Malcolm file-upload component ships the upstream FilePond PHP server (pqina/filepond-server-php) largely unmodified: Dockerfile copies all upstream *.php files and Malcolm only overwrites config.php and submit.php. Upstream index.php exposes a fetch API route that instructs the server to download an arbitrary URL with curl (including FOLLOWLOCATION) and, for HEAD requests, stores the fetched response body in the upload container's transfer directory and returns the transfer ID to the caller, enabling full readback of the fetched content.