Multiple windows, and (maybe) tabs.

Where is the dividing line between this and a browser?

Website publishing on SSB. Sites open in their own electron window and get permissioned access to the SSB/Patchwork APIs. (Possibly via git bundle?)

This is a browser :)
So basically its a succutlebut enable browser. It not the first domain spefic browser. Maybe there is a way to generalize this. What do you think about have a browser that supported node.js plugins?