Create a custom field definition

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

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

const definition = await client.customFieldDefinitions.create({
  namespace: 'specs',
  key: 'origin',
  label: 'Country of Origin',
  field_type: 'short_text',
  resource_type: 'Spree::Product',
  storefront_visible: true,
})

spree api post /custom_field_definitions -d '{"namespace":"specs","key":"origin","label":"Country of Origin","field_type":"short_text","resource_type":"Spree::Product","storefront_visible":true}'

{
  "id": "cfdef_EfhxLZ9ck8",
  "namespace": "specs",
  "key": "origin",
  "label": "Country of Origin",
  "field_type": "short_text",
  "resource_type": "Spree::Product",
  "storefront_visible": true,
  "created_at": "2026-07-26T14:24:19.677Z",
  "updated_at": "2026-07-26T14:24:19.677Z"
}