digraph techviz {
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  edge [fontname=Helvetica, fontsize=10, color="#364b5f", penwidth=1.4, arrowsize=0.75];
  n0 [label="클라이언트", shape=box, style="rounded,dashed,filled"];
  n1 [label="Keycloak", shape=box, style="rounded,filled"];
  n2 [label="PostgreSQL", shape=cylinder, style="rounded,filled"];
  n3 [label="디스크의 WAL", shape=cylinder, style="rounded,filled"];
  n0 -> n1 [label="로그인 요청", style=solid];
  n1 -> n2 [label="세션 INSERT · COMMIT", style=solid];
  n2 -> n3 [label="지연된 WAL 기록", style=solid];
}