file upload fix?

frontend/src/pages/api/[...path].ts

@@ -14,8 +14,10 @@ export const ALL: APIRoute = async ({ request, params }) => {
   url.search = requestUrl.search;
 
   const headers = new Headers();
-  // Filter headers to avoid conflicts. Content-Type is handled automatically for POST/PUT if we pass arrayBuffer.
-  const forbiddenHeaders = ['host', 'connection', 'origin', 'referer', 'content-length', 'transfer-encoding'];
+  // We must NOT forward 'host' (causes backend to reject if it doesn't match)
+  // We must NOT forward 'connection'
+  // We should let fetch recalculate 'content-length'
+  const forbiddenHeaders = ['host', 'connection', 'content-length', 'transfer-encoding', 'origin', 'referer'];
   
   request.headers.forEach((value, key) => {
     if (!forbiddenHeaders.includes(key.toLowerCase())) {
@@ -23,23 +25,28 @@ export const ALL: APIRoute = async ({ request, params }) => {
     }
   });
 
+  console.log(`\n[Proxy Req] ${request.method} -> ${url.toString()}`);
+  console.log(`[Proxy Req] Auth Header Present:`, headers.has('authorization'));
+  console.log(`[Proxy Req] Content-Type:`, headers.get('content-type'));
+
   try {
-    console.log(`[Proxy] ${request.method} ${requestUrl.pathname} -> ${url.toString()}`);
-    
-    let body: any = undefined;
-    if (request.method !== 'GET' && request.method !== 'HEAD') {
-      body = await request.arrayBuffer();
-    }
-
-    const response = await fetch(url.toString(), {
+    const fetchOptions: RequestInit = {
       method: request.method,
       headers: headers,
-      body: body,
-      // @ts-ignore
-      duplex: 'half'
-    });
+    };
 
-    console.log(`[Proxy] Backend returned ${response.status} for ${url.toString()}`);
+    // Only attach body for methods that allow it
+    if (request.method !== 'GET' && request.method !== 'HEAD') {
+        // Pass the raw stream directly. This is crucial for multipart/form-data.
+        fetchOptions.body = request.body;
+        // Required by Node.js fetch when body is a ReadableStream
+        // @ts-ignore
+        fetchOptions.duplex = 'half';
+    }
+
+    const response = await fetch(url.toString(), fetchOptions);
+
+    console.log(`[Proxy Res] Backend returned ${response.status}`);
 
     const responseHeaders = new Headers();
     response.headers.forEach((value, key) => {