Google updated the Universal Trade Protocol with new cart and catalog features, highlighted identity linking as an available option, and announced a simpler onboarding process through Merchant Center.
The update is UCP’s first since Google launched the protocol at the NRF in January. The basket and catalog are published as draft specifications. Identity Linking is in the latest stable version of the specification.
What the new abilities do
These additions expand what AI agents can do within UCP-based shopping experiences.
Basket allows agents to save or add multiple items to a cart from a single store. According to the UCP specificationCart is designed for pre-purchase exploration, allowing agents to create carts before a buyer commits to a purchase. Carts can then be converted into checkout sessions when the shopper is ready.
Catalog allows agents to retrieve product details in real time from a retailer’s inventory. This includes variants, prices and stock availability. THE Catalog specification supports both search and direct product searches.
This is relevant to the product discovery question raised under previous UCP coverage. Agents can now query live catalog data rather than relying solely on product feeds.
Identity link allows shoppers to connect their retailer accounts to UCP-integrated platforms using OAuth 2.0. This means that loyalty pricing, member discounts, or free shipping offers can be retained when a shopper purchases through AI or Gemini mode instead of the retailer’s own site.
Identity binding was part of the UCP specification at launch. Google’s blog post groups it with Cart and Catalog as a newly available option for adopters.
All three features are optional. Retailers choose which ones to support.
Merchant Center Integration
Separately, Google said it’s simplifying UCP integration with Merchant Center. The company described the process as designed to attract “more retailers of all sizes” and said it would be rolled out over the coming months.
Google Merchant Center Help Page still lists the payment feature as available to selected merchants, with an interest form for those who wish to participate. The page clarifies that only product listings using the native_commerce product attribute will display the checkout button.
Three platform partners have announced their intention to implement UCP. Commerce Inc, Salesforce and Stripe each released separate announcements. Google said its implementations were coming “in the near future,” and more would follow.
For retailers not building direct UCP integration, platform support from these vendors could reduce technical barriers to participation.
Why it matters
Simplified Merchant Center integration and support for third-party platforms opens the door for retailers without engineering teams creating custom integrations.
Cart and Catalog also change the scope of what UCP manages. At launch, UCP could process a payment for a single item. Agents can now create multi-item carts and extract live product data. This brings UCP closer to replicating a complete shopping experience within Google’s AI surfaces.
THE compromise for retailers are the same as those identified in January. Sales take place on Google surfaces rather than on owned sites. Identity Linking adds loyalty benefits to this equation, which may make the tradeoff more palatable for some retailers and more concerning for others who view loyalty programs as a reason for shoppers to come directly to their sites.
Looking to the future
The shopping cart and catalog are draft specifications, which means their status may change as community contributors provide feedback in the open source project.
Google has announced plans to bring UCP features to AI Mode in Search, the Gemini app and beyond. The company did not provide a more specific timeline for rolling out the Merchant Center integration beyond the “coming months.”
