Calendar multiday state inconsistent between legacy is_multi_day and getIsMultiDay()
>>> [!note] Migrated issue
<!-- Drupal.org comment -->
<!-- Migrated from issue #3571118. -->
Reported by: [joelpittet](https://www.drupal.org/user/160302)
Related to !84
>>>
<h3 id="summary-problem-motivation">Problem/Motivation</h3>
<p>Calendar sets the legacy <code>is_multi_day</code> property directly, but <code>CalendarEvent::getIsMultiDay()</code> relies on a separate internal flag that is not always updated. This causes inconsistent multi-day detection and rendering behaviour.</p>
<h4 id="summary-steps-reproduce">Steps to reproduce</h4>
<h3 id="summary-proposed-resolution">Proposed resolution</h3>
<p>TBD</p>
<h3 id="summary-remaining-tasks">Remaining tasks</h3>
<h3 id="summary-ui-changes">User interface changes</h3>
<h3 id="summary-api-changes">API changes</h3>
<h3 id="summary-data-model-changes">Data model changes</h3>
issue