complete();
+    return disconnect;
   } catch (err) {
     disconnectWaiter.cancel();
     throw err;
   }
-  if (params.abortSignal?.aborted) {
-    disconnectWaiter.cancel();
-    return null;
-  }
-  params.onStarted?.();
-  const disconnect = await disconnectWaiter.promise;
-  disconnectWaiter.complete();
-  return disconnect;
 }
 
 function resolveSlackSocketShutdownClient(app: unknown): SlackSocketShutdownClient | undefined {