{"abstract":"An uncacheable oversized value flushes unrelated cache entries.","category":"Caching","checks":4,"contract":"Input weights and budget are nonnegative; existing total fits budget. If candidate weight exceeds budget, bypass without modifying entries; otherwise replace/promote then evict oldest until it fits.","contract_signature":"entries, incoming, budget","evaluation_group":"xc-oversize-bypass-preserves","failed_approach":"Rejecting values equal to budget excludes a valid single-entry cache.","family":"xc-oversize-bypass-preserves","id":"FA-10406","implementations":{"attempt":{"sha256":"4beaef92745a71bf4bc92d51aed9bdad4ebcbb10c07d7938c1e3fe47112324f2","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(entries, incoming, budget):\n    if incoming[1]>=budget:\n        return list(entries)\n    out=[x for x in entries if x[0] != incoming[0]]+[incoming]\n    while sum(x[1] for x in 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', 2], ['b', 2]], ['c', 8], 5)), [['a', 2], ['b', 2]])\ncheck('fixture 2', solve(*([['a', 2]], ['b', 5], 5)), [['b', 5]])\ncheck('fixture 3', solve(*([], ['a', 0], 0)), [['a', 0]])\ncheck('fixture 4', solve(*([['a', 2]], ['b', 1], 5)), [['a', 2], ['b', 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":"e441c238d4b19cb790df27929ee9ae822c5e2d425de10a2af9f966cd1ec66750","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(entries, incoming, budget):\n    out=[x for x in entries if x[0] != incoming[0]]+[incoming]\n    while out and sum(x[1] for x in 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', 2], ['b', 2]], ['c', 8], 5)), [['a', 2], ['b', 2]])\ncheck('fixture 2', solve(*([['a', 2]], ['b', 5], 5)), [['b', 5]])\ncheck('fixture 3', solve(*([], ['a', 0], 0)), [['a', 0]])\ncheck('fixture 4', solve(*([['a', 2]], ['b', 1], 5)), [['a', 2], ['b', 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":"xc-oversize-bypass-preserves","generated_at":"2026-09-29T14:38:38.673024+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":"An oversized candidate enters the eviction loop before its cacheability is checked.","sha256":"cf6a93a67f72694585b4096a7806cda953ba97fd0f6a9b3f47fe3d2fc5088cc1","title":"An uncacheable oversized value flushes unrelated cache entries · 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":38.788,"exit_code":1,"observations":[{"actual":[["a",2],["b",2]],"check":"fixture 1","expected":[["a",2],["b",2]],"passed":true},{"actual":[["a",2]],"check":"fixture 2","expected":[["b",5]],"passed":false},{"actual":[],"check":"fixture 3","expected":[["a",0]],"passed":false},{"actual":[["a",2],["b",1]],"check":"fixture 4","expected":[["a",2],["b",1]],"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"fixture 1\", \"actual\": [[\"a\", 2], [\"b\", 2]], \"expected\": [[\"a\", 2], [\"b\", 2]], \"passed\": true}, {\"check\": \"fixture 2\", \"actual\": [[\"a\", 2]], \"expected\": [[\"b\", 5]], \"passed\": false}, {\"check\": \"fixture 3\", \"actual\": [], \"expected\": [[\"a\", 0]], \"passed\": false}, {\"check\": \"fixture 4\", \"actual\": [[\"a\", 2], [\"b\", 1]], \"expected\": [[\"a\", 2], [\"b\", 1]], \"passed\": true}], \"passed\": false}\n"},"broken":{"elapsed_ms":37.996,"exit_code":1,"observations":[{"actual":[],"check":"fixture 1","expected":[["a",2],["b",2]],"passed":false},{"actual":[["b",5]],"check":"fixture 2","expected":[["b",5]],"passed":true},{"actual":[["a",0]],"check":"fixture 3","expected":[["a",0]],"passed":true},{"actual":[["a",2],["b",1]],"check":"fixture 4","expected":[["a",2],["b",1]],"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"fixture 1\", \"actual\": [], \"expected\": [[\"a\", 2], [\"b\", 2]], \"passed\": false}, {\"check\": \"fixture 2\", \"actual\": [[\"b\", 5]], \"expected\": [[\"b\", 5]], \"passed\": true}, {\"check\": \"fixture 3\", \"actual\": [[\"a\", 0]], \"expected\": [[\"a\", 0]], \"passed\": true}, {\"check\": \"fixture 4\", \"actual\": [[\"a\", 2], [\"b\", 1]], \"expected\": [[\"a\", 2], [\"b\", 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."}}