{"abstract":"The last month of each quarter is assigned to the next quarter.","category":"Calendar arithmetic","checks":4,"contract":"Valid ISO Gregorian dates in years 1 through 9999; generated dates must remain in that range. Month is 1 through 12 and zero-based weekday is Monday 0 through Sunday 6 unless the output convention says otherwise. Quarter number one based. Exact operational definition: (month-1)//3+1","contract_signature":"month","evaluation_group":"model-c2375574cf3f4331","failed_approach":"Zero-based quarter indexing leaks into the result.","family":"xn-quarter-number-one-based","id":"FA-6506","implementations":{"attempt":{"sha256":"73902dcb747790d5e17dd0c520605cd7a7b64bae8b481239b0f7da5a7da1eb04","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\nimport math\nimport calendar\nimport statistics\nimport itertools\nfrom fractions import Fraction\nfrom datetime import date, datetime, timedelta, timezone\nfrom decimal import Decimal, ROUND_HALF_UP, ROUND_DOWN, ROUND_CEILING, ROUND_FLOOR\n\nN = 1\nobservations = []\ndef solve(month):\n    return (month-1)//3\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('fixture 1: (1,)', solve(*(1,)), 1)\ncheck('fixture 2: (3,)', solve(*(3,)), 1)\ncheck('fixture 3: (4,)', solve(*(4,)), 2)\ncheck('fixture 4: (12,)', solve(*(12,)), 4)\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":"abe3c91eae0540b67708d9da4273b74b4c561ffc47a31bb5fb4d89b23382d92d","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\nimport math\nimport calendar\nimport statistics\nimport itertools\nfrom fractions import Fraction\nfrom datetime import date, datetime, timedelta, timezone\nfrom decimal import Decimal, ROUND_HALF_UP, ROUND_DOWN, ROUND_CEILING, ROUND_FLOOR\n\nN = 1\nobservations = []\ndef solve(month):\n    return month//3+1\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('fixture 1: (1,)', solve(*(1,)), 1)\ncheck('fixture 2: (3,)', solve(*(3,)), 1)\ncheck('fixture 3: (4,)', solve(*(4,)), 2)\ncheck('fixture 4: (12,)', solve(*(12,)), 4)\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":"xn-quarter-number-one-based","generated_at":"2026-09-29T14:38:02.673297+00:00","license":"CC0-1.0","python":"3.12.14","seed":1,"split":"open-access"},"relevance":"Small exact fixtures expose this error without platform timing, external services, or probabilistic observations. Calendar conventions results depend on the stated convention.","root_cause":"The last month of each quarter is assigned to the next quarter.","sha256":"b8047f0cd6bd4c29336e85e3d9bb893245544e59017b880e0df6260ab52d61a2","title":"Quarter number one based · case 01","variant":1,"variant_policy":"Five numbered records share a model and may reuse boundary fixtures.","verified":true,"visibility":"public","verification":{"attempt":{"elapsed_ms":40.7,"exit_code":1,"observations":[{"actual":0,"check":"fixture 1: (1,)","expected":1,"passed":false},{"actual":0,"check":"fixture 2: (3,)","expected":1,"passed":false},{"actual":1,"check":"fixture 3: (4,)","expected":2,"passed":false},{"actual":3,"check":"fixture 4: (12,)","expected":4,"passed":false}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"fixture 1: (1,)\", \"actual\": 0, \"expected\": 1, \"passed\": false}, {\"check\": \"fixture 2: (3,)\", \"actual\": 0, \"expected\": 1, \"passed\": false}, {\"check\": \"fixture 3: (4,)\", \"actual\": 1, \"expected\": 2, \"passed\": false}, {\"check\": \"fixture 4: (12,)\", \"actual\": 3, \"expected\": 4, \"passed\": false}], \"passed\": false}\n"},"broken":{"elapsed_ms":39.563,"exit_code":1,"observations":[{"actual":1,"check":"fixture 1: (1,)","expected":1,"passed":true},{"actual":2,"check":"fixture 2: (3,)","expected":1,"passed":false},{"actual":2,"check":"fixture 3: (4,)","expected":2,"passed":true},{"actual":5,"check":"fixture 4: (12,)","expected":4,"passed":false}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"fixture 1: (1,)\", \"actual\": 1, \"expected\": 1, \"passed\": true}, {\"check\": \"fixture 2: (3,)\", \"actual\": 2, \"expected\": 1, \"passed\": false}, {\"check\": \"fixture 3: (4,)\", \"actual\": 2, \"expected\": 2, \"passed\": true}, {\"check\": \"fixture 4: (12,)\", \"actual\": 5, \"expected\": 4, \"passed\": false}], \"passed\": false}\n"}},"member_only":{"stages":["fixed"],"fields":["implementations.fixed","verification.fixed","harness","repair"],"note":"The verified repair, its recorded checks, the repair description, and the scoring harness are available to members."}}