{"abstract":"A signed octet is interpreted as an unsigned magnitude.","category":"Binary formats","checks":4,"contract":"Decode one octet as signed two-complement.","evaluation_group":"model-0fcd4419d9e1481e","failed_approach":"The attempted repair handles the primary example but still violates a separate boundary of the same contract.","family":"xp-binary-signed-twos","id":"FA-3611","implementations":{"attempt":{"sha256":"4055920f3a66d7e1088c3d51a3b60a629eccd711a69028f5cef524004df102b7","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-128 if x>=128 else 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(255), -1)\ncheck('boundary 2', solve(128), -128)\ncheck('boundary 3', solve(127), 127)\ncheck('boundary 4', solve(0), 0)\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":"2c739ff62280c0cfedbe27129640a67eadcad4865376d0ae645c5d6e5a81c3a8","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(255), -1)\ncheck('boundary 2', solve(128), -128)\ncheck('boundary 3', solve(127), 127)\ncheck('boundary 4', solve(0), 0)\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":"26a108c0dc936942b06f0bc273c2d9f3772422dce632bfb9bce02092563baae9","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-256 if x>=128 else 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(255), -1)\ncheck('boundary 2', solve(128), -128)\ncheck('boundary 3', solve(127), 127)\ncheck('boundary 4', solve(0), 0)\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-binary-signed-twos","generated_at":"2026-09-29T14:37:28.378065+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: Decode one octet as signed two-complement.","root_cause":"The implementation applies an operation whose text or grammar semantics violate this contract: Decode one octet as signed two-complement.","sha256":"13d2ad1678910676e0ec28d682261d092778600fe77ee2634ac34599d0a02591","title":"A signed octet is interpreted as an unsigned magnitude · case 01","variant":1,"variant_policy":"Five numbered records share a model and may reuse boundary fixtures.","verification":{"attempt":{"elapsed_ms":57.272,"exit_code":1,"observations":[{"actual":127,"check":"boundary 1","expected":-1,"passed":false},{"actual":0,"check":"boundary 2","expected":-128,"passed":false},{"actual":127,"check":"boundary 3","expected":127,"passed":true},{"actual":0,"check":"boundary 4","expected":0,"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"boundary 1\", \"actual\": 127, \"expected\": -1, \"passed\": false}, {\"check\": \"boundary 2\", \"actual\": 0, \"expected\": -128, \"passed\": false}, {\"check\": \"boundary 3\", \"actual\": 127, \"expected\": 127, \"passed\": true}, {\"check\": \"boundary 4\", \"actual\": 0, \"expected\": 0, \"passed\": true}], \"passed\": false}\n"},"broken":{"elapsed_ms":54.152,"exit_code":1,"observations":[{"actual":255,"check":"boundary 1","expected":-1,"passed":false},{"actual":128,"check":"boundary 2","expected":-128,"passed":false},{"actual":127,"check":"boundary 3","expected":127,"passed":true},{"actual":0,"check":"boundary 4","expected":0,"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"boundary 1\", \"actual\": 255, \"expected\": -1, \"passed\": false}, {\"check\": \"boundary 2\", \"actual\": 128, \"expected\": -128, \"passed\": false}, {\"check\": \"boundary 3\", \"actual\": 127, \"expected\": 127, \"passed\": true}, {\"check\": \"boundary 4\", \"actual\": 0, \"expected\": 0, \"passed\": true}], \"passed\": false}\n"},"fixed":{"elapsed_ms":58.508,"exit_code":0,"observations":[{"actual":-1,"check":"boundary 1","expected":-1,"passed":true},{"actual":-128,"check":"boundary 2","expected":-128,"passed":true},{"actual":127,"check":"boundary 3","expected":127,"passed":true},{"actual":0,"check":"boundary 4","expected":0,"passed":true}],"passed":true,"stderr":"","stdout":"{\"observations\": [{\"check\": \"boundary 1\", \"actual\": -1, \"expected\": -1, \"passed\": true}, {\"check\": \"boundary 2\", \"actual\": -128, \"expected\": -128, \"passed\": true}, {\"check\": \"boundary 3\", \"actual\": 127, \"expected\": 127, \"passed\": true}, {\"check\": \"boundary 4\", \"actual\": 0, \"expected\": 0, \"passed\": true}], \"passed\": true}\n"}},"verified":true,"visibility":"public"}