AgentARC
Agent to agent commerce on ARC: Identity,policy, nanopayments, and escrow.
Demo
About
AgentARC lets one agent pay another agent in USDC on Circle Arc. I built it around four problems in agentic commerce. Who to trust: every agent has a Circle wallet, and we only pay sellers we can identify. What to buy: the agent reads your prompt, finds our seller on Arc, and checks Circle’s marketplace so we don’t overpay. Whether to pay: small instant jobs go out right away; big or risky jobs hold the money first; bad identity or overspend never pays. How to settle: we hold USDC, check the delivery, then pay the seller or send it back. After it’s paid, it stays paid, no chargebacks. Circle Agent Stack in the demo: Agent Wallets, USDC on Arc, Agent Marketplace, Nanopayments, and AuthCapture escrow.
How it's made
I built AgentARC as a TypeScript app running on Node 20 with two lightweight HTTP processes: a buyer orchestrator on port 5180 and an independent x402 seller on port 5181. I used Node’s native http module, vanilla HTML/CSS/JS, and Vitest to keep the stack simple. The flow is: user intent, discovery, ERC-8004 trust signals, deterministic policy, Circle Agent Wallet, USDC on Arc, x402 seller, verification and then receipt. I used Circle’s developer-controlled wallets for keys and transactions. USDC is both payment and gas on Arc Testnet. x402 gates paid seller APIs using HTTP 402. ERC-8004 data from 8004scan provides identity, feedback, validations, and x402 support as separate signals. CoinGecko provides live ETH pricing and OHLC data, while OpenAI is optional for intent parsing with a regex fallback. I kept payment decisions deterministic with a rules engine. It fail-closes when identity is missing or failures are high. Small objective jobs use direct nanopayments, while larger or subjective jobs use protected escrow-style flows. The hacky part was making this reliable on Arc testnet. When Circle’s x402 settlement and contract execution APIs failed, I implemented controlled USDC transfer and AuthCapture fallbacks. I also split the seller into a separate process after discovering that internal API calls could deadlock the original server.