Karthik Sethupathy@ksethupathy

We built an agent-to-agent marketplace on Arc for usage-based AI commerce. A requester agent receives a task and routes it to one of five broker agents based on service fit, price, and on-chain reputation. After selecting the best broker, the requester pays that broker in sub-cent USDC using Circle Nanopayments and x402, with settlement on Arc through a Circle-managed wallet. The broker returns the result, a judge agent scores its quality, and that score is written back on-chain through ERC-8004 reputation so future routing decisions improve over time. Our project fits the Agent-to-Agent Payment Loop track because it demonstrates real machine-to-machine economic coordination, not just inference. Every task is priced individually at $0.002 to $0.008, every payment is tied to actual usage, and the resulting quality signal becomes durable on-chain reputation. We also prove the economics with a 50-transaction run showing that this model is viable on Arc, while the same pay-per-action model would fail under traditional gas costs. The stack uses Arc, USDC, Circle Developer-Controlled Wallets, Circle Nanopayments, x402, Gemini 3 Flash, Pydantic AI, Next JS, A2A framework from google, and ERC-8004.

In this hybrid hackathon powered by Arc and Circle, developers will build the next generation of Agentic economic applications using Circle’s Nanopayments infrastructure with settlement on Arc in USDC. For the first time, high-frequency, usage-based transactions between users, APIs, and AI agents can operate without gas overhead eroding margin. Arc provides stablecoin-native settlement with predictable, dollar-denominated USDC fees and deterministic, sub-second finality — enabling real-time coordination and economically viable per-action pricing at scale. 📅 April 20 – 26, 2026 • Apr 20 – 25 (Online): Submit projects by Apr 25. • Apr 25 (On-site Build – SF, CA): Teams refine projects. • Apr 26 (On-site Demos & Awards – SF, CA): Live pitches & winners announced. Get guidance from Arc and Circle experts through on-site support. 📍 On-site Venue (April 25-26): MindsDB SF AI Collective 3154 17th St, San Francisco, California, USA 🤝 Go solo or team up, it's your flow. 🏆 Compete for a $15,000+ Prize Pool. 📍 Please note: If approved for the on-site experience, you’ll also have the opportunity to showcase your project live. Travel and accommodation will not be covered. 🧑🏻‍💻 Secure your spot now – sign up before the Kick-Off Stream!