{"abstract":"Run-length encoding forgets the final run.","category":"Binary formats","checks":4,"contract":"Encode a list as count/value runs, retaining adjacent equal values in one run.","contract_signature":"x","evaluation_group":"model-3663fb557481fcdc","failed_approach":"The attempted repair handles the primary example but still violates a separate boundary of the same contract.","family":"xp-binary-rle-final-run","id":"FA-3711","implementations":{"attempt":{"sha256":"f45523c4e18e2b324c57baa88e291a1db818b894a5946b1e2ca8c0204875fb42","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        out=[]\n        for v in x:\n            if out and out[-1][1]==v: out[-1][0]+=1\n            else: out.append([1,v])\n        return out[:-1]\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, 1, 2]), [[2, 1], [1, 2]])\ncheck('boundary 2', solve([3]), [[1, 3]])\ncheck('boundary 3', solve([]), [])\ncheck('boundary 4', solve([1, 2, 1]), [[1, 1], [1, 2], [1, 1]])\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":"8e61752c025de1142054132ce40564551c81d065f4d803ada0760090d760e316","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 [[1,v] for v in 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, 1, 2]), [[2, 1], [1, 2]])\ncheck('boundary 2', solve([3]), [[1, 3]])\ncheck('boundary 3', solve([]), [])\ncheck('boundary 4', solve([1, 2, 1]), [[1, 1], [1, 2], [1, 1]])\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-rle-final-run","generated_at":"2026-09-29T14:37:29.842865+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: Encode a list as count/value runs, retaining adjacent equal values in one run.","sha256":"efe2bee06999bb7cb83f7fb24087d2eea1d4d8bc2b176e5663352607eca7061d","title":"Run-length encoding forgets the final run · 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":54.636,"exit_code":1,"observations":[{"actual":[[2,1]],"check":"boundary 1","expected":[[2,1],[1,2]],"passed":false},{"actual":[],"check":"boundary 2","expected":[[1,3]],"passed":false},{"actual":[],"check":"boundary 3","expected":[],"passed":true},{"actual":[[1,1],[1,2]],"check":"boundary 4","expected":[[1,1],[1,2],[1,1]],"passed":false}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"boundary 1\", \"actual\": [[2, 1]], \"expected\": [[2, 1], [1, 2]], \"passed\": false}, {\"check\": \"boundary 2\", \"actual\": [], \"expected\": [[1, 3]], \"passed\": false}, {\"check\": \"boundary 3\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"boundary 4\", \"actual\": [[1, 1], [1, 2]], \"expected\": [[1, 1], [1, 2], [1, 1]], \"passed\": false}], \"passed\": false}\n"},"broken":{"elapsed_ms":52.709,"exit_code":1,"observations":[{"actual":[[1,1],[1,1],[1,2]],"check":"boundary 1","expected":[[2,1],[1,2]],"passed":false},{"actual":[[1,3]],"check":"boundary 2","expected":[[1,3]],"passed":true},{"actual":[],"check":"boundary 3","expected":[],"passed":true},{"actual":[[1,1],[1,2],[1,1]],"check":"boundary 4","expected":[[1,1],[1,2],[1,1]],"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"boundary 1\", \"actual\": [[1, 1], [1, 1], [1, 2]], \"expected\": [[2, 1], [1, 2]], \"passed\": false}, {\"check\": \"boundary 2\", \"actual\": [[1, 3]], \"expected\": [[1, 3]], \"passed\": true}, {\"check\": \"boundary 3\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"boundary 4\", \"actual\": [[1, 1], [1, 2], [1, 1]], \"expected\": [[1, 1], [1, 2], [1, 1]], \"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."}}