diff --git a/websocket/index.js b/websocket/index.js
index 9f52464..caccacf 100644
--- a/websocket/index.js
+++ b/websocket/index.js
@@ -1,5 +1,6 @@
 const WebSocket = require("ws");
 const url = require("url");
+const db = require("../db/mysql");
 
 const { verifyToken } = require("../utils/jwt");
 
@@ -77,6 +78,9 @@ function handleMessage(username, data) {
     case "sendMessage":
       handleSendMessage(username, data);
       break;
+    case "ack":
+      handleAck(data);
+      break;
 
     default:
       console.log("未知消息类型：", data.type);
@@ -85,14 +89,55 @@ function handleMessage(username, data) {
 
 // 处理发送消息
 function handleSendMessage(senderName, data) {
+  const messageId = data.messageId;
   const receiverName = data.receiverName;
   const content = data.content;
-  const createdAt = data.createdAt;
 
   console.log(
     `${senderName} → ${receiverName}：${content}`
   );
 
+  const sql = `
+        INSERT INTO messages
+        (message_id, sender_name, receiver_name, content)
+        VALUES (?, ?, ?, ?)
+    `;
+
+  db.query(sql, [
+    messageId,
+    senderName,
+    receiverName,
+    content
+  ], (error, result) => {
+    if (error) {
+      console.error(error);
+
+      const senderWs = getConnection(senderName);
+      if (senderWs) {
+        senderWs.send(
+          JSON.stringify({
+            type: "sendError",
+            messageId: messageId,
+            message: "消息保存失败"
+          })
+        );
+
+      }
+      return;
+    }
+  });
+
+  // 告诉发送者：服务器已经保存成功
+  const senderWs = getConnection(senderName);
+  if (senderWs) {
+    senderWs.send(
+      JSON.stringify({
+        type: "sendSuccess",
+        messageId: messageId
+      })
+    );
+  }
+
   // 找到接收者的WebSocket
   const receiverWs = getConnection(receiverName);
   if (!receiverWs) {
@@ -105,13 +150,46 @@ function handleSendMessage(senderName, data) {
     JSON.stringify({
       type: "newMessage",
       message: {
+        messageId,
         senderName,
         receiverName,
-        content,
-        createdAt
+        content
       },
     })
   );
 }
 
+function handleAck(receiverName, data) {
+  const messageId = data.messageId;
+  const senderName = data.senderName;
+
+  console.log(
+    `${receiverName} 收到消息 ${messageId}，发送 ACK`
+  );
+
+  // 找到原发送者
+  const senderWs = getConnection(senderName);
+
+  if (!senderWs) {
+    console.log(
+      `${senderName} 当前不在线`
+    );
+    return;
+  }
+
+  // 把 ACK 转给原发送者
+  senderWs.send(
+    JSON.stringify({
+      type: "ack",
+      messageId:
+        messageId
+    })
+  );
+
+  console.log(
+    `ACK ${messageId} 已发送给 ${senderName}`
+  );
+}
+
+
 module.exports = initWebSocket;
\ No newline at end of file