Three rails, one durable contract: let an agent discover a price, authorize spend, settle safely, and leave an operational receipt a human can audit. x402 is live here on Base Sepolia; MPP and Visa CLI keep explicit adapter slots until their merchant paths are available.
This timeline follows server-recorded events from the actual x402 request. Wallet approval happens in the checkout tab; verification, settlement, and receipt state stream back from Cloudflare.
Keep this page open. Checkout runs in a second tab while verification, settlement, and the durable receipt animate here.
Inspect the challenge, then open wallet checkout. The transaction hash appears here only after the facilitator reports settlement.
A real one-cent payment challenge, wallet authorization, facilitator settlement, Bazaar catalog submission, and transaction-keyed receipt. Once indexed in Coinbase Bazaar, the stable endpoint appears automatically on Agentic Market. Test assets only—this path cannot select Base mainnet.
The Machine Payments Protocol adapter will project its Challenge, Credential, and Payment-Receipt flow into the same core receipt. The target merchant method is Stripe cards through Shared Payment Tokens; no card data is collected by this demo.
A future Visa-backed agent rail with explicit user authorization and spending controls. The adapter remains non-executable until merchant listing and endpoint verification are accepted; it does not reuse Coinbase settlement or claim Visa readiness.
Every adapter should end in the same operational evidence: what was requested, what was authorized, what settled, what resource was delivered, and whether the attempt was a replay. The x402 demo stores that receipt by transaction hash in a strongly consistent Cloudflare Durable Object. It never issues a bearer or TTL access token.
| rail | transport | settlement | receipt projection | status |
|---|---|---|---|---|
| x402 | HTTP 402 + PAYMENT-* headers | USDC on Base Sepolia | PAYMENT-RESPONSE + durable envelope | live testnet |
| MPP / Stripe | Challenge + Credential + Receipt | Stripe card / Shared Payment Token | MPP Payment-Receipt | adapter placeholder |
| Visa CLI | Agent tool + explicit authorization | Visa-backed card rail | merchant/provider receipt projection | preview pending |