{"abstract":"A token validator accepts a suffix after a match.","category":"Regular expressions","checks":4,"contract":"Accept exactly ASCII letters, at least one, with no final newline.","evaluation_group":"model-2c20da1fb5ee68b3","failed_approach":"The attempted repair handles the primary example but still violates a separate boundary of the same contract.","family":"xp-regex-fullmatch","id":"FA-3081","implementations":{"attempt":{"sha256":"a81534b927c5e01385a67da870c829fd93b7c66ef2b3ddcaf1281d2148a3d467","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.match('^[A-Za-z]+$',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('abc!'), False)\ncheck('boundary 2', solve('abc\\n'), False)\ncheck('boundary 3', solve('abc'), True)\ncheck('boundary 4', solve(''), 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":"1b76e0ac23ba1dcfe540a0483cc9ddb2682c829b741811e0b7597e21108ef50f","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.match('[A-Za-z]+',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('abc!'), False)\ncheck('boundary 2', solve('abc\\n'), False)\ncheck('boundary 3', solve('abc'), True)\ncheck('boundary 4', solve(''), 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"},"fixed":{"sha256":"630bef2880a81ed638a3c69a5728a8e99cd0f3a7eda27095c5e4740eef06bab1","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('[A-Za-z]+',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('abc!'), False)\ncheck('boundary 2', solve('abc\\n'), False)\ncheck('boundary 3', solve('abc'), True)\ncheck('boundary 4', solve(''), 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-regex-fullmatch","generated_at":"2026-09-29T14:37:21.283839+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: Accept exactly ASCII letters, at least one, with no final newline.","root_cause":"The implementation applies an operation whose text or grammar semantics violate this contract: Accept exactly ASCII letters, at least one, with no final newline.","sha256":"38f75d8cda41271038672edb13b3409e676aa4be8f796f0a561849bfddfddce7","title":"A token validator accepts a suffix after a match · case 01","variant":1,"variant_policy":"Five numbered records share a model and may reuse boundary fixtures.","verification":{"attempt":{"elapsed_ms":53.325,"exit_code":1,"observations":[{"actual":false,"check":"boundary 1","expected":false,"passed":true},{"actual":true,"check":"boundary 2","expected":false,"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\": true, \"expected\": false, \"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":54.318,"exit_code":1,"observations":[{"actual":true,"check":"boundary 1","expected":false,"passed":false},{"actual":true,"check":"boundary 2","expected":false,"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\": true, \"expected\": false, \"passed\": false}, {\"check\": \"boundary 2\", \"actual\": true, \"expected\": false, \"passed\": false}, {\"check\": \"boundary 3\", \"actual\": true, \"expected\": true, \"passed\": true}, {\"check\": \"boundary 4\", \"actual\": false, \"expected\": false, \"passed\": true}], \"passed\": false}\n"},"fixed":{"elapsed_ms":56.748,"exit_code":0,"observations":[{"actual":false,"check":"boundary 1","expected":false,"passed":true},{"actual":false,"check":"boundary 2","expected":false,"passed":true},{"actual":true,"check":"boundary 3","expected":true,"passed":true},{"actual":false,"check":"boundary 4","expected":false,"passed":true}],"passed":true,"stderr":"","stdout":"{\"observations\": [{\"check\": \"boundary 1\", \"actual\": false, \"expected\": false, \"passed\": true}, {\"check\": \"boundary 2\", \"actual\": false, \"expected\": false, \"passed\": true}, {\"check\": \"boundary 3\", \"actual\": true, \"expected\": true, \"passed\": true}, {\"check\": \"boundary 4\", \"actual\": false, \"expected\": false, \"passed\": true}], \"passed\": true}\n"}},"verified":true,"visibility":"public"}