{"abstract":"Weighted eviction frees fewer bytes than the new budget requires.","category":"Caching","checks":4,"contract":"Entries are [key,nonnegative weight] in eviction order. Remove a prefix until remaining weight is at most the nonnegative budget; retain zero-weight entries if no eviction is necessary.","contract_signature":"entries, budget","evaluation_group":"xc-weighted-eviction-loop","failed_approach":"An entry-count limit is substituted for a byte-weight budget.","family":"xc-weighted-eviction-loop","id":"FA-10396","implementations":{"attempt":{"sha256":"b101e10dd1c681942fa7a2a59558d4a9ce13ebca06aa7cdd347ae27a2077aeba","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(entries, budget):\n    out=list(entries)\n    while len(out)>budget:\n        out.pop(0)\n    return out\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('fixture 1', solve(*([['a', 4], ['b', 3], ['c', 2]], 2)), [['c', 2]])\ncheck('fixture 2', solve(*([['a', 4], ['b', 3]], 4)), [['b', 3]])\ncheck('fixture 3', solve(*([], 0)), [])\ncheck('fixture 4', solve(*([['a', 0], ['b', 0]], 0)), [['a', 0], ['b', 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":"db9f34fc78caf221e6e414dc65637d7859c4842857cba52a6ffbc43de2a5419a","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(entries, budget):\n    out=list(entries)\n    if sum(w for k,w in out)>budget:\n        out=out[1:]\n    return out\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('fixture 1', solve(*([['a', 4], ['b', 3], ['c', 2]], 2)), [['c', 2]])\ncheck('fixture 2', solve(*([['a', 4], ['b', 3]], 4)), [['b', 3]])\ncheck('fixture 3', solve(*([], 0)), [])\ncheck('fixture 4', solve(*([['a', 0], ['b', 0]], 0)), [['a', 0], ['b', 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":"xc-weighted-eviction-loop","generated_at":"2026-09-29T14:38:38.632379+00:00","license":"CC0-1.0","python":"3.12.14","seed":1,"split":"open-access"},"relevance":"A deterministic cache state transformation. Inputs are copied or treated as immutable; no remote storage, real clock, or concurrent interleaving is simulated.","root_cause":"One eviction is assumed to free enough space regardless of entry weight.","sha256":"9a62dc147cce7fef6c31abf5fd252f899da09c42c8827934f213fe72556d8b89","title":"Weighted eviction frees fewer bytes than the new budget requires · 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":39.271,"exit_code":1,"observations":[{"actual":[["b",3],["c",2]],"check":"fixture 1","expected":[["c",2]],"passed":false},{"actual":[["a",4],["b",3]],"check":"fixture 2","expected":[["b",3]],"passed":false},{"actual":[],"check":"fixture 3","expected":[],"passed":true},{"actual":[],"check":"fixture 4","expected":[["a",0],["b",0]],"passed":false}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"fixture 1\", \"actual\": [[\"b\", 3], [\"c\", 2]], \"expected\": [[\"c\", 2]], \"passed\": false}, {\"check\": \"fixture 2\", \"actual\": [[\"a\", 4], [\"b\", 3]], \"expected\": [[\"b\", 3]], \"passed\": false}, {\"check\": \"fixture 3\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"fixture 4\", \"actual\": [], \"expected\": [[\"a\", 0], [\"b\", 0]], \"passed\": false}], \"passed\": false}\n"},"broken":{"elapsed_ms":39.387,"exit_code":1,"observations":[{"actual":[["b",3],["c",2]],"check":"fixture 1","expected":[["c",2]],"passed":false},{"actual":[["b",3]],"check":"fixture 2","expected":[["b",3]],"passed":true},{"actual":[],"check":"fixture 3","expected":[],"passed":true},{"actual":[["a",0],["b",0]],"check":"fixture 4","expected":[["a",0],["b",0]],"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"fixture 1\", \"actual\": [[\"b\", 3], [\"c\", 2]], \"expected\": [[\"c\", 2]], \"passed\": false}, {\"check\": \"fixture 2\", \"actual\": [[\"b\", 3]], \"expected\": [[\"b\", 3]], \"passed\": true}, {\"check\": \"fixture 3\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"fixture 4\", \"actual\": [[\"a\", 0], [\"b\", 0]], \"expected\": [[\"a\", 0], [\"b\", 0]], \"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."}}