5-Whys Root Cause

digraph why {
  rankdir=TB;
  graph [bgcolor=transparent];
  node [shape=box, style="rounded,filled", fontname=Inter, fontsize=10, fillcolor="#dbeafe"];

  S [label="Symptom:\nCheckout 500s spike", fillcolor="#fee2e2"];
  W1 [label="Why? — DB connection pool exhausted"];
  W2 [label="Why? — Long-running query held connections"];
  W3 [label="Why? — Missing index on orders.created_at"];
  W4 [label="Why? — Migration removed it inadvertently"];
  W5 [label="Why? — No CI check for production indexes", fillcolor="#fef3c7"];
  R [label="Root cause:\nNo guardrail on index migrations", fillcolor="#dcfce7"];

  S -> W1 -> W2 -> W3 -> W4 -> W5 -> R;
}