Each robot runs a tight perception-plan-act loop at 50 Hz. The loop is the unit of determinism: given identical sensor input and identical state, two replicas produce byte-identical actuation commands.

Convergence holds when the merge is commutative; the audit loop replays every mutation deterministically so the log alone reconstructs final state — the core of determinism here.

When a node falls out of the determinism envelope, halt the actuation loop, snapshot the Yjs doc, and re-apply the audit tail before rejoining the fleet.

A deterministic control loop makes fleet behaviour reproducible in simulation; we diff actuation traces frame-by-frame to certify parity before any over-the-air rollout.