{"abstract":"UTF-16 BOM is interpreted as ordinary text.","category":"Encodings","checks":4,"contract":"Decode BOM-bearing UTF-16 hex data honoring the BOM.","contract_signature":"x","evaluation_group":"model-a8aeb41467e1a04a","failed_approach":"The attempted repair handles the primary example but still violates a separate boundary of the same contract.","family":"xp-utf16-endian-bom","id":"FA-2946","implementations":{"attempt":{"sha256":"2fd223beccfb563af83617172550f00ab78e4e93cc5eaa709cbffc0a7a668de8","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\nimport re, unicodedata, json, csv, io, html, base64, binascii, codecs, struct\nfrom urllib.parse import quote, unquote, unquote_to_bytes, urlencode, parse_qsl, urlsplit, urlunsplit\nfrom email.header import decode_header, make_header\nfrom email.utils import getaddresses\nfrom xml.etree import ElementTree as ET\nimport shlex, string, textwrap\n\nN = 1\nobservations = []\ndef solve(x):\n    try:\n        return bytes.fromhex(x)[2:].decode('utf-16-le')\n    except Exception as exc:\n        return {\"error\": type(exc).__name__}\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('boundary 1', solve('fffe4100'), 'A')\ncheck('boundary 2', solve('feff0041'), 'A')\ncheck('boundary 3', solve('fffe3dd800de'), '😀')\ncheck('boundary 4', solve('feff'), '')\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":"02dc52f2f10b90351d41de8af2c8bcfc65129f58f48653a980ae68cec721f42d","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\nimport re, unicodedata, json, csv, io, html, base64, binascii, codecs, struct\nfrom urllib.parse import quote, unquote, unquote_to_bytes, urlencode, parse_qsl, urlsplit, urlunsplit\nfrom email.header import decode_header, make_header\nfrom email.utils import getaddresses\nfrom xml.etree import ElementTree as ET\nimport shlex, string, textwrap\n\nN = 1\nobservations = []\ndef solve(x):\n    try:\n        return bytes.fromhex(x).decode('utf-16-le')\n    except Exception as exc:\n        return {\"error\": type(exc).__name__}\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('boundary 1', solve('fffe4100'), 'A')\ncheck('boundary 2', solve('feff0041'), 'A')\ncheck('boundary 3', solve('fffe3dd800de'), '😀')\ncheck('boundary 4', solve('feff'), '')\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":"xp-utf16-endian-bom","generated_at":"2026-09-29T14:37:19.511710+00:00","license":"CC0-1.0","python":"3.12.14","seed":1,"split":"open-access"},"relevance":"A local executable model for consumers of structured text; oracle values are authored literals, not outputs copied from the repaired implementation.","root_cause":"The implementation applies an operation whose text or grammar semantics violate this contract: Decode BOM-bearing UTF-16 hex data honoring the BOM.","sha256":"dfce44a6d26a45354adcad74e4da377e3b78a017f20a7f12d4806eb04275d5c2","title":"UTF-16 BOM is interpreted as ordinary text · 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":117.834,"exit_code":1,"observations":[{"actual":"A","check":"boundary 1","expected":"A","passed":true},{"actual":"䄀","check":"boundary 2","expected":"A","passed":false},{"actual":"😀","check":"boundary 3","expected":"😀","passed":true},{"actual":"","check":"boundary 4","expected":"","passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"boundary 1\", \"actual\": \"A\", \"expected\": \"A\", \"passed\": true}, {\"check\": \"boundary 2\", \"actual\": \"䄀\", \"expected\": \"A\", \"passed\": false}, {\"check\": \"boundary 3\", \"actual\": \"😀\", \"expected\": \"😀\", \"passed\": true}, {\"check\": \"boundary 4\", \"actual\": \"\", \"expected\": \"\", \"passed\": true}], \"passed\": false}\n"},"broken":{"elapsed_ms":57.416,"exit_code":1,"observations":[{"actual":"A","check":"boundary 1","expected":"A","passed":false},{"actual":"￾䄀","check":"boundary 2","expected":"A","passed":false},{"actual":"😀","check":"boundary 3","expected":"😀","passed":false},{"actual":"￾","check":"boundary 4","expected":"","passed":false}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"boundary 1\", \"actual\": \"A\", \"expected\": \"A\", \"passed\": false}, {\"check\": \"boundary 2\", \"actual\": \"￾䄀\", \"expected\": \"A\", \"passed\": false}, {\"check\": \"boundary 3\", \"actual\": \"😀\", \"expected\": \"😀\", \"passed\": false}, {\"check\": \"boundary 4\", \"actual\": \"￾\", \"expected\": \"\", \"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."}}