Remove 'First occurrence' fieldset
>>> [!note] Migrated issue
<!-- Drupal.org comment -->
<!-- Migrated from issue #3600880. -->
Reported by: [joelpittet](https://www.drupal.org/user/160302)
Related to !21
>>>
<h3 id="summary-problem-motivation">Problem/Motivation</h3>
<p>The interactive widget inherits the <code>First occurrence</code> fieldset from the parent widget.</p>
<p>In this module, the fieldset adds visual weight without much clarity, because the interactive RRULE controls already separate recurrence behaviour from the start and end date fields.</p>
<p><a href="https://www.drupal.org/files/issues/2026-06-15/Screenshot%202026-06-15%20at%2000.02.02.png"><img src="https://www.drupal.org/files/issues/2026-06-15/Screenshot%202026-06-15%20at%2000.02.02.png" alt="fieldset"></a></p>
<h3 id="summary-proposed-resolution">Proposed resolution</h3>
<p>Flatten the interactive widget form by removing the <code>first_occurrence</code> fieldset created by the parent widget and rendering the start and end date controls directly in the widget.</p>
<p>Preserve the existing form element parents, validation, submitted values, and JavaScript data attributes.</p>
<h3 id="summary-remaining-tasks">Remaining tasks</h3>
<ul>
<li>Remove the fieldset wrapper from the interactive widget.</li>
<li>Confirm the start and end date controls still submit and validate correctly.</li>
<li>Confirm the interactive widget JavaScript still receives the expected data attributes.</li>
</ul>
<h3 id="summary-ui-changes">User interface changes</h3>
<p>The <code>First occurrence</code> fieldset wrapper and legend are removed from the interactive widget. The start and end date controls remain visible.</p>
issue