Muster on the Logos stack

Pick a way of running it; the parts of the stack it leans on light up. Everything below the dark rule is infrastructure you do not run — and every box down there learns something.

The dark band is the point. A stack diagram usually stops at the runtime, which quietly implies the picture is complete — but a client that talks to nobody does nothing. Every box below the rule is a party that learns something from you using this, and naming them in the architecture diagram is the cheapest honesty available: it means you cannot describe the system without describing its observers.