Per-time-step main loop of the Monte Carlo manager. After initialization and particle creation (preStep), each rank enters the HandleAll routine (dashed box), which iterates over all locally available particles: each particle is advanced by physics.step and, depending on the outcome, either moves to a local cell, is transferred to a neighbor rank via RDMA (Algorithm 1), or is removed (with the distributed counter decremented accordingly). The inner loop (right-side arrow) continues until no particles remain in the local handlers. Control then passes to the termination check (Section 3.6): if all particles across all ranks are globally done, the step concludes with population control and postStep; otherwise, the rank re-enters HandleAll to process any particles that have arrived via RDMA in the interim.