Dont have state. Try to derive it from the data aka the environment. Rather prefer adding state to the environment (timestamps, recipesteps of a product), the

Dont have state. Try to derive it from the data aka the environment. Rather prefer adding state to the environment (timestamps, recipesteps of a product), then keeping seperate track from it, because seperation is, additional state. And state is a curse:re. So dont. If it cant be avoided, dont duplicate state, add a machine that resets it upon sensors detecting a changed environment (data) and revert wherever you can back to deriving it from data. If it is unavoidable, make it concise, so that at least the maintainers can follow the state and see were it goes wrong.