OrganonTweaks/Template/board/done_badge.php

<?php
/**
 * Done/Due badge on the board card face. Rendered by template:board:private:task:before-title; the
 * CSS in layout/done_style.php pins it to the top-right (below the header) and colors the two states.
 * Only shown to users who may edit the task (a read-only viewer sees no badge). Expanded cards only
 * (collapsed cards do not fire this hook).
 */
if (! $this->user->hasProjectAccess('TaskModificationController', 'edit', $task['project_id'])) {
    return;
}
$done = $this->OrganonDoneHelper->isDone($task);
?>
<span class="organontweaks-done<?= $done ? ' is-done' : '' ?>">
    <?= $this->url->link(
        $done ? '<i class="fa fa-check-square"></i> '.t('Done') : '<i class="fa fa-square"></i> '.t('Due'),
        'DoneController',
        'toggle',
        array('plugin' => 'OrganonTweaks', 'task_id' => $task['id'], 'project_id' => $task['project_id'], 'from' => 'board'),
        true,
        '',
        $done ? t('Mark as not done') : t('Mark as done')
    ) ?>
</span>