Stripe Add and Scale Subscription Item

arazzo: 1.0.1
info:
  title: Stripe Add and Scale Subscription Item
  summary: Add an item to a subscription, then update its quantity.
  description: >-
    The seat-management pattern for usage or quantity based plans. The workflow
    adds a new subscription item for a price to an existing subscription, then
    updates that item's quantity to scale it up or down with prorated billing.
    Every step spells out its form-encoded request inline so the flow can be read
    and executed without opening the underlying OpenAPI description.
  version: 1.0.0
sourceDescriptions:
- name: subscriptionApi
  url: ../openapi/stripe-subscription-api-openapi.yml
  type: openapi
workflows:
- workflowId: add-and-scale-subscription-item
  summary: Add a subscription item and then change its quantity.
  description: >-
    Adds an item for the supplied price to the subscription, then updates that
    item's quantity with proration to reflect the new seat count.
  inputs:
    type: object
    required:
    - subscription
    - price
    - quantity
    properties:
      subscription:
        type: string
        description: ID of the subscription to add the item to.
      price:
        type: string
        description: ID of the price to add as a subscription item.
      quantity:
        type: integer
        description: Initial quantity for the new subscription item.
      newQuantity:
        type: integer
        description: Updated quantity to scale the subscription item to.
  steps:
  - stepId: addItem
    description: Add a new item for the price to the existing subscription.
    operationId: PostSubscriptionItems
    requestBody:
      contentType: application/x-www-form-urlencoded
      payload:
        subscription: $inputs.subscription
        price: $inputs.price
        quantity: $inputs.quantity
    successCriteria:
    - condition: $statusCode == 200
    outputs:
      itemId: $response.body#/id
  - stepId: scaleItem
    description: Update the subscription item quantity with proration.
    operationId: PostSubscriptionItemsItem
    parameters:
    - name: item
      in: path
      value: $steps.addItem.outputs.itemId
    requestBody:
      contentType: application/x-www-form-urlencoded
      payload:
        quantity: $inputs.newQuantity
        proration_behavior: create_prorations
    successCriteria:
    - condition: $statusCode == 200
    outputs:
      quantity: $response.body#/quantity
  outputs:
    itemId: $steps.addItem.outputs.itemId
    quantity: $steps.scaleItem.outputs.quantity