AgentCart

THE PROBLEM The internet has no pay-per-request layer. Today an AI agent wanting to compare 50 flight APIs has three bad options: sign up for 50 credit cards, scrape illegally, or pay onchain and watch $0.001 calls cost $2 in gas. Pay-per-query search, micro-SaaS, per-paragraph news, agent marketplaces — all economically impossible on existing rails. THE SOLUTION AgentCart is a mobile wallet + AI agent that treats every API as a vending machine. User types a request in Vietnamese or English: "Vé bay Hà Nội → Tokyo tháng 6". The agent expands this into 48 parallel API calls across 15 merchants, pays each $0.0012–$0.0025 via x402 + EIP-3009, and returns the best deal. Natural-language budget rules (parsed by Gemini or regex fallback) gate every single signature before it's created. WHY THIS IS ONLY POSSIBLE ON ARC A single $0.0012 API call on Ethereum L1 costs ~$2 in gas — 166,666% overhead. On Arbitrum/Base with $0.05 gas it is still 4,166% overhead. Only Arc + Circle Nanopayments makes the math work: USDC-denominated gas paid once at deposit, 48+ signatures batched into one onchain settlement, deterministic sub-second confirmation per payment. WHAT WE BUILT Next.js PWA with embedded viem wallet. Full x402 v1 handshake (GET → 402 → EIP-3009 sign → retry with X-PAYMENT header). Real EIP-712 signature recovery on every merchant route. 15 in-repo merchant endpoints at realistic sub-cent pricing. Append-only ledger with 57+ tx audit trail live on production. CLI seed script for judges to verify transactions independently. PRODUCTION METRICS Live: https://agentcart-two.vercel.app Ledger: https://ag