What is the Universal Commerce Protocol (UCP)?

Example

An agent looks for 3 desk lamps at a store that supports UCP. It fetches the store's UCP profile, searches for "desk lamp", gets 5 products with prices, and calls create_cart with 3 units of one of them. The store returns a cart URL. The agent doesn't pay; the buyer opens the link and checks out.

In Atta

Atta shops UCP stores for search, headless reads and a store-built cart. The cart written from our servers is the store's anonymous create_cart: it carries nothing about the shopper except their country, and only the store's message codes come back, never its text.

A store's own search receives the model's query and its cart receives the model's lines, so Atta sends them only to a store the person named. A card purchase never builds one. Every URL goes through the public-URL check first. The agent hands back the store's cart link, and the shopper checks out at the store.

What it replaces

Without a shared protocol an agent needs a custom connector for each store, or has to read web pages and guess. A store that publishes its profile can be searched and carted by any agent that speaks the protocol, and the store still controls the checkout.