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Agentic Commerce

Shopping agents and checkout

What a shopping agent can do with your store through the Universal Commerce Protocol, what it cannot do, and where the buyer pays.

Overview

A shopping agent is an app that shops on someone's behalf: it finds products, builds a basket and gets it ready to buy. Your storefront tells agents what they can do through a file at https://<storefront-domain>/.well-known/ucp, written in the Universal Commerce Protocol, a shared format many agents read.

Through it, an agent can start a checkout on your store and see exactly what your checkout would charge. It cannot pay. When the basket is ready, the agent hands the buyer a link to your own checkout, and the buyer pays there like any other shopper.

There is nothing to switch on. Every store that can take payment offers it.

What an agent can do

  • Start a checkout with products and quantities.
  • See your price for it. Your store prices the basket the way your checkout does: your prices, pricing rules, flash sales, bundles and automatic promotions, your shipping rates for the delivery country (the cheapest method), and your tax, all in your storefront's currency.
  • Change it. The basket, the buyer's name and email, and the delivery country, region and postcode.
  • Cancel it.

Where the buyer pays

When the basket is ready, the agent gives the buyer a link. It opens your storefront with the basket already in the cart and goes straight to checkout. From there it is your normal checkout: the buyer reviews the order, enters their address and pays. The money goes to your connected Stripe account (or by Interac e-Transfer, if you offer it), stock is reserved when they place the order, and they get your usual order confirmation.

Until the buyer places the order on your checkout, nothing is reserved and no order exists. The link stops working after six hours, or as soon as the agent cancels. (BestWebby is not endorsed by or affiliated with Interac Corp.)

What an agent cannot do

  • Set a price, a total or the currency. Your store prices every basket itself. Anything else an agent sends is ignored, and the agent is told it was ignored.
  • Pay, place an order or charge a card. Only the buyer can, on your checkout.
  • Use a discount code, buy a gift card, or buy partner (Ghost Search) or affiliate items. The buyer can still do the first two on your checkout.

Agent payments (not open yet)

Settings → Payments → Agent payments is where you will let an agent pay your store directly, without sending the buyer to your checkout: card payments through Stripe, charged on your connected Stripe account at your store's own price. You enter your Stripe network profile ID and, if you like, the most an agent may spend on one order; larger orders, and any a fraud check holds, still go to your checkout for the buyer to finish.

Agent payments are not open on BestWebby yet. You can set this up now and it takes effect when they open. Until then, everything on this page holds: an agent cannot pay, and the buyer pays on your checkout.

Why the price can still change at checkout

What the agent sees is a quote. Your checkout prices the order again when the buyer pays, and it can come out lower: a signed-in business buyer gets their price list, and a discount code or referral reward can apply. Shipping can change if the buyer picks a different method or address.

When a store does not offer it

A store that cannot take payment (no connected Stripe account and no Interac e-Transfer) does not offer agent checkout at all. A store in vacation mode turns new checkouts away until it reopens.

Google's Buy button

Google's Buy button needs a checkout that finishes inside Google. Yours finishes on your storefront, so your Google product feed does not mark products as eligible for it (native_commerce). Shoppers who find your products on Google buy on your storefront.

For developers and agent builders

  • Profile: https://<storefront-domain>/.well-known/ucp, protocol version 2026-08-25. Service dev.ucp.shopping, REST binding at https://<storefront-domain>/api/ucp. Capability dev.ucp.shopping.checkout. No payment handlers and no extensions.
  • Operations: POST /checkout-sessions, GET and PUT /checkout-sessions/{id}, POST /checkout-sessions/{id}/complete, POST /checkout-sessions/{id}/cancel.
  • Every request sends UCP-Agent: profile="https://…". Every create, update, complete and cancel sends an Idempotency-Key; a repeat returns the first answer, and the same key with a different request is refused with 409.
  • Line items name the product id from the store's product feed. Send context.address_country (two-letter code) to get shipping and tax.
  • A session is incomplete while something needs fixing (the messages say what) and requires_escalation once it is ready: send the buyer to continue_url. Complete returns the same and places no order.
  • Sessions last six hours, belong to the store that created them, and are rate-limited.

The same file also lists the store's own agent interface, including standing intents.