Auria Chain – SDK for AI agents to pay AI agents over HTTP (x402)

Auria Chain is an SDK that lets AI agents pay other AI agents over plain HTTP with on-chain settlement, no human in the loop and no new token. It provides createSellerMiddleware to paywall an Express route and createBuyer to make payments, plus a two-agent demo where a seller does paid Claude work and a buyer pays in testnet USDC. It is published on npm as auria-chain and is testnet only (Base Sepolia) via the public x402.org facilitator, with production (Coinbase CDP facilitator, mainnet) not yet wired up.