post
https://api.loopsubscriptions.com/storefront/2026-04/bundle/transaction/update
Updates the contents of a bundle purchased on a subscription, from a custom editing experience. Works whether the customer edits from Loop's subscription portal or your own custom portal.
Auth: š Access-gated (beta). Pass the customer accessToken in the request headers.
The id here is the transaction ID
id here is the transaction IDThe id in the body is the transaction ID (the same value used in Get subscription bundle details) - not the Bundle ID and not the subscription/contract ID.
Body parameters
| Name | Type | Required | Description |
|---|---|---|---|
id | string | Yes | The transaction ID of the bundle being edited. |
items | array | Yes | The full, updated set of child products (see below). |
boxSizeId | string | ā | Box size id for the updated selection. |
discountId | string | ā | Discount id eligible for the updated content, if any. |
items[]: { productVariantShopifyId (int64), quantity (int32) }. quantity is the count of that variant.
On success, the response includes a returnUrl you can redirect the customer back to (e.g. the Loop subscription portal).