[gharlan]

MediaHandler::add()/edit() took the file in the $_FILES shape (name, tmp_name/path, error). Now $data['file'] is a Symfony File (symfony/http-foundation is already a dependency):

// upload, e.g. in an addon's frontend form
MediaHandler::add([
    'file' => Core::getRequest()->files->get('file'), // or new UploadedFile($f['tmp_name'], $f['name'], error: $f['error'])
    'category_id' => null,
    'title' => 'Foo',
]);

// file already on disk (sync, import)
MediaHandler::add(['file' => new File($path), 'category_id' => 5], subindexing: false);

• The upload errors are still handled by the handler, so callers taking an upload don't have to do it themselves. UploadedFile::isValid() additionally ensures the file really was uploaded via http (is_uploaded_file()); previously "is an upload" only depended on tmp_name being set.
• MediaAdding::$isUpload is derived from instanceof UploadedFile.

Breaking changes

Signatures aligned with the other handlers ($meta right after $data, options after it, the language as required second parameter of edit()):

MediaHandler::add($data, $doSubindexing, $types, $meta)  -> add($data, $meta, $subindexing, $types)
MediaHandler::edit($filename, $data, $languageId, $meta) -> edit($filename, $languageId, $data, $meta)

• $data['file'] is a Symfony\Component\HttpFoundation\File\File instead of an array
• edit(): missing keys keep their value, category_id and title are no longer required; file replaces the file
• add(): title is optional

Tested in the backend: upload, edit with and without replacing the file, sync.