Please note that you should also ignore subdirectories that are not meant to be namespaces. For example: Rails.autoloaders.main.ignore('lib/tasks', 'lib/assets') Otherwise, Zeitwerk would define a Tasks constant, but that is not your intention (and could potentially conflict with a genuine Tasks constant).

Another alternative that would feel a lot better would be app/my_app in the same way I do lib/my_app, and then app/my_app/my_file.rb would define MyApp::MyFile, like normal. That would be fine, preferable, even. But how do I tell Zeitwerk that?