{"abstract":"Eviction discards a dirty value without writing it back.","category":"Caching","checks":4,"contract":"Unique entries are [key,value,dirty]. Remove victim and return [remaining,writeback records]; emit [key,value] only for a dirty resident victim.","evaluation_group":"xc-dirty-eviction-writeback","failed_approach":"Writing every eviction publishes clean read-through values unnecessarily.","family":"xc-dirty-eviction-writeback","id":"FA-10436","implementations":{"attempt":{"sha256":"53787517d2b75bc2188aecae427340ab3584f5d326f2bf9eaaca7ae3fd204388","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(entries, victim):\n    return [[x for x in entries if x[0]!=victim],[[x[0],x[1]] for x in entries if x[0]==victim]]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('fixture 1', solve(*([['a', 3, True], ['b', 4, False]], 'a')), [[['b', 4, False]], [['a', 3]]])\ncheck('fixture 2', solve(*([['a', 3, False]], 'a')), [[], []])\ncheck('fixture 3', solve(*([['a', 3, True]], 'z')), [[['a', 3, True]], []])\ncheck('fixture 4', solve(*([], 'a')), [[], []])\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":"5218f2b3acae4dde0e0b447a1b9c91e5ed815830bb3213e10ef69c92e13243c7","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(entries, victim):\n    return [[x for x in entries if x[0]!=victim],[]]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('fixture 1', solve(*([['a', 3, True], ['b', 4, False]], 'a')), [[['b', 4, False]], [['a', 3]]])\ncheck('fixture 2', solve(*([['a', 3, False]], 'a')), [[], []])\ncheck('fixture 3', solve(*([['a', 3, True]], 'z')), [[['a', 3, True]], []])\ncheck('fixture 4', solve(*([], 'a')), [[], []])\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":"b521d4ec1665041ca6466e2ebd33cc6addeb4df6c97f20e509aa6483e6ae3e6d","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(entries, victim):\n    return [[x for x in entries if x[0]!=victim],[[x[0],x[1]] for x in entries if x[0]==victim and x[2]]]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('fixture 1', solve(*([['a', 3, True], ['b', 4, False]], 'a')), [[['b', 4, False]], [['a', 3]]])\ncheck('fixture 2', solve(*([['a', 3, False]], 'a')), [[], []])\ncheck('fixture 3', solve(*([['a', 3, True]], 'z')), [[['a', 3, True]], []])\ncheck('fixture 4', solve(*([], 'a')), [[], []])\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-dirty-eviction-writeback","generated_at":"2026-09-29T14:38:39.007049+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.","repair":"Preserve the cache-state invariant: Unique entries are [key,value,dirty]. Remove victim and return [remaining,writeback records]; emit [key,value] only for a dirty resident victim.","root_cause":"The eviction path removes the resident record before preserving its pending write.","sha256":"5c31d2c66638ab6779f881bce0ca38dacbfd7144fec4a1c75f8162e0d9a5d368","title":"Eviction discards a dirty value without writing it back · case 01","variant":1,"variant_policy":"Five numbered records share a model and may reuse boundary fixtures.","verification":{"attempt":{"elapsed_ms":37.896,"exit_code":1,"observations":[{"actual":[[["b",4,false]],[["a",3]]],"check":"fixture 1","expected":[[["b",4,false]],[["a",3]]],"passed":true},{"actual":[[],[["a",3]]],"check":"fixture 2","expected":[[],[]],"passed":false},{"actual":[[["a",3,true]],[]],"check":"fixture 3","expected":[[["a",3,true]],[]],"passed":true},{"actual":[[],[]],"check":"fixture 4","expected":[[],[]],"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"fixture 1\", \"actual\": [[[\"b\", 4, false]], [[\"a\", 3]]], \"expected\": [[[\"b\", 4, false]], [[\"a\", 3]]], \"passed\": true}, {\"check\": \"fixture 2\", \"actual\": [[], [[\"a\", 3]]], \"expected\": [[], []], \"passed\": false}, {\"check\": \"fixture 3\", \"actual\": [[[\"a\", 3, true]], []], \"expected\": [[[\"a\", 3, true]], []], \"passed\": true}, {\"check\": \"fixture 4\", \"actual\": [[], []], \"expected\": [[], []], \"passed\": true}], \"passed\": false}\n"},"broken":{"elapsed_ms":39.791,"exit_code":1,"observations":[{"actual":[[["b",4,false]],[]],"check":"fixture 1","expected":[[["b",4,false]],[["a",3]]],"passed":false},{"actual":[[],[]],"check":"fixture 2","expected":[[],[]],"passed":true},{"actual":[[["a",3,true]],[]],"check":"fixture 3","expected":[[["a",3,true]],[]],"passed":true},{"actual":[[],[]],"check":"fixture 4","expected":[[],[]],"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"fixture 1\", \"actual\": [[[\"b\", 4, false]], []], \"expected\": [[[\"b\", 4, false]], [[\"a\", 3]]], \"passed\": false}, {\"check\": \"fixture 2\", \"actual\": [[], []], \"expected\": [[], []], \"passed\": true}, {\"check\": \"fixture 3\", \"actual\": [[[\"a\", 3, true]], []], \"expected\": [[[\"a\", 3, true]], []], \"passed\": true}, {\"check\": \"fixture 4\", \"actual\": [[], []], \"expected\": [[], []], \"passed\": true}], \"passed\": false}\n"},"fixed":{"elapsed_ms":41.223,"exit_code":0,"observations":[{"actual":[[["b",4,false]],[["a",3]]],"check":"fixture 1","expected":[[["b",4,false]],[["a",3]]],"passed":true},{"actual":[[],[]],"check":"fixture 2","expected":[[],[]],"passed":true},{"actual":[[["a",3,true]],[]],"check":"fixture 3","expected":[[["a",3,true]],[]],"passed":true},{"actual":[[],[]],"check":"fixture 4","expected":[[],[]],"passed":true}],"passed":true,"stderr":"","stdout":"{\"observations\": [{\"check\": \"fixture 1\", \"actual\": [[[\"b\", 4, false]], [[\"a\", 3]]], \"expected\": [[[\"b\", 4, false]], [[\"a\", 3]]], \"passed\": true}, {\"check\": \"fixture 2\", \"actual\": [[], []], \"expected\": [[], []], \"passed\": true}, {\"check\": \"fixture 3\", \"actual\": [[[\"a\", 3, true]], []], \"expected\": [[[\"a\", 3, true]], []], \"passed\": true}, {\"check\": \"fixture 4\", \"actual\": [[], []], \"expected\": [[], []], \"passed\": true}], \"passed\": true}\n"}},"verified":true,"visibility":"public"}