{"abstract":"A refresh failure destroys a still-usable stale cache entry.","category":"Caching","checks":4,"contract":"For this stale-allowed cache policy, error preserves the prior value; success replaces it with body, including zero or None. Expiration eligibility is handled before this operation.","contract_signature":"entry, outcome, body","evaluation_group":"xc-revalidation-error-keeps-stale","failed_approach":"Always preserving the old entry prevents successful refresh from updating it.","family":"xc-revalidation-error-keeps-stale","id":"FA-10496","implementations":{"attempt":{"sha256":"2f1ebe6eb07c3342836e5fb436881858b81aaa9f34ccc21fc3266e96a6525f3e","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(entry, outcome, body):\n    return entry\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('fixture 1', solve(*('stale', 'error', None)), 'stale')\ncheck('fixture 2', solve(*('old', 'success', 'new')), 'new')\ncheck('fixture 3', solve(*(None, 'success', 0)), 0)\ncheck('fixture 4', solve(*('', 'error', None)), '')\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":"6f236f1531a31a414792c6c90a904144d2cd2954387f466c6f851fdff116ecf4","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(entry, outcome, body):\n    return None if outcome=='error' else body\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('fixture 1', solve(*('stale', 'error', None)), 'stale')\ncheck('fixture 2', solve(*('old', 'success', 'new')), 'new')\ncheck('fixture 3', solve(*(None, 'success', 0)), 0)\ncheck('fixture 4', solve(*('', 'error', None)), '')\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-revalidation-error-keeps-stale","generated_at":"2026-09-29T14:38:39.535592+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":"Failed revalidation is treated as an authoritative deletion.","sha256":"bac884bbb6ac7c75c5c136faa91fd0be3c6c1ec19b677821b0b0a39c50ce4b79","title":"A refresh failure destroys a still-usable stale cache entry · 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":40.213,"exit_code":1,"observations":[{"actual":"stale","check":"fixture 1","expected":"stale","passed":true},{"actual":"old","check":"fixture 2","expected":"new","passed":false},{"actual":null,"check":"fixture 3","expected":0,"passed":false},{"actual":"","check":"fixture 4","expected":"","passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"fixture 1\", \"actual\": \"stale\", \"expected\": \"stale\", \"passed\": true}, {\"check\": \"fixture 2\", \"actual\": \"old\", \"expected\": \"new\", \"passed\": false}, {\"check\": \"fixture 3\", \"actual\": null, \"expected\": 0, \"passed\": false}, {\"check\": \"fixture 4\", \"actual\": \"\", \"expected\": \"\", \"passed\": true}], \"passed\": false}\n"},"broken":{"elapsed_ms":37.774,"exit_code":1,"observations":[{"actual":null,"check":"fixture 1","expected":"stale","passed":false},{"actual":"new","check":"fixture 2","expected":"new","passed":true},{"actual":0,"check":"fixture 3","expected":0,"passed":true},{"actual":null,"check":"fixture 4","expected":"","passed":false}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"fixture 1\", \"actual\": null, \"expected\": \"stale\", \"passed\": false}, {\"check\": \"fixture 2\", \"actual\": \"new\", \"expected\": \"new\", \"passed\": true}, {\"check\": \"fixture 3\", \"actual\": 0, \"expected\": 0, \"passed\": true}, {\"check\": \"fixture 4\", \"actual\": null, \"expected\": \"\", \"passed\": false}], \"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."}}