Missing <p> and <br> tags

I investigated issue and it might be because of outdated FilterHtml plugin definition in core. More about it: https://www.drupal.org/project/drupal/issues/3402515 🐛 CKEditor 5 html filter - fundamental elements Active

The only AJAX change from the core "Limit allowed HTML" filter that I see is from the default elements allowed without CKEditor5
<a href hreflang> <em> <strong> <cite> <blockquote cite> <code> <ul type> <ol start type='1 A I'> <li> <dl> <dt> <dd> <h2 id='jump-*'> <h3 id> <h4 id> <h5 id> <h6 id>

to the default elements allowed with CKEditor5
<br> <p> <h2> <h3> <h4> <h5> <h6> <strong> <em>

Adding <p> and <br> to the settings for "Extended HTML filter" just moves to another error:

The current CKEditor 5 build requires the following elements and attributes:
<br> <p> <h2> <h3> <h4> <h5> <h6> <strong> <em>
The following elements are not supported:
<a href hreflang> <cite> <blockquote cite> <code> <ul type> <ol start type="1 A I"> <li> <dl> <dt> <dd> <h2 id="jump-*"> <h3 id> <h4 id> <h5 id> <h6 id> <* style lang dir="ltr rtl">

That <* style> is wrong, in that it would allow any value for the style attribute, instead of the whitelisted values in the plugin config.

And in any case, trying to add <* style lang dir="ltr rtl"> to the Allowed HTML tags causes a fatal error in the validation:

Uncaught PHP Exception InvalidArgumentException: ""__zqh6vxfbk3cg__" is not a valid HTML tag name." at /path/to/drupal/web/core/modules/ckeditor5/src/HTMLRestrictions.php line 177,

There is core code expanding wildcards to that arbitrary string value, which is fine for attributes but not so much for elements.

@brad.bulger figured out the reason.

https://www.drupal.org/node/3283526 →

I've added extended_html_filter.ckeditor5.yml file with:

# https://html.spec.whatwg.org/multipage/dom.html#attr-dir
extended_html_filter_globalAttributeDir:
  ckeditor5:
    plugins: [htmlSupport.GeneralHtmlSupport]
    config:
      htmlSupport:
        allow:
          -
            # @see \Drupal\ckeditor5\Plugin\CKEditor5Plugin\GlobalAttribute::getDynamicPluginConfig()
            name: ~
            attributes:
              - key: dir
                value:
                  regexp:
                    pattern: /^(ltr|rtl)$/
  drupal:
    label: Global `dir` attribute
    class: \Drupal\ckeditor5\Plugin\CKEditor5Plugin\GlobalAttribute
    # @see \Drupal\filter\Plugin\Filter\FilterHtml::getHTMLRestrictions()
    elements:
      - <* dir="ltr rtl">
    library: core/ckeditor5.htmlSupport
    conditions:
      filter: extended_html_filter

# https://html.spec.whatwg.org/multipage/dom.html#attr-lang
extended_html_filter_globalAttributeLang:
  ckeditor5:
    plugins: [htmlSupport.GeneralHtmlSupport]
    config:
      htmlSupport:
        allow:
          -
            # @see \Drupal\ckeditor5\Plugin\CKEditor5Plugin\GlobalAttribute::getDynamicPluginConfig()
            name: ~
            attributes: lang
  drupal:
    label: Global `lang` attribute
    class: \Drupal\ckeditor5\Plugin\CKEditor5Plugin\GlobalAttribute
    # @see \Drupal\filter\Plugin\Filter\FilterHtml::getHTMLRestrictions()
    elements:
      - <* lang>
    library: core/ckeditor5.htmlSupport
    conditions:
      filter: extended_html_filter

extended_html_filter_globalAttributeStyle:
  ckeditor5:
    plugins: [htmlSupport.GeneralHtmlSupport]
    config:
      htmlSupport:
        allow:
          -
            # @see \Drupal\ckeditor5\Plugin\CKEditor5Plugin\GlobalAttribute::getDynamicPluginConfig()
            name: ~
            attributes: style
  drupal:
    label: Global `style` attribute
    class: \Drupal\ckeditor5\Plugin\CKEditor5Plugin\GlobalAttribute
    # @see \Drupal\filter\Plugin\Filter\FilterHtml::getHTMLRestrictions()
    elements:
      - <* style>
    library: core/ckeditor5.htmlSupport
    conditions:
      filter: extended_html_filter

and form is saving now, but it does not seem to be working as expected so, I suppose there still still plenty to do to support CKE5.

Ah, I had missed that change.

Yes, it seems complicated. Possibly the changes in ✨ Match the filter_html <> ckeditor5 integration in Drupal core Needs work address this, or need to do so.

✨ Match the filter_html <> ckeditor5 integration in Drupal core Needs work fixes this.