>>> [!note] Migrated issue <!-- Drupal.org comment --> <!-- Migrated from issue #3582840. --> Reported by: [attilatilman](https://www.drupal.org/user/3528404) Related to !858 >>> <p>When creating a canvas_page via POST /canvas/api/v0/content/canvas_page, the UUID is always auto-generated by Drupal. External clients (e.g. CLI tools) that manage content across environments need to control the UUID to ensure stable references.</p> <p>Add support for an optional uuid field in the POST request body. When provided, it is set on the new entity before saving. Duplicate creation is unaffected &mdash; duplicates always receive a new UUID. Invalid or already-used UUIDs are rejected via the existing entity validation flow.</p>