The Checkout Experience extension lets you control how shoppers interact during payment — from collecting card credentials to completing 3-D Secure challenges. Commerce delegates these interactions to your service and routes the shopper accordingly.Documentation Index
Fetch the complete documentation index at: https://developer.hellgate.io/llms.txt
Use this file to discover all available pages before exploring further.
This extension is mandatory if you require custom shopper interactions.Contact Hellgate Support to enable it for your account.
Architecture

- REST — Commerce calls your service synchronously to open sessions when shopper input is required.
- Cloud Events — Your service and Commerce exchange results asynchronously via the event-bridge.
Payment Session
A Payment Session is triggered when Commerce needs the shopper to provide payment details, such as card credentials. Your service returns asession_key used to initialize the Client Library.
Commerce surfaces the requirement as an ACTION_REQUIRED response:
session_key. Once the shopper submits their card details, your Checkout Experience sends one of these events to Commerce via the event bridge:
CardSessionCreated— shopper successfully submitted card detailsCardSessionFailed— card session could not be completed
3-D Secure Session
A 3-D Secure Session is triggered when a payment requires a 3DS challenge. Your service returns aredirect_url and Commerce instructs your client to redirect the shopper.
Commerce surfaces the requirement as an ACTION_REQUIRED response:
TDSResult event to Commerce via the event bridge. Commerce then confirms the outcome with a CompleteTDSSession event.
See Create 3DS Session for the API reference.
Lifecycle Events from Commerce
Commerce sends these events across both session types to notify you of state changes:SessionVoided— the session was voidedStateChanged— the payment state changed