diff --git a/src/services/core/wsService.ts b/src/services/core/wsService.ts
index fc07fb1..27ff0f1 100644
--- a/src/services/core/wsService.ts
+++ b/src/services/core/wsService.ts
@@ -41,7 +41,8 @@ export type WSMessageType =
   | 'call_ended'
   | 'call_peer_muted'
   | 'call_invited'
-  | 'call_answered_elsewhere';
+  | 'call_answered_elsewhere'
+  | 'sync_required';
 
 export interface WSCallIncomingMessage {
   type: 'call_incoming';
@@ -249,6 +250,10 @@ export interface WSGroupRecallMessage {
   message_id: string;
 }
 
+export interface WSSyncRequiredMessage {
+  type: 'sync_required';
+}
+
 export interface WSServerMessage {
   event_id?: number;
   type: string;
@@ -279,7 +284,8 @@ export type WSMessage =
   | WSCallPeerMutedMessage
   | WSCallInvitedMessage
   | WSCallAnsweredElsewhereMessage
-  | WSErrorMessage;
+  | WSErrorMessage
+  | WSSyncRequiredMessage;
 
 type MessageHandler<T extends WSMessage = WSMessage> = (message: T) => void;
 type ConnectionHandler = () => void;
@@ -496,6 +502,9 @@ class WebSocketService {
       case 'call_answered_elsewhere':
         this.handleCallAnsweredElsewhere(payload);
         break;
+      case 'sync_required':
+        this.emit('sync_required', { type: 'sync_required' });
+        break;
       default:
         console.log('Unknown message type:', type);
     }
@@ -886,6 +895,11 @@ class WebSocketService {
     this.ws.send(JSON.stringify(message));
   }
 
+  // 发送 ACK 确认（fire-and-forget）
+  sendAck(messageId: string): void {
+    this.sendFireAndForget('ack', { message_id: messageId });
+  }
+
   // 通过WebSocket发送
   private sendViaWebSocket(type: string, payload: any): Promise<any> {
     return new Promise((resolve, reject) => {
diff --git a/src/stores/message/services/WSMessageHandler.ts b/src/stores/message/services/WSMessageHandler.ts
index 8f6164b..194c9d9 100644
--- a/src/stores/message/services/WSMessageHandler.ts
+++ b/src/stores/message/services/WSMessageHandler.ts
@@ -155,7 +155,7 @@ export class WSMessageHandler implements IWSMessageHandler {
       if (now - this.lastReconnectSyncAt > 1500) {
         this.lastReconnectSyncAt = now;
         const activeConversation = useMessageStore.getState().getActiveConversation();
-        
+
         if (!activeConversation) {
           this.fetchConversationsCallback(true, 'sse-reconnect').catch(error => {
             console.error('[WSMessageHandler] 连接后同步会话失败:', error);
@@ -165,7 +165,7 @@ export class WSMessageHandler implements IWSMessageHandler {
             console.error('[WSMessageHandler] 连接后同步未读数失败:', error);
           });
         }
-        
+
         if (activeConversation) {
           this.fetchMessagesCallback(activeConversation).catch(error => {
             console.error('[WSMessageHandler] 连接后同步当前会话消息失败:', error);
@@ -174,6 +174,25 @@ export class WSMessageHandler implements IWSMessageHandler {
       }
     });
 
+    // 监听 sync_required 事件，触发增量同步
+    wsService.on('sync_required', () => {
+      console.log('[WSMessageHandler] 收到 sync_required，开始增量同步');
+      const activeConversation = useMessageStore.getState().getActiveConversation();
+
+      this.fetchConversationsCallback(true, 'sync_required').catch(error => {
+        console.error('[WSMessageHandler] sync_required 同步会话失败:', error);
+      });
+      this.fetchUnreadCountCallback().catch(error => {
+        console.error('[WSMessageHandler] sync_required 同步未读数失败:', error);
+      });
+
+      if (activeConversation) {
+        this.fetchMessagesCallback(activeConversation).catch(error => {
+          console.error('[WSMessageHandler] sync_required 同步消息失败:', error);
+        });
+      }
+    });
+
     wsService.onDisconnect(() => {
       useMessageStore.getState().setSSEConnected(false);
     });
@@ -263,6 +282,9 @@ export class WSMessageHandler implements IWSMessageHandler {
     }
     this.deduplication.markMessageAsProcessed(id);
 
+    // 发送 ACK 确认
+    wsService.sendAck(id);
+
     // 对于群聊消息，获取发送者信息
     if (message.type === 'group_message' && sender_id && sender_id !== currentUserId && sender_id !== '10000') {
       this.userCacheService.getSenderInfo(sender_id).then(user => {