For your first question: nope, the important edge case is that deep changes on _non_ observable objects won't be observed. But that is no different from the ed

For your first question: nope, the important edge case is that deep changes on _non_ observable objects won't be observed. But that is no different from the edge that deep changes on (conceptually) immutable objects are not observed. For the last question: yes exactly. Note that the observables can (should) usually be updated from a 'nice' place, for example from controller or class methods, as directly manipulating data inside event handlers (as done in the tutorial for brevity) will quickly result in your code becoming a mess. But besides that state should be updated in the most straight forward way possible :). So MobX is unopiniated from a technical perspective, but you should have some opinion about it so that code is regularly structured and easy to grasp by others.