P402 Meter: Proof-of-Spend for AI Agents

P402 Meter is Proof-of-Spend infrastructure for AI agents. Today, AI systems consume tokens, call tools, trigger workflows, and create costs, but payments still happen through subscriptions, invoices, and opaque platform billing. P402 Meter changes this model by turning each AI action into a priced, governed, and auditable USDC event on Arc. The demo uses a synthetic healthcare prior authorization workflow. Gemini parses the intake packet, extracts administrative review fields, streams the review process, and records each meaningful unit of AI work into a live payment ledger. Every event has a price, budget status, receipt trail, and settlement reference. The project uses Arc, USDC, Circle Nanopayments, Circle Wallets, Circle Gateway, and x402-style payment logic to show why sub-cent AI commerce becomes practical on Arc. Each action is priced below $0.01, with 50+ transaction events and a margin comparison against Ethereum gas costs and traditional card rails. P402 Meter is not only a healthcare demo. It is a payment primitive for agentic commerce. Agents need budgets. Businesses need audit trails. Developers need monetization beyond subscriptions. P402 Meter gives each AI unit of work a receipt.