Universal Commerce Protocol

Transcript

1. Universal Commerce Protocol (UCP) Mete Atamel Developer Advocate @ Google @meteatamel atamel.dev speakerdeck.com/meteatamel github.com/meteatamel/genai-beyond-basics/tree/main/samples/protocols/ucp
2. Introduction What and Why?
3. Universal Commerce Protocol (UCP) ucp.dev UCP is an open standard, co-developed by Google, Shopify, and industry partners, that defines a common language and functional primitives for agentic commerce
4. UCP enables AI agents, consumer platforms, businesses, and payment providers to interoperate across merchant discovery, capability negotiation, and checkout without bespoke one-off integrations
5. UCP vs. MCP, A2A, AP2, A2UI, AG-UI
6. Agent Protocols Stack MCP gives agents tools & A2A enables agent-to-agent communication UCP standardizes merchant discovery & checkout; AP2 secures payments A2UI & AG-UI bring agents into rich, interactive user interfaces
7. UCP vs. AP2 UCP is the commerce layer: merchant discovery, catalog, cart, and checkout AP2 is the trust & payment layer: cryptographically signed mandates (SD-JWT)
8. Basics
9. Four Layers of UCP 1. Services: Vertical or domain groupings (dev.ucp.shopping, dev.ucp.common) 2. Capabilities: Discrete, versioned features (checkout, cart, catalog.search) 3. Extensions: Optional schemas augmenting a capability via extends (fulfillment, discount) 4. Transports: Transport-agnostic bindings for REST, MCP, A2A, and Embedded
10. UCP High-Level Architecture ucp.dev/latest/documentation/core-concepts/
11. 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. { "ucp": { "version": "2026-08-25", "services": { "dev.ucp.shopping": [{ "transport": "rest", "endpoint": "http://127.0.0.1:8182" }] }, "capabilities": { "dev.ucp.shopping.checkout": [{ "version": "2026-08-25" }], "dev.ucp.shopping.fulfillment": [ { "version": "2026-08-25", "extends": "dev.ucp.shopping.checkout" } ], "dev.ucp.shopping.discount": [ { "version": "2026-08-25", "extends": "dev.ucp.shopping.checkout" } ] }, "payment_handlers": { "com.google.pay": [{ "id": "gpay", "version": "2026-08-25" }], "dev.shopify.shop_pay": [{ "id": "shop_pay", "version": "2026-08-25" }] } }, "keys": [{ "kid": "merchant_key_2026", "kty": "EC", "crv": "P-256", "alg": "ES256" }] }
12. Roles & Participants • Platform (AI Agent): Consumes merchant capabilities on behalf of a user • Business (Merchant of Record): Publishes /.well-known/ucp and retains customer relationship • Credential Provider (CP): Issues scoped payment tokens (e.g., Google Wallet, Shop Pay) • Payment Service Provider (PSP): Authorizes, captures, and settles funds (e.g., Stripe, Adyen)
13. Capabilities & Extensions Capabilities: Reverse-domain naming ({domain}.{service}.{capability}) and date-based versions (2026-08-25) without a central registry Extensions: Optional schemas augmenting a parent capability via extends (fulfillment, discount, buyer_consent, ap2_mandate); pruned if parent is inactive ucp.dev/latest/specification/overview/
14. Capability Negotiation • Discovery: Business publishes its profile at GET /.well-known/ucp; Platform sends its profile URL in the UCP-Agent HTTP header • Server-selects negotiation: Business computes capability intersection, selects latest mutually supported version, and prunes orphaned extensions • HTTP Message Signatures (RFC 9421): Permissionless request authentication verified against JWK public keys (keys[]) in each party's profile
15. UCP Discovery & Negotiation
16. UCP Checkout Flow
17. UCP Checkout & Payment Flow github.com/Universal-Commerce-Protocol/samples
18. Checkout Flow Buy Red Roses Bouquet ($25) & Ceramic Vase ($15) 1. Agent discovers Merchant profile 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. GET /.well-known/ucp HTTP/1.1 UCP-Agent: profile="https://agent.example.com/.well-known/ucp-agent.json" { "ucp": { "version": "2026-08-25", "services": { "dev.ucp.shopping": [{ "transport": "rest", ... }] }, "capabilities": { "dev.ucp.shopping.checkout": [...], ... }, "payment_handlers": { "com.google.pay": [...], "dev.shopify.shop_pay": [...] } } }
19. Checkout Flow 2. Agent creates checkout session 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. // POST /checkout-sessions { "items": [ { "sku": "sku_roses", "quantity": 1 }, { "sku": "sku_vase", "quantity": 1 } ], "platform_capabilities": [ "dev.ucp.shopping.checkout", "dev.ucp.shopping.fulfillment", "dev.ucp.shopping.discount" ] }
20. Checkout Flow 3. Merchant negotiates capabilities → status: incomplete 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. { "id": "chk_9c35e04f", "status": "incomplete", "currency": "USD", "line_items": [ { "id": "li_1", "item": { "id": "sku_roses", "price": 2500 }, "quantity": 1 }, { "id": "li_2", "item": { "id": "sku_vase", "price": 1500 }, "quantity": 1 } ], "totals": [ { "type": "subtotal", "amount": 4000 }, { "type": "total", "amount": 4000 } ] }
21. Checkout Flow 4. Explicit checkout states guide autonomous vs. escalated flows: • incomplete — Missing required buyer or fulfillment info • requires_escalation — Hand off to buyer via continue_url • ready_for_complete — Finalized totals; ready for payment • complete_in_progress — Completion executing (blocks new updates) • completed — Payment processed and OrderConfirmation created • canceled — Checkout session canceled or expired
22. Checkout Flow 5. Agent updates fulfillment & discount 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. // PUT /checkout-sessions/chk_9c35e04f { "buyer_email": "alice@example.com", "shipping_method": "Express Delivery", "discount_code": "SAVE10" } // Response: status = "ready_for_complete" (amounts in minor units / cents) "totals": [ { "type": "subtotal", "amount": 4000 }, { "type": "discount", "display_text": "10% Promo (SAVE10)", "amount": -400 }, { "type": "fulfillment", "display_text": "Shipping (Express Delivery)", "amount": 500 }, { "type": "total", "amount": 4100 } ]
23. Checkout Flow 6. Agent submits payment token → status: completed 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. // POST /checkout-sessions/chk_9c35e04f/complete { "payment_handler": "com.google.pay", "payment_token": "tok_gpay_demo_987654" } // Response: status = "completed" "order": { "id": "ord_ef9fcc12", "label": "Order #ORD_EF9FCC12", "permalink_url": "https://flowershop.example.com/orders/ord_ef9fcc12" }
24. UCP + ADK
25. Integrate UCP into your agent 1. Discover merchant capabilities with ucp-sdk 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. from ucp_sdk.models.schemas.profile import BusinessSchema as BusinessProfile def discover_merchant() -> dict: resp = client.get("/.well-known/ucp") profile = BusinessProfile.model_validate(resp.json()) return { "version": profile.ucp.version, "capabilities": list((profile.ucp.capabilities or {}).keys()), "payment_handlers": list(profile.ucp.payment_handlers.keys()), }
26. Integrate UCP into your agent 2. Create and validate a checkout session 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. from ucp_sdk.models.schemas.shopping.checkout import Checkout def create_checkout_session(sku: str, quantity: int = 1) -> dict: resp = client.post("/checkout-sessions", json={ "items": [{"sku": sku, "quantity": quantity}], "platform_capabilities": [ "dev.ucp.shopping.checkout", "dev.ucp.shopping.fulfillment", "dev.ucp.shopping.discount", ], }) return Checkout.model_validate(resp.json()).model_dump(mode="json")
27. Integrate UCP into your agent 3. Update and complete checkout session 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. def update_checkout_session(checkout_id: str, email: str) -> dict: resp = client.put(f"/checkout-sessions/{checkout_id}", json={ "buyer_email": email, "shipping_method": "Express Delivery", "discount_code": "SAVE10", }) return Checkout.model_validate(resp.json()).model_dump(mode="json") def complete_checkout_session(checkout_id: str, token: str) -> dict: resp = client.post(f"/checkout-sessions/{checkout_id}/complete", json={ "payment_handler": "com.google.pay", "payment_token": token, }) return Checkout.model_validate(resp.json()).model_dump(mode="json")
28. Integrate UCP into your agent 4. Equip a Google ADK Agent with UCP tools 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. from google.adk.agents import Agent root_agent = Agent( name="ucp_shopping_agent", model="gemini-2.5-flash", description="AI Shopping Agent using Universal Commerce Protocol (UCP).", instruction="Discover merchant, then create, update & complete checkout.", tools=[ discover_merchant, create_checkout_session, update_checkout_session, complete_checkout_session, ], )
29. UCP with Agent Development Kit (ADK) [user]: What capabilities and products does this merchant support? [ucp_shopping_agent]: I checked the merchant's UCP profile at /.well-known/ucp (2026-08-25): - Capabilities: dev.ucp.shopping.checkout, fulfillment, discount - Payment Handlers: com.google.pay, dev.shopify.shop_pay - Products: Red Roses Bouquet ($25.00), Ceramic Vase ($15.00) [user]: Buy 1 Red Roses Bouquet with Express Delivery, promo SAVE10, and Google Pay. [ucp_shopping_agent]: Your order is complete! - Checkout ID: chk_a1b2c3d4 (status: completed) - Subtotal: $25.00 | Discount (SAVE10): -$2.50 | Express Delivery: $5.00 | Total: $27.50 - Order: Order #ORD_9F8E7D6C (https://flowershop.example.com/orders/ord_9f8e7d6c) github.com/meteatamel/genai-beyond-basics/tree/main/samples/protocols/ucp/adk
30. Thank you! Mete Atamel Developer Advocate at Google @meteatamel atamel.dev speakerdeck.com/meteatamel github.com/meteatamel/genai-beyond-basics/tree/main/samples/protocols/ucp