---
title: "Changes to POST /agent-commerce/ucp/checkout-sessions"
method: POST
path: "/agent-commerce/ucp/checkout-sessions"
---

# Changes to POST /agent-commerce/ucp/checkout-sessions

`POST /agent-commerce/ucp/checkout-sessions`

> Every recorded change to this operation, newest first.

## Timeline

Changed in 3 of 7 revisions.

- **2026-11-09** `5c50dd5066f8`: 2 breaking, 2 warning
- **2026-10-19** `8a0a695bcfb5`: 1 breaking, 3 info
- **2026-10-18** `4990dc8b3ef4`: 1 info

## Changes

- **2026-11-09** `5c50dd5066f8`: 2 breaking, 2 warning
  - added the pattern `^(?:[A-Za-z0-9_'+\-]+\.)*[A-Za-z0-9_'+\-]*[A-Za-z0-9_+-]@(?:[A-Za-z0-9][A-Za-z0-9\-]*\.)+[A-Za-z]{2,}$` to the request property `buyer/email`
  - added the pattern `^([0-9a-fA-F]{8}-[0-9a-fA-F]{4}-[1-8][0-9a-fA-F]{3}-[89abAB][0-9a-fA-F]{3}-[0-9a-fA-F]{12}|00000000-0000-0000-0000-000000000000|ffffffff-ffff-ffff-ffff-ffffffffffff)$` to the request property `id`
  - the `mondoir/editionNumber` request property's max was set to `9007199254740991.00`
  - the `mondoir/editionNumbers/items/` request property's max was set to `9007199254740991.00`
- **2026-10-19** `8a0a695bcfb5`: 1 breaking, 3 info
  - the `mondoir/payer` request property type changed from `string` to no type
  - added the new optional request property `mondoir/network`
  - added `subschema #1, subschema #2` to the `mondoir/payer` request property `anyOf` list
  - removed the pattern `^0x[0-9a-fA-F]{40}$` from the request property `mondoir/payer`
- **2026-10-18** `4990dc8b3ef4`: 1 info
  - endpoint added

---

[Operation](https://skmtc.dev/mondoir/apis/mondoir-api/docs/agent-commerce/ucp/checkout-sessions/post.md) - [API](https://skmtc.dev/mondoir/apis/mondoir-api.md) - [Page](https://skmtc.dev/mondoir/apis/mondoir-api/changes/agent-commerce/ucp/checkout-sessions/post)