For example this tool generates controllers and then puts them in the /Controllers folder with names like UserController.cs. While they carry the partial keyword, the naming of the files and the placement in the folder structure makes it difficult for users to actually extend.
Please use the convention of using the extension ".g.cs" for any csharp code generated files. This would allow us to define the rest of the partial UserController class in the place where everyone is going to be looking for it, and not in some other folder.
Generated code should not be in the forefront of any codebase, because its not something to be maintained, only regenerated.