{"abstract":"Removing a prefix eats a set of leading characters.","category":"Text processing","checks":4,"contract":"Remove the exact leading text prefix pre: once.","evaluation_group":"model-dbaa01a4d2946113","failed_approach":"The attempted repair handles the primary example but still violates a separate boundary of the same contract.","family":"xp-prefix-is-not-strip","id":"FA-2976","implementations":{"attempt":{"sha256":"29a1ccb05c4c68767662b320a1c1cf6edfe79266f546d6fe9795fe8c91d75bba","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('pre:','')\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('pre:prep'), 'prep')\ncheck('boundary 2', solve('peer'), 'peer')\ncheck('boundary 3', solve('pre:pre:x'), 'pre:x')\ncheck('boundary 4', solve('xpre:'), 'xpre:')\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":"a1bfef970e619408971b5a639489743e8d74e700e9b3d449f61b51acb30b276f","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.lstrip('pre:')\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('pre:prep'), 'prep')\ncheck('boundary 2', solve('peer'), 'peer')\ncheck('boundary 3', solve('pre:pre:x'), 'pre:x')\ncheck('boundary 4', solve('xpre:'), 'xpre:')\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":"0a772269b22788e74dd63dad19ff7e91a0796679a35380e4cb7a7218acf57a86","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.removeprefix('pre:')\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('pre:prep'), 'prep')\ncheck('boundary 2', solve('peer'), 'peer')\ncheck('boundary 3', solve('pre:pre:x'), 'pre:x')\ncheck('boundary 4', solve('xpre:'), 'xpre:')\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-prefix-is-not-strip","generated_at":"2026-09-29T14:37:19.794244+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: Remove the exact leading text prefix pre: once.","root_cause":"The implementation applies an operation whose text or grammar semantics violate this contract: Remove the exact leading text prefix pre: once.","sha256":"334c9fdeb8962f75850dd0bc99799cefb415cc98a1690276b722e7c2613e230a","title":"Removing a prefix eats a set of leading characters · case 01","variant":1,"variant_policy":"Five numbered records share a model and may reuse boundary fixtures.","verification":{"attempt":{"elapsed_ms":58.246,"exit_code":1,"observations":[{"actual":"prep","check":"boundary 1","expected":"prep","passed":true},{"actual":"peer","check":"boundary 2","expected":"peer","passed":true},{"actual":"x","check":"boundary 3","expected":"pre:x","passed":false},{"actual":"x","check":"boundary 4","expected":"xpre:","passed":false}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"boundary 1\", \"actual\": \"prep\", \"expected\": \"prep\", \"passed\": true}, {\"check\": \"boundary 2\", \"actual\": \"peer\", \"expected\": \"peer\", \"passed\": true}, {\"check\": \"boundary 3\", \"actual\": \"x\", \"expected\": \"pre:x\", \"passed\": false}, {\"check\": \"boundary 4\", \"actual\": \"x\", \"expected\": \"xpre:\", \"passed\": false}], \"passed\": false}\n"},"broken":{"elapsed_ms":53.061,"exit_code":1,"observations":[{"actual":"","check":"boundary 1","expected":"prep","passed":false},{"actual":"","check":"boundary 2","expected":"peer","passed":false},{"actual":"x","check":"boundary 3","expected":"pre:x","passed":false},{"actual":"xpre:","check":"boundary 4","expected":"xpre:","passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"boundary 1\", \"actual\": \"\", \"expected\": \"prep\", \"passed\": false}, {\"check\": \"boundary 2\", \"actual\": \"\", \"expected\": \"peer\", \"passed\": false}, {\"check\": \"boundary 3\", \"actual\": \"x\", \"expected\": \"pre:x\", \"passed\": false}, {\"check\": \"boundary 4\", \"actual\": \"xpre:\", \"expected\": \"xpre:\", \"passed\": true}], \"passed\": false}\n"},"fixed":{"elapsed_ms":52.372,"exit_code":0,"observations":[{"actual":"prep","check":"boundary 1","expected":"prep","passed":true},{"actual":"peer","check":"boundary 2","expected":"peer","passed":true},{"actual":"pre:x","check":"boundary 3","expected":"pre:x","passed":true},{"actual":"xpre:","check":"boundary 4","expected":"xpre:","passed":true}],"passed":true,"stderr":"","stdout":"{\"observations\": [{\"check\": \"boundary 1\", \"actual\": \"prep\", \"expected\": \"prep\", \"passed\": true}, {\"check\": \"boundary 2\", \"actual\": \"peer\", \"expected\": \"peer\", \"passed\": true}, {\"check\": \"boundary 3\", \"actual\": \"pre:x\", \"expected\": \"pre:x\", \"passed\": true}, {\"check\": \"boundary 4\", \"actual\": \"xpre:\", \"expected\": \"xpre:\", \"passed\": true}], \"passed\": true}\n"}},"verified":true,"visibility":"public"}