{"abstract":"A three-byte field is padded on the wrong side.","category":"Binary formats","checks":4,"contract":"Decode a little-endian unsigned 24-bit field represented by exactly three bytes.","evaluation_group":"model-a7bc52b604a71e8f","failed_approach":"The attempted repair handles the primary example but still violates a separate boundary of the same contract.","family":"xp-binary-u24-width","id":"FA-3681","implementations":{"attempt":{"sha256":"7b3ed67deb3fb186153097968c6ced1f2137aa7054e00fbff2719b32934acd40","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([0]+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, 0]), 1)\ncheck('boundary 2', solve([0, 0, 1]), 65536)\ncheck('boundary 3', solve([255, 255, 255]), 16777215)\ncheck('boundary 4', solve([0, 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":"ab9aced69b043c5f8d62fbc9b38f443955e1af0d5a1e56f248df4f9afba383b7","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+[0]),\"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, 0]), 1)\ncheck('boundary 2', solve([0, 0, 1]), 65536)\ncheck('boundary 3', solve([255, 255, 255]), 16777215)\ncheck('boundary 4', solve([0, 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":"b866fe0fc0aa34ae5e987bdde39469fc73710793a2c029ef4a5c9dfb73c3529f","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, 0]), 1)\ncheck('boundary 2', solve([0, 0, 1]), 65536)\ncheck('boundary 3', solve([255, 255, 255]), 16777215)\ncheck('boundary 4', solve([0, 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-u24-width","generated_at":"2026-09-29T14:37:29.508143+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 a little-endian unsigned 24-bit field represented by exactly three bytes.","root_cause":"The implementation applies an operation whose text or grammar semantics violate this contract: Decode a little-endian unsigned 24-bit field represented by exactly three bytes.","sha256":"dbd83fc0fa9a184d5fd58da96713e136ac9099c6ffff12f2d338d6c3f78c4539","title":"A three-byte field is padded on the wrong side · case 01","variant":1,"variant_policy":"Five numbered records share a model and may reuse boundary fixtures.","verification":{"attempt":{"elapsed_ms":152.059,"exit_code":1,"observations":[{"actual":256,"check":"boundary 1","expected":1,"passed":false},{"actual":16777216,"check":"boundary 2","expected":65536,"passed":false},{"actual":4294967040,"check":"boundary 3","expected":16777215,"passed":false},{"actual":0,"check":"boundary 4","expected":0,"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"boundary 1\", \"actual\": 256, \"expected\": 1, \"passed\": false}, {\"check\": \"boundary 2\", \"actual\": 16777216, \"expected\": 65536, \"passed\": false}, {\"check\": \"boundary 3\", \"actual\": 4294967040, \"expected\": 16777215, \"passed\": false}, {\"check\": \"boundary 4\", \"actual\": 0, \"expected\": 0, \"passed\": true}], \"passed\": false}\n"},"broken":{"elapsed_ms":61.033,"exit_code":1,"observations":[{"actual":16777216,"check":"boundary 1","expected":1,"passed":false},{"actual":256,"check":"boundary 2","expected":65536,"passed":false},{"actual":4294967040,"check":"boundary 3","expected":16777215,"passed":false},{"actual":0,"check":"boundary 4","expected":0,"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"boundary 1\", \"actual\": 16777216, \"expected\": 1, \"passed\": false}, {\"check\": \"boundary 2\", \"actual\": 256, \"expected\": 65536, \"passed\": false}, {\"check\": \"boundary 3\", \"actual\": 4294967040, \"expected\": 16777215, \"passed\": false}, {\"check\": \"boundary 4\", \"actual\": 0, \"expected\": 0, \"passed\": true}], \"passed\": false}\n"},"fixed":{"elapsed_ms":53.668,"exit_code":0,"observations":[{"actual":1,"check":"boundary 1","expected":1,"passed":true},{"actual":65536,"check":"boundary 2","expected":65536,"passed":true},{"actual":16777215,"check":"boundary 3","expected":16777215,"passed":true},{"actual":0,"check":"boundary 4","expected":0,"passed":true}],"passed":true,"stderr":"","stdout":"{\"observations\": [{\"check\": \"boundary 1\", \"actual\": 1, \"expected\": 1, \"passed\": true}, {\"check\": \"boundary 2\", \"actual\": 65536, \"expected\": 65536, \"passed\": true}, {\"check\": \"boundary 3\", \"actual\": 16777215, \"expected\": 16777215, \"passed\": true}, {\"check\": \"boundary 4\", \"actual\": 0, \"expected\": 0, \"passed\": true}], \"passed\": true}\n"}},"verified":true,"visibility":"public"}