{"abstract":"The operation returns a result or retained state that violates this contract: Return the positional interior, excluding first and last elements.","category":"Sequence semantics","checks":4,"contract":"Return the positional interior, excluding first and last elements. Inputs are the finite Python values shown by the executable fixtures; no concurrent execution is assumed.","evaluation_group":"model-6a03b2c06ae36823","failed_approach":"Removing only the final endpoint leaves the leading endpoint.","family":"xr-interior-excludes-both-ends","id":"FA-4146","implementations":{"attempt":{"sha256":"6284a31bb379c75ebb1cf3c3038a6d38a604d6e7a37f50f140fe62eeded867b8","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(x, y=None):\n    return x[:-1]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('empty collection', solve([]), [])\ncheck('singleton collection', solve(['a']), [])\ncheck('two distinct elements', solve(['a', 'b']), [])\ncheck('nonadjacent duplicate and unsorted order', solve(['b', 'a', 'b', 'c']), ['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":"49add9dbe2997c910ff811d2e6331de12dffe0cf7adea5addf6c4af53a5bd8b0","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(x, y=None):\n    return x[1:]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('empty collection', solve([]), [])\ncheck('singleton collection', solve(['a']), [])\ncheck('two distinct elements', solve(['a', 'b']), [])\ncheck('nonadjacent duplicate and unsorted order', solve(['b', 'a', 'b', 'c']), ['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"},"fixed":{"sha256":"7fa550bc2ed4620ef11de2bc262f380e66863d1c4dac3451d145840fafb275f8","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(x, y=None):\n    return x[1:-1]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('empty collection', solve([]), [])\ncheck('singleton collection', solve(['a']), [])\ncheck('two distinct elements', solve(['a', 'b']), [])\ncheck('nonadjacent duplicate and unsorted order', solve(['b', 'a', 'b', 'c']), ['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":"xr-interior-excludes-both-ends","generated_at":"2026-09-29T14:37:36.192434+00:00","license":"CC0-1.0","python":"3.12.14","seed":1,"split":"open-access"},"relevance":"A controlled local-runtime regression for collection APIs, language semantics, or ownership wrappers. Fixtures include boundary and interaction cases.","repair":"Return the positional interior, excluding first and last elements.","root_cause":"The trailing endpoint remains in the selected interior.","sha256":"2f9eef75eb99c1ae2dfc5346d51560323bd19f431056acf665125790fd41fc41","title":"Interior excludes both ends · case 01","variant":1,"variant_policy":"Five execution reruns of a fixed adversarial fixture suite; variant number does not alter semantic inputs.","verification":{"attempt":{"elapsed_ms":38.172,"exit_code":1,"observations":[{"actual":[],"check":"empty collection","expected":[],"passed":true},{"actual":[],"check":"singleton collection","expected":[],"passed":true},{"actual":["a"],"check":"two distinct elements","expected":[],"passed":false},{"actual":["b","a","b"],"check":"nonadjacent duplicate and unsorted order","expected":["a","b"],"passed":false}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"empty collection\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"singleton collection\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"two distinct elements\", \"actual\": [\"a\"], \"expected\": [], \"passed\": false}, {\"check\": \"nonadjacent duplicate and unsorted order\", \"actual\": [\"b\", \"a\", \"b\"], \"expected\": [\"a\", \"b\"], \"passed\": false}], \"passed\": false}\n"},"broken":{"elapsed_ms":35.586,"exit_code":1,"observations":[{"actual":[],"check":"empty collection","expected":[],"passed":true},{"actual":[],"check":"singleton collection","expected":[],"passed":true},{"actual":["b"],"check":"two distinct elements","expected":[],"passed":false},{"actual":["a","b","c"],"check":"nonadjacent duplicate and unsorted order","expected":["a","b"],"passed":false}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"empty collection\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"singleton collection\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"two distinct elements\", \"actual\": [\"b\"], \"expected\": [], \"passed\": false}, {\"check\": \"nonadjacent duplicate and unsorted order\", \"actual\": [\"a\", \"b\", \"c\"], \"expected\": [\"a\", \"b\"], \"passed\": false}], \"passed\": false}\n"},"fixed":{"elapsed_ms":39.005,"exit_code":0,"observations":[{"actual":[],"check":"empty collection","expected":[],"passed":true},{"actual":[],"check":"singleton collection","expected":[],"passed":true},{"actual":[],"check":"two distinct elements","expected":[],"passed":true},{"actual":["a","b"],"check":"nonadjacent duplicate and unsorted order","expected":["a","b"],"passed":true}],"passed":true,"stderr":"","stdout":"{\"observations\": [{\"check\": \"empty collection\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"singleton collection\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"two distinct elements\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"nonadjacent duplicate and unsorted order\", \"actual\": [\"a\", \"b\"], \"expected\": [\"a\", \"b\"], \"passed\": true}], \"passed\": true}\n"}},"verified":true,"visibility":"public"}