{"abstract":"An ISBN-like lexeme admits X outside its final position.","category":"Lexical grammars","checks":4,"contract":"Accept nine ASCII digits and a final digit or uppercase X, without separators; no checksum assertion.","contract_signature":"x","evaluation_group":"model-a8eb5f2b821217ab","failed_approach":"The candidate grammar '[0-9]{10}' still disagrees with the explicit boundary fixtures.","family":"xp-isbn-hyphen-body","id":"FA-3596","implementations":{"attempt":{"sha256":"966b8d93b8d07b1d0c50b9710d85e009738ceae4fe31d716f45b73d36d17e0e5","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 bool(re.fullmatch('[0-9]{10}',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('X123456789'), False)\ncheck('boundary 2', solve('123456789X'), True)\ncheck('boundary 3', solve('0123456789'), True)\ncheck('boundary 4', solve('123'), False)\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":"13b952813dbcc8b251a8b6d83e641d81bdf4caaf2b79e2ca2e65fb761fcc8211","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 bool(re.fullmatch('[0-9X]{10}',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('X123456789'), False)\ncheck('boundary 2', solve('123456789X'), True)\ncheck('boundary 3', solve('0123456789'), True)\ncheck('boundary 4', solve('123'), False)\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-isbn-hyphen-body","generated_at":"2026-09-29T14:37:28.200308+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 recognizer uses '[0-9X]{10}', which admits or omits a token shape forbidden by the stated grammar.","sha256":"95c9329d716b2ca81d4ef8db82c558418b545dd8cfc55b88dc1ab39433b622c5","title":"An ISBN-like lexeme admits X outside its final position · 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":56.811,"exit_code":1,"observations":[{"actual":false,"check":"boundary 1","expected":false,"passed":true},{"actual":false,"check":"boundary 2","expected":true,"passed":false},{"actual":true,"check":"boundary 3","expected":true,"passed":true},{"actual":false,"check":"boundary 4","expected":false,"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"boundary 1\", \"actual\": false, \"expected\": false, \"passed\": true}, {\"check\": \"boundary 2\", \"actual\": false, \"expected\": true, \"passed\": false}, {\"check\": \"boundary 3\", \"actual\": true, \"expected\": true, \"passed\": true}, {\"check\": \"boundary 4\", \"actual\": false, \"expected\": false, \"passed\": true}], \"passed\": false}\n"},"broken":{"elapsed_ms":56.304,"exit_code":1,"observations":[{"actual":true,"check":"boundary 1","expected":false,"passed":false},{"actual":true,"check":"boundary 2","expected":true,"passed":true},{"actual":true,"check":"boundary 3","expected":true,"passed":true},{"actual":false,"check":"boundary 4","expected":false,"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"boundary 1\", \"actual\": true, \"expected\": false, \"passed\": false}, {\"check\": \"boundary 2\", \"actual\": true, \"expected\": true, \"passed\": true}, {\"check\": \"boundary 3\", \"actual\": true, \"expected\": true, \"passed\": true}, {\"check\": \"boundary 4\", \"actual\": false, \"expected\": false, \"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."}}