� ENHANCE FILE UPLOAD: Allow document upload without assistant

✅ 改进文档上传功能：
- � 移除必须选择Assistant才能上传文档的限制
- � 文字改为 "Drag or drop a file"
- � 现在可以直接上传文档到知识库
- � 支持在没有选择Assistant时查看所有已上传文档

� 用户体验提升：
- 更直观的文件上传界面
- 无需预先选择Assistant即可管理文档
- 符合用户期望的拖拽上传体验

� My Device页面文档管理更加灵活！

frontend/src/components/playground/DocumentsTab.tsx

@@ -47,7 +47,26 @@ export function DocumentsTab({
   useEffect(() => {
     const loadDocuments = async () => {
       if (!currentAssistant) {
-        setUploadedFiles([])
+        // Load all documents when no assistant is selected
+        try {
+          const response = await fetch('/rag/documents')
+          if (response.ok) {
+            const data = await response.json()
+            const allFiles: UploadedFile[] = data.documents.map((doc: any) => ({
+              id: doc.id,
+              name: doc.filename,
+              size: doc.size || 0,
+              type: doc.content_type || 'application/octet-stream',
+              uploadedAt: doc.upload_date,
+              status: 'processed',
+              chunks: doc.chunk_count,
+              assistantId: doc.assistant_id
+            }))
+            setUploadedFiles(allFiles)
+          }
+        } catch (error) {
+          console.error('Error loading documents:', error)
+        }
         return
       }
 
@@ -82,15 +101,17 @@ export function DocumentsTab({
 
   const handleFileUpload = async (event: React.ChangeEvent<HTMLInputElement>) => {
     const files = event.target.files
-    if (!files || !currentAssistant) return
+    if (!files) return
 
     setIsUploading(true)
     
     try {
       const formData = new FormData()
       
-      // Add assistant ID to the upload
-      formData.append('assistant_id', currentAssistant.id)
+      // Add assistant ID to the upload (if available)
+      if (currentAssistant) {
+        formData.append('assistant_id', currentAssistant.id)
+      }
       
       for (const file of Array.from(files)) {
         formData.append('files', file)
@@ -162,11 +183,81 @@ export function DocumentsTab({
     <div className="space-y-4 pb-6">
       {!currentAssistant ? (
         <Card>
-          <CardContent className="pt-6 text-center">
-            <BookOpen className="h-8 w-8 text-muted-foreground mx-auto mb-3" />
-            <p className="text-sm text-muted-foreground">
-              Select an assistant to manage documents
-            </p>
+          <CardHeader>
+            <CardTitle className="flex items-center gap-2">
+              <BookOpen className="h-4 w-4 text-blue-600" />
+              <span>Documents & Knowledge Base</span>
+            </CardTitle>
+          </CardHeader>
+          <CardContent className="space-y-4">
+            {/* Upload Area */}
+            <div className="border-2 border-dashed border-gray-200 rounded-lg p-6 text-center hover:border-gray-300 transition-colors">
+              <input
+                type="file"
+                id="file-upload"
+                multiple
+                accept=".pdf,.txt,.docx,.md"
+                onChange={handleFileUpload}
+                className="hidden"
+                disabled={isUploading || isLoading}
+              />
+              <Label
+                htmlFor="file-upload"
+                className="cursor-pointer flex flex-col items-center space-y-2"
+              >
+                <Upload className="h-8 w-8 text-gray-400" />
+                <span className="text-sm font-medium">
+                  {isUploading ? 'Uploading...' : 'Drag or drop a file'}
+                </span>
+                <span className="text-xs text-muted-foreground">
+                  PDF, TXT, DOCX, MD supported
+                </span>
+              </Label>
+            </div>
+
+            {/* Documents List */}
+            {uploadedFiles.length > 0 && (
+              <div className="space-y-2">
+                <Label className="text-sm font-medium">Documents ({uploadedFiles.length})</Label>
+                
+                <div className="space-y-1">
+                  {uploadedFiles.map((file) => (
+                    <div
+                      key={file.id}
+                      className="flex items-center justify-between p-2 border rounded bg-gray-50/50 hover:bg-gray-50"
+                    >
+                      <div className="flex items-center space-x-2 flex-1 min-w-0">
+                        <File className="h-3 w-3 text-blue-600 flex-shrink-0" />
+                        <span className="text-sm truncate">{file.name}</span>
+                        {file.chunks && (
+                          <span className="text-xs text-muted-foreground flex-shrink-0">
+                            {file.chunks} chunks
+                          </span>
+                        )}
+                      </div>
+                      <Button
+                        size="sm"
+                        variant="ghost"
+                        onClick={() => removeFile(file.id)}
+                        disabled={isLoading}
+                        className="h-6 w-6 p-0 text-red-500 hover:text-red-600 hover:bg-red-50"
+                      >
+                        <X className="h-3 w-3" />
+                      </Button>
+                    </div>
+                  ))}
+                </div>
+              </div>
+            )}
+
+            {/* Empty State */}
+            {uploadedFiles.length === 0 && (
+              <div className="text-center py-3">
+                <p className="text-xs text-muted-foreground">
+                  No documents uploaded yet
+                </p>
+              </div>
+            )}
           </CardContent>
         </Card>
       ) : (

static/index.html

@@ -5,7 +5,7 @@
     <link rel="icon" type="image/svg+xml" href="/vite.svg" />
     <meta name="viewport" content="width=device-width, initial-scale=1.0" />
     <title>Edge LLM</title>
-    <script type="module" crossorigin src="/assets/index-0da51a3f.js"></script>
+    <script type="module" crossorigin src="/assets/index-7336e918.js"></script>
     <link rel="stylesheet" href="/assets/index-529e312c.css">
   </head>
   <body>