diff --git a/frontend/src/api/im.js b/frontend/src/api/im.js
new file mode 100644
index 0000000..191e2fe
--- /dev/null
+++ b/frontend/src/api/im.js
@@ -0,0 +1,57 @@
+/**
+ * IM 即时通讯模块 API
+ *
+ * 对应后端路由：/api/v1/im/*
+ * 消息发送/撤回/标记已读通过 WebSocket 进行，此处仅包含 REST API
+ */
+
+import { get, put, del } from '@/utils/request'
+
+/** 获取会话列表 */
+const getConversations = () => {
+  return get('/api/v1/im/conversations')
+}
+
+/** 获取历史消息（游标分页） */
+const getHistoryMessages = (conversationId, beforeId = 0, limit = 30) => {
+  return get('/api/v1/im/messages', {
+    conversation_id: conversationId,
+    before_id: beforeId,
+    limit
+  })
+}
+
+/** 置顶/取消置顶会话 */
+const pinConversation = (conversationId, isPinned) => {
+  return put(`/api/v1/im/conversations/${conversationId}/pin`, { is_pinned: isPinned })
+}
+
+/** 删除会话 */
+const deleteConversation = (conversationId) => {
+  return del(`/api/v1/im/conversations/${conversationId}`)
+}
+
+/** 清空聊天记录 */
+const clearHistory = (conversationId) => {
+  return del(`/api/v1/im/conversations/${conversationId}/messages`)
+}
+
+/** 全局消息搜索 */
+const searchMessages = (keyword, limit = 50) => {
+  return get('/api/v1/im/messages/search', { keyword, limit })
+}
+
+/** 获取全局未读消息总数 */
+const getTotalUnread = () => {
+  return get('/api/v1/im/unread')
+}
+
+export default {
+  getConversations,
+  getHistoryMessages,
+  pinConversation,
+  deleteConversation,
+  clearHistory,
+  searchMessages,
+  getTotalUnread
+}
diff --git a/frontend/src/components/CustomTabBar.vue b/frontend/src/components/CustomTabBar.vue
index 4f2ad82..2d2e6d5 100644
--- a/frontend/src/components/CustomTabBar.vue
+++ b/frontend/src/components/CustomTabBar.vue
@@ -21,8 +21,10 @@
       :class="{ 'tab-active': currentIndex === index }"
       @tap="switchTo(index)"
     >
-      <!-- 图标区域：使用 Unicode 字符占位，后续替换为 SVG -->
-      <text class="tab-icon">{{ item.icon }}</text>
+      <view class="tab-icon-wrap">
+        <text class="tab-icon">{{ item.icon }}</text>
+        <text v-if="getBadge(index) > 0" class="tab-badge">{{ getBadge(index) > 99 ? '99+' : getBadge(index) }}</text>
+      </view>
       <text class="tab-label">{{ item.label }}</text>
     </view>
   </view>
@@ -35,8 +37,12 @@
  * Props:
  * - current: 当前选中的 Tab 索引
  *
- * 跳转使用 uni.switchTab，确保与 pages.json tabBar 配置的页面一致
+ * 功能：
+ * - 跳转使用 uni.switchTab，确保与 pages.json tabBar 配置的页面一致
+ * - 消息 Tab（index=0）显示全局未读消息 badge
  */
+import { useChatStore } from '@/store/chat'
+
 export default {
   name: 'CustomTabBar',
   props: {
@@ -70,6 +76,18 @@ export default {
     switchTo(index) {
       if (index === this.currentIndex) return
       uni.switchTab({ url: this.tabs[index].path })
+    },
+    /**
+     * 获取指定 Tab 的 badge 数
+     * @param {number} index - Tab 索引
+     * @returns {number} badge 数量（0 表示不显示）
+     */
+    getBadge(index) {
+      if (index === 0) {
+        const chatStore = useChatStore()
+        return chatStore.totalUnread
+      }
+      return 0
     }
   }
 }
@@ -108,11 +126,33 @@ export default {
   transition: color 200ms ease;
 }
 
+.tab-icon-wrap {
+  position: relative;
+  display: flex;
+  align-items: center;
+  justify-content: center;
+}
+
 .tab-icon {
   font-size: 40rpx;
   margin-bottom: 4rpx;
 }
 
+.tab-badge {
+  position: absolute;
+  top: -8rpx;
+  right: -20rpx;
+  min-width: 32rpx;
+  height: 32rpx;
+  padding: 0 8rpx;
+  font-size: 20rpx;
+  line-height: 32rpx;
+  color: #FFFFFF;
+  background-color: #EF4444;
+  border-radius: 16rpx;
+  text-align: center;
+}
+
 .tab-label {
   font-size: 22rpx;
   color: #94A3B8;
diff --git a/frontend/src/store/chat.js b/frontend/src/store/chat.js
new file mode 100644
index 0000000..9456605
--- /dev/null
+++ b/frontend/src/store/chat.js
@@ -0,0 +1,359 @@
+/**
+ * 即时通讯状态 Store
+ *
+ * 管理会话列表、消息、未读数，提供：
+ * - 会话列表 CRUD + 排序（置顶优先 → 最后消息时间降序）
+ * - 当前会话消息管理（发送/接收/撤回/历史加载）
+ * - 全局未读数（TabBar badge 显示）
+ * - WebSocket 事件监听（im.message.new / im.message.recalled / im.offline.sync）
+ * - 三态消息确认（sending → sent → failed）
+ *
+ * 对应后端 API：/api/v1/im/*
+ * 对应 WS 事件：im.message.send / im.message.recall / im.conversation.read / im.typing
+ */
+
+import { defineStore } from 'pinia'
+import { ref, computed } from 'vue'
+import imApi from '@/api/im'
+import wsService from '@/services/websocket'
+
+export const useChatStore = defineStore('chat', () => {
+  /** 会话列表 */
+  const conversationList = ref([])
+
+  /** 当前聊天会话 ID */
+  const currentConversationId = ref(null)
+
+  /** 消息缓存 conversationId -> Message[] */
+  const messagesMap = ref({})
+
+  /** 发送中消息队列 clientMsgId -> { status, ... } */
+  const pendingMessages = ref({})
+
+  /** 全局未读消息总数（用于 TabBar badge） */
+  const totalUnread = ref(0)
+
+  /** 正在输入状态 conversationId -> boolean */
+  const typingMap = ref({})
+
+  /** 是否还有更多历史消息 conversationId -> boolean */
+  const hasMoreMap = ref({})
+
+  // ==================== Computed ====================
+
+  /** 当前会话的消息列表 */
+  const currentMessages = computed(() => {
+    if (!currentConversationId.value) return []
+    return messagesMap.value[currentConversationId.value] || []
+  })
+
+  /** 按排序规则的会话列表（置顶优先 → 最后消息时间降序） */
+  const sortedConversations = computed(() => {
+    return [...conversationList.value].sort((a, b) => {
+      if (a.is_pinned !== b.is_pinned) return a.is_pinned ? -1 : 1
+      const timeA = a.last_msg_time ? new Date(a.last_msg_time).getTime() : 0
+      const timeB = b.last_msg_time ? new Date(b.last_msg_time).getTime() : 0
+      return timeB - timeA
+    })
+  })
+
+  // ==================== Actions ====================
+
+  /** 加载会话列表 */
+  const fetchConversations = async () => {
+    const res = await imApi.getConversations()
+    conversationList.value = (res.data && res.data.list) || []
+    _recalcTotalUnread()
+    return conversationList.value
+  }
+
+  /** 加载全局未读数（从后端获取，同步 Redis 数据） */
+  const fetchTotalUnread = async () => {
+    const res = await imApi.getTotalUnread()
+    if (res.data) {
+      totalUnread.value = res.data.total_unread || 0
+    }
+  }
+
+  /**
+   * 发送消息
+   * @param {Object} params - { conversationId, targetUserId, content, type }
+   * @returns {string} clientMsgId
+   */
+  const sendMessage = (params) => {
+    const clientMsgId = _generateClientMsgId()
+    const { conversationId, targetUserId, content, type = 1 } = params
+
+    const tempMsg = {
+      id: 0,
+      conversation_id: conversationId || 0,
+      sender_id: 0,
+      type,
+      content,
+      status: 1,
+      client_msg_id: clientMsgId,
+      created_at: new Date().toISOString().replace('T', ' ').substring(0, 19),
+      _sending: true
+    }
+
+    if (conversationId) {
+      _appendMessage(conversationId, tempMsg)
+    }
+
+    pendingMessages.value[clientMsgId] = { status: 'sending', tempMsg }
+
+    const seq = wsService.send('im.message.send', {
+      conversation_id: conversationId || 0,
+      target_user_id: targetUserId || 0,
+      type,
+      content,
+      client_msg_id: clientMsgId
+    })
+
+    if (seq === -1) {
+      pendingMessages.value[clientMsgId].status = 'failed'
+      tempMsg._sending = false
+      tempMsg._failed = true
+    }
+
+    return clientMsgId
+  }
+
+  /** 撤回消息 */
+  const recallMessage = (messageId) => {
+    wsService.send('im.message.recall', { message_id: messageId })
+  }
+
+  /** 标记会话已读 */
+  const markRead = (conversationId) => {
+    const conv = conversationList.value.find(c => c.id === conversationId)
+    if (conv && conv.unread_count > 0) {
+      totalUnread.value = Math.max(0, totalUnread.value - conv.unread_count)
+      conv.unread_count = 0
+    }
+    wsService.send('im.conversation.read', { conversation_id: conversationId })
+  }
+
+  /** 发送正在输入通知 */
+  const sendTyping = (conversationId) => {
+    wsService.send('im.typing', { conversation_id: conversationId })
+  }
+
+  /** 加载历史消息 */
+  const loadHistoryMessages = async (conversationId) => {
+    const messages = messagesMap.value[conversationId] || []
+    const beforeId = messages.length > 0 ? messages[0].id : 0
+
+    const res = await imApi.getHistoryMessages(conversationId, beforeId)
+    if (res.data) {
+      const list = res.data.list || []
+      hasMoreMap.value[conversationId] = res.data.has_more
+
+      if (list.length > 0) {
+        const existing = messagesMap.value[conversationId] || []
+        messagesMap.value[conversationId] = [...list.reverse(), ...existing]
+      }
+    }
+  }
+
+  /** 置顶/取消置顶 */
+  const pinConversation = async (conversationId, isPinned) => {
+    await imApi.pinConversation(conversationId, isPinned)
+    const conv = conversationList.value.find(c => c.id === conversationId)
+    if (conv) conv.is_pinned = isPinned
+  }
+
+  /** 删除会话 */
+  const deleteConversation = async (conversationId) => {
+    await imApi.deleteConversation(conversationId)
+    conversationList.value = conversationList.value.filter(c => c.id !== conversationId)
+    if (currentConversationId.value === conversationId) {
+      currentConversationId.value = null
+    }
+    _recalcTotalUnread()
+  }
+
+  /** 清空聊天记录 */
+  const clearHistory = async (conversationId) => {
+    await imApi.clearHistory(conversationId)
+    messagesMap.value[conversationId] = []
+    const conv = conversationList.value.find(c => c.id === conversationId)
+    if (conv) {
+      conv.last_msg_content = ''
+      conv.last_msg_time = ''
+    }
+  }
+
+  /** 设置当前会话 */
+  const setCurrentConversation = (conversationId) => {
+    currentConversationId.value = conversationId
+    if (conversationId) {
+      markRead(conversationId)
+    }
+  }
+
+  // ==================== WS 事件监听 ====================
+
+  let _wsInitialized = false
+
+  /** 初始化 WebSocket 事件监听（幂等） */
+  const initWsListeners = () => {
+    if (_wsInitialized) return
+    _wsInitialized = true
+
+    wsService.on('im.message.new', _onNewMessage)
+    wsService.on('im.message.recalled', _onMessageRecalled)
+    wsService.on('im.message.send.ack', _onSendACK)
+    wsService.on('im.offline.sync', _onOfflineSync)
+    wsService.on('im.typing', _onTyping)
+  }
+
+  /** 收到新消息推送 */
+  const _onNewMessage = (msg) => {
+    if (!msg || !msg.data) return
+    const data = msg.data
+
+    _appendMessage(data.conversation_id, {
+      id: data.id,
+      conversation_id: data.conversation_id,
+      sender_id: data.sender_id,
+      type: data.type,
+      content: data.content,
+      status: 1,
+      client_msg_id: data.client_msg_id || '',
+      created_at: data.created_at
+    })
+
+    _updateConversationPreview(data.conversation_id, data.content, data.created_at, data.sender_id)
+
+    if (data.conversation_id !== currentConversationId.value) {
+      const conv = conversationList.value.find(c => c.id === data.conversation_id)
+      if (conv) {
+        conv.unread_count = (conv.unread_count || 0) + 1
+      }
+      totalUnread.value++
+    } else {
+      markRead(data.conversation_id)
+    }
+  }
+
+  /** 消息撤回推送 */
+  const _onMessageRecalled = (msg) => {
+    if (!msg || !msg.data) return
+    const { message_id, conversation_id } = msg.data
+    const messages = messagesMap.value[conversation_id]
+    if (messages) {
+      const idx = messages.findIndex(m => m.id === message_id)
+      if (idx !== -1) {
+        messages[idx].status = 2
+        messages[idx].content = '[消息已撤回]'
+      }
+    }
+  }
+
+  /** 发送消息 ACK 响应 */
+  const _onSendACK = (msg) => {
+    if (!msg) return
+    const { code, data } = msg
+    if (!data || !data.client_msg_id) return
+
+    const pending = pendingMessages.value[data.client_msg_id]
+    if (!pending) return
+
+    if (code === 0) {
+      pending.status = 'sent'
+      const convId = data.conversation_id
+      const messages = messagesMap.value[convId]
+      if (messages) {
+        const idx = messages.findIndex(m => m.client_msg_id === data.client_msg_id)
+        if (idx !== -1) {
+          messages[idx] = { ...messages[idx], ...data, _sending: false }
+        } else {
+          _appendMessage(convId, { ...data, _sending: false })
+        }
+      } else {
+        _appendMessage(convId, { ...data, _sending: false })
+      }
+      _updateConversationPreview(convId, data.content, data.created_at, data.sender_id)
+    } else {
+      pending.status = 'failed'
+      if (pending.tempMsg) {
+        pending.tempMsg._sending = false
+        pending.tempMsg._failed = true
+      }
+    }
+    delete pendingMessages.value[data.client_msg_id]
+  }
+
+  /** 离线消息同步推送 */
+  const _onOfflineSync = (msg) => {
+    if (!msg || !msg.data) return
+    const { total_unread } = msg.data
+    totalUnread.value = total_unread || 0
+    fetchConversations()
+  }
+
+  /** 正在输入通知 */
+  const _onTyping = (msg) => {
+    if (!msg || !msg.data) return
+    const { conversation_id } = msg.data
+    typingMap.value[conversation_id] = true
+    setTimeout(() => {
+      typingMap.value[conversation_id] = false
+    }, 3000)
+  }
+
+  // ==================== 内部工具方法 ====================
+
+  /** 追加消息到缓存 */
+  const _appendMessage = (conversationId, message) => {
+    if (!messagesMap.value[conversationId]) {
+      messagesMap.value[conversationId] = []
+    }
+    messagesMap.value[conversationId].push(message)
+  }
+
+  /** 更新会话列表中的预览信息 */
+  const _updateConversationPreview = (conversationId, content, time, senderId) => {
+    const conv = conversationList.value.find(c => c.id === conversationId)
+    if (conv) {
+      conv.last_msg_content = content
+      conv.last_msg_time = time
+      conv.last_msg_sender_id = senderId
+    }
+  }
+
+  /** 根据会话列表重新计算总未读数 */
+  const _recalcTotalUnread = () => {
+    totalUnread.value = conversationList.value.reduce((sum, c) => sum + (c.unread_count || 0), 0)
+  }
+
+  /** 生成客户端消息唯一 ID */
+  const _generateClientMsgId = () => {
+    return `${Date.now()}-${Math.random().toString(36).substring(2, 10)}`
+  }
+
+  return {
+    conversationList,
+    currentConversationId,
+    messagesMap,
+    pendingMessages,
+    totalUnread,
+    typingMap,
+    hasMoreMap,
+    currentMessages,
+    sortedConversations,
+    fetchConversations,
+    fetchTotalUnread,
+    sendMessage,
+    recallMessage,
+    markRead,
+    sendTyping,
+    loadHistoryMessages,
+    pinConversation,
+    deleteConversation,
+    clearHistory,
+    setCurrentConversation,
+    initWsListeners
+  }
+})