anchor.diff:  
   -spec build_recon_struct(method(), OldSyncStruct::sync_struct() | {},
                            DestI::intervals:non_empty_interval(), db_chunk(),
  -                         Params::parameters() | {}, FinishRecon::boolean())
  +                         Params::parameters() | {}, BeginSync::boolean())
           -> sync_struct().
   build_recon_struct(bloom, _OldSyncStruct = {}, I, DBItems, _Params, true) ->
       % note: for bloom, parameters don't need to match - use our own
  
positive.code:     HFCount = bloom:calc_HF_numEx(ElementNum, Fpr),
      BF = bloom:new(ElementNum, Fpr, ?REP_HFS:new(HFCount), DBItems),
      #bloom_recon_struct{ interval = I, bloom = BF };
  build_recon_struct(merkle_tree, _OldSyncStruct = {}, I, DBItems, Params, FinishRecon) ->
      ?ASSERT(not intervals:is_empty(I)),
      case Params of
          {} ->
  
negative.code:            % more DB items to come... stay with merkle tree
             Tree
      end;
  build_recon_struct(art, OldSyncStruct, _I, DBItems, _Params = {}, BeginSync) ->
      % similar to continued merkle build
      ?ASSERT(not intervals:is_empty(_I)),
      ?ASSERT(merkle_tree:is_merkle_tree(OldSyncStruct)),
      Tree1 = merkle_tree:insert_list(DBItems, OldSyncStruct),
      if BeginSync ->
             % no more DB items -> finish tree, remove buckets, create art struct:
             NTree = merkle_tree:gen_hash(Tree1, true),
             #art_recon_struct{art = art:new(NTree, get_art_config()),
  