fix: directory picker cannot navigate into subdirectories (#19)

Root cause: ArcoDesign Tree loadMore callback receives NodeInstance where
the key is at node.props.dataRef.key, not node.props.key. The old code
passed node.props directly which resulted in undefined key, causing
child directory loading to silently fail.

Fix:
- Access node key via node.props.dataRef?.key ?? node.props._key
- Add showLine + blockNode + folder icons for better visual hierarchy
- Add path display with copy button in selection modal
- Add unmountOnExit to reset state on close

Closes #19

web/src/components/common/DirectoryPicker.tsx

@@ -1,4 +1,5 @@
-import { Button, Input, Modal, Space, Spin, Tree, Typography } from '@arco-design/web-react'
+import { Button, Input, Message, Modal, Space, Spin, Tree, Typography } from '@arco-design/web-react'
+import { IconFolder, IconFile } from '@arco-design/web-react/icon'
 import { useCallback, useState } from 'react'
 import { listNodeDirectory } from '../../services/nodes'
 import type { DirEntry } from '../../types/nodes'
@@ -14,8 +15,10 @@ interface DirectoryPickerProps {
 interface TreeNodeData {
   key: string
   title: string
+  icon?: React.ReactNode
   isLeaf: boolean
   children?: TreeNodeData[]
+  loaded?: boolean
 }
 
 function entriesToTreeNodes(entries: DirEntry[], mode: 'directory' | 'file'): TreeNodeData[] {
@@ -24,8 +27,8 @@ function entriesToTreeNodes(entries: DirEntry[], mode: 'directory' | 'file'): Tr
     .map((entry) => ({
       key: entry.path,
       title: entry.name,
+      icon: entry.isDir ? <IconFolder /> : <IconFile />,
       isLeaf: !entry.isDir,
-      children: entry.isDir ? [] : undefined,
     }))
 }
 
@@ -34,16 +37,15 @@ export function DirectoryPicker({ value, onChange, placeholder, mode = 'director
   const [treeData, setTreeData] = useState<TreeNodeData[]>([])
   const [loading, setLoading] = useState(false)
   const [selectedPath, setSelectedPath] = useState('')
-  const [error, setError] = useState('')
 
   const loadDirectory = useCallback(
-    async (path: string) => {
+    async (path: string): Promise<TreeNodeData[]> => {
       if (nodeId === undefined) return []
       try {
         const entries = await listNodeDirectory(nodeId, path)
         return entriesToTreeNodes(entries, mode)
       } catch {
-        setError('加载目录失败')
+        Message.error(`加载目录失败: ${path}`)
         return []
       }
     },
@@ -53,7 +55,6 @@ export function DirectoryPicker({ value, onChange, placeholder, mode = 'director
   async function handleOpen() {
     setModalVisible(true)
     setSelectedPath(value || '')
-    setError('')
     setLoading(true)
     try {
       const rootNodes = await loadDirectory('/')
@@ -63,21 +64,26 @@ export function DirectoryPicker({ value, onChange, placeholder, mode = 'director
     }
   }
 
-  async function handleLoadMore(node: TreeNodeData) {
-    const children = await loadDirectory(node.key)
+  // ArcoDesign Tree loadMore: node.props.dataRef 指向 treeData 中的原始对象
+  async function handleLoadMore(treeNode: any): Promise<void> {
+    const nodeKey = treeNode.props.dataRef?.key ?? treeNode.props._key
+    if (!nodeKey) return
+
+    const children = await loadDirectory(nodeKey)
+
     setTreeData((prev) => {
-      function updateChildren(nodes: TreeNodeData[]): TreeNodeData[] {
+      function insertChildren(nodes: TreeNodeData[]): TreeNodeData[] {
         return nodes.map((n) => {
-          if (n.key === node.key) {
-            return { ...n, children }
+          if (n.key === nodeKey) {
+            return { ...n, children, loaded: true }
           }
-          if (n.children) {
-            return { ...n, children: updateChildren(n.children) }
+          if (n.children && n.children.length > 0) {
+            return { ...n, children: insertChildren(n.children) }
           }
           return n
         })
       }
-      return updateChildren(prev)
+      return insertChildren(prev)
     })
   }
 
@@ -88,6 +94,7 @@ export function DirectoryPicker({ value, onChange, placeholder, mode = 'director
     setModalVisible(false)
   }
 
+  // 没有 nodeId 时退化为普通输入框
   if (nodeId === undefined) {
     return <Input value={value} placeholder={placeholder} onChange={onChange} />
   }
@@ -108,30 +115,37 @@ export function DirectoryPicker({ value, onChange, placeholder, mode = 'director
         onOk={handleConfirm}
         okText="选择"
         cancelText="取消"
-        style={{ width: 520 }}
+        style={{ width: 560 }}
         okButtonProps={{ disabled: !selectedPath }}
+        unmountOnExit
       >
-        {error && <Typography.Text type="error">{error}</Typography.Text>}
         {selectedPath && (
-          <Typography.Text type="secondary" style={{ display: 'block', marginBottom: 8 }}>
-            已选择: {selectedPath}
-          </Typography.Text>
+          <div style={{ padding: '8px 12px', marginBottom: 12, background: 'var(--color-fill-2)', borderRadius: 4 }}>
+            <Typography.Text copyable style={{ fontSize: 13 }}>
+              {selectedPath}
+            </Typography.Text>
+          </div>
         )}
         {loading ? (
-          <Spin style={{ display: 'block', textAlign: 'center', padding: 24 }} />
+          <Spin style={{ display: 'block', textAlign: 'center', padding: 40 }} />
         ) : treeData.length === 0 ? (
-          <Typography.Text type="secondary">目录为空</Typography.Text>
+          <Typography.Text type="secondary" style={{ display: 'block', textAlign: 'center', padding: 40 }}>
+            目录为空
+          </Typography.Text>
         ) : (
-          <div style={{ maxHeight: 400, overflow: 'auto' }}>
+          <div style={{ maxHeight: 420, overflow: 'auto', border: '1px solid var(--color-border)', borderRadius: 4, padding: '4px 0' }}>
             <Tree
+              blockNode
+              showLine
               treeData={treeData as any}
+              selectedKeys={selectedPath ? [selectedPath] : []}
               onSelect={(keys) => {
                 if (keys.length > 0) {
                   setSelectedPath(keys[0] as string)
                 }
               }}
-              selectedKeys={selectedPath ? [selectedPath] : []}
-              loadMore={(node: any) => handleLoadMore(node.props)}
+              loadMore={handleLoadMore}
+              icons={{ switcherIcon: <IconFolder style={{ fontSize: 14 }} /> }}
             />
           </div>
         )}