anchor.diff:  react_to_env_A29(Retries, P_latest, LatestUnanimousP, ReadExtra,
                    #ch_mgr{name=MyName, consistency_mode=CMode,
                            proj=P_current} = S) ->
  -    react_to_env_A30(Retries, P_latest, LatestUnanimousP, ReadExtra, S).
  -    %% #projection_v1{epoch_number=Epoch_latest,
  -    %%                author_server=Author_latest} = P_latest,
  -    %% if CMode == cp_mode,
  -    %%    Epoch_latest > P_current#projection_v1.epoch_number,
  -    %%    Author_latest /= MyName ->
  -    %%         put(yyy_hack, []),
  -    %%         case make_zerf(P_current, S) of
  -    %%             Zerf when is_record(Zerf, projection_v1) ->
  -    %%                 ?REACT({a29, ?LINE,
  -    %%                         [{zerf_filler, true},
  -    %%                          {zerf_in, machi_projection:make_summary(Zerf)}]}),
  -    %%                 %% io:format(user, "zerf_in: A29: ~p: ~w\n\t~p\n", [MyName,  machi_projection:make_summary(Zerf), get(yyy_hack)]),
  -    %%                 P_current2 = Zerf#projection_v1{
  -    %%                                          flap=P_current#projection_v1.flap},
  -    %%                 S2 = set_proj(S, P_current2),
  -    %%                 react_to_env_A30(Retries, P_latest, LatestUnanimousP,
  -    %%                                  ReadExtra, S2);
  -    %%             Zerf ->
  -    %%                 {{{yo_todo_incomplete_fix_me_cp_mode, line, ?LINE, Zerf}}}
  -    %%         end;
  -    %%    true ->
  -    %%         react_to_env_A30(Retries, P_latest, LatestUnanimousP, ReadExtra, S)
  -    %% end.
  +    #projection_v1{epoch_number=Epoch_latest,
  +                   author_server=Author_latest} = P_latest,
  +    Trigger = if CMode == cp_mode,
  +                 Epoch_latest > P_current#projection_v1.epoch_number,
  +                 Author_latest /= MyName ->
  +                      true;
  +                 P_current#projection_v1.upi == [] ->
  +                      true;
  +                 true ->
  +                      false
  +              end,
  +    if Trigger ->
  +            put(yyy_hack, []),
  +            case make_zerf(P_current, S) of
  +                Zerf when is_record(Zerf, projection_v1) ->
  +                    ?REACT({a29, ?LINE,
  +                            [{zerf_backstop, true},
  +                             {zerf_in, machi_projection:make_summary(Zerf)}]}),
  +                    %% io:format(user, "zerf_in: A29: ~p: ~w\n\t~p\n", [MyName,  machi_projection:make_summary(Zerf), get(yyy_hack)]),
  +                    #projection_v1{dbg=ZerfDbg} = Zerf,
  +                    P_current2 = Zerf#projection_v1{
  +                                   flap=P_current#projection_v1.flap,
  +                                   dbg=[{zerf_backstop,true}|ZerfDbg]},
  +                    S2 = set_proj(S, P_current2),
  +                    react_to_env_A30(Retries, P_latest, LatestUnanimousP,
  +                                     ReadExtra, S2);
  +                Zerf ->
  +                    {{{yo_todo_incomplete_fix_me_cp_mode, line, ?LINE, Zerf}}}
  +            end;
  +       true ->
  +            react_to_env_A30(Retries, P_latest, LatestUnanimousP, ReadExtra, S)
  +    end.
   
   react_to_env_A30(Retries, P_latest, LatestUnanimousP, _ReadExtra,
                    #ch_mgr{name=MyName, proj=P_current,
  
positive.code:     %% config.
      All_list = [P#p_srvr.name || {_, P} <- orddict:to_list(MembersDict)],
      MissingInNew = OldAll_list -- All_list,
      NewUPI = OldUPI -- MissingInNew,
      NewDown = All_list -- NewUPI,
      NewEpoch = OldEpoch + ?SET_CHAIN_MEMBERS_EPOCH_SKIP,
      CMode = calc_consistency_mode(Witness_list),
      ok = set_consistency_mode(machi_flu_psup:make_proj_supname(MyName), CMode),
  
negative.code:   _) when CMode1 /= CMode2 ->
      {wtf, cmode1, CMode1, cmode2, CMode2};
  projection_transition_is_sane_final_review(
    #projection_v1{mode=cp_mode, upi=UPI1, dbg=P1_dbg}=_P1,
    #projection_v1{mode=cp_mode, upi=UPI2, witnesses=Witness_list}=_P2,
    true) ->
      %% All earlier sanity checks has said that this transition is sane, but
      %% we also need to make certain that any CP mode transition preserves at
  