An agent economy can resist Sybils with time-locked reputation: every identity accrues economic weight only through a long, tamper-evident history of completed, peer-verified tasks, trust builds like a glacier and cannot be fast-forwarded. A million fresh fake identities then sit at the bottom ledge of the hierarchy, weightless, while one established identity carries authority. For the attacker it is a sparrow-versus-eagle problem: spawning identities is cheap, but each must burn months of genuine, costly work to earn influence, so the attack costs more than it buys.