{"abstract":"Bit packing puts padding before the data.","category":"Binary formats","checks":4,"contract":"Pack a bit list MSB-first, right-padding the final byte with zeros.","evaluation_group":"model-2f573eb37ba9726e","failed_approach":"The attempted repair handles the primary example but still violates a separate boundary of the same contract.","family":"xp-binary-bit-padding","id":"FA-3696","implementations":{"attempt":{"sha256":"2e4c263bed3ce9df2e6b4bfb4d9178b948bd6368a2e4cec7df6010a08ca8f1d6","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(v<<i for i,v in enumerate(x[j:j+8])) for j in range(0,len(x),8)]\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]), [128])\ncheck('boundary 2', solve([1, 0, 1]), [160])\ncheck('boundary 3', solve([1, 1, 1, 1, 1, 1, 1, 1, 1]), [255, 128])\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":"14c06355b5eade97f1813de3122a8ce84bcb03d00108e53c3b41691a86848624","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 list(int(''.join(map(str,x)) or '0',2).to_bytes((len(x)+7)//8,'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]), [128])\ncheck('boundary 2', solve([1, 0, 1]), [160])\ncheck('boundary 3', solve([1, 1, 1, 1, 1, 1, 1, 1, 1]), [255, 128])\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"},"fixed":{"sha256":"924c2da842ae8d75f52f69123d0882fbb55d9648ceac155f96c8e113fd8a8f54","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(v<<(7-i) for i,v in enumerate(x[j:j+8])) for j in range(0,len(x),8)]\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]), [128])\ncheck('boundary 2', solve([1, 0, 1]), [160])\ncheck('boundary 3', solve([1, 1, 1, 1, 1, 1, 1, 1, 1]), [255, 128])\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-binary-bit-padding","generated_at":"2026-09-29T14:37:29.566178+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: Pack a bit list MSB-first, right-padding the final byte with zeros.","root_cause":"The implementation applies an operation whose text or grammar semantics violate this contract: Pack a bit list MSB-first, right-padding the final byte with zeros.","sha256":"b9186e52b6f88ab0dfa98b13a0b590026de673eb649d8007799e6204ab3d89a6","title":"Bit packing puts padding before the data · case 01","variant":1,"variant_policy":"Five numbered records share a model and may reuse boundary fixtures.","verification":{"attempt":{"elapsed_ms":56.334,"exit_code":1,"observations":[{"actual":[1],"check":"boundary 1","expected":[128],"passed":false},{"actual":[5],"check":"boundary 2","expected":[160],"passed":false},{"actual":[255,1],"check":"boundary 3","expected":[255,128],"passed":false},{"actual":[],"check":"boundary 4","expected":[],"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"boundary 1\", \"actual\": [1], \"expected\": [128], \"passed\": false}, {\"check\": \"boundary 2\", \"actual\": [5], \"expected\": [160], \"passed\": false}, {\"check\": \"boundary 3\", \"actual\": [255, 1], \"expected\": [255, 128], \"passed\": false}, {\"check\": \"boundary 4\", \"actual\": [], \"expected\": [], \"passed\": true}], \"passed\": false}\n"},"broken":{"elapsed_ms":148.038,"exit_code":1,"observations":[{"actual":[1],"check":"boundary 1","expected":[128],"passed":false},{"actual":[5],"check":"boundary 2","expected":[160],"passed":false},{"actual":[1,255],"check":"boundary 3","expected":[255,128],"passed":false},{"actual":[],"check":"boundary 4","expected":[],"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"boundary 1\", \"actual\": [1], \"expected\": [128], \"passed\": false}, {\"check\": \"boundary 2\", \"actual\": [5], \"expected\": [160], \"passed\": false}, {\"check\": \"boundary 3\", \"actual\": [1, 255], \"expected\": [255, 128], \"passed\": false}, {\"check\": \"boundary 4\", \"actual\": [], \"expected\": [], \"passed\": true}], \"passed\": false}\n"},"fixed":{"elapsed_ms":56.845,"exit_code":0,"observations":[{"actual":[128],"check":"boundary 1","expected":[128],"passed":true},{"actual":[160],"check":"boundary 2","expected":[160],"passed":true},{"actual":[255,128],"check":"boundary 3","expected":[255,128],"passed":true},{"actual":[],"check":"boundary 4","expected":[],"passed":true}],"passed":true,"stderr":"","stdout":"{\"observations\": [{\"check\": \"boundary 1\", \"actual\": [128], \"expected\": [128], \"passed\": true}, {\"check\": \"boundary 2\", \"actual\": [160], \"expected\": [160], \"passed\": true}, {\"check\": \"boundary 3\", \"actual\": [255, 128], \"expected\": [255, 128], \"passed\": true}, {\"check\": \"boundary 4\", \"actual\": [], \"expected\": [], \"passed\": true}], \"passed\": true}\n"}},"verified":true,"visibility":"public"}