BookStack/app/Activity/Notifications/Handlers/NotificationHandler.php

<?php

namespace BookStack\Activity\Notifications\Handlers;

use BookStack\Activity\Models\Activity;
use BookStack\Activity\Models\Loggable;
use BookStack\Users\Models\User;

interface NotificationHandler
{
    /**
     * Run this handler.
     * Provides the activity, related activity detail/model
     * along with the user that triggered the activity.
     */
    public function handle(Activity $activity, string|Loggable $detail, User $user): void;
}