{"abstract":"Digit separators occur at token edges.","category":"Lexical grammars","checks":4,"contract":"Accept decimal digit groups separated by single underscores.","contract_signature":"x","evaluation_group":"model-6b044fba3746a4f7","failed_approach":"The candidate grammar '[0-9][0-9_]*[0-9]|[0-9]' still disagrees with the explicit boundary fixtures.","family":"xp-numeric-separator-adjacency","id":"FA-3391","implementations":{"attempt":{"sha256":"6f99538e2e6fa986e933b32aad9ad0ad4e91a379fe416f41c3f63885596a9512","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][0-9_]*[0-9]|[0-9]',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('_1'), False)\ncheck('boundary 2', solve('1__2'), False)\ncheck('boundary 3', solve('1_000'), True)\ncheck('boundary 4', solve('7'), True)\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":"c16d69f4dd58127241687b99f4aa3db9086110ecea94370cdf413119fcdaa243","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_]+',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('_1'), False)\ncheck('boundary 2', solve('1__2'), False)\ncheck('boundary 3', solve('1_000'), True)\ncheck('boundary 4', solve('7'), True)\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-numeric-separator-adjacency","generated_at":"2026-09-29T14:37:25.369376+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 '[0-9_]+', which admits or omits a token shape forbidden by the stated grammar.","sha256":"934bd139f807aa52b14f81a59cc40ded7b165a1b33d7d5375c93be139a3ee3b1","title":"Digit separators occur at token edges · 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":56.429,"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":true,"check":"boundary 4","expected":true,"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\": true, \"expected\": true, \"passed\": true}], \"passed\": false}\n"},"broken":{"elapsed_ms":53.754,"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":true,"check":"boundary 4","expected":true,"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\": true, \"expected\": true, \"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."}}