{"abstract":"Projection aliases overwrite the input name environment.","category":"Data systems","checks":7,"contract":"Evaluate ordered projection [output-name,input-name] pairs against each immutable input record, not earlier output aliases. Missing inputs yield None. Repeated output names occupy distinct result columns, and empty projections retain one empty result per input row.","contract_signature":"d","evaluation_group":"s3-data-systems-projection-alias-snapshot","failed_approach":"Adding only new aliases still allows later inputs to refer to output names absent from source.","family":"s3-data-systems-projection-alias-snapshot-alias-writeback","id":"FA-44761","implementations":{"attempt":{"sha256":"3320143d65faf419578dc25e36a666fb1f5a9f3736774b8c21fec8ffa8cf6eb9","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(d):\n    try:\n        rows,projection=d\n        out=[]\n        for source in rows:\n            record=[]\n            env=source.copy()\n            for alias,name in projection:\n                value=env.get(name)\n                record.append([alias,value]); env.setdefault(alias,value)\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('shadowed input', solve([[{'a': 1, 'b': 2}], [['b', 'a'], ['c', 'b']]]), [[['b', 1], ['c', 2]]])\n    check('new alias not input', solve([[{'a': 1}], [['x', 'a'], ['y', 'x']]]), [[['x', 1], ['y', None]]])\n    check('repeated label', solve([[{'a': 1, 'b': 2}], [['x', 'a'], ['x', 'b']]]), [[['x', 1], ['x', 2]]])\n    check('multiple rows', solve([[{'a': 1}, {'a': 2}], [['z', 'a']]]), [[['z', 1]], [['z', 2]]])\n    check('missing with alias present', solve([[{'x': 1}], [['x', 'missing']]]), [[['x', None]]])\n    check('empty projection', solve([[{'a': 1}, {'a': 2}], []]), [[], []])\n    check('empty input', solve([[], [['x', 'a']]]), [])\nelif N == 2:\n    check('shadowed input', solve([[{'a': 2, 'b': 3}], [['b', 'a'], ['c', 'b']]]), [[['b', 2], ['c', 3]]])\n    check('new alias not input', solve([[{'a': 2}], [['x', 'a'], ['y', 'x']]]), [[['x', 2], ['y', None]]])\n    check('repeated label', solve([[{'a': 2, 'b': 3}], [['x', 'a'], ['x', 'b']]]), [[['x', 2], ['x', 3]]])\n    check('multiple rows', solve([[{'a': 2}, {'a': 3}], [['z', 'a']]]), [[['z', 2]], [['z', 3]]])\n    check('missing with alias present', solve([[{'x': 2}], [['x', 'missing']]]), [[['x', None]]])\n    check('empty projection', solve([[{'a': 2}, {'a': 3}], []]), [[], []])\n    check('empty input', solve([[], [['x', 'a']]]), [])\nelif N == 3:\n    check('shadowed input', solve([[{'a': 3, 'b': 4}], [['b', 'a'], ['c', 'b']]]), [[['b', 3], ['c', 4]]])\n    check('new alias not input', solve([[{'a': 3}], [['x', 'a'], ['y', 'x']]]), [[['x', 3], ['y', None]]])\n    check('repeated label', solve([[{'a': 3, 'b': 4}], [['x', 'a'], ['x', 'b']]]), [[['x', 3], ['x', 4]]])\n    check('multiple rows', solve([[{'a': 3}, {'a': 4}], [['z', 'a']]]), [[['z', 3]], [['z', 4]]])\n    check('missing with alias present', solve([[{'x': 3}], [['x', 'missing']]]), [[['x', None]]])\n    check('empty projection', solve([[{'a': 3}, {'a': 4}], []]), [[], []])\n    check('empty input', solve([[], [['x', 'a']]]), [])\nelif N == 4:\n    check('shadowed input', solve([[{'a': 4, 'b': 5}], [['b', 'a'], ['c', 'b']]]), [[['b', 4], ['c', 5]]])\n    check('new alias not input', solve([[{'a': 4}], [['x', 'a'], ['y', 'x']]]), [[['x', 4], ['y', None]]])\n    check('repeated label', solve([[{'a': 4, 'b': 5}], [['x', 'a'], ['x', 'b']]]), [[['x', 4], ['x', 5]]])\n    check('multiple rows', solve([[{'a': 4}, {'a': 5}], [['z', 'a']]]), [[['z', 4]], [['z', 5]]])\n    check('missing with alias present', solve([[{'x': 4}], [['x', 'missing']]]), [[['x', None]]])\n    check('empty projection', solve([[{'a': 4}, {'a': 5}], []]), [[], []])\n    check('empty input', solve([[], [['x', 'a']]]), [])\nelif N == 5:\n    check('shadowed input', solve([[{'a': 5, 'b': 6}], [['b', 'a'], ['c', 'b']]]), [[['b', 5], ['c', 6]]])\n    check('new alias not input', solve([[{'a': 5}], [['x', 'a'], ['y', 'x']]]), [[['x', 5], ['y', None]]])\n    check('repeated label', solve([[{'a': 5, 'b': 6}], [['x', 'a'], ['x', 'b']]]), [[['x', 5], ['x', 6]]])\n    check('multiple rows', solve([[{'a': 5}, {'a': 6}], [['z', 'a']]]), [[['z', 5]], [['z', 6]]])\n    check('missing with alias present', solve([[{'x': 5}], [['x', 'missing']]]), [[['x', None]]])\n    check('empty projection', solve([[{'a': 5}, {'a': 6}], []]), [[], []])\n    check('empty input', solve([[], [['x', 'a']]]), [])\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":"a60846c4f55dd23e199878ccaaf92e2562f731d51e30fa636a42176134b75381","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(d):\n    try:\n        rows,projection=d\n        out=[]\n        for source in rows:\n            record=[]\n            env=source.copy()\n            for alias,name in projection:\n                value=env.get(name)\n                record.append([alias,value]); env[alias]=value\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('shadowed input', solve([[{'a': 1, 'b': 2}], [['b', 'a'], ['c', 'b']]]), [[['b', 1], ['c', 2]]])\n    check('new alias not input', solve([[{'a': 1}], [['x', 'a'], ['y', 'x']]]), [[['x', 1], ['y', None]]])\n    check('repeated label', solve([[{'a': 1, 'b': 2}], [['x', 'a'], ['x', 'b']]]), [[['x', 1], ['x', 2]]])\n    check('multiple rows', solve([[{'a': 1}, {'a': 2}], [['z', 'a']]]), [[['z', 1]], [['z', 2]]])\n    check('missing with alias present', solve([[{'x': 1}], [['x', 'missing']]]), [[['x', None]]])\n    check('empty projection', solve([[{'a': 1}, {'a': 2}], []]), [[], []])\n    check('empty input', solve([[], [['x', 'a']]]), [])\nelif N == 2:\n    check('shadowed input', solve([[{'a': 2, 'b': 3}], [['b', 'a'], ['c', 'b']]]), [[['b', 2], ['c', 3]]])\n    check('new alias not input', solve([[{'a': 2}], [['x', 'a'], ['y', 'x']]]), [[['x', 2], ['y', None]]])\n    check('repeated label', solve([[{'a': 2, 'b': 3}], [['x', 'a'], ['x', 'b']]]), [[['x', 2], ['x', 3]]])\n    check('multiple rows', solve([[{'a': 2}, {'a': 3}], [['z', 'a']]]), [[['z', 2]], [['z', 3]]])\n    check('missing with alias present', solve([[{'x': 2}], [['x', 'missing']]]), [[['x', None]]])\n    check('empty projection', solve([[{'a': 2}, {'a': 3}], []]), [[], []])\n    check('empty input', solve([[], [['x', 'a']]]), [])\nelif N == 3:\n    check('shadowed input', solve([[{'a': 3, 'b': 4}], [['b', 'a'], ['c', 'b']]]), [[['b', 3], ['c', 4]]])\n    check('new alias not input', solve([[{'a': 3}], [['x', 'a'], ['y', 'x']]]), [[['x', 3], ['y', None]]])\n    check('repeated label', solve([[{'a': 3, 'b': 4}], [['x', 'a'], ['x', 'b']]]), [[['x', 3], ['x', 4]]])\n    check('multiple rows', solve([[{'a': 3}, {'a': 4}], [['z', 'a']]]), [[['z', 3]], [['z', 4]]])\n    check('missing with alias present', solve([[{'x': 3}], [['x', 'missing']]]), [[['x', None]]])\n    check('empty projection', solve([[{'a': 3}, {'a': 4}], []]), [[], []])\n    check('empty input', solve([[], [['x', 'a']]]), [])\nelif N == 4:\n    check('shadowed input', solve([[{'a': 4, 'b': 5}], [['b', 'a'], ['c', 'b']]]), [[['b', 4], ['c', 5]]])\n    check('new alias not input', solve([[{'a': 4}], [['x', 'a'], ['y', 'x']]]), [[['x', 4], ['y', None]]])\n    check('repeated label', solve([[{'a': 4, 'b': 5}], [['x', 'a'], ['x', 'b']]]), [[['x', 4], ['x', 5]]])\n    check('multiple rows', solve([[{'a': 4}, {'a': 5}], [['z', 'a']]]), [[['z', 4]], [['z', 5]]])\n    check('missing with alias present', solve([[{'x': 4}], [['x', 'missing']]]), [[['x', None]]])\n    check('empty projection', solve([[{'a': 4}, {'a': 5}], []]), [[], []])\n    check('empty input', solve([[], [['x', 'a']]]), [])\nelif N == 5:\n    check('shadowed input', solve([[{'a': 5, 'b': 6}], [['b', 'a'], ['c', 'b']]]), [[['b', 5], ['c', 6]]])\n    check('new alias not input', solve([[{'a': 5}], [['x', 'a'], ['y', 'x']]]), [[['x', 5], ['y', None]]])\n    check('repeated label', solve([[{'a': 5, 'b': 6}], [['x', 'a'], ['x', 'b']]]), [[['x', 5], ['x', 6]]])\n    check('multiple rows', solve([[{'a': 5}, {'a': 6}], [['z', 'a']]]), [[['z', 5]], [['z', 6]]])\n    check('missing with alias present', solve([[{'x': 5}], [['x', 'missing']]]), [[['x', None]]])\n    check('empty projection', solve([[{'a': 5}, {'a': 6}], []]), [[], []])\n    check('empty input', solve([[], [['x', 'a']]]), [])\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-projection-alias-snapshot-alias-writeback","generated_at":"2026-09-29T14:44:15.641066+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":"projection-alias-snapshot: Projection aliases overwrite the input name environment.","sha256":"38acbc07e3842de1763153a31978bf4aec701834820d7fbc884792551a591270","title":"Projection aliases overwrite the input name environment · 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":41.637,"exit_code":1,"observations":[{"actual":[[["b",1],["c",2]]],"check":"shadowed input","expected":[[["b",1],["c",2]]],"passed":true},{"actual":[[["x",1],["y",1]]],"check":"new alias not input","expected":[[["x",1],["y",null]]],"passed":false},{"actual":[[["x",1],["x",2]]],"check":"repeated label","expected":[[["x",1],["x",2]]],"passed":true},{"actual":[[["z",1]],[["z",2]]],"check":"multiple rows","expected":[[["z",1]],[["z",2]]],"passed":true},{"actual":[[["x",null]]],"check":"missing with alias present","expected":[[["x",null]]],"passed":true},{"actual":[[],[]],"check":"empty projection","expected":[[],[]],"passed":true},{"actual":[],"check":"empty input","expected":[],"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"shadowed input\", \"actual\": [[[\"b\", 1], [\"c\", 2]]], \"expected\": [[[\"b\", 1], [\"c\", 2]]], \"passed\": true}, {\"check\": \"new alias not input\", \"actual\": [[[\"x\", 1], [\"y\", 1]]], \"expected\": [[[\"x\", 1], [\"y\", null]]], \"passed\": false}, {\"check\": \"repeated label\", \"actual\": [[[\"x\", 1], [\"x\", 2]]], \"expected\": [[[\"x\", 1], [\"x\", 2]]], \"passed\": true}, {\"check\": \"multiple rows\", \"actual\": [[[\"z\", 1]], [[\"z\", 2]]], \"expected\": [[[\"z\", 1]], [[\"z\", 2]]], \"passed\": true}, {\"check\": \"missing with alias present\", \"actual\": [[[\"x\", null]]], \"expected\": [[[\"x\", null]]], \"passed\": true}, {\"check\": \"empty projection\", \"actual\": [[], []], \"expected\": [[], []], \"passed\": true}, {\"check\": \"empty input\", \"actual\": [], \"expected\": [], \"passed\": true}], \"passed\": false}\n"},"broken":{"elapsed_ms":42.536,"exit_code":1,"observations":[{"actual":[[["b",1],["c",1]]],"check":"shadowed input","expected":[[["b",1],["c",2]]],"passed":false},{"actual":[[["x",1],["y",1]]],"check":"new alias not input","expected":[[["x",1],["y",null]]],"passed":false},{"actual":[[["x",1],["x",2]]],"check":"repeated label","expected":[[["x",1],["x",2]]],"passed":true},{"actual":[[["z",1]],[["z",2]]],"check":"multiple rows","expected":[[["z",1]],[["z",2]]],"passed":true},{"actual":[[["x",null]]],"check":"missing with alias present","expected":[[["x",null]]],"passed":true},{"actual":[[],[]],"check":"empty projection","expected":[[],[]],"passed":true},{"actual":[],"check":"empty input","expected":[],"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"shadowed input\", \"actual\": [[[\"b\", 1], [\"c\", 1]]], \"expected\": [[[\"b\", 1], [\"c\", 2]]], \"passed\": false}, {\"check\": \"new alias not input\", \"actual\": [[[\"x\", 1], [\"y\", 1]]], \"expected\": [[[\"x\", 1], [\"y\", null]]], \"passed\": false}, {\"check\": \"repeated label\", \"actual\": [[[\"x\", 1], [\"x\", 2]]], \"expected\": [[[\"x\", 1], [\"x\", 2]]], \"passed\": true}, {\"check\": \"multiple rows\", \"actual\": [[[\"z\", 1]], [[\"z\", 2]]], \"expected\": [[[\"z\", 1]], [[\"z\", 2]]], \"passed\": true}, {\"check\": \"missing with alias present\", \"actual\": [[[\"x\", null]]], \"expected\": [[[\"x\", null]]], \"passed\": true}, {\"check\": \"empty projection\", \"actual\": [[], []], \"expected\": [[], []], \"passed\": true}, {\"check\": \"empty input\", \"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."}}