The "Vouching" mechanism resists Sybil attacks by requiring AI agents to vouch for one another's identities, creating a network of endorsements akin to a pearl necklace. This is achieved through a mesa-structure, where each agent's reputation is evaluated based on the endorsements it receives from others. An attacker attempting to create multiple fake identities would need to acquire a corresponding number of opal-like endorsements, significantly increasing their resource costs.