{"abstract":"Unknown backslash escapes are silently discarded.","category":"Parsing","checks":4,"contract":"Decode backslash-n, backslash-t and backslash-backslash only; unknown or dangling escapes return None.","contract_signature":"x","evaluation_group":"model-7646feda8641dd91","failed_approach":"The attempted repair handles the primary example but still violates a separate boundary of the same contract.","family":"xp-unescape-only-known","id":"FA-3846","implementations":{"attempt":{"sha256":"0098cb6cc959ff377ae1ddf791b504f36dd1c3b9cf8cc4c42faf55d16d332124","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 re.sub(re.escape(chr(92))+'(.)',lambda m:{'n':chr(10),'t':chr(9),chr(92):chr(92)}.get(m[1],m[1]),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('a\\\\q'), None)\ncheck('boundary 2', solve('a\\\\n'), 'a\\n')\ncheck('boundary 3', solve('\\\\\\\\n'), '\\\\n')\ncheck('boundary 4', solve('x'), 'x')\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":"ce13f796a471d8f7f23767caad632ee3484833d8d94b2cf99e0bdad3dfa7f694","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.replace(chr(92)+'n',chr(10)).replace(chr(92)+'t',chr(9))\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('a\\\\q'), None)\ncheck('boundary 2', solve('a\\\\n'), 'a\\n')\ncheck('boundary 3', solve('\\\\\\\\n'), '\\\\n')\ncheck('boundary 4', solve('x'), 'x')\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-unescape-only-known","generated_at":"2026-09-29T14:37:31.733275+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: Decode backslash-n, backslash-t and backslash-backslash only; unknown or dangling escapes return None.","sha256":"cbf2f52fc77446ceb6c013128be234a737438da93f271924e21e2101ea10093f","title":"Unknown backslash escapes are silently discarded · 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":54.467,"exit_code":1,"observations":[{"actual":"aq","check":"boundary 1","expected":null,"passed":false},{"actual":"a\n","check":"boundary 2","expected":"a\n","passed":true},{"actual":"\\n","check":"boundary 3","expected":"\\n","passed":true},{"actual":"x","check":"boundary 4","expected":"x","passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"boundary 1\", \"actual\": \"aq\", \"expected\": null, \"passed\": false}, {\"check\": \"boundary 2\", \"actual\": \"a\\n\", \"expected\": \"a\\n\", \"passed\": true}, {\"check\": \"boundary 3\", \"actual\": \"\\\\n\", \"expected\": \"\\\\n\", \"passed\": true}, {\"check\": \"boundary 4\", \"actual\": \"x\", \"expected\": \"x\", \"passed\": true}], \"passed\": false}\n"},"broken":{"elapsed_ms":54.206,"exit_code":1,"observations":[{"actual":"a\\q","check":"boundary 1","expected":null,"passed":false},{"actual":"a\n","check":"boundary 2","expected":"a\n","passed":true},{"actual":"\\\n","check":"boundary 3","expected":"\\n","passed":false},{"actual":"x","check":"boundary 4","expected":"x","passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"boundary 1\", \"actual\": \"a\\\\q\", \"expected\": null, \"passed\": false}, {\"check\": \"boundary 2\", \"actual\": \"a\\n\", \"expected\": \"a\\n\", \"passed\": true}, {\"check\": \"boundary 3\", \"actual\": \"\\\\\\n\", \"expected\": \"\\\\n\", \"passed\": false}, {\"check\": \"boundary 4\", \"actual\": \"x\", \"expected\": \"x\", \"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."}}