From 822d0bf730d977a29f3efd656421daccffe583a7 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=EC=9E=AC=EC=9A=B1?= <haensol976520@gmail.com>
Date: Thu, 19 Mar 2026 23:37:49 +0900
Subject: [PATCH 1/2] feat(sio): add ackTimeout option for broadcast
 emitWithAck

---
 packages/socket.io/lib/broadcast-operator.ts | 13 ++++++++++++-
 packages/socket.io/lib/index.ts              |  4 ++++
 2 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/packages/socket.io/lib/broadcast-operator.ts b/packages/socket.io/lib/broadcast-operator.ts
index ca7eccf2f..b2d9c127c 100644
--- a/packages/socket.io/lib/broadcast-operator.ts
+++ b/packages/socket.io/lib/broadcast-operator.ts
@@ -325,6 +325,14 @@ export class BroadcastOperator<EmitEvents extends EventsMap, SocketData>
     ev: Ev,
     ...args: AllButLast<EventParams<EmitEvents, Ev>>
   ): Promise<FirstNonErrorArg<Last<EventParams<EmitEvents, Ev>>>> {
+    const defaultTimeout = this.adapter.nsp.server?.opts?.ackTimeout;
+    const operator =
+      this.flags.timeout === undefined && defaultTimeout !== undefined
+        ? new BroadcastOperator(this.adapter, this.rooms, this.exceptRooms, {
+            ...this.flags,
+            timeout: defaultTimeout,
+          })
+        : this;
     return new Promise((resolve, reject) => {
       args.push((err, responses) => {
         if (err) {
@@ -334,7 +342,10 @@ export class BroadcastOperator<EmitEvents extends EventsMap, SocketData>
           return resolve(responses);
         }
       });
-      this.emit(ev, ...(args as any[] as EventParams<EmitEvents, Ev>));
+      (operator as this).emit(
+        ev,
+        ...(args as any[] as EventParams<EmitEvents, Ev>),
+      );
     });
   }
 
diff --git a/packages/socket.io/lib/index.ts b/packages/socket.io/lib/index.ts
index 0cebc9254..4855b83d2 100644
--- a/packages/socket.io/lib/index.ts
+++ b/packages/socket.io/lib/index.ts
@@ -94,6 +94,10 @@ interface ServerOptions extends EngineOptions, AttachOptions {
    * @default 45000
    */
   connectTimeout: number;
+  /**
+   * the default timeout in milliseconds used when waiting for an acknowledgement
+   */
+  ackTimeout: number;
   /**
    * Whether to enable the recovery of connection state when a client temporarily disconnects.
    *

From 6a83fc034e9031fed82fe846643012d741215f54 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=EC=9E=AC=EC=9A=B1?= <haensol976520@gmail.com>
Date: Fri, 20 Mar 2026 08:06:16 +0900
Subject: [PATCH 2/2] feat(sio): add ackTimeout option and enable io/namespace
 emitWithAck

---
 packages/socket.io/lib/index.ts     | 18 +++++++++++++++++-
 packages/socket.io/lib/namespace.ts | 18 ++++++++++++++++++
 2 files changed, 35 insertions(+), 1 deletion(-)

diff --git a/packages/socket.io/lib/index.ts b/packages/socket.io/lib/index.ts
index 4855b83d2..bfbf7a464 100644
--- a/packages/socket.io/lib/index.ts
+++ b/packages/socket.io/lib/index.ts
@@ -45,6 +45,7 @@ import {
   RemoveAcknowledgements,
   EventNamesWithAck,
   FirstNonErrorArg,
+  EventNamesWithError,
 } from "./typed-events";
 import { patchAdapter, restoreAdapter, serveFile } from "./uws";
 import corsMiddleware from "cors";
@@ -97,7 +98,7 @@ interface ServerOptions extends EngineOptions, AttachOptions {
   /**
    * the default timeout in milliseconds used when waiting for an acknowledgement
    */
-  ackTimeout: number;
+  ackTimeout?: number;
   /**
    * Whether to enable the recovery of connection state when a client temporarily disconnects.
    *
@@ -1090,6 +1091,21 @@ export class Server<
     return this.sockets.timeout(timeout);
   }
 
+  /**
+   * Emits an event and waits for an acknowledgement from all clients.
+   *
+   * @example
+   * const responses = await io.emitWithAck("some-event");
+   *
+   * @return a Promise that will be fulfilled when all clients have acknowledged the event
+   */
+  public emitWithAck<Ev extends EventNamesWithError<EmitEvents>>(
+    ev: Ev,
+    ...args: AllButLast<EventParams<EmitEvents, Ev>>
+  ): Promise<FirstNonErrorArg<Last<EventParams<EmitEvents, Ev>>>> {
+    return this.sockets.emitWithAck(ev, ...args);
+  }
+
   /**
    * Returns the matching socket instances.
    *
diff --git a/packages/socket.io/lib/namespace.ts b/packages/socket.io/lib/namespace.ts
index 72df7301e..ae2ca0335 100644
--- a/packages/socket.io/lib/namespace.ts
+++ b/packages/socket.io/lib/namespace.ts
@@ -14,6 +14,7 @@ import {
   EventNamesWithAck,
   FirstNonErrorArg,
   EventNamesWithoutAck,
+  EventNamesWithError,
 } from "./typed-events";
 import type { Client } from "./client";
 import debugModule from "debug";
@@ -469,6 +470,23 @@ export class Namespace<
     );
   }
 
+  /**
+   * Emits an event and waits for an acknowledgement from all clients.
+   *
+   * @example
+   * const responses = await myNamespace.emitWithAck("some-event");
+   *
+   * @return a Promise that will be fulfilled when all clients have acknowledged the event
+   */
+  public emitWithAck<Ev extends EventNamesWithError<EmitEvents>>(
+    ev: Ev,
+    ...args: AllButLast<EventParams<EmitEvents, Ev>>
+  ): Promise<FirstNonErrorArg<Last<EventParams<EmitEvents, Ev>>>> {
+    return new BroadcastOperator<EmitEvents, SocketData>(
+      this.adapter,
+    ).emitWithAck(ev, ...args);
+  }
+
   /**
    * Sends a `message` event to all clients.
    *