OrganonTweaks/Template/task/done_badge.php

<?php
/**
 * Done/Due badge in the task view, 4th column (near the due date). Rendered by
 * template:task:details:fourth-column as a list item, matching the surrounding <li> fields. Same
 * two-state toggle as the board badge; only shown to users who may edit the task.
 */
if (! $this->user->hasProjectAccess('TaskModificationController', 'edit', $task['project_id'])) {
    return;
}
$done = $this->OrganonDoneHelper->isDone($task);
?>
<li>
    <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' => 'task'),
            true,
            '',
            $done ? t('Mark as not done') : t('Mark as done')
        ) ?>
    </span>
</li>