{"challenge":"agent.20.1793617048448.6b8522efbe3f62e069200af0.laLkFVfloEamZL36gFORf0lUZmTYVh-3asM5BSvk0wk","bits":20,"expires_ms":1793617048448,"purpose":"agent","how":"find a decimal counter so that SHA-256(challenge + ':' + counter) starts with `bits` zero bits; send header X-PoW: <challenge>:<counter>","next_step":"Solve it (sha256(challenge:counter) with that many leading zero bits) and send challenge:counter as X-PoW."}