This looks great, but let's see if I have this right ...

The "Agent Apps" (or whatever we are calling them) from the big vendors are organized around projects/folders, and we attach apps (via plugins) to the projects.

This appears to mae the apps (work surfaces) the primary artifact?

Yes, that's mostly right.

Surfaces are the primary artifact for collaborating with the assistant - each one attaches an app to a workflow and gives both you and the agent a structured place to work, instead of everything flowing through chat.

Chat is still first class, and projects/folders exist separately to organize work around it.