{
  "kind": "illustrative teaching contract, not a customer requirement",
  "authority": "Fictional service owner, authored explicitly for this fixture",
  "mutation": {
    "id": "EX-TOKEN-1",
    "rule": "Allow a token only while active and strictly before its expiry instant.",
    "clauses": {
      "active_before_expiry": "An active token at time 99 with expiry 100 is allowed.",
      "expiry_boundary": "At time 100 a token with expiry 100 is expired and denied.",
      "revocation": "An inactive token is denied even before expiry."
    },
    "oracle_basis": "Expected results implement these explicit clauses, not output copied from the baseline or mutants.",
    "clock": "Injected integer time; expiry is an exclusive upper bound."
  },
  "migration": {
    "id": "EX-TENANT-1",
    "rule": "A tenant may update its own document label. A request from another tenant receives 403 and must leave all stored document rows unchanged.",
    "request_id": "A nonempty correlation field. Its exact generated value is not part of behavioral equivalence in this fixture.",
    "scope": "One existing document, two sequential calls in isolated databases; no concurrency, missing-document or network behavior."
  }
}