loaded model available in view without passing it explicitly from controller

It's not a bug, but not something that I would recommend taking advantage of very often, either.

It is due to the way that the $this object (or get_instance()) in CodeIgniter points back to the controller. Since you're in the controller any calls to $this that don't match anything in the class itself, will look to the main controller instance, which happens to have links to the models.

So, while it's technically possible - don't rely on it because it gets pretty confusing for devs that don't understand the nuance. Stick with the way you mentioned - pass it to a variable in the controller to the view. It's all good.

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