CKEditor 5 backwards-compatibility policy needed

Documentation location/URL

Pages which may need an update:

• https://www.drupal.org/about/core/policies/core-change-policies/bc-policy →
• https://www.drupal.org/about/core/policies/core-change-policies/frontend... →

Problem/Motivation

The backwards-compatibility policy for CKEditor 5 appears to be undocumented, despite Drupal 10.x minor updates updating CKEditor to versions which are introducing breaking changes. Most recently, a CKEditor 5 update in the Drupal 10.3 beta contained a change which broke the core functionality of my module CKEditor 5 Icons → . As you can imagine this isn't a fun thing to have happen for a module I previously released for and considered stable on Drupal 10.x.

Although it didn't happen in this case, the possibility also exists for a breaking change to render the editor completely useless on whatever site has the affected plugin enabled.

Proposed resolution

Update the documentation to clarify the official backwards-compatibility policy for the increasing number of projects providing plugins for the CKEditor 5 framework.