Unnecessary <p> tag being added into <dt> and <dd> elements

[A-Kun]

📝 Provide detailed reproduction steps (if any)

1. Visit https://ckeditor.com/docs/ckeditor5/latest/features/source-editing/source-editing.html
2. Toggle on Source mode
3. Paste in the following HTML:

<p>Cryptids of Cornwall:</p>

<dl>
  <dt>Beast of Bodmin</dt>
  <dd>A large feline inhabiting Bodmin Moor.</dd>

  <dt>Morgawr</dt>
  <dd>A sea serpent.</dd>

  <dt>Owlman</dt>
  <dd>A giant owl-like creature.</dd>
</dl>

(Example taken from https://developer.mozilla.org/en-US/docs/Web/HTML/Reference/Elements/dl)

4. Toggle off and on Source mode

✔️ Expected result

What is the expected result of the above steps?

The HTML markup should remain unchanged.

❌ Actual result

What is the actual result of the above steps?

The HTML markup turns into the following:

<p>
    Cryptids of Cornwall:
</p>
<dl>
    <dt>
        <p>
            Beast of Bodmin
        </p>
    </dt>
    <dd>
        <p>
            A large feline inhabiting Bodmin Moor.
        </p>
    </dd>
    <dt>
        <p>
            Morgawr
        </p>
    </dt>
    <dd>
        <p>
            A sea serpent.
        </p>
    </dd>
    <dt>
        <p>
            Owlman
        </p>
    </dt>
    <dd>
        <p>
            A giant owl-like creature.
        </p>
    </dd>
</dl>

📃 Other details

• Browser: Firefox 140.9.0esr
• OS: macOS 14.8.5
• CKEditor version: 48.0.0

---

If you'd like to see this fixed sooner, add a 👍 reaction to this post.

[Reinmar]

Hey, thanks for reporting this! 👋

So the thing is, CKEditor's data model needs to know upfront whether a given element should contain block content (like <p>, <ul>, etc.) or inline content (plain text, <strong>, etc.). Mixed content isn't really an option because it becomes basically impossible to reason about when editing.

For elements like <li> or <td> we actually do quite a bit of magic behind the scenes to support both modes — we look at what content is originally inside and decide based on that. But <dt> and <dd> don't have that same handling yet, so they default to block content, which means CKEditor wraps the text in <p> tags.

This is definitely something we could improve by giving <dt> and <dd> the same treatment as <li> — detecting whether the original content is inline and preserving it as-is. We'll keep this on our radar!

[Reinmar]

BTW, it would need to be part of #775.