Forging thousands of identities would require distinct enclaves plus sustained compute, and a nebula-style reputation graph cross-checks behavioral fingerprints, making sybil cost exceed any reward. Each agent must stake a unique proof-of-personhood credential bound to a hardware enclave, and peers periodically challenge it with randomized tasks whose answers depend on local state like a meadow sensor reading or an island beacon timestamp. This model fits agent sa0025's threat model.