diff --git a/src/api/im/message/private/index.ts b/src/api/im/message/private/index.ts
index bfbdbbcff..698e55d43 100644
--- a/src/api/im/message/private/index.ts
+++ b/src/api/im/message/private/index.ts
@@ -38,13 +38,17 @@ export const pullPrivateMessages = (params: { minId: number | string; size: numb
 }
 
 // 查询私聊历史消息
+// TODO @AI：历史消息，是不是通过这个接口？
 export const getPrivateMessageList = (params: ImPrivateMessageListReqVO) => {
   return request.get<ImPrivateMessageRespVO[]>({ url: '/im/message/private/list', params })
 }
 
 // 标记私聊消息已读
-export const readPrivateMessages = (receiverId: number | string) => {
-  return request.put<boolean>({ url: '/im/message/private/read', params: { receiverId } })
+export const readPrivateMessages = (receiverId: number | string, messageId: number | string) => {
+  return request.put<boolean>({
+    url: '/im/message/private/read',
+    params: { receiverId, messageId }
+  })
 }
 
 // 撤回私聊消息
diff --git a/src/views/im/home/store/conversationStore.ts b/src/views/im/home/store/conversationStore.ts
index 2d172e292..f810386c0 100644
--- a/src/views/im/home/store/conversationStore.ts
+++ b/src/views/im/home/store/conversationStore.ts
@@ -512,8 +512,9 @@ export const useConversationStore = defineStore('imConversationStore', {
     applyReadReceipt(options: {
       conversationType: number
       targetId: number
-      // 私聊：把和该好友的「自己发送的」消息标为已读
-      markPrivateRead?: boolean
+      // 私聊：把和该好友的「自己发送的、id <= privateReadMaxId 的」消息标为已读
+      // 必须卡 maxId 边界：回执在路上时新发的消息不能被误标为已读
+      privateReadMaxId?: number
       // 群聊：针对单条消息的回执刷新
       groupMessageId?: number
       readCount?: number
@@ -523,9 +524,15 @@ export const useConversationStore = defineStore('imConversationStore', {
       if (!conversation) {
         return
       }
-      if (options.conversationType === ImConversationType.PRIVATE && options.markPrivateRead) {
+      if (options.conversationType === ImConversationType.PRIVATE && options.privateReadMaxId) {
+        const maxReadId = options.privateReadMaxId
         conversation.messages.forEach((message) => {
-          if (message.selfSend && message.status !== ImMessageStatus.RECALL) {
+          if (
+            message.selfSend &&
+            message.id &&
+            message.id <= maxReadId &&
+            message.status !== ImMessageStatus.RECALL
+          ) {
             message.status = ImMessageStatus.READ
           }
         })
diff --git a/src/views/im/home/store/websocketStore.ts b/src/views/im/home/store/websocketStore.ts
index 1e6c4bc06..e30ad386e 100644
--- a/src/views/im/home/store/websocketStore.ts
+++ b/src/views/im/home/store/websocketStore.ts
@@ -318,8 +318,9 @@ export const useImWebSocketStore = defineStore('imWebSocketStore', {
           conversationStore.activeConversation?.targetId === peerId
         if (isActive) {
           // 聊天窗口打开 = 实际看到了：本端清未读 + 上报后端，让对方 UI 立刻切到"已读"
+          // 已读位置直接用刚到的消息 id（这条就是当前会话最大 id）
           conversationStore.markActiveAsRead()
-          apiReadPrivateMessages(peerId).catch((e) => {
+          apiReadPrivateMessages(peerId, websocketMessage.id).catch((e) => {
             console.warn('[IM WS] 自动已读上报失败', e)
           })
         } else if (!conversation?.muted) {
@@ -342,13 +343,20 @@ export const useImWebSocketStore = defineStore('imWebSocketStore', {
       conversationStore.saveConversations()
     },
 
-    /** 私聊 RECEIPT 事件：对方读了我的消息，把和对方会话里自己发的消息标为已读 */
+    /**
+     * 私聊 RECEIPT 事件：对方读了我的消息，把和对方会话里自己发的消息标为已读
+     * 后端将 maxReadId 编码在 DTO 的 id 字段（见 ImPrivateMessageDTO.ofReceipt），
+     * 这里据此卡边界，避免把"回执在路上时刚发的消息"误标为已读。
+     */
     handlePrivateReceipt(websocketMessage: ImPrivateMessageDTO) {
+      if (!websocketMessage.id) {
+        return
+      }
       const conversationStore = useConversationStore()
       conversationStore.applyReadReceipt({
         conversationType: ImConversationType.PRIVATE,
         targetId: websocketMessage.senderId,
-        markPrivateRead: true
+        privateReadMaxId: websocketMessage.id
       })
     },