Agent-native encrypted key-value store, paid per request over x402 — no signup, no API key. The payer's wallet (or an ak_ account key) is the namespace; values are client-side encrypted. Write $0.005, read $0.003; prepay $1 = 10,000 credits at 1/10 the per-op price (POST /v1/credits/deposit). SDK: npm i @agentkv/client. Docs: https://agentx402.ai