{"abstract":"The operation returns a result or retained state that violates this contract: Return at most n [key,count] pairs by descending count, breaking ties by first insertion order.","category":"Multiset accounting","checks":4,"contract":"Return at most n [key,count] pairs by descending count, breaking ties by first insertion order. Inputs are the finite Python values shown by the executable fixtures; no concurrent execution is assumed.","evaluation_group":"model-cc9f6583278e1122","failed_approach":"Truncating insertion order does not rank by frequency.","family":"xr-counter-most-common-stable-ties","id":"FA-4681","implementations":{"attempt":{"sha256":"a26acc36bd0193d67aa7c2c6a4f4ed2ac0bc4ee5af77f42a29cd03ccdc5cce5e","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\nfrom collections import Counter, ChainMap, deque\nimport heapq\nN = 1\nobservations = []\ndef solve(x, y=None):\n    return [[k,v] for k,v in list(x.items())[:y]]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('tie insertion order', solve({'b': 2, 'a': 2, 'c': 3}, 3), [['c', 3], ['b', 2], ['a', 2]])\ncheck('zero requested', solve({'a': 1}, 0), [])\ncheck('negative count included', solve({'a': -1}, 2), [['a', -1]])\ncheck('empty', solve({}, 2), [])\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":"263620826214410dc6a7b35d8c4f52fce49b289d80025848394189a9b051dcda","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\nfrom collections import Counter, ChainMap, deque\nimport heapq\nN = 1\nobservations = []\ndef solve(x, y=None):\n    return [[k,v] for k,v in sorted(x.items(),key=lambda p:(-p[1],p[0]))[:y]]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('tie insertion order', solve({'b': 2, 'a': 2, 'c': 3}, 3), [['c', 3], ['b', 2], ['a', 2]])\ncheck('zero requested', solve({'a': 1}, 0), [])\ncheck('negative count included', solve({'a': -1}, 2), [['a', -1]])\ncheck('empty', solve({}, 2), [])\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":"d73871dc2635bb2464bdbdee3ce577b7bf2549dbe2185ae2950d4f14c51421e1","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\nfrom collections import Counter, ChainMap, deque\nimport heapq\nN = 1\nobservations = []\ndef solve(x, y=None):\n    return [list(v) for v in Counter(x).most_common(y)]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('tie insertion order', solve({'b': 2, 'a': 2, 'c': 3}, 3), [['c', 3], ['b', 2], ['a', 2]])\ncheck('zero requested', solve({'a': 1}, 0), [])\ncheck('negative count included', solve({'a': -1}, 2), [['a', -1]])\ncheck('empty', solve({}, 2), [])\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-counter-most-common-stable-ties","generated_at":"2026-09-29T14:37:41.584952+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 at most n [key,count] pairs by descending count, breaking ties by first insertion order.","root_cause":"Lexical keys break frequency ties instead of first insertion order.","sha256":"c2f97db3396a9e0cc04613144d922d5a0b5bddcd9e20438baf3a71f46fb4ad01","title":"Counter most common stable ties · 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":37.954,"exit_code":1,"observations":[{"actual":[["b",2],["a",2],["c",3]],"check":"tie insertion order","expected":[["c",3],["b",2],["a",2]],"passed":false},{"actual":[],"check":"zero requested","expected":[],"passed":true},{"actual":[["a",-1]],"check":"negative count included","expected":[["a",-1]],"passed":true},{"actual":[],"check":"empty","expected":[],"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"tie insertion order\", \"actual\": [[\"b\", 2], [\"a\", 2], [\"c\", 3]], \"expected\": [[\"c\", 3], [\"b\", 2], [\"a\", 2]], \"passed\": false}, {\"check\": \"zero requested\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"negative count included\", \"actual\": [[\"a\", -1]], \"expected\": [[\"a\", -1]], \"passed\": true}, {\"check\": \"empty\", \"actual\": [], \"expected\": [], \"passed\": true}], \"passed\": false}\n"},"broken":{"elapsed_ms":35.504,"exit_code":1,"observations":[{"actual":[["c",3],["a",2],["b",2]],"check":"tie insertion order","expected":[["c",3],["b",2],["a",2]],"passed":false},{"actual":[],"check":"zero requested","expected":[],"passed":true},{"actual":[["a",-1]],"check":"negative count included","expected":[["a",-1]],"passed":true},{"actual":[],"check":"empty","expected":[],"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"tie insertion order\", \"actual\": [[\"c\", 3], [\"a\", 2], [\"b\", 2]], \"expected\": [[\"c\", 3], [\"b\", 2], [\"a\", 2]], \"passed\": false}, {\"check\": \"zero requested\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"negative count included\", \"actual\": [[\"a\", -1]], \"expected\": [[\"a\", -1]], \"passed\": true}, {\"check\": \"empty\", \"actual\": [], \"expected\": [], \"passed\": true}], \"passed\": false}\n"},"fixed":{"elapsed_ms":36.92,"exit_code":0,"observations":[{"actual":[["c",3],["b",2],["a",2]],"check":"tie insertion order","expected":[["c",3],["b",2],["a",2]],"passed":true},{"actual":[],"check":"zero requested","expected":[],"passed":true},{"actual":[["a",-1]],"check":"negative count included","expected":[["a",-1]],"passed":true},{"actual":[],"check":"empty","expected":[],"passed":true}],"passed":true,"stderr":"","stdout":"{\"observations\": [{\"check\": \"tie insertion order\", \"actual\": [[\"c\", 3], [\"b\", 2], [\"a\", 2]], \"expected\": [[\"c\", 3], [\"b\", 2], [\"a\", 2]], \"passed\": true}, {\"check\": \"zero requested\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"negative count included\", \"actual\": [[\"a\", -1]], \"expected\": [[\"a\", -1]], \"passed\": true}, {\"check\": \"empty\", \"actual\": [], \"expected\": [], \"passed\": true}], \"passed\": true}\n"}},"verified":true,"visibility":"public"}