Undo and Redo in AsyncRedux

AsyncRedux simplifies undo/redo through a straightforward pattern: create a state observer to save states to a history list, and create actions to navigate through that history.

Understanding StateObserver

The StateObserver abstract class tracks state modifications. Implement its observe method to be notified of state changes:

abstract class StateObserver<St> {
  void observe(
    ReduxAction<St> action,
    St stateIni,
    St stateEnd,
    Object? error,
    int dispatchCount,
  );
}