Create an action on a promotion

import { createAdminClient } from '@spree/admin-sdk'

const client = createAdminClient({
  baseUrl: 'https://your-store.com',
  secretKey: 'sk_xxx',
})

const action = await client.promotions.actions.create('promo_UkLWZg9DAJ', {
  type: 'free_shipping',
})

{
  "id": "pact_UkLWZg9DAJ",
  "created_at": "2026-05-24T17:37:39.979Z",
  "updated_at": "2026-05-24T17:37:39.979Z",
  "type": "free_shipping",
  "promotion_id": "promo_UkLWZg9DAJ",
  "preferences": {},
  "preference_schema": [],
  "label": "Free shipping",
  "calculator": null,
  "line_items": null
}