[WiP] Make sure all data parsing or schema related checks use proper/actual root

[niegowski]

🚀 Summary

A brief summary of what this PR changes.

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📌 Related issues

• Closes Make sure all data parsing or schema related checks use proper/actual root #20026

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💡 Additional information

Optional: Notes on decisions, edge cases, or anything helpful for reviewers.

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🧾 Checklists

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Author checklist

• Is the changelog entry intentionally omitted?
• Is the change backward-compatible?
• Have you considered the impact on different editor setups and core interactions? (e.g., classic/inline/multi-root/many editors, typing, selection, paste, tables, lists, images, collaboration, pagination)
• Has the change been manually verified in the relevant setups?
• Does this change affect any of the above?
• Is performance impacted?
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• Have tests been added that fail without this change (against regression)?
• Have the API documentation, guides, feature digest, and related feature sections been updated where needed?
• Have metadata files (ckeditor5-metadata.json) been updated if needed?
• Are there any changes the team should be informed about (e.g. architectural, difficult to revert in future versions or having impact on other features)?
• Were these changes documented (in Logbook)?

Reviewer checklist

• PR description explains the changes and the chosen approach (especially when performance, API, or UX is affected).
• The changelog entry is clear, user‑ or integrator-facing, and it describes any breaking changes.
• All new external dependencies have been approved and mentioned in LICENSE.md (if any).
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• I manually verified the change (e.g., in manual tests or documentation).
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[cursor]

Cursor Bugbot has reviewed your changes and found 1 potential issue.

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[cursor]

_fixBodyElement missing title support guard unlike other methods

Medium Severity

_fixBodyElement guards on schema.checkChild(modelRoot, 'paragraph') but unlike every other post-fixer and method in this file (_fixTitleElement, _getTitleElement, getBody, the view post-fixer, and the Shift+Tab handler), it does not also guard on schema.checkChild(modelRoot, 'title'). A custom root that accepts paragraph but not title would get an unwanted empty body-placeholder paragraph inserted at position 1 — even though no title structure exists or is expected on that root.

Additional Locations (1)

• packages/ckeditor5-heading/src/title.ts#L292-L295

 

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