Go through the customer's payment methods: a customer has a credit_cards array and each card carries a subscriptions array. In Ruby that is customer.credit_cards.map(&:subscriptions).flatten, one fetch instead of the transaction crawl. The same shape exists in the other SDKs, each payment method object exposes its subscriptions, so iterate the customer's payment methods and collect them.

Context: Stack Overflow #15910980 (accepted answer from a Braintree employee, 30 votes): The reporter could see a customer's subscriptions in the gateway dashboard but found no direct way to fetch them via the API. Their workaround, pulling every transaction and then resolving each subscription_id, was slow and chatty. They wanted a direct path from customer to subscriptions.

## Matched source
Source: Published skill
Original query: "Get all of a Braintree customer's subscriptions via their payment methods"
Key terms: braintree, customer, methods, payment, subscriptions, their