{"abstract":"Cached fragments with different validators cannot be joined.","category":"HTTP ranges","checks":6,"contract":"Fragments are [strong-validator,payload] in byte order. Return their joined body when all validators agree, None otherwise; no fragments returns empty.","evaluation_group":"s3-http_ranges-cache-assembly","failed_approach":"The partial repair uses return \"\".join(p for tag,p in fragments) if len({tag for tag,p in fragments if p})<=1 else None, which still violates the stated contract.","family":"s3-http_ranges-cache-revision-splice","id":"FA-26491","implementations":{"attempt":{"sha256":"faf2099a520dbc222a38984cd3f4e55d768e5c5b2dc0b26483c21739d7576cfb","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(fragments):\n    return \"\".join(p for tag,p in fragments) if len({tag for tag,p in fragments if p})<=1 else None\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('cache-revision-splice fixture 0', solve([[\"a\",\"x\"*N],[\"b\",\"y\"]]), None)\ncheck('cache-revision-splice fixture 1', solve([[\"a\",\"x\"],[\"b\",\"\"]]), None)\ncheck('cache-revision-splice fixture 2', solve([[\"a\",\"x\"*N],[\"a\",\"y\"]]), \"x\"*N+\"y\")\ncheck('cache-revision-splice fixture 3', solve([]), \"\")\ncheck('cache-revision-splice fixture 4', solve([[\"a\",\"\"]]), \"\")\ncheck('cache-revision-splice fixture 5', solve([[\"a\",\"x\"]]), \"x\")\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":"1660ce9a8ad1b9017e21969dcbf03bc04c56f214f8f7c0d57526272f1eaacf64","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(fragments):\n    return \"\".join(p for tag,p in fragments)\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('cache-revision-splice fixture 0', solve([[\"a\",\"x\"*N],[\"b\",\"y\"]]), None)\ncheck('cache-revision-splice fixture 1', solve([[\"a\",\"x\"],[\"b\",\"\"]]), None)\ncheck('cache-revision-splice fixture 2', solve([[\"a\",\"x\"*N],[\"a\",\"y\"]]), \"x\"*N+\"y\")\ncheck('cache-revision-splice fixture 3', solve([]), \"\")\ncheck('cache-revision-splice fixture 4', solve([[\"a\",\"\"]]), \"\")\ncheck('cache-revision-splice fixture 5', solve([[\"a\",\"x\"]]), \"x\")\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":"e7008226af38e70ab7f105d4bcc7cd99e9566f87c9c864823bdbcaa007a907da","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(fragments):\n    return \"\".join(p for tag,p in fragments) if len({tag for tag,p in fragments})<=1 else None\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('cache-revision-splice fixture 0', solve([[\"a\",\"x\"*N],[\"b\",\"y\"]]), None)\ncheck('cache-revision-splice fixture 1', solve([[\"a\",\"x\"],[\"b\",\"\"]]), None)\ncheck('cache-revision-splice fixture 2', solve([[\"a\",\"x\"*N],[\"a\",\"y\"]]), \"x\"*N+\"y\")\ncheck('cache-revision-splice fixture 3', solve([]), \"\")\ncheck('cache-revision-splice fixture 4', solve([[\"a\",\"\"]]), \"\")\ncheck('cache-revision-splice fixture 5', solve([[\"a\",\"x\"]]), \"x\")\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":"Deterministic simplified range service, with stipulated local policies and already parsed trusted inputs; not a complete HTTP implementation. 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":"s3-http_ranges-cache-revision-splice","generated_at":"2026-09-29T14:41:16.448858+00:00","license":"CC0-1.0","python":"3.12.14","seed":1,"split":"open-access"},"relevance":"Range responses combine representation identity, conditional requests, framing, and partial-object state.","repair":"Apply the bounded decision exactly: return \"\".join(p for tag,p in fragments) if len({tag for tag,p in fragments})<=1 else None","root_cause":"The cache-revision-splice decision uses return \"\".join(p for tag,p in fragments).","sha256":"b592bedb901261268ede1ec1e463ec1e4f3a0771c34cf618418879da8d90b981","title":"Cached fragments with different validators cannot be joined · case 01","variant":1,"variant_policy":"Five numbered records share a model and may reuse boundary fixtures.","verification":{"attempt":{"elapsed_ms":38.998,"exit_code":1,"observations":[{"actual":null,"check":"cache-revision-splice fixture 0","expected":null,"passed":true},{"actual":"x","check":"cache-revision-splice fixture 1","expected":null,"passed":false},{"actual":"xy","check":"cache-revision-splice fixture 2","expected":"xy","passed":true},{"actual":"","check":"cache-revision-splice fixture 3","expected":"","passed":true},{"actual":"","check":"cache-revision-splice fixture 4","expected":"","passed":true},{"actual":"x","check":"cache-revision-splice fixture 5","expected":"x","passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"cache-revision-splice fixture 0\", \"actual\": null, \"expected\": null, \"passed\": true}, {\"check\": \"cache-revision-splice fixture 1\", \"actual\": \"x\", \"expected\": null, \"passed\": false}, {\"check\": \"cache-revision-splice fixture 2\", \"actual\": \"xy\", \"expected\": \"xy\", \"passed\": true}, {\"check\": \"cache-revision-splice fixture 3\", \"actual\": \"\", \"expected\": \"\", \"passed\": true}, {\"check\": \"cache-revision-splice fixture 4\", \"actual\": \"\", \"expected\": \"\", \"passed\": true}, {\"check\": \"cache-revision-splice fixture 5\", \"actual\": \"x\", \"expected\": \"x\", \"passed\": true}], \"passed\": false}\n"},"broken":{"elapsed_ms":39.542,"exit_code":1,"observations":[{"actual":"xy","check":"cache-revision-splice fixture 0","expected":null,"passed":false},{"actual":"x","check":"cache-revision-splice fixture 1","expected":null,"passed":false},{"actual":"xy","check":"cache-revision-splice fixture 2","expected":"xy","passed":true},{"actual":"","check":"cache-revision-splice fixture 3","expected":"","passed":true},{"actual":"","check":"cache-revision-splice fixture 4","expected":"","passed":true},{"actual":"x","check":"cache-revision-splice fixture 5","expected":"x","passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"cache-revision-splice fixture 0\", \"actual\": \"xy\", \"expected\": null, \"passed\": false}, {\"check\": \"cache-revision-splice fixture 1\", \"actual\": \"x\", \"expected\": null, \"passed\": false}, {\"check\": \"cache-revision-splice fixture 2\", \"actual\": \"xy\", \"expected\": \"xy\", \"passed\": true}, {\"check\": \"cache-revision-splice fixture 3\", \"actual\": \"\", \"expected\": \"\", \"passed\": true}, {\"check\": \"cache-revision-splice fixture 4\", \"actual\": \"\", \"expected\": \"\", \"passed\": true}, {\"check\": \"cache-revision-splice fixture 5\", \"actual\": \"x\", \"expected\": \"x\", \"passed\": true}], \"passed\": false}\n"},"fixed":{"elapsed_ms":39.187,"exit_code":0,"observations":[{"actual":null,"check":"cache-revision-splice fixture 0","expected":null,"passed":true},{"actual":null,"check":"cache-revision-splice fixture 1","expected":null,"passed":true},{"actual":"xy","check":"cache-revision-splice fixture 2","expected":"xy","passed":true},{"actual":"","check":"cache-revision-splice fixture 3","expected":"","passed":true},{"actual":"","check":"cache-revision-splice fixture 4","expected":"","passed":true},{"actual":"x","check":"cache-revision-splice fixture 5","expected":"x","passed":true}],"passed":true,"stderr":"","stdout":"{\"observations\": [{\"check\": \"cache-revision-splice fixture 0\", \"actual\": null, \"expected\": null, \"passed\": true}, {\"check\": \"cache-revision-splice fixture 1\", \"actual\": null, \"expected\": null, \"passed\": true}, {\"check\": \"cache-revision-splice fixture 2\", \"actual\": \"xy\", \"expected\": \"xy\", \"passed\": true}, {\"check\": \"cache-revision-splice fixture 3\", \"actual\": \"\", \"expected\": \"\", \"passed\": true}, {\"check\": \"cache-revision-splice fixture 4\", \"actual\": \"\", \"expected\": \"\", \"passed\": true}, {\"check\": \"cache-revision-splice fixture 5\", \"actual\": \"x\", \"expected\": \"x\", \"passed\": true}], \"passed\": true}\n"}},"verified":true,"visibility":"public"}