No I don't think app.js should be duplicated.
Originally Posted by Carlos Nunes
I think you should create, eventually, multiple Viewport.js (and so you have to avoid autoload it).
// scss coffee
So you can run the correct Viewport.
launch: <generate this function with .net>
A different approach could be: have only one viewport which will build differently, based upon some values that you generate through .net.
This could be the best option (the second one) because you'll stick with ExtJS app structure.
So you can keep .net mvc directory structure too, even for views
Notice that I don't use .net MVC, but I did something similar with Ruby on Rails. Don't know if it's a good idea, but looks interesting for me.