Fix multipart parsing in NIP-95 upload proxy by removing manual Content-Type header and improving error handling

lib/nip95.ts

@@ -77,11 +77,7 @@ async function tryUploadEndpoint(endpoint: string, formData: FormData, useProxy:
   const response = await fetch(targetUrl, {
     method: 'POST',
     body: formData,
-    ...(useProxy && {
-      headers: {
-        'Content-Type': 'multipart/form-data',
-      },
-    }),
+    // Don't set Content-Type manually - browser will set it with boundary automatically
   })
 
   if (!response.ok) {

pages/api/nip95-upload.ts

@@ -24,15 +24,21 @@ export default async function handler(req: NextApiRequest, res: NextApiResponse)
 
   try {
     // Parse multipart form data
+    // formidable needs the raw Node.js IncomingMessage, which NextApiRequest extends
     const form = new IncomingForm({
       maxFileSize: MAX_FILE_SIZE,
       keepExtensions: true,
     })
 
     const parseResult = await new Promise<ParseResult>((resolve, reject) => {
-      form.parse(req, (err, fields, files) => {
-        if (err) reject(err)
-        else resolve({ fields: fields as Record<string, string[]>, files: files as Record<string, FormidableFile[]> })
+      // Cast req to any to work with formidable - NextApiRequest extends IncomingMessage
+      form.parse(req as any, (err, fields, files) => {
+        if (err) {
+          console.error('Formidable parse error:', err)
+          reject(err)
+        } else {
+          resolve({ fields: fields as Record<string, string[]>, files: files as Record<string, FormidableFile[]> })
+        }
       })
     })