{"abstract":"The next page omits records sharing the final sort key of the previous page.","category":"Data systems","checks":3,"contract":"Compare the complete ordered key, including the unique record identifier.","evaluation_group":"model-4d18ba257272c9fc","failed_approach":"Using an inclusive primary-key comparison repeats records already delivered.","family":"cursor-ties","id":"FA-011","implementations":{"attempt":{"sha256":"7bd74a1728775f33fdc9535bbd3f99ab9cec85694979b43bf0c6257cf4a4232f","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(rows, cursor):\n    return [r for r in rows if r[0] >= cursor[0]]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\nrows = [[N, 1], [N, 2], [N+1, 3]]\ncheck('tied next record', solve(rows, [N, 1]), rows[1:])\ncheck('last record', solve(rows, [N+1, 3]), [])\ncheck('before first', solve(rows, [N-1, 0]), rows)\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":"d437cd350107b431811e96b6c1484c26825a540dce4b28985fe8a922ad2289d0","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(rows, cursor):\n    return [r for r in rows if r[0] > cursor[0]]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\nrows = [[N, 1], [N, 2], [N+1, 3]]\ncheck('tied next record', solve(rows, [N, 1]), rows[1:])\ncheck('last record', solve(rows, [N+1, 3]), [])\ncheck('before first', solve(rows, [N-1, 0]), rows)\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":"da0ab4e3db1f0c937e6b1773b544689edcd5ceb82852f2b3e982962de8b34b80","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(rows, cursor):\n    return [r for r in rows if tuple(r) > tuple(cursor)]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\nrows = [[N, 1], [N, 2], [N+1, 3]]\ncheck('tied next record', solve(rows, [N, 1]), rows[1:])\ncheck('last record', solve(rows, [N+1, 3]), [])\ncheck('before first', solve(rows, [N-1, 0]), rows)\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":"cursor-ties","generated_at":"2026-09-29T14:36:49.849899+00:00","license":"CC0-1.0","python":"3.12.14","seed":1,"split":"open-access"},"relevance":"A compact reasoning and repair task with executable evidence.","repair":"Compare the complete ordered key, including the unique record identifier.","root_cause":"The cursor stores the primary sort key but omits its stable tie breaker.","sha256":"42ec68c8b0917bdcac3ec1bf7a1fb11874f2da91451a7a6ad37c758520fe2f41","title":"A cursor skips records with equal sort keys · case 01","variant":1,"variant_policy":"Five numbered records share a model and may reuse boundary fixtures.","verification":{"attempt":{"elapsed_ms":31.744,"exit_code":1,"observations":[{"actual":[[1,1],[1,2],[2,3]],"check":"tied next record","expected":[[1,2],[2,3]],"passed":false},{"actual":[[2,3]],"check":"last record","expected":[],"passed":false},{"actual":[[1,1],[1,2],[2,3]],"check":"before first","expected":[[1,1],[1,2],[2,3]],"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"tied next record\", \"actual\": [[1, 1], [1, 2], [2, 3]], \"expected\": [[1, 2], [2, 3]], \"passed\": false}, {\"check\": \"last record\", \"actual\": [[2, 3]], \"expected\": [], \"passed\": false}, {\"check\": \"before first\", \"actual\": [[1, 1], [1, 2], [2, 3]], \"expected\": [[1, 1], [1, 2], [2, 3]], \"passed\": true}], \"passed\": false}\n"},"broken":{"elapsed_ms":38.412,"exit_code":1,"observations":[{"actual":[[2,3]],"check":"tied next record","expected":[[1,2],[2,3]],"passed":false},{"actual":[],"check":"last record","expected":[],"passed":true},{"actual":[[1,1],[1,2],[2,3]],"check":"before first","expected":[[1,1],[1,2],[2,3]],"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"tied next record\", \"actual\": [[2, 3]], \"expected\": [[1, 2], [2, 3]], \"passed\": false}, {\"check\": \"last record\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"before first\", \"actual\": [[1, 1], [1, 2], [2, 3]], \"expected\": [[1, 1], [1, 2], [2, 3]], \"passed\": true}], \"passed\": false}\n"},"fixed":{"elapsed_ms":31.146,"exit_code":0,"observations":[{"actual":[[1,2],[2,3]],"check":"tied next record","expected":[[1,2],[2,3]],"passed":true},{"actual":[],"check":"last record","expected":[],"passed":true},{"actual":[[1,1],[1,2],[2,3]],"check":"before first","expected":[[1,1],[1,2],[2,3]],"passed":true}],"passed":true,"stderr":"","stdout":"{\"observations\": [{\"check\": \"tied next record\", \"actual\": [[1, 2], [2, 3]], \"expected\": [[1, 2], [2, 3]], \"passed\": true}, {\"check\": \"last record\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"before first\", \"actual\": [[1, 1], [1, 2], [2, 3]], \"expected\": [[1, 1], [1, 2], [2, 3]], \"passed\": true}], \"passed\": true}\n"}},"verified":true,"visibility":"public"}