I read through those docs and tried the sample app, but it's all about restoring view controller state. That already works - I can open various windows, quit the app, relaunch it, and they come back as they were, via NSUserActivity.
My question is about how to make macOS understand that for one particular window type (meaning one particular UISceneConfiguration), when the window is closed using the stoplight button and reopened, it should be restored, not recreated from scratch.