change to use state_machine gem?

[ShiningRay]

state_machine provides more features such as transition events. and if users define methods with the same name as those defined in state modules, it won't override them.

[nyarly]

I'm not sure I see the advantage of making a change at this point. In general, FSMs using modules are kind of a pain in Ruby - if anything I'd want states to be simple objects with delegation.