Architecture-as-Code is
source code. It can be compiled/rendered to other forms, like diagrams. (
Ideally I'd like sonething like CSS to control styling the diagrams in so that you could adjust rendering, even selectively hiding pieces that aren’t interesting to a particular audience, without touching the logical description.)
In a perfect world, the architecture description would also be part of the “working” source code, interacting with more normal program code (and/or IAC) specifying the concrete components, and playing a concrete role in building and deploying systems, so that the work that goes into architecture specs isn’t duplicated and the arcuitecture description doesn’t get out of sync with reality.