feat: update input_file data format to include data URL scheme

src/server/services/proxyInputFileResolver.test.ts

@@ -71,7 +71,7 @@ describe('proxyInputFileResolver', () => {
             type: 'input_file',
             file_id: 'file-metapi-123',
             filename: 'brief.pdf',
-            file_data: Buffer.from('%PDF-local').toString('base64'),
+            file_data: `data:application/pdf;base64,${Buffer.from('%PDF-local').toString('base64')}`,
           },
         ],
       },

src/server/services/proxyInputFileResolver.ts

@@ -1,5 +1,6 @@
 import type { ProxyResourceOwner } from '../middleware/auth.js';
 import { getProxyFileByPublicIdForOwner, LOCAL_PROXY_FILE_ID_PREFIX } from './proxyFileStore.js';
+import { ensureBase64DataUrl } from '../transformers/shared/inputFile.js';
 
 function isRecord(value: unknown): value is Record<string, unknown> {
   return !!value && typeof value === 'object' && !Array.isArray(value);
@@ -213,7 +214,7 @@ function toResponsesResolvedBlock(file: { fileId?: string; filename: string; fil
     type: 'input_file',
     ...(file.fileId ? { file_id: file.fileId } : {}),
     filename: file.filename,
-    file_data: file.fileData,
+    file_data: ensureBase64DataUrl(file.fileData, file.mimeType),
   };
 }