@cocoaphony My understanding is that NSImage is just a really awkward fit for sendability checking because developers often do a bunch of thread-confined mutation right after creating an instance and then pass it freely between threads without further mutation. It’s safe when used that way, but there’s no way to programmatically stop you from using the mutation APIs that would be unsafe; you just need to be careful with it in the way you always have been.

@beccadax I think you're right. The situation we've gotten ourselves into is trying to port UIImage code over with a (possibly ill-advised) platform-dependent typealias. UIImage is truly Sendable, and it's just not safe to assume you can do everything with NSImage you can do with UIImage. In other products, I've just jumped to CGImage, but you do give up a lot of UIImage performance features when you do that. Tough to make things work cross-platform (when SwiftUI on macOS is still a bit weak).