[bbsimonbb]

I looked at and rejected state machines, because I didn't like/understand the need for the formalism of defining every possible state.

[davidkpiano]

You don't need to define every possible state. A state machine can serve as a higher-level structure of some of the states (statuses, modes) of parts of your app, for ease of structuring logic. But you can also create a single-state state machine and represent non-finite data as "external state".