CKEditor 5 "left" alignment doesn't inject "text-align-left" class to elements

Can you reproduce this in a fresh install?

@larowlan I recorded this evidence → from simplytest.me with a "Drupal Core" 10.2.1 sandbox.

If you need it, I can also take an evidence from a local fresh environment.

Thanks! :)

Thanks

So you're saying this used to work correctly in 10.0 and 10.1? 🤔

This is happens and to the drupal 10.1.6

We're experiencing exactly the same issue with a site running Drupal 10.3.9. All the "text-align-*" classes get properly set except for the "text-align-left" one.

For anyone experiencing the issue where text-align-left is never output (because CKEditor 5 considers "left" the default and does not store it in the model), here is a workaround.

You can implement this as a custom CKEditor 5 plugin. It overrides the alignment command to ensure that "left" is explicitly written to the model, allowing the downcast to output the correct class.

 const classMap = {
      left: 'text-align-left',
      center: 'text-align-center',
      right: 'text-align-right',
      justify: 'text-align-justify',
    };

    editor.once('ready', () => {
      const command = editor.commands.get('alignment');

      if (command) {
        this.listenTo(command, 'execute', (evt, data) => {
          const value = Array.isArray(data) ? data[0]?.value : data?.value;
          const selection = editor.model.document.selection;
          if (value === 'left') {
            editor.model.change(writer => {
              for (const block of selection.getSelectedBlocks()) {
                writer.setAttribute('alignment', 'left', block);
              }
            });
            evt.stop();
          }
        });
      }
    });

    editor.conversion.for('downcast').attributeToAttribute({
      model: 'alignment',
      view: (modelValue) => {
        const cls = classMap[modelValue];
        return cls ? { key: 'class', value: cls } : null;
      },
      converterPriority: 'high',
    });