{"abstract":"Odd hex nybbles become a complete byte.","category":"Binary formats","checks":4,"contract":"Decode whitespace-separated hexadecimal byte pairs to integer bytes; malformed input returns None.","contract_signature":"x","evaluation_group":"model-305220f3c0d481c9","failed_approach":"The attempted repair handles the primary example but still violates a separate boundary of the same contract.","family":"xp-hex-byte-pairs","id":"FA-2971","implementations":{"attempt":{"sha256":"22dda72272dd987a759f446a11e76f7269f60c8462ebc31e038dd547d9668ae4","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        try:\n            return list(bytes.fromhex(x.replace(' ','')))\n        except ValueError:\n            return None\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('f'), None)\ncheck('boundary 2', solve('a b'), None)\ncheck('boundary 3', solve('0a ff'), [10, 255])\ncheck('boundary 4', solve(''), [])\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":"91d34b28adbd06851c5c213e25273ff06dac44d6e69dd9caca612a39e1f48cdc","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        try:\n            return list(bytes.fromhex('0'+x if len(x)%2 else x))\n        except ValueError:\n            return None\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('f'), None)\ncheck('boundary 2', solve('a b'), None)\ncheck('boundary 3', solve('0a ff'), [10, 255])\ncheck('boundary 4', solve(''), [])\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-hex-byte-pairs","generated_at":"2026-09-29T14:37:19.792738+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 whitespace-separated hexadecimal byte pairs to integer bytes; malformed input returns None.","sha256":"63cadeccc59b9cc29f67fbbecb70b5f8caba62e02d349d77e9011af5e4840532","title":"Odd hex nybbles become a complete byte · 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":56.081,"exit_code":1,"observations":[{"actual":null,"check":"boundary 1","expected":null,"passed":true},{"actual":[171],"check":"boundary 2","expected":null,"passed":false},{"actual":[10,255],"check":"boundary 3","expected":[10,255],"passed":true},{"actual":[],"check":"boundary 4","expected":[],"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"boundary 1\", \"actual\": null, \"expected\": null, \"passed\": true}, {\"check\": \"boundary 2\", \"actual\": [171], \"expected\": null, \"passed\": false}, {\"check\": \"boundary 3\", \"actual\": [10, 255], \"expected\": [10, 255], \"passed\": true}, {\"check\": \"boundary 4\", \"actual\": [], \"expected\": [], \"passed\": true}], \"passed\": false}\n"},"broken":{"elapsed_ms":53.993,"exit_code":1,"observations":[{"actual":[15],"check":"boundary 1","expected":null,"passed":false},{"actual":null,"check":"boundary 2","expected":null,"passed":true},{"actual":null,"check":"boundary 3","expected":[10,255],"passed":false},{"actual":[],"check":"boundary 4","expected":[],"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"boundary 1\", \"actual\": [15], \"expected\": null, \"passed\": false}, {\"check\": \"boundary 2\", \"actual\": null, \"expected\": null, \"passed\": true}, {\"check\": \"boundary 3\", \"actual\": null, \"expected\": [10, 255], \"passed\": false}, {\"check\": \"boundary 4\", \"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."}}