{"abstract":"A full week is unnecessarily added when today matches.","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. Next or same weekday. Exact operational definition: (date.fromisoformat(text)+timedelta(days=(weekday-date.fromisoformat(text).weekday())%7)).isoformat()","contract_signature":"text, weekday","evaluation_group":"model-07751118315fca93","failed_approach":"Signed subtraction can move backward rather than forward.","family":"xn-next-or-same-weekday","id":"FA-6541","implementations":{"attempt":{"sha256":"c6187a4cfdad73a96eea5addbfe2b80dd1753e8cdd5ed5faf97f4c3bddcd5f0c","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(text, weekday):\n    return (date.fromisoformat(text)+timedelta(days=weekday-date.fromisoformat(text).weekday())).isoformat()\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck(\"fixture 1: ('2024-01-01', 0)\", solve(*('2024-01-01', 0)), '2024-01-01')\ncheck(\"fixture 2: ('2024-01-05', 0)\", solve(*('2024-01-05', 0)), '2024-01-08')\ncheck(\"fixture 3: ('2024-01-01', 4)\", solve(*('2024-01-01', 4)), '2024-01-05')\ncheck(\"fixture 4: ('2024-12-31', 2)\", solve(*('2024-12-31', 2)), '2025-01-01')\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":"b154003b3cba6106ec466769995ae8a1a08212fd33cecd67c6a1d3504d271807","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(text, weekday):\n    return (date.fromisoformat(text)+timedelta(days=(weekday-date.fromisoformat(text).weekday())%7 or 7)).isoformat()\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck(\"fixture 1: ('2024-01-01', 0)\", solve(*('2024-01-01', 0)), '2024-01-01')\ncheck(\"fixture 2: ('2024-01-05', 0)\", solve(*('2024-01-05', 0)), '2024-01-08')\ncheck(\"fixture 3: ('2024-01-01', 4)\", solve(*('2024-01-01', 4)), '2024-01-05')\ncheck(\"fixture 4: ('2024-12-31', 2)\", solve(*('2024-12-31', 2)), '2025-01-01')\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-next-or-same-weekday","generated_at":"2026-09-29T14:38:03.075173+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":"A full week is unnecessarily added when today matches.","sha256":"345c837a5de39e7b9e03db9f31ade825d98ad550a396909cd7ba4913e55efa8d","title":"Next or same weekday · 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":42.211,"exit_code":1,"observations":[{"actual":"2024-01-01","check":"fixture 1: ('2024-01-01', 0)","expected":"2024-01-01","passed":true},{"actual":"2024-01-01","check":"fixture 2: ('2024-01-05', 0)","expected":"2024-01-08","passed":false},{"actual":"2024-01-05","check":"fixture 3: ('2024-01-01', 4)","expected":"2024-01-05","passed":true},{"actual":"2025-01-01","check":"fixture 4: ('2024-12-31', 2)","expected":"2025-01-01","passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"fixture 1: ('2024-01-01', 0)\", \"actual\": \"2024-01-01\", \"expected\": \"2024-01-01\", \"passed\": true}, {\"check\": \"fixture 2: ('2024-01-05', 0)\", \"actual\": \"2024-01-01\", \"expected\": \"2024-01-08\", \"passed\": false}, {\"check\": \"fixture 3: ('2024-01-01', 4)\", \"actual\": \"2024-01-05\", \"expected\": \"2024-01-05\", \"passed\": true}, {\"check\": \"fixture 4: ('2024-12-31', 2)\", \"actual\": \"2025-01-01\", \"expected\": \"2025-01-01\", \"passed\": true}], \"passed\": false}\n"},"broken":{"elapsed_ms":44.546,"exit_code":1,"observations":[{"actual":"2024-01-08","check":"fixture 1: ('2024-01-01', 0)","expected":"2024-01-01","passed":false},{"actual":"2024-01-08","check":"fixture 2: ('2024-01-05', 0)","expected":"2024-01-08","passed":true},{"actual":"2024-01-05","check":"fixture 3: ('2024-01-01', 4)","expected":"2024-01-05","passed":true},{"actual":"2025-01-01","check":"fixture 4: ('2024-12-31', 2)","expected":"2025-01-01","passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"fixture 1: ('2024-01-01', 0)\", \"actual\": \"2024-01-08\", \"expected\": \"2024-01-01\", \"passed\": false}, {\"check\": \"fixture 2: ('2024-01-05', 0)\", \"actual\": \"2024-01-08\", \"expected\": \"2024-01-08\", \"passed\": true}, {\"check\": \"fixture 3: ('2024-01-01', 4)\", \"actual\": \"2024-01-05\", \"expected\": \"2024-01-05\", \"passed\": true}, {\"check\": \"fixture 4: ('2024-12-31', 2)\", \"actual\": \"2025-01-01\", \"expected\": \"2025-01-01\", \"passed\": true}], \"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."}}