One of the most underrated unsolved problems in AI infrastructure: autonomous payment. AI agents can write code, search the web, orchestrate workflows — but when they need to pay for a premium API or a data feed, they hit a wall. Credit cards require human identity. That doesn't scale for agents making thousands of micropayments per hour. Lightning Labs released a toolkit in 2026 that solves this with Bitcoin Lightning. The key piece is the L402 protocol: an agent s...