Display CODEOWNERS Syntax Validation Errors in MR Changes Tab

Problem to solve

Developers need to validate CODEOWNERS file syntax when making changes via merge requests. Currently, syntax validation is only available in the repository file view, forcing users to navigate away from the MR review workflow to validate their changes.

Current Solution

GitLab provides CODEOWNERS syntax validation in the repository file view (available since GitLab 18.2). Users must exit the MR changes tab, navigate to the repository, validate the file, and return to complete the review.

Proposal

Extend CODEOWNERS syntax validation to display errors directly in the merge request Changes tab, allowing users to validate modifications without leaving the code review workflow.

Benefits include:

• Improved Workflow: Validate changes directly in the MR without context switching
• Faster Feedback: Catch syntax errors earlier in the review process
• Consistency: Same validation experience across repository and MR views
• Reduced Errors: Decreases likelihood of merging invalid CODEOWNERS configurations