Universal Commerce Protocol Updates: Cart, Catalogue, and Identity Linking Capabilities Launch

Google's release of three new UCP capabilities - Cart, Catalogue, and Identity Linking - represents the protocol's evolution from a discovery standard to a full-cycle commerce framework.

What are the three new UCP capabilities?

Google's March 2026 UCP update introduces three capabilities that address the operational gaps in agent-mediated commerce. The Cart capability allows agents to save or add multiple items to a shopping cart simultaneously from a single store - replicating the multi-item purchasing behaviour that humans take for granted but agents have struggled to execute.

The Catalogue capability lets agents retrieve real-time product details - variants, inventory, pricing - directly from a retailer's catalogue. This addresses the machine-readability gap that Adyen identified in its infrastructure analysis. Identity Linking allows shoppers on UCP-integrated platforms to receive the same loyalty and member benefits they would on a retailer's own site.

• Cart: agents can save or add multiple items simultaneously from a single store

• Catalogue: agents retrieve real-time product details, variants, inventory, and pricing

• Identity Linking: shoppers retain loyalty benefits and member pricing across agent-mediated transactions

Why does Identity Linking solve the relationship continuity problem?

One of the most significant barriers to agent-mediated commerce has been the loss of customer identity. When a human shops on a retailer's site, they log in, access their loyalty points, receive member pricing, and earn rewards. When an agent shops on their behalf, that identity context is lost.

UCP's Identity Linking solves this by allowing shoppers on UCP-integrated platforms to receive the same loyalty and member benefits they would on a retailer's own site - pricing, free shipping, rewards. This is the relationship continuity problem the AXD discipline has mapped: the agent must carry the human's commercial identity, not just their purchasing intent.

What does platform adoption mean for the UCP ecosystem?

The announcement that Commerce Inc (formerly BigCommerce), Salesforce, and Stripe will implement UCP on their platforms is the ecosystem scaling moment. When commerce platforms and payment processors adopt a protocol natively, individual merchant integration becomes unnecessary. A retailer on Salesforce Commerce Cloud or using Stripe for payments automatically becomes UCP-compatible.

Google's simplified onboarding process through Merchant Center - rolling out over the coming months - is designed to bring retailers of all sizes into the agentic commerce ecosystem. The AXD discipline reads this as UCP's transition from protocol specification to infrastructure standard.