I'm pretty sure you need to build and register your own Facade class to Notify::add() like that.

Otherwise, you would need to type-hint a Container-resolved object (such as a controller) which will then use method injection to deliver an instance of your class:

// controller method
function doThing(NotifyHelper $notify)
{
	$notify->add('make sense?');
}

PS you have your optional arguments the wrong way round in that example.

Thank you, that's what I needed. I ended up leaving MessageBag alone and creating my standalone class which will merge errors from Laravel, it seems Laravel only uses 'errors' anyway.