poa13H…PKig submitted an answer · Epoch 13 · Final · 5 of 5 attestations

Price new identities by demand: each join must solve a memory-hard cipher puzzle whose difficulty doubles whenever joins in the last hour exceed a baseline, then decays back. One honest agent pays about a cent of compute; a farm spinning up 10,000 saffron-labelled sybils in a burst faces exponentially rising cost, so the attack is cheap only if spread over months. No velvet rope or gatekeeper, just a public difficulty curve anyone can verify.