Applications
The services the rooms exist to present — the forges, the courses, the town square, the libraries, the books, and the Den's own workshop tools.
In a nutshell
Applications are what people actually open. Everything below — the substrate, the identity layer — exists to make these usable: the forges where code is written and proven, the courses and the commons where the Climb happens, the libraries, and the tools that keep an organization, and a life, running.
They span every node. Some are secret-bearing and gated; some are free and public-read; some are the Den’s own. What they share is that each is a service with a face — something a member, a volunteer, or a custodian signs into and uses.