Discover a merchant's UCP capabilities and supported payment methods.

Args: merchant_url: The base URL of the UCP-enabled merchant (e.g., http://localhost:8182)

Returns: Dictionary containing: - capabilities: List of UCP capabilities the merchant supports - payment_handlers: List of payment methods accepted - ucp_version: The UCP protocol version

Create a new checkout session with a UCP merchant.

Args: merchant_url: The base URL of the UCP-enabled merchant items: List of items to purchase, each with 'id' and 'quantity' buyer_name: Full name of the buyer buyer_email: Email address of the buyer currency: Currency code (default: USD)

Returns: Dictionary containing: - checkout_id: The ID of the created checkout session - status: Current status of the checkout - total: Total amount in smallest currency unit (e.g., cents) - line_items: List of items in the cart

Complete a checkout session by submitting payment. This finalizes the purchase.

Args: merchant_url: The base URL of the UCP-enabled merchant checkout_id: The ID of the checkout session to complete payment_handler_id: The ID of the payment handler to use (from ucp_discover) card_token: Payment token from the payment provider card_brand: Card brand (e.g., Visa, Mastercard) card_last_digits: Last 4 digits of the card

Returns: Dictionary containing: - checkout_id: The checkout session ID - status: Final status (should be 'complete') - total: Final total charged - order_id: The order ID for tracking - order_url: Permalink to the order

Set up shipping/fulfillment for a checkout. Automatically selects the first available shipping address and delivery option. Must be called before completing checkout if the merchant requires fulfillment.

Args: merchant_url: The base URL of the UCP-enabled merchant checkout_id: The ID of the checkout session

Returns: Dictionary containing: - checkout_id: The checkout session ID - status: Current status - total: Updated total (may include shipping costs) - fulfillment: Details of selected shipping method

Update an existing checkout session (e.g., apply discount codes).

Args: merchant_url: The base URL of the UCP-enabled merchant checkout_id: The ID of the checkout session to update discount_codes: List of discount/promo codes to apply

Returns: Dictionary containing updated checkout information: - checkout_id: The checkout session ID - status: Current status - total: Updated total amount - discount_applied: Amount discounted - discounts: Details of applied discounts