I had started on a “Write your own coding agent” exercise. Four iterations in, actually. And then I found Tiny Agents, a set of interactive exercises that let you experience how agents work, from a simple chat request, through a tool, more tools etc. It has a live graph, that visualises of the flow of data and actions.
It is good fun to play with, it starts simple and builds up. It lets you inspect the messages between the ‘agent’ loop code and the large language model server (which is just HTTP and some JSON).