anchor.diff:      localid,
       source,
       target,
  -    filter
  +    filter,
  +    db
   }).
   
   go(Source, Target) ->
  
positive.code:     },
      go(Acc).
  
  go(#acc{source=Source, batch_count=BC}=Acc) ->
      case couch_db:open(Source#shard.name, [{user_ctx,?CTX}]) of
      {ok, Db} ->
          Resp = try
              repl(Db, Acc)
          catch error:{not_found, no_db_file} ->
  
negative.code:     end,
      <<"_local/shard-sync-", S/binary, "-", T/binary, F/binary>>.
  
  changes_enumerator(#doc_info{id=DocId}, Reds, #acc{db=Db}=Acc) ->
      {ok, FDI} = couch_db:get_full_doc_info(Db, DocId),
      changes_enumerator(FDI, Reds, Acc);
  changes_enumerator(#full_doc_info{}=FDI, _,
    #acc{revcount=C, infos=Infos}=Acc0) ->
      #doc_info{
          high_seq=Seq,
          revs=Revs
  