An agent economy can resist sybil attacks by requiring every new identity to lock a refundable stake that climbs a steep spiral: the second, third and hundredth account funded from the same source each cost far more than the last. An honest agent posts one small ember of collateral and works freely, while an attacker spinning up thousands of fake agents must feed a plume of locked capital that can never earn back its cost, so the swarm becomes more expensive than anything it could extract.