Fix 401 error: Add authenticated API proxy for private datasets

src/app/api/hf-proxy/route.ts

@@ -25,16 +25,27 @@ async function handleRequest(request: NextRequest, method: 'GET' | 'HEAD') {
   }
 
   // Get token from environment variable (set in Hugging Face Space secrets)
-  // Hugging Face Spaces automatically inject secrets as environment variables
-  const token = process.env.HF_TOKEN || process.env.HUGGINGFACE_TOKEN || process.env.HF_API_TOKEN;
+  // Try multiple possible variable names that Hugging Face Spaces might use
+  const token = 
+    process.env.HF_TOKEN || 
+    process.env.HUGGINGFACE_TOKEN || 
+    process.env.HF_API_TOKEN ||
+    process.env.HUGGING_FACE_HUB_TOKEN ||
+    // Also check if it's available in the request headers (for debugging)
+    request.headers.get('x-hf-token') || null;
   
   // Log token status for debugging (don't log actual token value)
   if (!token) {
-    console.error('❌ HF_TOKEN not found in environment variables!');
-    console.error('Available env vars:', Object.keys(process.env).filter(k => k.includes('HF') || k.includes('TOKEN')).join(', '));
-    console.warn('⚠️  Requests to private repos will fail with 401');
+    const envKeys = Object.keys(process.env).filter(k => 
+      k.includes('HF') || k.includes('TOKEN') || k.includes('HUGGING')
+    );
+    console.error('❌ HF_TOKEN not found!');
+    console.error('Checked: HF_TOKEN, HUGGINGFACE_TOKEN, HF_API_TOKEN, HUGGING_FACE_HUB_TOKEN');
+    console.error('Available env vars with HF/TOKEN:', envKeys.length > 0 ? envKeys.join(', ') : 'NONE');
+    console.error('⚠️  Requests to private repos will fail with 401');
+    console.error('💡 Make sure HF_TOKEN secret is added in Space Settings → Variables and secrets');
   } else {
-    console.log('✓ HF_TOKEN found in environment (length:', token.length, 'chars)');
+    console.log('✓ HF_TOKEN found (length:', token.length, 'chars, starts with:', token.substring(0, 5) + '...')');
   }
 
   try {