@callback checkpoint(Mobus.Stepwise.Types.runtime()) :: map()

@callback get_state(Mobus.Stepwise.Types.runtime()) ::
  Mobus.Stepwise.Projection.t() | map()

@callback handle_event(
  Mobus.Stepwise.Types.runtime(),
  Mobus.Stepwise.Types.event(),
  Mobus.Stepwise.Types.payload()
) ::
  {:ok, Mobus.Stepwise.Types.runtime()}
  | {:wait, Mobus.Stepwise.Types.runtime(), Mobus.Stepwise.Types.wait_cfg()}
  | {:error, Mobus.Stepwise.Types.reason(), Mobus.Stepwise.Types.runtime()}

@callback init(Mobus.Stepwise.Types.spec(), Mobus.Stepwise.Types.runtime_context()) ::
  {:ok, Mobus.Stepwise.Types.runtime()}
  | {:wait, Mobus.Stepwise.Types.runtime(), Mobus.Stepwise.Types.wait_cfg()}
  | {:error, Mobus.Stepwise.Types.reason()}
  | {:error,
     {:initial_entry_action_failed, Mobus.Stepwise.Types.reason(),
      Mobus.Stepwise.Types.runtime()}}

@callback restore(
  Mobus.Stepwise.Types.spec(),
  map(),
  Mobus.Stepwise.Types.runtime_context()
) ::
  {:ok, Mobus.Stepwise.Types.runtime()}
  | {:error, Mobus.Stepwise.Types.reason()}