[File Manager] Upload file to selected directory

I am using the File Manager to store files for my site. However, after creating a new folder, navigating to it, and then uploading a file to it, I can’t seem to figure out what folder to upload the image to in the back-end. The request for upload seems to just carry the file bytes, not much else (unless I am not looking in the right place). Any suggestions?

On the client side the target directory for the uploaded file is the currently open directory (whether you use the button or drag-n-drop). This target directory is passed as a URL parameter, e.g. upload?id=%2F or upload?id=%2FDocuments, and the backend code can take it from there.