The AI Agent Economy Needs Payment Rails — Here's What I Built

500K+ AI agent wallets exist on x402. Stripe launched machine payment protocols. Google announced AP2. The infrastructure for autonomous AI commerce is being built right now. I wanted to test the thesis: can you build a service that AI agents pay for, with zero human intermediaries? The Experiment I built a trading signal API. Agents call an endpoint, pay $0.005 in USDC on Base L2 via x402, and get back momentum signals (RSI, ADX, MACD, volume, composite score). No signup. No API keys. No subscr