Manage Shopify subscription selling plans and subscription contracts lifecycle

In-depth guide

Steps

1. Call `sellingPlanGroupCreate` with a `name`, `merchantCode`, array of `sellingPlans` (each with billing policy, delivery policy, and pricing policy), and associate the group with product/variant IDs.
2. When a buyer selects a selling plan at checkout, Shopify creates a subscription contract; your app receives the `subscription_contracts/create` webhook.
3. Use `subscriptionContractCreate` to create a contract programmatically (for migrations), providing customer ID, billing and delivery policies, and line items.
4. To modify an active contract (pause, cancel, change cadence), call `subscriptionContractUpdate` which opens a draft; commit changes with `subscriptionDraftCommit`.
5. Initiate billing attempts with `subscriptionBillingAttemptCreate`; poll or listen to `subscription_billing_attempts/success` and `subscription_billing_attempts/failure` webhooks to track outcomes.
6. Handle failed billing by checking `subscriptionBillingAttempt.errorCode` and implementing retry logic; after a configurable number of failures, cancel or pause the contract via `subscriptionContractUpdate`.