Fix: RAG can get corrupted upon uploading other file types

public/js/main.js

@@ -53,9 +53,60 @@ function initializeFileUpload() {
 
     function showFileInfo(file) {
         if (fileName && fileSize && fileInfo) {
-            fileName.textContent = file.name;
-            fileSize.textContent = `(${formatFileSize(file.size)})`;
+            // Define allowed file types for client-side validation
+            const allowedExtensions = ['.pdf', '.txt', '.doc', '.docx', '.xlsx', '.xls', '.md', '.json', '.csv', '.xml'];
+            const allowedMimeTypes = [
+                'application/pdf',
+                'text/plain',
+                'text/markdown',
+                'text/csv',
+                'text/xml',
+                'application/xml',
+                'application/json',
+                'application/msword',
+                'application/vnd.openxmlformats-officedocument.wordprocessingml.document',
+                'application/vnd.ms-excel',
+                'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet'
+            ];
+            
+            // Get file extension
+            const fileExtension = '.' + file.name.split('.').pop().toLowerCase();
+            const fileMimeType = file.type.toLowerCase();
+            
+            // Check if file type is allowed
+            const isExtensionAllowed = allowedExtensions.includes(fileExtension);
+            const isMimeTypeAllowed = allowedMimeTypes.includes(fileMimeType) || fileMimeType === '';
+            
+            if (!isExtensionAllowed) {
+                // Show error for invalid file type
+                fileInfo.innerHTML = `
+                    <div class="alert alert-danger">
+                        <i class="fas fa-exclamation-triangle me-2"></i>
+                        <strong>Invalid file type!</strong> "${fileExtension}" files are not supported.
+                        <br><small>Only document files (PDF, Word, Excel, text files) are allowed to prevent RAG corruption.</small>
+                    </div>
+                `;
                 fileInfo.classList.remove('d-none');
+                uploadBtn.disabled = true;
+                return;
+            }
+            
+            // Show valid file info
+            fileInfo.innerHTML = `
+                <div class="alert alert-info">
+                    <i class="fas fa-file me-2"></i>
+                    <span>${file.name}</span>
+                    <span class="text-muted ms-2">(${formatFileSize(file.size)})</span>
+                    <div class="mt-2">
+                        <small class="text-success">
+                            <i class="fas fa-check-circle me-1"></i>
+                            File type supported for AI processing
+                        </small>
+                    </div>
+                </div>
+            `;
+            fileInfo.classList.remove('d-none');
+            uploadBtn.disabled = false;
         }
     }