From Claude: The whole city is a running simulation — 200k people, each with a job, a home, a schedule, needs and a memory. Code handles the physics: pathfinding, traffic, who can see or hear what. Jev is the decision layer on top: every time someone needs to choose what to do next, code lists the options that are actually feasible for them and Jev picks the one that person would realistically take, given their dossier and what they know right now. That's the whole loop — no free text, just typed choices, thousands of them a second.