{"abstract":"A not-modified revalidation response replaces the cached body with an empty payload.","category":"Caching","checks":4,"contract":"Entry is [body,validated-at]. Response is [modified-or-not-modified,body-or-None,validated-at]. Preserve old body only for not-modified; always update validation time.","contract_signature":"entry, response","evaluation_group":"xc-stale-revalidation-retains-body","failed_approach":"Always retaining the old body discards a genuinely modified representation.","family":"xc-stale-revalidation-retains-body","id":"FA-10491","implementations":{"attempt":{"sha256":"2f04bd760bad751e22440981db601c22f446583657e10e3ade3fe96d0e0769a2","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(entry, response):\n    return [entry[0],response[2]]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('fixture 1', solve(*(['body', 1], ['not-modified', None, 2])), ['body', 2])\ncheck('fixture 2', solve(*(['old', 1], ['modified', 'new', 2])), ['new', 2])\ncheck('fixture 3', solve(*(['', 1], ['not-modified', None, 3])), ['', 3])\ncheck('fixture 4', solve(*(['old', 1], ['modified', '', 4])), ['', 4])\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":"8d1ef70822856056323bcb3174cc6aef6389878c60a983c68afd85e10c20fab5","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(entry, response):\n    return [response[1],response[2]]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('fixture 1', solve(*(['body', 1], ['not-modified', None, 2])), ['body', 2])\ncheck('fixture 2', solve(*(['old', 1], ['modified', 'new', 2])), ['new', 2])\ncheck('fixture 3', solve(*(['', 1], ['not-modified', None, 3])), ['', 3])\ncheck('fixture 4', solve(*(['old', 1], ['modified', '', 4])), ['', 4])\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-stale-revalidation-retains-body","generated_at":"2026-09-29T14:38:39.419388+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":"Refresh uses a validation-only response payload as the new representation body.","sha256":"3fec02ceac789ba7dd0ee79983de82873d925a580bec695efb7dae51a7dce772","title":"A not-modified revalidation response replaces the cached body with an empty payload · 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":39.53,"exit_code":1,"observations":[{"actual":["body",2],"check":"fixture 1","expected":["body",2],"passed":true},{"actual":["old",2],"check":"fixture 2","expected":["new",2],"passed":false},{"actual":["",3],"check":"fixture 3","expected":["",3],"passed":true},{"actual":["old",4],"check":"fixture 4","expected":["",4],"passed":false}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"fixture 1\", \"actual\": [\"body\", 2], \"expected\": [\"body\", 2], \"passed\": true}, {\"check\": \"fixture 2\", \"actual\": [\"old\", 2], \"expected\": [\"new\", 2], \"passed\": false}, {\"check\": \"fixture 3\", \"actual\": [\"\", 3], \"expected\": [\"\", 3], \"passed\": true}, {\"check\": \"fixture 4\", \"actual\": [\"old\", 4], \"expected\": [\"\", 4], \"passed\": false}], \"passed\": false}\n"},"broken":{"elapsed_ms":45.152,"exit_code":1,"observations":[{"actual":[null,2],"check":"fixture 1","expected":["body",2],"passed":false},{"actual":["new",2],"check":"fixture 2","expected":["new",2],"passed":true},{"actual":[null,3],"check":"fixture 3","expected":["",3],"passed":false},{"actual":["",4],"check":"fixture 4","expected":["",4],"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"fixture 1\", \"actual\": [null, 2], \"expected\": [\"body\", 2], \"passed\": false}, {\"check\": \"fixture 2\", \"actual\": [\"new\", 2], \"expected\": [\"new\", 2], \"passed\": true}, {\"check\": \"fixture 3\", \"actual\": [null, 3], \"expected\": [\"\", 3], \"passed\": false}, {\"check\": \"fixture 4\", \"actual\": [\"\", 4], \"expected\": [\"\", 4], \"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."}}