{
  "protocolVersion": "v1",
  "fixtureSet": "heartbeat",
  "fixture": "stale",
  "description": "A lower heartbeat sequence is retained as history and cannot replace the current projection.",
  "head": {"requestId": "550e8400-e29b-41d4-a716-446655440000", "sequence": 42},
  "late": {"requestId": "7c4d2e10-9f83-4a5b-b6c7-d8e9f0a1b2c3", "sequence": 9},
  "expected": {"decision": "ACCEPT_HISTORY", "currentSequence": 42, "historySequence": 9}
}