Exactly right on recording derefs, which is why you have to use Reagent's atom implementation rather than the builtin. As for the exact mechanics of rendering, it can vary a bit depending on how the component is built, and how the changing state is passed in, but it usually comes down to .forceUpdate: https://github.com/reagent-project/reagent/blob/master/src/reagent/impl/batching.cljs#L39

@me1987 thanks! Yeah, I already figured as much 🙂