Proof using.
rewrite /step_star_lb_step_reachable.
move => net l.
move => net' tr tr' H_star H_st.
invcs H_st.
- set net' := {| nwPackets := _ ; nwState := _ |}.
apply (@refl_trans_1n_trace_trans _ _ _ _ net) => //.
have ->: [(pDst p, inr out)] = [(pDst p, inr out)] ++ [] by [].
apply: (@RT1nTStep _ _ _ _ net'); last exact: RT1nTBase.
apply: (@StepAsync_deliver _ _ _ _ _ xs ys _ d l0) => //.
rewrite /net_handlers /= /unlabeled_net_handlers /=.
repeat break_let.
by tuple_inversion.
- set net' := {| nwPackets := _ ; nwState := _ |}.
apply (@refl_trans_1n_trace_trans _ _ _ _ net) => //.
have ->: [(h, inl inp); (h, inr out)] = [(h, inl inp); (h, inr out)] ++ [] by [].
apply: (@RT1nTStep _ _ _ _ net'); last exact: RT1nTBase.
apply: StepAsync_input => //.
rewrite /input_handlers /= /unlabeled_input_handlers /=.
repeat break_let.
by tuple_inversion.
- by have ->: tr' ++ [] = tr' by auto with datatypes.
Qed.

(* Specifications: *)
Lemma step_async_star_lb_step_execution :
forall s, event_step_star step_async step_async_init (hd s) ->
lb_step_execution lb_step_async s ->
always (now (event_step_star step_async step_async_init)) s.