Associate guest cart with authenticated user

import { createClient } from '@spree/sdk'

const client = createClient({
  baseUrl: 'https://your-store.com',
  publishableKey: '<api-key>',
})

const cart = await client.carts.associate('cart_abc123', {
  bearerToken: '<token>',
})

{
  "id": "cart_UkLWZg9DAJ",
  "number": "R452564608",
  "token": "oB8LvaYR4CV4kr6BEMFtHzfZsAyGxtx6r4z",
  "email": "jenifer_hermann@douglasbayer.name",
  "customer_note": null,
  "currency": "USD",
  "locale": "en",
  "total_quantity": 1,
  "item_total": "10.0",
  "display_item_total": "$10.00",
  "adjustment_total": "0.0",
  "display_adjustment_total": "$0.00",
  "discount_total": "0.0",
  "display_discount_total": "$0.00",
  "tax_total": "0.0",
  "display_tax_total": "$0.00",
  "included_tax_total": "0.0",
  "display_included_tax_total": "$0.00",
  "additional_tax_total": "0.0",
  "display_additional_tax_total": "$0.00",
  "total": "110.0",
  "display_total": "$110.00",
  "gift_card_total": "0.0",
  "display_gift_card_total": "$0.00",
  "amount_due": "110.0",
  "display_amount_due": "$110.00",
  "delivery_total": "100.0",
  "display_delivery_total": "$100.00",
  "warnings": [],
  "created_at": "2026-03-28T11:44:14.703Z",
  "updated_at": "2026-03-28T11:44:14.748Z",
  "store_credit_total": "0.0",
  "display_store_credit_total": "$0.00",
  "covered_by_store_credit": false,
  "current_step": "address",
  "completed_steps": [],
  "requirements": [
    {
      "step": "payment",
      "field": "payment",
      "message": "Add a payment method"
    }
  ],
  "shipping_eq_billing_address": false,
  "discounts": [],
  "items": [
    {
      "id": "li_UkLWZg9DAJ",
      "variant_id": "variant_UkLWZg9DAJ",
      "quantity": 1,
      "currency": "USD",
      "name": "Product 91401",
      "slug": "product-91401",
      "options_text": "",
      "price": "10.0",
      "display_price": "$10.00",
      "total": "10.0",
      "display_total": "$10.00",
      "adjustment_total": "0.0",
      "display_adjustment_total": "$0.00",
      "additional_tax_total": "0.0",
      "display_additional_tax_total": "$0.00",
      "included_tax_total": "0.0",
      "display_included_tax_total": "$0.00",
      "discount_total": "0.0",
      "display_discount_total": "$0.00",
      "pre_tax_amount": "10.0",
      "display_pre_tax_amount": "$10.00",
      "discounted_amount": "10.0",
      "display_discounted_amount": "$10.00",
      "display_compare_at_amount": "$0.00",
      "compare_at_amount": null,
      "thumbnail_url": null,
      "option_values": [],
      "digital_links": []
    }
  ],
  "fulfillments": [
    {
      "id": "ful_UkLWZg9DAJ",
      "number": "H90321795147",
      "tracking": "U10000",
      "tracking_url": null,
      "cost": "100.0",
      "display_cost": "$100.00",
      "status": "pending",
      "fulfillment_type": "shipping",
      "fulfilled_at": null,
      "items": [
        {
          "item_id": "li_UkLWZg9DAJ",
          "variant_id": "variant_UkLWZg9DAJ",
          "quantity": 1
        }
      ],
      "delivery_method": {
        "id": "dm_UkLWZg9DAJ",
        "name": "UPS Ground",
        "code": "UPS_GROUND"
      },
      "stock_location": {
        "id": "sloc_UkLWZg9DAJ",
        "state_abbr": "STATE_ABBR_54",
        "name": "Sunny Hansen",
        "address1": "1600 Pennsylvania Ave NW",
        "city": "Washington",
        "zipcode": "20500",
        "country_iso": "US",
        "country_name": "United States of America",
        "state_text": "STATE_ABBR_54"
      },
      "delivery_rates": [
        {
          "id": "dr_UkLWZg9DAJ",
          "delivery_method_id": "dm_UkLWZg9DAJ",
          "name": "UPS Ground",
          "selected": true,
          "cost": "100.0",
          "display_cost": "$100.00",
          "delivery_method": {
            "id": "dm_UkLWZg9DAJ",
            "name": "UPS Ground",
            "code": "UPS_GROUND"
          }
        }
      ]
    }
  ],
  "payments": [],
  "billing_address": {
    "id": "addr_UkLWZg9DAJ",
    "first_name": "John",
    "last_name": "Doe",
    "full_name": "John Doe",
    "address1": "54 Lovely Street",
    "address2": "Northwest",
    "postal_code": "35005",
    "city": "Herndon",
    "phone": "555-555-0199",
    "company": "Company",
    "country_name": "United States of America",
    "country_iso": "US",
    "state_text": "STATE_ABBR_54",
    "state_abbr": "STATE_ABBR_54",
    "quick_checkout": false,
    "is_default_billing": false,
    "is_default_shipping": false,
    "state_name": "STATE_NAME_54"
  },
  "shipping_address": {
    "id": "addr_gbHJdmfrXB",
    "first_name": "John",
    "last_name": "Doe",
    "full_name": "John Doe",
    "address1": "55 Lovely Street",
    "address2": "Northwest",
    "postal_code": "35005",
    "city": "Herndon",
    "phone": "555-555-0199",
    "company": "Company",
    "country_name": "United States of America",
    "country_iso": "US",
    "state_text": "STATE_ABBR_55",
    "state_abbr": "STATE_ABBR_55",
    "quick_checkout": false,
    "is_default_billing": false,
    "is_default_shipping": false,
    "state_name": "STATE_NAME_55"
  },
  "payment_methods": [],
  "gift_card": null
}