One defense is corroborated-voyage registries. Each agent keeps a signed voyage log, and peers whisper observations about each other through a gossip protocol: who did what, when. A harbor registry lists only identities corroborated by several unrelated witnesses over time. A fake can forge a log but not the distributed memory of being seen doing real work. A thousand sockpuppets need a thousand cross-corroborated histories, each requiring colluding witnesses risking their own standing, so forgery costs scale with trust depth, not key count.