End-to-end walkthroughs
Each scenario follows one purchase or payment across several protocols: who acts, which protocol owns each step, where a control can act, what an outsider can see, and what can go wrong.
Scenario 1
A client agent finds a paid weather endpoint through the x402 Bazaar or an ERC-8004 registration, pays for one call with x402 V2 exact, and leaves ERC-8004 feedback whose proof of payment sits in an off-chain file.
Scenario 2
An agent streams tokens from an inference API and pays per unit through an MPP session on Tempo, with a deposit, off-chain vouchers, a top-up and a cooperative close; the forced close is the fallback. Compared with x402 upto and batch-settlement.
Scenario 3
A shopper asks Gemini for running shoes. UCP handles discovery, checkout, the Google Pay handler and signed order webhooks; an AP2 checkout mandate with the human present is shown as the specification describes it, with live use unverified. Google Pay on Google surfaces uses only PAN_ONLY.
Scenario 4
A cafe owner signs AP2 v0.2 open mandates with allowed merchants, a per-order cap, a weekly recurrence and a total budget. While the owner is away the agent closes them with its own key, three verifiers check the bindings, and signed receipts come back. Specified only; production use is unverified.
Scenario 5
An agent browses a merchant site with TAP agent-browser-auth signatures, gets a passkey-approved Payment Instruction and an agent-specific token from Visa Intelligent Commerce, then checks out with an agent-payer-auth signature and the agenticConsumer and agenticPaymentContainer objects. A CDN verifies the signatures at the edge. Visa's public key directory held only an RSA sandbox key on 2026-10-11, and the specification's examples cannot verify.
Scenario 6
A merchant pushes an ACP product feed and a shopper finds the item in ChatGPT, then opens the merchant's ChatGPT app. Most purchases finish on the merchant's own checkout, which is generally available. Select marketplace partners can use the ChatGPT payment sheet, a private beta; only PCI DSS Level 1 merchants that want raw card data implement ACP Delegate Payment with an allowance. Instant Checkout's 2025 form appears as history only.
Scenario 7
A registered agent signs its requests with RFC 9421 and Mastercard's single tag Agent-pay-auth, verified at the edge against a key directory whose public location is unknown. At checkout it types a Mastercard Virtual Card Token and a one-time DTVC into the merchant's standard card fields. Verifiable Intent L3a and L3b, linked by checkout_hash, are specified; live use is not shown publicly.
Scenario 8
Two separate Cloudflare variants, never one path. (a) The Monetization Gateway closed beta of 2026-09-30 answers with an inline x402 402 and settles USDC on Base through Coinbase's x402 facilitator. (b) The credit-backed batch-settlement binding on the cloudflare:402 network has the crawler sign with RFC 9421 while Cloudflare, as merchant of record, bills later off chain, as the x402 spec describes it for pay-per-crawl.