---
title: "ACP: update line items and/or buyer"
method: POST
path: "/checkout_sessions/{id}"
tags: ["commerce"]
---

# ACP: update line items and/or buyer

`POST /checkout_sessions/{id}`

## Request

- Base URL: `https://mitosislabs.ai`
- URL: `https://mitosislabs.ai/checkout_sessions/{id}`
- Auth: none required

## Path parameters

- `id` string, required

## Request body

- CheckoutSessionCreate
  - `line_items` object[]
    - `item` object, required
      - `id` string, required
    - `quantity` integer
  - `items` object[]: 2025-09-29 shape, accepted for compatibility
    - `id` string, required
    - `quantity` integer
  - `buyer` object
    - `first_name` string
    - `last_name` string
    - `email` string, email
    - `phone_number` string

## Response `200`

Checkout session

- CheckoutSession
  - `id` string, required
  - `protocol` object
    - `version` string
  - `status` 'not_ready_for_payment' | 'ready_for_payment' | 'requires_escalation' | 'completed' | 'canceled' | 'expired', required
  - `currency` string, required
  - `buyer` object
  - `line_items` object[], required
  - `fulfillment_options` object[]
  - `fulfillment_option_id` string
  - `totals` object[], required
    - `type` string, required
    - `display_text` string, required
    - `amount` integer, required
  - `messages` object[], required
  - `links` object[], required
    - `type` string, required
    - `url` string, uri, required
  - `continue_url` string, uri: Where the account owner completes payment
  - `expires_at` string, date-time
  - `capabilities` object

## Other responses

- `400`: ACP error
- `404`: Unknown session

---

[API](https://skmtc.dev/mitosislabs/apis/mitosis-public-api.md) · [All operations](https://skmtc.dev/mitosislabs/apis/mitosis-public-api/llms.txt) · [OpenAPI document](https://skmtc.dev/mitosislabs/apis/mitosis-public-api/revisions/c82bbc6785c1?raw)