{
  "synthetic": true,
  "problem": "A replayed event is counted twice.",
  "input": [
    {
      "id": "DEMO-01",
      "amount": 12000
    },
    {
      "id": "DEMO-01",
      "amount": 12000
    },
    {
      "id": "DEMO-02",
      "amount": 3500
    }
  ],
  "before_total_centavos": 27500,
  "expected_and_after_total_centavos": 15500,
  "root_cause": "No stable-event-id deduplication in this fixture.",
  "regression_checks": [
    "replay does not change total",
    "distinct IDs are preserved"
  ],
  "limits": "In-memory teaching fixture. Real systems need a persistent dedupe key, transaction boundaries and conflict handling. This is not a customer repair."
}