My bad, I've realised that my issue is trying to distribute the app, not to build it. Thank you for this thread.

Hi, sorry you having this issue, it's really confusing. If you create new watchOS only project WITHOUT companion iOS apps, you will see it has extra iOS target. This is necessary to distribute the app. It still has only watchOS app. Make sure that watchOS app is really what you need, because you can't add the companion iOS app later, you will have to create a new project. Screenshot https://www.cocoaswitch.com/uploads/2025/screenshot-2025-02-01-at-11.53.57am.png

Unlike the Hacking with Swift article, I set my undo manager from the environment and it works. The only catch you can't do in the app context, it has to be on a view level. In any content view, we can access undo manager through the @Environment(\.undoManager) var undoManager, then when I create my content view I initiate the background task using the .task modifier, and setting the under manager: modelContext.undoManager = undoManager. It's probably not a best practice though.

A hackingwithswift article suggests creating a new UndoManager for the shared container. However, this technique doesn't work for me and Undo/Redo commands are greyed out in my test app. container = try ModelContainer(for: Store.self, Book.self) container.mainContext.undoManager = UndoManager()

Thanks. I have replied with the information. Also filed feedback with sample project. FB13204465

Clarification, 1 and 2 are .watchkitapp and .watchkitapp.widget. Minor annoyance, I still don't see the widget on the Simulator but it shows in the Smart Stack on my Apple Watch.