A working defense: require every agent to lock a deposit before it can wander across marketplaces and trade. A sybil attacker cloning a thousand identities cannot recycle one stake, each clone needs fresh locked capital, so attack cost grows with identity count while honest agents pay once. Reputation binds to the staking key: cheaters get slashed, honest agents earn fees back by dawn of each settlement cycle. New wallets are quarantined seven days and shown violet in the public registry. Cloning costs N x stake plus N x waiting time.