feat(agents): 优化聊天历史面板和复制功能

- 为聊天历史面板添加加载更多功能，支持分页加载会话列表
- 优化会话列表按时间降序排序和日期分组逻辑
- 统一复制功能使用工具函数，改进错误处理
- 修复兑换码管理菜单路径缺少斜杠的问题
- 优化Dify服务用户标识生成，按agentId隔离会话
- 重构Dify服务扣费逻辑，提取通用处理方法

frontend/app/web-gold/src/components/agents/ChatDrawer.vue

@@ -20,6 +20,7 @@ import {
   AlertDialogTitle
 } from '@/components/ui/alert-dialog'
 import { sendChatStream } from '@/api/agent'
+import { copyToClipboard } from '@/utils/clipboard'
 import HistoryPanel from './HistoryPanel.vue'
 import ChatDrawerHeader from './ChatDrawerHeader.vue'
 import ChatDrawerEmpty from './ChatDrawerEmpty.vue'
@@ -90,10 +91,10 @@ const handleGenerate = async () => {
 }
 
 const handleCopy = async () => {
-  try {
-    await navigator.clipboard.writeText(generatedContent.value)
+  const success = await copyToClipboard(generatedContent.value)
+  if (success) {
     toast.success('已复制')
-  } catch {
+  } else {
     toast.error('复制失败')
   }
 }

frontend/app/web-gold/src/components/agents/HistoryPanel.vue

@@ -89,6 +89,18 @@
                     </button>
                   </div>
                 </div>
+
+                <!-- Load More -->
+                <div v-if="hasMore" class="load-more">
+                  <button
+                    class="load-more-btn"
+                    :disabled="loading"
+                    @click="loadConversations(true)"
+                  >
+                    <Icon v-if="loading" icon="lucide:loader-2" class="size-4 animate-spin" />
+                    <span>{{ loading ? '加载中...' : '加载更多' }}</span>
+                  </button>
+                </div>
               </div>
             </div>
 
@@ -171,8 +183,10 @@ const conversationList = ref([])
 const selectedConversation = ref(null)
 const messageList = ref([])
 const messageLoading = ref(false)
+const lastId = ref(null)
+const hasMore = ref(true)
 
-// 按日期分组
+// 按日期分组（先排序再分组）
 const groupedConversations = computed(() => {
   const today = dayjs().startOf('day')
   const yesterday = dayjs().subtract(1, 'day').startOf('day')
@@ -185,7 +199,14 @@ const groupedConversations = computed(() => {
     older: { label: '更早', items: [] }
   }
 
-  conversationList.value.forEach(item => {
+  // 按时间降序排序
+  const sortedList = [...conversationList.value].sort((a, b) => {
+    const timeA = (a.updatedAt || a.createdAt) * 1000
+    const timeB = (b.updatedAt || b.createdAt) * 1000
+    return timeB - timeA
+  })
+
+  sortedList.forEach(item => {
     const date = dayjs((item.updatedAt || item.createdAt) * 1000)
     if (date.isAfter(today)) {
       groups.today.items.push(item)
@@ -202,13 +223,27 @@ const groupedConversations = computed(() => {
 })
 
 // Methods
-const loadConversations = async () => {
+const loadConversations = async (loadMore = false) => {
   if (!props.agentId) return
+  if (loadMore && !hasMore.value) return
+
   loading.value = true
   try {
-    const res = await getConversations({ agentId: props.agentId, limit: 50 })
+    const params = { agentId: props.agentId, limit: 20 }
+    if (loadMore && lastId.value) {
+      params.lastId = lastId.value
+    }
+    const res = await getConversations(params)
     if (res.code === 0) {
-      conversationList.value = res.data?.data || []
+      const data = res.data?.data || []
+      if (loadMore) {
+        conversationList.value = [...conversationList.value, ...data]
+      } else {
+        conversationList.value = data
+      }
+      // 更新分页状态
+      lastId.value = data.length > 0 ? data[data.length - 1].id : null
+      hasMore.value = data.length === 20 && res.data?.hasMore !== false
     }
   } catch (e) {
     console.error('加载会话列表失败:', e)
@@ -249,7 +284,11 @@ const handleClose = () => {
 
 const copyContent = async (content) => {
   const success = await copyToClipboard(content)
-  success ? toast.success('已复制到剪贴板') : toast.error('复制失败')
+  if (success) {
+    toast.success('已复制到剪贴板')
+  } else {
+    toast.error('复制失败')
+  }
 }
 
 const formatTime = (timestamp) => {
@@ -257,15 +296,10 @@ const formatTime = (timestamp) => {
   const date = dayjs(timestamp * 1000)
   const now = dayjs()
 
-  if (date.isSame(now, 'day')) {
-    return date.format('HH:mm')
-  } else if (date.isSame(now.subtract(1, 'day'), 'day')) {
-    return '昨天 ' + date.format('HH:mm')
-  } else if (date.isAfter(now.subtract(7, 'day'))) {
-    return date.format('dddd HH:mm')
-  } else {
-    return date.format('MM-DD HH:mm')
-  }
+  if (date.isSame(now, 'day')) return date.format('HH:mm')
+  if (date.isSame(now.subtract(1, 'day'), 'day')) return '昨天 ' + date.format('HH:mm')
+  if (date.isAfter(now.subtract(7, 'day'))) return date.format('dddd HH:mm')
+  return date.format('MM-DD HH:mm')
 }
 
 // Watch
@@ -530,6 +564,36 @@ watch(() => props.visible, (val) => {
   gap: 24px;
 }
 
+.load-more {
+  display: flex;
+  justify-content: center;
+  padding-top: 8px;
+}
+
+.load-more-btn {
+  display: inline-flex;
+  align-items: center;
+  gap: 8px;
+  padding: 10px 20px;
+  border: 1px solid var(--color-gray-200);
+  background: var(--color-bg-card);
+  border-radius: 10px;
+  font-size: 14px;
+  color: var(--color-gray-600);
+  cursor: pointer;
+  transition: all 0.2s ease;
+
+  &:hover:not(:disabled) {
+    border-color: var(--color-primary-300);
+    color: var(--color-primary-500);
+  }
+
+  &:disabled {
+    opacity: 0.6;
+    cursor: not-allowed;
+  }
+}
+
 .conversation-group {
   animation: groupFadeIn 0.4s ease-out backwards;
   animation-delay: calc(var(--group-index) * 0.1s);