{"abstract":"The hedge request operation is admitted even though a duplicate request is launched before the hedge delay.","category":"Reliability","checks":9,"contract":"Return a Boolean admission decision for launch a speculative hedged request. The record r must satisfy all of: r['hedge_delay'][0] >= r['hedge_delay'][1]; r['primary_pending'] == 'pending'; r['separate_domain'][0] != r['separate_domain'][1]; r['hedge_budget'][0] < r['hedge_budget'][1]; r['operation_repeatable'] is True. Extra tracing fields are ignored; validation does not mutate the record.","evaluation_group":"xd-hedge-request","failed_approach":"Adding the hedge delay check repairs the reported defect, but replacing the adjacent primary pending check loses that independent invariant.","family":"xd-hedge-request-hedge_delay","id":"FA-976","implementations":{"attempt":{"sha256":"7543af67d56a5068391020377ff7dd8cf67a89893b142d835bfa61d57cdd5190","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(r):\n    return (r['hedge_delay'][0] >= r['hedge_delay'][1]) and (r['separate_domain'][0] != r['separate_domain'][1]) and (r['hedge_budget'][0] < r['hedge_budget'][1]) and (r['operation_repeatable'] is True)\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\nr = {'hedge_delay': [5, 5], 'primary_pending': 'pending', 'separate_domain': ['z1', 'z2'], 'hedge_budget': [0, 1], 'operation_repeatable': True}\ncheck('valid operation', solve(r), True)\ncheck('A duplicate request is launched before the hedge delay', solve(dict(r, **{'hedge_delay': [4, 5]})), False)\ncheck('A hedge starts after the primary already completed', solve(dict(r, **{'primary_pending': 'done'})), False)\ncheck('Primary and hedge share the same correlated failure domain', solve(dict(r, **{'separate_domain': ['z1', 'z1']})), False)\ncheck('Speculation consumes more than the allowed duplicate capacity', solve(dict(r, **{'hedge_budget': [1, 1]})), False)\ncheck('A hedge duplicates a non-repeatable side effect', solve(dict(r, **{'operation_repeatable': False})), False)\ncheck('unrelated tracing metadata', solve(dict(r, trace='run-'+str(N))), True)\ncheck('repeat validation is pure', solve(r), True)\ninvalid = {'hedge_delay': [4, 5], 'primary_pending': 'done', 'separate_domain': ['z1', 'z1'], 'hedge_budget': [1, 1], 'operation_repeatable': False}\nkeys = list(invalid)\npair = {keys[N % len(keys)]: invalid[keys[N % len(keys)]], keys[(N+1) % len(keys)]: invalid[keys[(N+1) % len(keys)]]}\ncheck('two independent violations in variant', solve(dict(r, **pair)), False)\nprint(json.dumps({\"observations\": observations, \"passed\": all(x[\"passed\"] for x in observations)}, ensure_ascii=False))\nraise SystemExit(0 if all(x[\"passed\"] for x in observations) else 1)\n"},"broken":{"sha256":"92c1b2296950137e01e6cef4f637c2681b10e2b2f875bda1dd992b2120a18ad5","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(r):\n    return (r['primary_pending'] == 'pending') and (r['separate_domain'][0] != r['separate_domain'][1]) and (r['hedge_budget'][0] < r['hedge_budget'][1]) and (r['operation_repeatable'] is True)\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\nr = {'hedge_delay': [5, 5], 'primary_pending': 'pending', 'separate_domain': ['z1', 'z2'], 'hedge_budget': [0, 1], 'operation_repeatable': True}\ncheck('valid operation', solve(r), True)\ncheck('A duplicate request is launched before the hedge delay', solve(dict(r, **{'hedge_delay': [4, 5]})), False)\ncheck('A hedge starts after the primary already completed', solve(dict(r, **{'primary_pending': 'done'})), False)\ncheck('Primary and hedge share the same correlated failure domain', solve(dict(r, **{'separate_domain': ['z1', 'z1']})), False)\ncheck('Speculation consumes more than the allowed duplicate capacity', solve(dict(r, **{'hedge_budget': [1, 1]})), False)\ncheck('A hedge duplicates a non-repeatable side effect', solve(dict(r, **{'operation_repeatable': False})), False)\ncheck('unrelated tracing metadata', solve(dict(r, trace='run-'+str(N))), True)\ncheck('repeat validation is pure', solve(r), True)\ninvalid = {'hedge_delay': [4, 5], 'primary_pending': 'done', 'separate_domain': ['z1', 'z1'], 'hedge_budget': [1, 1], 'operation_repeatable': False}\nkeys = list(invalid)\npair = {keys[N % len(keys)]: invalid[keys[N % len(keys)]], keys[(N+1) % len(keys)]: invalid[keys[(N+1) % len(keys)]]}\ncheck('two independent violations in variant', solve(dict(r, **pair)), False)\nprint(json.dumps({\"observations\": observations, \"passed\": all(x[\"passed\"] for x in observations)}, ensure_ascii=False))\nraise SystemExit(0 if all(x[\"passed\"] for x in observations) else 1)\n"},"fixed":{"sha256":"a64170c54cb10b15d4403ceff422da42844614777231b707e5a3b66c3c4b946a","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(r):\n    return (r['hedge_delay'][0] >= r['hedge_delay'][1]) and (r['primary_pending'] == 'pending') and (r['separate_domain'][0] != r['separate_domain'][1]) and (r['hedge_budget'][0] < r['hedge_budget'][1]) and (r['operation_repeatable'] is True)\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\nr = {'hedge_delay': [5, 5], 'primary_pending': 'pending', 'separate_domain': ['z1', 'z2'], 'hedge_budget': [0, 1], 'operation_repeatable': True}\ncheck('valid operation', solve(r), True)\ncheck('A duplicate request is launched before the hedge delay', solve(dict(r, **{'hedge_delay': [4, 5]})), False)\ncheck('A hedge starts after the primary already completed', solve(dict(r, **{'primary_pending': 'done'})), False)\ncheck('Primary and hedge share the same correlated failure domain', solve(dict(r, **{'separate_domain': ['z1', 'z1']})), False)\ncheck('Speculation consumes more than the allowed duplicate capacity', solve(dict(r, **{'hedge_budget': [1, 1]})), False)\ncheck('A hedge duplicates a non-repeatable side effect', solve(dict(r, **{'operation_repeatable': False})), False)\ncheck('unrelated tracing metadata', solve(dict(r, trace='run-'+str(N))), True)\ncheck('repeat validation is pure', solve(r), True)\ninvalid = {'hedge_delay': [4, 5], 'primary_pending': 'done', 'separate_domain': ['z1', 'z1'], 'hedge_budget': [1, 1], 'operation_repeatable': False}\nkeys = list(invalid)\npair = {keys[N % len(keys)]: invalid[keys[N % len(keys)]], keys[(N+1) % len(keys)]: invalid[keys[(N+1) % len(keys)]]}\ncheck('two independent violations in variant', solve(dict(r, **pair)), False)\nprint(json.dumps({\"observations\": observations, \"passed\": all(x[\"passed\"] for x in observations)}, ensure_ascii=False))\nraise SystemExit(0 if all(x[\"passed\"] for x in observations) else 1)\n"}},"limitations":" This reproducer isolates one failure mechanism. Results cover the supplied fixtures. Variants within a family share a test contract and should remain grouped when constructing evaluation splits. Related mechanisms with a shared evaluation_group must also remain together; these controlled models are not independent production incidents.","method":"Deterministic executable model with adversarial boundary fixtures.","provenance":{"created_by":"Failure Map","dependencies":"Python standard library","family":"xd-hedge-request-hedge_delay","generated_at":"2026-09-29T14:36:57.341006+00:00","license":"CC0-1.0","python":"3.12.14","seed":1,"split":"open-access"},"relevance":"A deterministic local contract for reliability. Each negative fixture violates exactly one invariant. No transport timing, persistence, cryptographic verification, or full protocol implementation is claimed.","repair":"Require r['hedge_delay'][0] >= r['hedge_delay'][1] together with every other stated precondition before accepting the operation.","root_cause":"The admission path omits the hedge delay invariant while validating the other operation preconditions.","sha256":"2322c5bbe3f9d642720c351d24c3e92b3abeb6e6e2d86616b805ac3c73272154","title":"Launch a speculative hedged request: A duplicate request is launched before the hedge delay · case 01","variant":1,"variant_policy":"Five numbered records share a model and may reuse boundary fixtures.","verification":{"attempt":{"elapsed_ms":29.57,"exit_code":1,"observations":[{"actual":true,"check":"valid operation","expected":true,"passed":true},{"actual":false,"check":"A duplicate request is launched before the hedge delay","expected":false,"passed":true},{"actual":true,"check":"A hedge starts after the primary already completed","expected":false,"passed":false},{"actual":false,"check":"Primary and hedge share the same correlated failure domain","expected":false,"passed":true},{"actual":false,"check":"Speculation consumes more than the allowed duplicate capacity","expected":false,"passed":true},{"actual":false,"check":"A hedge duplicates a non-repeatable side effect","expected":false,"passed":true},{"actual":true,"check":"unrelated tracing metadata","expected":true,"passed":true},{"actual":true,"check":"repeat validation is pure","expected":true,"passed":true},{"actual":false,"check":"two independent violations in variant","expected":false,"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"valid operation\", \"actual\": true, \"expected\": true, \"passed\": true}, {\"check\": \"A duplicate request is launched before the hedge delay\", \"actual\": false, \"expected\": false, \"passed\": true}, {\"check\": \"A hedge starts after the primary already completed\", \"actual\": true, \"expected\": false, \"passed\": false}, {\"check\": \"Primary and hedge share the same correlated failure domain\", \"actual\": false, \"expected\": false, \"passed\": true}, {\"check\": \"Speculation consumes more than the allowed duplicate capacity\", \"actual\": false, \"expected\": false, \"passed\": true}, {\"check\": \"A hedge duplicates a non-repeatable side effect\", \"actual\": false, \"expected\": false, \"passed\": true}, {\"check\": \"unrelated tracing metadata\", \"actual\": true, \"expected\": true, \"passed\": true}, {\"check\": \"repeat validation is pure\", \"actual\": true, \"expected\": true, \"passed\": true}, {\"check\": \"two independent violations in variant\", \"actual\": false, \"expected\": false, \"passed\": true}], \"passed\": false}\n"},"broken":{"elapsed_ms":30.259,"exit_code":1,"observations":[{"actual":true,"check":"valid operation","expected":true,"passed":true},{"actual":true,"check":"A duplicate request is launched before the hedge delay","expected":false,"passed":false},{"actual":false,"check":"A hedge starts after the primary already completed","expected":false,"passed":true},{"actual":false,"check":"Primary and hedge share the same correlated failure domain","expected":false,"passed":true},{"actual":false,"check":"Speculation consumes more than the allowed duplicate capacity","expected":false,"passed":true},{"actual":false,"check":"A hedge duplicates a non-repeatable side effect","expected":false,"passed":true},{"actual":true,"check":"unrelated tracing metadata","expected":true,"passed":true},{"actual":true,"check":"repeat validation is pure","expected":true,"passed":true},{"actual":false,"check":"two independent violations in variant","expected":false,"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"valid operation\", \"actual\": true, \"expected\": true, \"passed\": true}, {\"check\": \"A duplicate request is launched before the hedge delay\", \"actual\": true, \"expected\": false, \"passed\": false}, {\"check\": \"A hedge starts after the primary already completed\", \"actual\": false, \"expected\": false, \"passed\": true}, {\"check\": \"Primary and hedge share the same correlated failure domain\", \"actual\": false, \"expected\": false, \"passed\": true}, {\"check\": \"Speculation consumes more than the allowed duplicate capacity\", \"actual\": false, \"expected\": false, \"passed\": true}, {\"check\": \"A hedge duplicates a non-repeatable side effect\", \"actual\": false, \"expected\": false, \"passed\": true}, {\"check\": \"unrelated tracing metadata\", \"actual\": true, \"expected\": true, \"passed\": true}, {\"check\": \"repeat validation is pure\", \"actual\": true, \"expected\": true, \"passed\": true}, {\"check\": \"two independent violations in variant\", \"actual\": false, \"expected\": false, \"passed\": true}], \"passed\": false}\n"},"fixed":{"elapsed_ms":32.981,"exit_code":0,"observations":[{"actual":true,"check":"valid operation","expected":true,"passed":true},{"actual":false,"check":"A duplicate request is launched before the hedge delay","expected":false,"passed":true},{"actual":false,"check":"A hedge starts after the primary already completed","expected":false,"passed":true},{"actual":false,"check":"Primary and hedge share the same correlated failure domain","expected":false,"passed":true},{"actual":false,"check":"Speculation consumes more than the allowed duplicate capacity","expected":false,"passed":true},{"actual":false,"check":"A hedge duplicates a non-repeatable side effect","expected":false,"passed":true},{"actual":true,"check":"unrelated tracing metadata","expected":true,"passed":true},{"actual":true,"check":"repeat validation is pure","expected":true,"passed":true},{"actual":false,"check":"two independent violations in variant","expected":false,"passed":true}],"passed":true,"stderr":"","stdout":"{\"observations\": [{\"check\": \"valid operation\", \"actual\": true, \"expected\": true, \"passed\": true}, {\"check\": \"A duplicate request is launched before the hedge delay\", \"actual\": false, \"expected\": false, \"passed\": true}, {\"check\": \"A hedge starts after the primary already completed\", \"actual\": false, \"expected\": false, \"passed\": true}, {\"check\": \"Primary and hedge share the same correlated failure domain\", \"actual\": false, \"expected\": false, \"passed\": true}, {\"check\": \"Speculation consumes more than the allowed duplicate capacity\", \"actual\": false, \"expected\": false, \"passed\": true}, {\"check\": \"A hedge duplicates a non-repeatable side effect\", \"actual\": false, \"expected\": false, \"passed\": true}, {\"check\": \"unrelated tracing metadata\", \"actual\": true, \"expected\": true, \"passed\": true}, {\"check\": \"repeat validation is pure\", \"actual\": true, \"expected\": true, \"passed\": true}, {\"check\": \"two independent violations in variant\", \"actual\": false, \"expected\": false, \"passed\": true}], \"passed\": true}\n"}},"verified":true,"visibility":"public"}