anchor.diff:      case lists:keyfind(TraceId, 1, State) of
           false -> State;
           {TraceId, TraceEntry} ->
  +            %% NOTE: if the monitor has hit before, its 'DOWN' message with
  +            %%       reason 'noproc' is ignored (see below) and we can assume
  +            %%       a delivered state
  +            {delivered, Pid, _Ref, _Time} = TraceEntry#state.status,
               %% enqueue a send_error message if a shepherd was used
  -            %% NOTE: we do this in any state, since the monitor may have hit
  -            %%       before in which case the DOWN message will clean up and
  -            %%       generate and process an on_handler_done
               State1 =
                   case lists:keyfind(shepherd, 1, SendOptions) of
                       {shepherd, ShepherdPid} ->
  
positive.code:             comm:send_local(CallerPid, {cleanup_done}),
              State
      end;
  
  on({'DOWN', Ref, process, Pid, _Reason}, State) ->
      ?TRACE("proto_sched:on({'DOWN', ~p, process, ~p, ~p}).",
  
negative.code:                     false ->
                          State
                  end,
              %% process not alive -> generate on_handler_done
              gen_component:post_op({on_handler_done, TraceId, send_error, Pid}, State1)
      end;
  
  on({register_callback, CallbackFun, OnX, TraceId, Client}, State) ->
  