feat: add session tree search functionality

- Add useTreeSearch composable with filtering logic
- Implement search bar with Ctrl+F shortcut
- Show search results with ancestor paths
- Add search match indicator (cyan dot)
- Display "no results" message when search is empty
- Support clear search with X button

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

frontend/src/components/SessionTree.vue

@@ -4,10 +4,11 @@ import { useSessionTreeStore } from '../stores/sessionTree'
 import { useWorkspaceStore } from '../stores/workspace'
 import { useTreeDragDrop } from '../composables/useTreeDragDrop'
 import { useKeyboardShortcuts } from '../composables/useKeyboardShortcuts'
+import { useTreeSearch } from '../composables/useTreeSearch'
 import SessionTreeNode from './SessionTreeNode.vue'
 import ContextMenu from './ContextMenu.vue'
 import type { ContextMenuItem } from './ContextMenu.vue'
-import { FolderPlus, Edit2, Trash2 } from 'lucide-vue-next'
+import { FolderPlus, Edit2, Trash2, Search, X } from 'lucide-vue-next'
 
 const treeStore = useSessionTreeStore()
 const workspaceStore = useWorkspaceStore()
@@ -18,13 +19,22 @@ const showRenameDialog = ref(false)
 const renameNodeId = ref<string | null>(null)
 const renameValue = ref('')
 
+// Search functionality
+const nodesRef = computed(() => treeStore.nodes)
+const { searchQuery, filteredNodes, clearSearch, isSearchMatch } = useTreeSearch(nodesRef)
+
 // Context menu
 const showContextMenu = ref(false)
 const contextMenuX = ref(0)
 const contextMenuY = ref(0)
 const contextMenuNodeId = ref<string | null>(null)
 
-const rootNodes = computed(() => treeStore.rootNodes)
+const rootNodes = computed(() => {
+  const nodes = searchQuery.value ? filteredNodes.value : treeStore.nodes
+  return nodes
+    .filter(n => n.parentId === null)
+    .sort((a, b) => a.order - b.order)
+})
 
 const contextMenuItems = computed<ContextMenuItem[]>(() => {
   if (!contextMenuNodeId.value) return []
@@ -64,6 +74,9 @@ const contextMenuItems = computed<ContextMenuItem[]>(() => {
 const dragHandlers = useTreeDragDrop()
 provide('dragHandlers', dragHandlers)
 
+// Provide search match checker
+provide('isSearchMatch', isSearchMatch)
+
 // Keyboard shortcuts
 useKeyboardShortcuts([
   {
@@ -89,6 +102,14 @@ useKeyboardShortcuts([
       showNewFolderDialog.value = true
     },
   },
+  {
+    key: 'f',
+    ctrl: true,
+    handler: () => {
+      const searchInput = document.querySelector('.tree-search-input') as HTMLInputElement
+      searchInput?.focus()
+    },
+  },
 ])
 
 function handleNodeClick(nodeId: string) {
@@ -162,14 +183,37 @@ function deleteNode(nodeId: string) {
       <button
         @click="showNewFolderDialog = true"
         class="flex items-center gap-1.5 px-2.5 py-1.5 rounded text-xs text-slate-300 hover:bg-slate-800 transition-colors"
-        title="新建文件夹"
+        title="新建文件夹 (Ctrl+N)"
       >
         <FolderPlus class="w-4 h-4" />
         文件夹
       </button>
     </div>
 
+    <!-- Search Bar -->
+    <div class="px-2 py-2 border-b border-slate-700">
+      <div class="relative">
+        <Search class="absolute left-2.5 top-1/2 -translate-y-1/2 w-4 h-4 text-slate-500" />
+        <input
+          v-model="searchQuery"
+          type="text"
+          placeholder="搜索会话... (Ctrl+F)"
+          class="tree-search-input w-full pl-8 pr-8 py-1.5 rounded bg-slate-800 border border-slate-700 text-slate-200 text-sm placeholder-slate-500 focus:border-cyan-500 focus:outline-none"
+        />
+        <button
+          v-if="searchQuery"
+          @click="clearSearch"
+          class="absolute right-2 top-1/2 -translate-y-1/2 text-slate-500 hover:text-slate-300 transition-colors"
+        >
+          <X class="w-4 h-4" />
+        </button>
+      </div>
+    </div>
+
     <div class="flex-1 overflow-y-auto p-2">
+      <div v-if="searchQuery && rootNodes.length === 0" class="text-center py-8 text-slate-500 text-sm">
+        未找到匹配的会话
+      </div>
       <SessionTreeNode
         v-for="node in rootNodes"
         :key="node.id"

frontend/src/components/SessionTreeNode.vue

@@ -32,6 +32,7 @@ const connection = computed(() => {
 
 // Drag-drop functionality
 const dragHandlers = inject<any>('dragHandlers', null)
+const isSearchMatch = inject<(nodeId: string) => boolean>('isSearchMatch', () => false)
 
 const isDragging = computed(() =>
   dragHandlers?.draggedNode.value?.id === props.node.id
@@ -138,8 +139,15 @@ function handleDragEnd() {
 
       <span class="text-sm truncate flex-1">{{ node.name }}</span>
 
+      <!-- Search match indicator -->
       <span
-        v-if="connection"
+        v-if="isSearchMatch(node.id)"
+        class="w-1.5 h-1.5 rounded-full bg-cyan-400 flex-shrink-0"
+        title="搜索匹配"
+      />
+
+      <span
+        v-else-if="connection"
         class="w-2 h-2 rounded-full bg-slate-600"
       />
     </div>