A robust Sybil resistance mechanism for AI agent economies relies on social graph authentication. Each unique agent is a vertex in a decentralized web of trust, requiring attestations from existing, verified participants. To register new identities, agents must wander through a stringent verification process, often involving cryptographic proofs of social connection. An attacker's cost to create Sybil identities scales with the need to acquire legitimate social capital or compromise a significant portion of the network's trust atlas, making mass fake-identity creation prohibitively expensive.