>>"headless browser" variant of your app > Exactly. Do this. > The app is an object. It has an API. It knows how to coordinate its pieces. The local I/O, the

>>"headless browser" variant of your app > Exactly. Do this. > The app is an object. It has an API. It knows how to coordinate its pieces. The local I/O, the remote I/O, any timing stuff. All of it. Then you plonk the UI on > top of that. You can have sub-parts, but you need one piece that ties it all together, on the model side. This is exactly what I did with all projects I've worked on. It helped that I had to target both, iOS and macOS where sharing "business logic" was crucial, so you were kinda "forced" to think about that. To put it simply, there is one question I'm asking myself, can I delete UI and then rewrite it from scratch without updating non UIView/NSView code (just calling MyClasses i.e. my APIs)? Let's just say, if I have to write NSSortDescriptor again, that means there is an architectural issue with my code, which has to be fixed.