{"abstract":"Bit expansion emits least-significant bits first.","category":"Binary formats","checks":4,"contract":"Return eight bits for an octet in most-significant-first order.","contract_signature":"x","evaluation_group":"model-27146ca3bfacd496","failed_approach":"The attempted repair handles the primary example but still violates a separate boundary of the same contract.","family":"xp-binary-msb-bit-order","id":"FA-3651","implementations":{"attempt":{"sha256":"afe45f994a7f929fc4dd094a84fb44b0e9a35edb9f3e964e1971368485c97bab","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(c) for c in bin(x)[2:]]\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, 0, 0, 0, 0, 0, 1])\ncheck('boundary 2', solve(128), [1, 0, 0, 0, 0, 0, 0, 0])\ncheck('boundary 3', solve(0), [0, 0, 0, 0, 0, 0, 0, 0])\ncheck('boundary 4', solve(255), [1, 1, 1, 1, 1, 1, 1, 1])\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":"d4bca758ed6d72e954baa948879312989e200f8666f7b0e4058969c90a928a47","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 [(x>>i)&1 for i in range(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), [0, 0, 0, 0, 0, 0, 0, 1])\ncheck('boundary 2', solve(128), [1, 0, 0, 0, 0, 0, 0, 0])\ncheck('boundary 3', solve(0), [0, 0, 0, 0, 0, 0, 0, 0])\ncheck('boundary 4', solve(255), [1, 1, 1, 1, 1, 1, 1, 1])\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-msb-bit-order","generated_at":"2026-09-29T14:37:29.115552+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: Return eight bits for an octet in most-significant-first order.","sha256":"fc1f8e77ad113094b106d343ef84451fde26b901daad85e4439d62b0e2b89500","title":"Bit expansion emits least-significant bits first · 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":49.119,"exit_code":1,"observations":[{"actual":[1],"check":"boundary 1","expected":[0,0,0,0,0,0,0,1],"passed":false},{"actual":[1,0,0,0,0,0,0,0],"check":"boundary 2","expected":[1,0,0,0,0,0,0,0],"passed":true},{"actual":[0],"check":"boundary 3","expected":[0,0,0,0,0,0,0,0],"passed":false},{"actual":[1,1,1,1,1,1,1,1],"check":"boundary 4","expected":[1,1,1,1,1,1,1,1],"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"boundary 1\", \"actual\": [1], \"expected\": [0, 0, 0, 0, 0, 0, 0, 1], \"passed\": false}, {\"check\": \"boundary 2\", \"actual\": [1, 0, 0, 0, 0, 0, 0, 0], \"expected\": [1, 0, 0, 0, 0, 0, 0, 0], \"passed\": true}, {\"check\": \"boundary 3\", \"actual\": [0], \"expected\": [0, 0, 0, 0, 0, 0, 0, 0], \"passed\": false}, {\"check\": \"boundary 4\", \"actual\": [1, 1, 1, 1, 1, 1, 1, 1], \"expected\": [1, 1, 1, 1, 1, 1, 1, 1], \"passed\": true}], \"passed\": false}\n"},"broken":{"elapsed_ms":142.367,"exit_code":1,"observations":[{"actual":[1,0,0,0,0,0,0,0],"check":"boundary 1","expected":[0,0,0,0,0,0,0,1],"passed":false},{"actual":[0,0,0,0,0,0,0,1],"check":"boundary 2","expected":[1,0,0,0,0,0,0,0],"passed":false},{"actual":[0,0,0,0,0,0,0,0],"check":"boundary 3","expected":[0,0,0,0,0,0,0,0],"passed":true},{"actual":[1,1,1,1,1,1,1,1],"check":"boundary 4","expected":[1,1,1,1,1,1,1,1],"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"boundary 1\", \"actual\": [1, 0, 0, 0, 0, 0, 0, 0], \"expected\": [0, 0, 0, 0, 0, 0, 0, 1], \"passed\": false}, {\"check\": \"boundary 2\", \"actual\": [0, 0, 0, 0, 0, 0, 0, 1], \"expected\": [1, 0, 0, 0, 0, 0, 0, 0], \"passed\": false}, {\"check\": \"boundary 3\", \"actual\": [0, 0, 0, 0, 0, 0, 0, 0], \"expected\": [0, 0, 0, 0, 0, 0, 0, 0], \"passed\": true}, {\"check\": \"boundary 4\", \"actual\": [1, 1, 1, 1, 1, 1, 1, 1], \"expected\": [1, 1, 1, 1, 1, 1, 1, 1], \"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."}}