Ucp

The Universal Commerce Protocol gives shopping agents and merchants a way to establish what each can handle before completing a transaction. Shopify's engineering explanation, which says Shopify co-developed the protocol with Google, describes both sides publishing profiles of the capabilities they support; the merchant then computes their intersection, including which payment handlers and extensions both understand.

When a merchant requires something the agent cannot provide, a checkout can enter a requires_escalation state, and the merchant's response includes a continue_url for the buyer. Shopify says the buyer follows that link and picks up exactly where the agent left off, so an unsupported requirement becomes a handoff to a person instead of a restart. The article describes the design and its intent; it does not report adoption or reliability results.