Five nouns, and that is the whole surface.

Concept	Meaning
Agent	A Laravel AI agent class: instructions and tools
Session	Durable identity, context, configuration, optional workspace
Run	One execution attempt inside a session
Event	An append only fact emitted during a run
Artifact	A durable output: a document, report, image, export

A session holds many runs, one after another, and only one of them can be active at a time.