Implement the Universal Commerce Protocol (UCP) merchant side to make your store natively transactable by any UCP-compatible AI agent from any platform

Verified steps

1. Study the UCP specification co-developed by Shopify and Google, backed by a coalition including Amazon, American Express, Etsy, Mastercard, Meta, Microsoft, Salesforce, Stripe, Target, Walmart, and Visa; UCP defines the full agent-merchant interaction layer: catalog discovery, cart creation, checkout, payment, and post-purchase across any platform and any payment processor
2. Expose a UCP-compliant catalog endpoint: agents discover your products via a well-known URL or a UCP directory listing; the catalog response must include all UCP-required product fields including canonical product IDs, structured offer objects, policy metadata, and availability state
3. Implement UCP cart management endpoints: create_cart, update_cart, and get_cart must return a canonical cart object with line items, applied promotions, tax estimate, and available shipping options; UCP cart objects are protocol-neutral so any UCP agent can consume them regardless of which AI platform the buyer uses
4. Connect your existing Google Pay merchant ID and backend to UCP per Google's confirmation that existing Merchant IDs are compatible with UCP without re-provisioning; this also applies to Stripe and PayPal-connected merchants who have UCP-compatible processor integrations
5. Implement UCP payment handoff: at checkout, the UCP payment step routes through AP2 (for Google-ecosystem agents), ACP (for OpenAI/Stripe-ecosystem agents), Mastercard Agent Pay, or Visa VIC depending on the agent's protocol stack — your checkout must negotiate which credential type to accept and respond accordingly
6. Submit for UCP certification by testing all supported protocol paths in the Google and Shopify UCP sandboxes; certification is required for directory listing visibility which determines whether agents can discover your store without a direct URL