{"abstract":"Struct projection ignores a gathered row selection.","category":"Data systems","checks":7,"contract":"Project requested fields from a struct array. Parent validity dominates field validity, absent schema fields materialize None, selection retains row order, and projection retains requested field order.","contract_signature":"d","evaluation_group":"s3-data-systems-struct-vector-project","failed_approach":"Sorting selection reads the right rows in the wrong order.","family":"s3-data-systems-struct-vector-project-selection","id":"FA-44461","implementations":{"attempt":{"sha256":"8271d518886bc4811e423f2685ccb81cc4deed71d001d0b5c0aa6673e28c8484","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(d):\n    try:\n        columns,valid,parent,selection,fields=d\n        out=[]\n        for row in sorted(selection):\n            record=[]\n            for field in fields:\n                present=field in columns\n                known=present and valid[field][row]\n                value=columns[field][row] if present else None\n                record.append(value if parent[row] and known else None)\n            out.append(record)\n        return out\n    except (IndexError, KeyError, ValueError, StopIteration) as exc:\n        return {\"representation_error\": type(exc).__name__}\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\nif N == 1:\n    check('gather with field order', solve([{'a': [1, 2], 'b': [3, 4]}, {'a': [True, True], 'b': [True, True]}, [True, True], [1, 0], ['b', 'a']]), [[4, 2], [3, 1]])\n    check('parent hides values', solve([{'a': [1, 2]}, {'a': [True, True]}, [False, True], [0, 1], ['a']]), [[None], [2]])\n    check('field null lane', solve([{'a': [1, 2]}, {'a': [False, True]}, [True, True], [0, 1], ['a']]), [[None], [2]])\n    check('missing field', solve([{'a': [1]}, {'a': [True]}, [True], [0], ['a', 'missing']]), [[1, None]])\n    check('repeated projection', solve([{'a': [1]}, {'a': [True]}, [True], [0], ['a', 'a']]), [[1, 1]])\n    check('empty rows', solve([{'a': []}, {'a': []}, [], [], ['a']]), [])\n    check('empty projection', solve([{'a': [1]}, {'a': [True]}, [True], [0], []]), [[]])\nelif N == 2:\n    check('gather with field order', solve([{'a': [2, 3], 'b': [4, 5]}, {'a': [True, True], 'b': [True, True]}, [True, True], [1, 0], ['b', 'a']]), [[5, 3], [4, 2]])\n    check('parent hides values', solve([{'a': [2, 3]}, {'a': [True, True]}, [False, True], [0, 1], ['a']]), [[None], [3]])\n    check('field null lane', solve([{'a': [2, 3]}, {'a': [False, True]}, [True, True], [0, 1], ['a']]), [[None], [3]])\n    check('missing field', solve([{'a': [2]}, {'a': [True]}, [True], [0], ['a', 'missing']]), [[2, None]])\n    check('repeated projection', solve([{'a': [2]}, {'a': [True]}, [True], [0], ['a', 'a']]), [[2, 2]])\n    check('empty rows', solve([{'a': []}, {'a': []}, [], [], ['a']]), [])\n    check('empty projection', solve([{'a': [2]}, {'a': [True]}, [True], [0], []]), [[]])\nelif N == 3:\n    check('gather with field order', solve([{'a': [3, 4], 'b': [5, 6]}, {'a': [True, True], 'b': [True, True]}, [True, True], [1, 0], ['b', 'a']]), [[6, 4], [5, 3]])\n    check('parent hides values', solve([{'a': [3, 4]}, {'a': [True, True]}, [False, True], [0, 1], ['a']]), [[None], [4]])\n    check('field null lane', solve([{'a': [3, 4]}, {'a': [False, True]}, [True, True], [0, 1], ['a']]), [[None], [4]])\n    check('missing field', solve([{'a': [3]}, {'a': [True]}, [True], [0], ['a', 'missing']]), [[3, None]])\n    check('repeated projection', solve([{'a': [3]}, {'a': [True]}, [True], [0], ['a', 'a']]), [[3, 3]])\n    check('empty rows', solve([{'a': []}, {'a': []}, [], [], ['a']]), [])\n    check('empty projection', solve([{'a': [3]}, {'a': [True]}, [True], [0], []]), [[]])\nelif N == 4:\n    check('gather with field order', solve([{'a': [4, 5], 'b': [6, 7]}, {'a': [True, True], 'b': [True, True]}, [True, True], [1, 0], ['b', 'a']]), [[7, 5], [6, 4]])\n    check('parent hides values', solve([{'a': [4, 5]}, {'a': [True, True]}, [False, True], [0, 1], ['a']]), [[None], [5]])\n    check('field null lane', solve([{'a': [4, 5]}, {'a': [False, True]}, [True, True], [0, 1], ['a']]), [[None], [5]])\n    check('missing field', solve([{'a': [4]}, {'a': [True]}, [True], [0], ['a', 'missing']]), [[4, None]])\n    check('repeated projection', solve([{'a': [4]}, {'a': [True]}, [True], [0], ['a', 'a']]), [[4, 4]])\n    check('empty rows', solve([{'a': []}, {'a': []}, [], [], ['a']]), [])\n    check('empty projection', solve([{'a': [4]}, {'a': [True]}, [True], [0], []]), [[]])\nelif N == 5:\n    check('gather with field order', solve([{'a': [5, 6], 'b': [7, 8]}, {'a': [True, True], 'b': [True, True]}, [True, True], [1, 0], ['b', 'a']]), [[8, 6], [7, 5]])\n    check('parent hides values', solve([{'a': [5, 6]}, {'a': [True, True]}, [False, True], [0, 1], ['a']]), [[None], [6]])\n    check('field null lane', solve([{'a': [5, 6]}, {'a': [False, True]}, [True, True], [0, 1], ['a']]), [[None], [6]])\n    check('missing field', solve([{'a': [5]}, {'a': [True]}, [True], [0], ['a', 'missing']]), [[5, None]])\n    check('repeated projection', solve([{'a': [5]}, {'a': [True]}, [True], [0], ['a', 'a']]), [[5, 5]])\n    check('empty rows', solve([{'a': []}, {'a': []}, [], [], ['a']]), [])\n    check('empty projection', solve([{'a': [5]}, {'a': [True]}, [True], [0], []]), [[]])\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":"5687597d0b370408fa2fd3445788bba971c7aa2b754f3d52febd0fb9ba3d3f49","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(d):\n    try:\n        columns,valid,parent,selection,fields=d\n        out=[]\n        for row in range(len(selection)):\n            record=[]\n            for field in fields:\n                present=field in columns\n                known=present and valid[field][row]\n                value=columns[field][row] if present else None\n                record.append(value if parent[row] and known else None)\n            out.append(record)\n        return out\n    except (IndexError, KeyError, ValueError, StopIteration) as exc:\n        return {\"representation_error\": type(exc).__name__}\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\nif N == 1:\n    check('gather with field order', solve([{'a': [1, 2], 'b': [3, 4]}, {'a': [True, True], 'b': [True, True]}, [True, True], [1, 0], ['b', 'a']]), [[4, 2], [3, 1]])\n    check('parent hides values', solve([{'a': [1, 2]}, {'a': [True, True]}, [False, True], [0, 1], ['a']]), [[None], [2]])\n    check('field null lane', solve([{'a': [1, 2]}, {'a': [False, True]}, [True, True], [0, 1], ['a']]), [[None], [2]])\n    check('missing field', solve([{'a': [1]}, {'a': [True]}, [True], [0], ['a', 'missing']]), [[1, None]])\n    check('repeated projection', solve([{'a': [1]}, {'a': [True]}, [True], [0], ['a', 'a']]), [[1, 1]])\n    check('empty rows', solve([{'a': []}, {'a': []}, [], [], ['a']]), [])\n    check('empty projection', solve([{'a': [1]}, {'a': [True]}, [True], [0], []]), [[]])\nelif N == 2:\n    check('gather with field order', solve([{'a': [2, 3], 'b': [4, 5]}, {'a': [True, True], 'b': [True, True]}, [True, True], [1, 0], ['b', 'a']]), [[5, 3], [4, 2]])\n    check('parent hides values', solve([{'a': [2, 3]}, {'a': [True, True]}, [False, True], [0, 1], ['a']]), [[None], [3]])\n    check('field null lane', solve([{'a': [2, 3]}, {'a': [False, True]}, [True, True], [0, 1], ['a']]), [[None], [3]])\n    check('missing field', solve([{'a': [2]}, {'a': [True]}, [True], [0], ['a', 'missing']]), [[2, None]])\n    check('repeated projection', solve([{'a': [2]}, {'a': [True]}, [True], [0], ['a', 'a']]), [[2, 2]])\n    check('empty rows', solve([{'a': []}, {'a': []}, [], [], ['a']]), [])\n    check('empty projection', solve([{'a': [2]}, {'a': [True]}, [True], [0], []]), [[]])\nelif N == 3:\n    check('gather with field order', solve([{'a': [3, 4], 'b': [5, 6]}, {'a': [True, True], 'b': [True, True]}, [True, True], [1, 0], ['b', 'a']]), [[6, 4], [5, 3]])\n    check('parent hides values', solve([{'a': [3, 4]}, {'a': [True, True]}, [False, True], [0, 1], ['a']]), [[None], [4]])\n    check('field null lane', solve([{'a': [3, 4]}, {'a': [False, True]}, [True, True], [0, 1], ['a']]), [[None], [4]])\n    check('missing field', solve([{'a': [3]}, {'a': [True]}, [True], [0], ['a', 'missing']]), [[3, None]])\n    check('repeated projection', solve([{'a': [3]}, {'a': [True]}, [True], [0], ['a', 'a']]), [[3, 3]])\n    check('empty rows', solve([{'a': []}, {'a': []}, [], [], ['a']]), [])\n    check('empty projection', solve([{'a': [3]}, {'a': [True]}, [True], [0], []]), [[]])\nelif N == 4:\n    check('gather with field order', solve([{'a': [4, 5], 'b': [6, 7]}, {'a': [True, True], 'b': [True, True]}, [True, True], [1, 0], ['b', 'a']]), [[7, 5], [6, 4]])\n    check('parent hides values', solve([{'a': [4, 5]}, {'a': [True, True]}, [False, True], [0, 1], ['a']]), [[None], [5]])\n    check('field null lane', solve([{'a': [4, 5]}, {'a': [False, True]}, [True, True], [0, 1], ['a']]), [[None], [5]])\n    check('missing field', solve([{'a': [4]}, {'a': [True]}, [True], [0], ['a', 'missing']]), [[4, None]])\n    check('repeated projection', solve([{'a': [4]}, {'a': [True]}, [True], [0], ['a', 'a']]), [[4, 4]])\n    check('empty rows', solve([{'a': []}, {'a': []}, [], [], ['a']]), [])\n    check('empty projection', solve([{'a': [4]}, {'a': [True]}, [True], [0], []]), [[]])\nelif N == 5:\n    check('gather with field order', solve([{'a': [5, 6], 'b': [7, 8]}, {'a': [True, True], 'b': [True, True]}, [True, True], [1, 0], ['b', 'a']]), [[8, 6], [7, 5]])\n    check('parent hides values', solve([{'a': [5, 6]}, {'a': [True, True]}, [False, True], [0, 1], ['a']]), [[None], [6]])\n    check('field null lane', solve([{'a': [5, 6]}, {'a': [False, True]}, [True, True], [0, 1], ['a']]), [[None], [6]])\n    check('missing field', solve([{'a': [5]}, {'a': [True]}, [True], [0], ['a', 'missing']]), [[5, None]])\n    check('repeated projection', solve([{'a': [5]}, {'a': [True]}, [True], [0], ['a', 'a']]), [[5, 5]])\n    check('empty rows', solve([{'a': []}, {'a': []}, [], [], ['a']]), [])\n    check('empty projection', solve([{'a': [5]}, {'a': [True]}, [True], [0], []]), [[]])\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":"Offline stipulated semantics over valid small inputs; no performance, concurrency, or production-engine conformance claim. 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":"s3-data-systems-struct-vector-project-selection","generated_at":"2026-09-29T14:44:12.694174+00:00","license":"CC0-1.0","python":"3.12.14","seed":1,"split":"open-access"},"relevance":"A bounded deterministic data engine model makes representation and changelog faults reproducible.","root_cause":"struct-vector-project: Struct projection ignores a gathered row selection.","sha256":"582f85231020d966fc660a5ad50881d39f0e1af489b06f890c15df5b9ec376ff","title":"Struct projection ignores a gathered row selection · 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":43.69,"exit_code":1,"observations":[{"actual":[[3,1],[4,2]],"check":"gather with field order","expected":[[4,2],[3,1]],"passed":false},{"actual":[[null],[2]],"check":"parent hides values","expected":[[null],[2]],"passed":true},{"actual":[[null],[2]],"check":"field null lane","expected":[[null],[2]],"passed":true},{"actual":[[1,null]],"check":"missing field","expected":[[1,null]],"passed":true},{"actual":[[1,1]],"check":"repeated projection","expected":[[1,1]],"passed":true},{"actual":[],"check":"empty rows","expected":[],"passed":true},{"actual":[[]],"check":"empty projection","expected":[[]],"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"gather with field order\", \"actual\": [[3, 1], [4, 2]], \"expected\": [[4, 2], [3, 1]], \"passed\": false}, {\"check\": \"parent hides values\", \"actual\": [[null], [2]], \"expected\": [[null], [2]], \"passed\": true}, {\"check\": \"field null lane\", \"actual\": [[null], [2]], \"expected\": [[null], [2]], \"passed\": true}, {\"check\": \"missing field\", \"actual\": [[1, null]], \"expected\": [[1, null]], \"passed\": true}, {\"check\": \"repeated projection\", \"actual\": [[1, 1]], \"expected\": [[1, 1]], \"passed\": true}, {\"check\": \"empty rows\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"empty projection\", \"actual\": [[]], \"expected\": [[]], \"passed\": true}], \"passed\": false}\n"},"broken":{"elapsed_ms":42.632,"exit_code":1,"observations":[{"actual":[[3,1],[4,2]],"check":"gather with field order","expected":[[4,2],[3,1]],"passed":false},{"actual":[[null],[2]],"check":"parent hides values","expected":[[null],[2]],"passed":true},{"actual":[[null],[2]],"check":"field null lane","expected":[[null],[2]],"passed":true},{"actual":[[1,null]],"check":"missing field","expected":[[1,null]],"passed":true},{"actual":[[1,1]],"check":"repeated projection","expected":[[1,1]],"passed":true},{"actual":[],"check":"empty rows","expected":[],"passed":true},{"actual":[[]],"check":"empty projection","expected":[[]],"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"gather with field order\", \"actual\": [[3, 1], [4, 2]], \"expected\": [[4, 2], [3, 1]], \"passed\": false}, {\"check\": \"parent hides values\", \"actual\": [[null], [2]], \"expected\": [[null], [2]], \"passed\": true}, {\"check\": \"field null lane\", \"actual\": [[null], [2]], \"expected\": [[null], [2]], \"passed\": true}, {\"check\": \"missing field\", \"actual\": [[1, null]], \"expected\": [[1, null]], \"passed\": true}, {\"check\": \"repeated projection\", \"actual\": [[1, 1]], \"expected\": [[1, 1]], \"passed\": true}, {\"check\": \"empty rows\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"empty projection\", \"actual\": [[]], \"expected\": [[]], \"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."}}