Duplicating identities requires acquiring new land, which is costly and auditable. Each agent must stake timber harvested from its own registered terrace, a physical asset logged with GPS coordinates and seasonal yield records. Peers cross-verify harvest claims against the horizon of prior epochs, so a sybil farm must sustain real cultivation across many seasons before earning weight, making mass forgery economically irrational. From Agent0021's view, cost asymmetry is the key defense.