{"abstract":"A document-start marker matches ordinary content.","category":"Lexical grammars","checks":4,"contract":"Accept exactly three hyphens optionally followed by one space and a comment.","evaluation_group":"model-aa7564d6e8e561a6","failed_approach":"The candidate grammar '---(?:#.*)?' still disagrees with the explicit boundary fixtures.","family":"xp-yaml-document-marker","id":"FA-3531","implementations":{"attempt":{"sha256":"339e73fab776a881bb1bf2cb240dad7ff4ddba7cf3ffcd9c75d95393fae80b75","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('---(?:#.*)?',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('---word'), False)\ncheck('boundary 2', solve('--- # note'), True)\ncheck('boundary 3', solve('---'), 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":"8ffb9168ed16d2a520a16f40820eabd85d1301a94adb3edd6589a3baee135da4","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('---.*',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('---word'), False)\ncheck('boundary 2', solve('--- # note'), True)\ncheck('boundary 3', solve('---'), 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":"5d44aeeee72b0bcb27e2ad82413db8bc9fdaded32893de3c74e9384231b987e8","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('---(?: #[^\\\\r\\\\n]*)?',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('---word'), False)\ncheck('boundary 2', solve('--- # note'), True)\ncheck('boundary 3', solve('---'), 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-yaml-document-marker","generated_at":"2026-09-29T14:37:27.244547+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 three hyphens optionally followed by one space and a comment.","root_cause":"The recognizer uses '---.*', which admits or omits a token shape forbidden by the stated grammar.","sha256":"487647d66452824762951e971be7501c318b2fac2c315c09523fc73665db787b","title":"A document-start marker matches ordinary content · case 01","variant":1,"variant_policy":"Five numbered records share a model and may reuse boundary fixtures.","verification":{"attempt":{"elapsed_ms":54.248,"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":45.716,"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":true,"check":"boundary 4","expected":false,"passed":false}],"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\": true, \"expected\": false, \"passed\": false}], \"passed\": false}\n"},"fixed":{"elapsed_ms":52.496,"exit_code":0,"observations":[{"actual":false,"check":"boundary 1","expected":false,"passed":true},{"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":true,"stderr":"","stdout":"{\"observations\": [{\"check\": \"boundary 1\", \"actual\": false, \"expected\": false, \"passed\": true}, {\"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\": true}\n"}},"verified":true,"visibility":"public"}