I suspect my knowledge is behind the times, but I never understood the appeal of putting stuff like "current thread" in the app state at all. To me, it makes much more sense if the stores (or the single data tree, in the redux case) just contain the flat dumb data, and the URL is used to pick the relevant data that the components need. This way, no state is duplicated anywhere, the stores are dumb, and the URL is lea…
So the SPA's state is different than just "we're now pointing to this resource" -- much more full and complex.