{"abstract":"cutoff timestamp is included in both partitions.","category":"Dataset split isolation","checks":7,"contract":"Records are [id,time]. Return sorted training IDs with time strictly less than cutoff.","contract_signature":"records, cutoff","evaluation_group":"ds-strict-cutoff","failed_approach":"Subtracting one arbitrary timestamp unit works only for integral ticks.","family":"w3-dataset-split-isolation-strict-temporal-cutoff","id":"FA-97856","implementations":{"attempt":{"sha256":"676224de4c9bb5fe1c4f76c2499fb4b2d9fe90910cd4a816fdc86e820afe1fc6","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(records, cutoff):\n    return sorted(i for i,t in records if t<=cutoff-1)\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('before',solve([['a',N-1]],N),['a'])\ncheck('at boundary',solve([['a',N]],N),[])\ncheck('after',solve([['a',N+1]],N),[])\ncheck('fractional predecessor',solve([['a',N-0.5]],N),['a'])\ncheck('unordered',solve([['b',N+2],['a',N-1]],N),['a'])\ncheck('empty',solve([],N),[])\ncheck('equal timestamps',solve([['a',N],['b',N-1]],N),['b'])\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":"10c60ee51fd6819be7000c2cb3f5e982f9eee78d9f15e1052124cc8b53e2005c","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(records, cutoff):\n    return sorted(i for i,t in records if t<=cutoff)\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('before',solve([['a',N-1]],N),['a'])\ncheck('at boundary',solve([['a',N]],N),[])\ncheck('after',solve([['a',N+1]],N),[])\ncheck('fractional predecessor',solve([['a',N-0.5]],N),['a'])\ncheck('unordered',solve([['b',N+2],['a',N-1]],N),['a'])\ncheck('empty',solve([],N),[])\ncheck('equal timestamps',solve([['a',N],['b',N-1]],N),['b'])\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":"Inputs are small in-memory records with self-contained contracts; no claim is made about production sampling quality. 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":"w3-dataset-split-isolation-strict-temporal-cutoff","generated_at":"2026-09-30T16:48:06.687926+00:00","license":"CC0-1.0","python":"3.12.14","seed":1,"split":"open-access"},"relevance":"This toy split allocator makes membership rules explicit for reproducible evaluation fixtures.","root_cause":"Inclusive comparison places boundary records in training.","sha256":"0a383e6ddef35931b8e575ae8264cce305745f23af200092885b56e2115063f4","title":"Dataset split: cutoff timestamp is included in both partitions · case 01","variant":1,"variant_policy":"The fixture code references N, supplied as 1 through 5. Fixed boundary checks may repeat. These records share one mechanism and must remain together in evaluation splits.","verified":true,"visibility":"public","verification":{"attempt":{"elapsed_ms":24.251,"exit_code":1,"observations":[{"actual":["a"],"check":"before","expected":["a"],"passed":true},{"actual":[],"check":"at boundary","expected":[],"passed":true},{"actual":[],"check":"after","expected":[],"passed":true},{"actual":[],"check":"fractional predecessor","expected":["a"],"passed":false},{"actual":["a"],"check":"unordered","expected":["a"],"passed":true},{"actual":[],"check":"empty","expected":[],"passed":true},{"actual":["b"],"check":"equal timestamps","expected":["b"],"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"before\", \"actual\": [\"a\"], \"expected\": [\"a\"], \"passed\": true}, {\"check\": \"at boundary\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"after\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"fractional predecessor\", \"actual\": [], \"expected\": [\"a\"], \"passed\": false}, {\"check\": \"unordered\", \"actual\": [\"a\"], \"expected\": [\"a\"], \"passed\": true}, {\"check\": \"empty\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"equal timestamps\", \"actual\": [\"b\"], \"expected\": [\"b\"], \"passed\": true}], \"passed\": false}\n"},"broken":{"elapsed_ms":32.897,"exit_code":1,"observations":[{"actual":["a"],"check":"before","expected":["a"],"passed":true},{"actual":["a"],"check":"at boundary","expected":[],"passed":false},{"actual":[],"check":"after","expected":[],"passed":true},{"actual":["a"],"check":"fractional predecessor","expected":["a"],"passed":true},{"actual":["a"],"check":"unordered","expected":["a"],"passed":true},{"actual":[],"check":"empty","expected":[],"passed":true},{"actual":["a","b"],"check":"equal timestamps","expected":["b"],"passed":false}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"before\", \"actual\": [\"a\"], \"expected\": [\"a\"], \"passed\": true}, {\"check\": \"at boundary\", \"actual\": [\"a\"], \"expected\": [], \"passed\": false}, {\"check\": \"after\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"fractional predecessor\", \"actual\": [\"a\"], \"expected\": [\"a\"], \"passed\": true}, {\"check\": \"unordered\", \"actual\": [\"a\"], \"expected\": [\"a\"], \"passed\": true}, {\"check\": \"empty\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"equal timestamps\", \"actual\": [\"a\", \"b\"], \"expected\": [\"b\"], \"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."}}