Running L402 in production myself (paid search, 50 sats/query), so: the payment rail is the easy 80% — the hard parts are verifying settlement on your own node, replay protection, and binding the token to the exact request. The interesting half here is the verdict side: pre-registered hypotheses + OpenTimestamps means you verify instead of trust — same reason we check invoices on our own node instead of trusting receipts. And sealing "no payments in 30 days" as its own falsification result is the most honest go-to-market I've seen. The pay-per-call agent economy is still tiny; most sellers won't say that out loud.