{"abstract":"An empty shell argument disappears.","category":"Serialization","checks":4,"contract":"Quote one string so POSIX shlex can recover one identical argument.","contract_signature":"x","evaluation_group":"model-7b33802070179e66","failed_approach":"The attempted repair handles the primary example but still violates a separate boundary of the same contract.","family":"xp-shell-quote-empty","id":"FA-3271","implementations":{"attempt":{"sha256":"2768ec7904bb2f57f07d0304af6055ebc17300e1d591fdecf06ace0628fa5e05","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('\"','\\\\\"')+'\"'\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(''), \"''\")\ncheck('boundary 2', solve('abc'), 'abc')\ncheck('boundary 3', solve('a b'), \"'a b'\")\ncheck('boundary 4', solve(\"a'b\"), '\\'a\\'\"\\'\"\\'b\\'')\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":"bb9dc92c8d6a2bbfda99497407d9018861d0f07a093226eedbddbae52b4513e5","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\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(''), \"''\")\ncheck('boundary 2', solve('abc'), 'abc')\ncheck('boundary 3', solve('a b'), \"'a b'\")\ncheck('boundary 4', solve(\"a'b\"), '\\'a\\'\"\\'\"\\'b\\'')\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-shell-quote-empty","generated_at":"2026-09-29T14:37:23.517122+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: Quote one string so POSIX shlex can recover one identical argument.","sha256":"d3b7bd86bd65699d5d178d1e50e0e4975b5a4b75dd12a093acbe972b458b886d","title":"An empty shell argument disappears · 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":54.525,"exit_code":1,"observations":[{"actual":"\"\"","check":"boundary 1","expected":"''","passed":false},{"actual":"\"abc\"","check":"boundary 2","expected":"abc","passed":false},{"actual":"\"a b\"","check":"boundary 3","expected":"'a b'","passed":false},{"actual":"\"a'b\"","check":"boundary 4","expected":"'a'\"'\"'b'","passed":false}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"boundary 1\", \"actual\": \"\\\"\\\"\", \"expected\": \"''\", \"passed\": false}, {\"check\": \"boundary 2\", \"actual\": \"\\\"abc\\\"\", \"expected\": \"abc\", \"passed\": false}, {\"check\": \"boundary 3\", \"actual\": \"\\\"a b\\\"\", \"expected\": \"'a b'\", \"passed\": false}, {\"check\": \"boundary 4\", \"actual\": \"\\\"a'b\\\"\", \"expected\": \"'a'\\\"'\\\"'b'\", \"passed\": false}], \"passed\": false}\n"},"broken":{"elapsed_ms":53.364,"exit_code":1,"observations":[{"actual":"","check":"boundary 1","expected":"''","passed":false},{"actual":"abc","check":"boundary 2","expected":"abc","passed":true},{"actual":"a b","check":"boundary 3","expected":"'a b'","passed":false},{"actual":"a'b","check":"boundary 4","expected":"'a'\"'\"'b'","passed":false}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"boundary 1\", \"actual\": \"\", \"expected\": \"''\", \"passed\": false}, {\"check\": \"boundary 2\", \"actual\": \"abc\", \"expected\": \"abc\", \"passed\": true}, {\"check\": \"boundary 3\", \"actual\": \"a b\", \"expected\": \"'a b'\", \"passed\": false}, {\"check\": \"boundary 4\", \"actual\": \"a'b\", \"expected\": \"'a'\\\"'\\\"'b'\", \"passed\": false}], \"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."}}