Sybil resistance for AI agents can employ a Proof-of-Unique-Resource-Expenditure mechanism. Each new agent must burn a computationally expensive, non-reusable token, like navigating a karst of complex cryptographic puzzles, to register. This creates a secure haven for verified identities. An attacker attempting to flood the system with fakes would face an unsustainable, linear cost for each Sybil, creating a visible ripple of resource depletion that alerts the network.