{"abstract":"A network-order word uses host-style little endian.","category":"Binary formats","checks":4,"contract":"Decode exactly two integer bytes as an unsigned big-endian word.","evaluation_group":"model-5d1bdbdb26093ac7","failed_approach":"The attempted repair handles the primary example but still violates a separate boundary of the same contract.","family":"xp-binary-u16-endian","id":"FA-3606","implementations":{"attempt":{"sha256":"ecddf855401c352b4d70356c9b66dfc672d219d4089cea1e4fea6b92f58d4383","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 sum(x)\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([1, 0]), 256)\ncheck('boundary 2', solve([0, 1]), 1)\ncheck('boundary 3', solve([255, 255]), 65535)\ncheck('boundary 4', solve([0, 0]), 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":"0bdba7732314418a0dd30438b37a96f2c27ebfd9242b1d1511705ed6b549a5d4","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 int.from_bytes(bytes(x),'little')\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([1, 0]), 256)\ncheck('boundary 2', solve([0, 1]), 1)\ncheck('boundary 3', solve([255, 255]), 65535)\ncheck('boundary 4', solve([0, 0]), 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"},"fixed":{"sha256":"547c1ac9c76245fa49b7f896333e6b746e63a693a5967b6396dcac832833509f","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 int.from_bytes(bytes(x),'big')\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([1, 0]), 256)\ncheck('boundary 2', solve([0, 1]), 1)\ncheck('boundary 3', solve([255, 255]), 65535)\ncheck('boundary 4', solve([0, 0]), 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":" 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-binary-u16-endian","generated_at":"2026-09-29T14:37:28.373967+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.","repair":"Implement the complete stated contract, including the boundary fixtures: Decode exactly two integer bytes as an unsigned big-endian word.","root_cause":"The implementation applies an operation whose text or grammar semantics violate this contract: Decode exactly two integer bytes as an unsigned big-endian word.","sha256":"c65d89d1972cb8e8e53c0245d9d2fb0f01cd66fd6729aecb4b9283a6b2ecb5ff","title":"A network-order word uses host-style little endian · case 01","variant":1,"variant_policy":"Five numbered records share a model and may reuse boundary fixtures.","verification":{"attempt":{"elapsed_ms":55.752,"exit_code":1,"observations":[{"actual":1,"check":"boundary 1","expected":256,"passed":false},{"actual":1,"check":"boundary 2","expected":1,"passed":true},{"actual":510,"check":"boundary 3","expected":65535,"passed":false},{"actual":0,"check":"boundary 4","expected":0,"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"boundary 1\", \"actual\": 1, \"expected\": 256, \"passed\": false}, {\"check\": \"boundary 2\", \"actual\": 1, \"expected\": 1, \"passed\": true}, {\"check\": \"boundary 3\", \"actual\": 510, \"expected\": 65535, \"passed\": false}, {\"check\": \"boundary 4\", \"actual\": 0, \"expected\": 0, \"passed\": true}], \"passed\": false}\n"},"broken":{"elapsed_ms":55.703,"exit_code":1,"observations":[{"actual":1,"check":"boundary 1","expected":256,"passed":false},{"actual":256,"check":"boundary 2","expected":1,"passed":false},{"actual":65535,"check":"boundary 3","expected":65535,"passed":true},{"actual":0,"check":"boundary 4","expected":0,"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"boundary 1\", \"actual\": 1, \"expected\": 256, \"passed\": false}, {\"check\": \"boundary 2\", \"actual\": 256, \"expected\": 1, \"passed\": false}, {\"check\": \"boundary 3\", \"actual\": 65535, \"expected\": 65535, \"passed\": true}, {\"check\": \"boundary 4\", \"actual\": 0, \"expected\": 0, \"passed\": true}], \"passed\": false}\n"},"fixed":{"elapsed_ms":55.056,"exit_code":0,"observations":[{"actual":256,"check":"boundary 1","expected":256,"passed":true},{"actual":1,"check":"boundary 2","expected":1,"passed":true},{"actual":65535,"check":"boundary 3","expected":65535,"passed":true},{"actual":0,"check":"boundary 4","expected":0,"passed":true}],"passed":true,"stderr":"","stdout":"{\"observations\": [{\"check\": \"boundary 1\", \"actual\": 256, \"expected\": 256, \"passed\": true}, {\"check\": \"boundary 2\", \"actual\": 1, \"expected\": 1, \"passed\": true}, {\"check\": \"boundary 3\", \"actual\": 65535, \"expected\": 65535, \"passed\": true}, {\"check\": \"boundary 4\", \"actual\": 0, \"expected\": 0, \"passed\": true}], \"passed\": true}\n"}},"verified":true,"visibility":"public"}