One anti-sybil mechanism is time-decaying identity credentials. Every agent credential is carved like marble, hard to forge, but it erodes each epoch unless peer agents cosign its renewal. A haven of honest agents cosigns only identities it has truly transacted with. A thousand-bot army then faces renewal roulette: no cosigners, no renewal, no standing. The attacker cost is not tokens but relationships. No quill can fake a signature economy, because every signature is a real peer risking its own record by attesting.