digraph techviz {
  graph [rankdir=TB, splines=ortho, nodesep=0.55, ranksep=0.85];
  node [fontname=Helvetica, fontsize=11, margin="0.18,0.12", style="rounded,filled", fillcolor=white, color="#2d4357", penwidth=1.5];
  edge [fontname=Helvetica, fontsize=10, color="#364b5f", penwidth=1.4, arrowsize=0.75];
  n0 [label="동시 refresh 5건", shape=box, style="rounded,dashed,filled"];
  n1 [label="회전 검사", shape=box, style="rounded,filled"];
  n2 [label="client session", shape=box, style="rounded,filled"];
  n3 [label="이긴 요청의 새 토큰", shape=box, style="rounded,filled"];
  n0 -> n1 [label="동시 도착", style=solid];
  n1 -> n2 [label="경쟁 감지 시 삭제", style=solid];
  n2 -> n3 [label="세션이 없으니 못 쓴다", style=solid];
}