ZipStream writes via fwrite(php://output) which FrankenPHP silently drops, resulting in 0-byte ZIP downloads. Switch to ZipArchive to build the ZIP as a temp file on disk, then serve with response()->download(). - Rewrite download() to use ZipArchive + BinaryFileResponse - Remove decryptFileToCallback() from FileEncryptionService - Update tests for BinaryFileResponse instead of StreamedResponse - Remove maennchen/zipstream-php dependency Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>