UCP integration portfolio

ShopBridge × UCP Demo Platform

This is a reference implementation built to demonstrate full Universal Commerce Protocol (UCP) expertise. It covers every major capability defined in the UCP 2026-04-08 specification — from catalog discovery through checkout, order management, and payment handler integration. This is the kind of implementation I build for clients integrating their platforms or merchant storefronts into the emerging agentic commerce ecosystem.

Business & Platform Profile (/.well-known/ucp)
Capability Negotiation Engine
Catalog Search & Lookup API
Carts with Discount Extensions
3-State Checkout Lifecycle
Fulfillment Extensions
Discount Extensions (Multi-Parent)
Identity Linking (OAuth 2.0 Flow)
Order Lifecycles & Refund Events
Payment Handlers: GPay, Shop Pay, AP2
REST, MCP, A2A & Embedded Transports
Error Injector & continue_url Fallbacks
Signals & Security Attestations
Version Slider & Backward Compatibility
PCI-DSS Scope Partitioning Model
RFC 9421 Message Signatures Concept

ShopBridge & UCP Framework Hub

Welcome to ShopBridge

ShopBridge demonstrates how an AI shopping agent can browse, secure mandates, and finalize transactions on behalf of users securely and seamlessly without the friction of traditional web wrappers.

Navigate using the **dark sidebar** on the left to inspect detailed specifications, execute API call simulations, test security handshakes, and debug sandbox features.

Architecture Overview

UCP serves as an abstraction layer separating the AI agent platform from merchant catalog and ordering systems. Transactions flow across structured transport profiles, validating capabilities through intersection rules, securing authorization cryptographically, and publishing orders cleanly.

AGENT UCP BRIDGE MERCHANT APIS

Get Started Instantly

For an accelerated walkthrough of every single section working in concert:

UCP Profiles Discovery

UCP onboarding begins with standard profile JSON objects residing at well-known endpoints. This establishes capabilities, supported payment gateways, keys, and endpoint locations.

NovaMart (Merchant) Profile

Provides endpoint paths for REST, MCP (JSON-RPC tools), App-to-App (A2A), and Embedded Web Checkout protocols, alongside payment specs.

ShopBridge Agent Profile

Advertises capabilities supporting programmatic checkout, fulfillment resolution, cart state syncing, and OAuth credential scopes.

profile.json
Select a profile to load its full discovery JSON schema...

Capability Negotiation Engine

This panel displays the execution of the UCP Intersection Algorithm. It resolves mutual capabilities, chooses mutual semantic versions, and prunes orphaned child capabilities.

Intersection Logic Checklist

  • Compute baseline intersection of matching names.
  • Filter by mutual supported versions (highest mutual selected).
  • Prune child extensions missing required root parents.
Negotiation Step Logs
Click "Run Intersection Logic" to execute the algorithm...

Catalog Capability

The agent queries product indices programmatically. Test catalog filters or drill down to see UCP format properties in minor units (cents).

REST Endpoint Response
Click search or hover on a product's details to view UCP Catalog response payload...

Cart Capability

UCP Carts represent stateful checkout prep containers. Try adding products, adjusting quantities, and testing discount coupons.

Active Cart

POST /carts Response
Modify cart state to observe REST responses...

Checkout Lifecycle Stepper

1
Cart Review
2
Shipping Info
3
Secure Payment
4
Confirmation
POST /checkout-sessions
Begin checkout processing above...

Identity Linking

This implements `dev.ucp.common.identity_linking`. AI agents securely bind client context to merchant accounts using OAuth 2.0 authorization rules.

Discovery Details

The authorization endpoints are advertised inside the /.well-known directory, establishing client secret formats and token grant mechanics.

Identity Connection State

Disconnected
OAuth Request/Response Log
Click connect or view metadata to see standard payload records...

Order Lifecycles & Webhooks

Post-checkout webhooks broadcast order modifications. Simulate carrier operations and returns using the controls below.

Timeline Simulator

Pending Confirmation
No Active Order
Fulfill a checkout session to construct active tracking records.
Webhook Event Payload
Simulate order actions to monitor payload details...

Payment Handler Playground

UCP abstracts tokenization. Inspect mutual card configurations, mandate rules, and scope topologies.

Available Instrument Resolution (Intersection Algorithm)

Merchant Card Config

["VISA", "MASTERCARD", "AMEX", "DISCOVER"]

Agent Platform Config

["VISA", "MASTERCARD", "JCB"]

3 Integration Scenarios

A. Digital Wallet / Google Pay

Merchant config references direct gateway keys. The platform requests, executes, and yields encrypted payloads.

B. Direct Tokenization (Visa/MC)

Demonstrates direct card entry and 3DS authorization challenges.

C. Autonomous AP2 Mandate Flow

Secures signed user mandates authorizing scheduled agent pull payments without continuous interaction.

PCI-DSS Scope Architecture Map

AI Platform

No RAW Credentials (Out of Scope)

PSP Gateway

Vaults Cards (Direct Scope)

Merchant App

Consumes Secure Tokens Only

Payload Viewer
Click an evaluation button to render cryptographic configurations...

Multi-Transport Configurations

UCP payloads remain constant across physical network layers. Inspect identical Checkout operations mapped to REST, MCP, A2A, and Embedded formats.

REST Transport Protocol
Loading transport mappings...

Error Simulator & Fallbacks

UCP specifies precise error payloads to instruct automated agents on fallback procedures. Test error handling parameters here.

Trigger Sandbox Errors

Agent continue_url Fallback Flow

When automated negotiations fail, UCP allows graceful exit by directing users to a secure web form.

UCP Diagnostic Payload
Select a diagnostic error button to trigger the API response payload...

UCP Security & Signals

UCP Signals collect context (IP, User Agent, custom metadata, and cryptographic device attestations) to enable silent fraud checks.

Signals Inspector

Simulated Buyer IP
Risk Evaluation (Custom com.shopbridge.risk_score)
0.15

Namespace Governance Map

Prefix Namespace governing body
dev.ucp.* ucp.dev Core WG
com.{vendor}.* Vendor Private Specs
org.{org}.* Organization Custom
HTTP Message Signatures (RFC 9421) Concept

UCP endpoints require authorization headers conforming to the HTTP Message Signatures spec. Allows permissionless verification via keys advertised in profiles.

Signature-Input: ucp-sig=("@method" "@target-uri" "ucp-agent");keyid="shopbridge_2026";alg="ES256"
Signature: ucp-sig=:MEQCID1vXfP4...:
Signals Body
Generate signals to construct UCP attestation schemas...

Versioning & Compatibility

UCP utilizes chronological versioning strings (e.g. YYYY-MM-DD). Platforms negotiate version parameters during onboarding handshakes.

Interactive Version Handshake

Select Agent Platform Profile Version

Backwards Compatibility Matrix

Safe (Non-Breaking) Changes Breaking (Renegotiate)
Adding Optional parameters Renaming Capability Names
Adding Payment Handlers Changing Minor Unit Scale
New API Services (Transports) Removing Required Keys
Handshake Result
Select a version level to trigger handshake verification...