{"abstract":"Representation checksum excludes multipart envelope bytes.","category":"HTTP ranges","checks":6,"contract":"Local checksum is sum ASCII code points modulo 257 over payloads only. Framing headers are not representation data.","evaluation_group":"s3-http_ranges-stream-transfer","failed_approach":"The partial repair uses return sum(map(ord,\"\".join(payloads))), which still violates the stated contract.","family":"s3-http_ranges-stream-checksum-body-only","id":"FA-26581","implementations":{"attempt":{"sha256":"292646ece0e94c5f859be937809529d3f3d7d10da04366f36b51b871d92880f5","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(payloads, headers):\n    return sum(map(ord,\"\".join(payloads)))\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('stream-checksum-body-only fixture 0', solve( [\"z\"*(N+3)],[\"Header\"]), (122*(N+3))%257)\ncheck('stream-checksum-body-only fixture 1', solve([\"a\"],[\"b\"]), 97)\ncheck('stream-checksum-body-only fixture 2', solve([],[\"header\"]), 0)\ncheck('stream-checksum-body-only fixture 3', solve([],[]), 0)\ncheck('stream-checksum-body-only fixture 4', solve([\"ab\"],[]), 195)\ncheck('stream-checksum-body-only fixture 5', solve([\"z\",\"z\",\"z\"],[]), 109)\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":"92380ff7cfad2ad813f0ea98f0a9aeb565bb1a356a5253387b9a2b6be18916a3","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(payloads, headers):\n    return sum(map(ord,\"\".join(payloads+headers)))%257\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('stream-checksum-body-only fixture 0', solve( [\"z\"*(N+3)],[\"Header\"]), (122*(N+3))%257)\ncheck('stream-checksum-body-only fixture 1', solve([\"a\"],[\"b\"]), 97)\ncheck('stream-checksum-body-only fixture 2', solve([],[\"header\"]), 0)\ncheck('stream-checksum-body-only fixture 3', solve([],[]), 0)\ncheck('stream-checksum-body-only fixture 4', solve([\"ab\"],[]), 195)\ncheck('stream-checksum-body-only fixture 5', solve([\"z\",\"z\",\"z\"],[]), 109)\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":"b9a758f3c6aa6f828d04678710d8d94e9b059f001b0b63bd3c5ec7e2699539dc","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(payloads, headers):\n    return sum(map(ord,\"\".join(payloads)))%257\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('stream-checksum-body-only fixture 0', solve( [\"z\"*(N+3)],[\"Header\"]), (122*(N+3))%257)\ncheck('stream-checksum-body-only fixture 1', solve([\"a\"],[\"b\"]), 97)\ncheck('stream-checksum-body-only fixture 2', solve([],[\"header\"]), 0)\ncheck('stream-checksum-body-only fixture 3', solve([],[]), 0)\ncheck('stream-checksum-body-only fixture 4', solve([\"ab\"],[]), 195)\ncheck('stream-checksum-body-only fixture 5', solve([\"z\",\"z\",\"z\"],[]), 109)\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-stream-checksum-body-only","generated_at":"2026-09-29T14:41:17.319425+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 sum(map(ord,\"\".join(payloads)))%257","root_cause":"The stream-checksum-body-only decision uses return sum(map(ord,\"\".join(payloads+headers)))%257.","sha256":"db5133d8a992d88ca501b9803ef430472fbcbe79ba1593f00c4863e00421c7f4","title":"Representation checksum excludes multipart envelope bytes · case 01","variant":1,"variant_policy":"Five numbered records share a model and may reuse boundary fixtures.","verification":{"attempt":{"elapsed_ms":44.403,"exit_code":1,"observations":[{"actual":488,"check":"stream-checksum-body-only fixture 0","expected":231,"passed":false},{"actual":97,"check":"stream-checksum-body-only fixture 1","expected":97,"passed":true},{"actual":0,"check":"stream-checksum-body-only fixture 2","expected":0,"passed":true},{"actual":0,"check":"stream-checksum-body-only fixture 3","expected":0,"passed":true},{"actual":195,"check":"stream-checksum-body-only fixture 4","expected":195,"passed":true},{"actual":366,"check":"stream-checksum-body-only fixture 5","expected":109,"passed":false}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"stream-checksum-body-only fixture 0\", \"actual\": 488, \"expected\": 231, \"passed\": false}, {\"check\": \"stream-checksum-body-only fixture 1\", \"actual\": 97, \"expected\": 97, \"passed\": true}, {\"check\": \"stream-checksum-body-only fixture 2\", \"actual\": 0, \"expected\": 0, \"passed\": true}, {\"check\": \"stream-checksum-body-only fixture 3\", \"actual\": 0, \"expected\": 0, \"passed\": true}, {\"check\": \"stream-checksum-body-only fixture 4\", \"actual\": 195, \"expected\": 195, \"passed\": true}, {\"check\": \"stream-checksum-body-only fixture 5\", \"actual\": 366, \"expected\": 109, \"passed\": false}], \"passed\": false}\n"},"broken":{"elapsed_ms":37.81,"exit_code":1,"observations":[{"actual":45,"check":"stream-checksum-body-only fixture 0","expected":231,"passed":false},{"actual":195,"check":"stream-checksum-body-only fixture 1","expected":97,"passed":false},{"actual":103,"check":"stream-checksum-body-only fixture 2","expected":0,"passed":false},{"actual":0,"check":"stream-checksum-body-only fixture 3","expected":0,"passed":true},{"actual":195,"check":"stream-checksum-body-only fixture 4","expected":195,"passed":true},{"actual":109,"check":"stream-checksum-body-only fixture 5","expected":109,"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"stream-checksum-body-only fixture 0\", \"actual\": 45, \"expected\": 231, \"passed\": false}, {\"check\": \"stream-checksum-body-only fixture 1\", \"actual\": 195, \"expected\": 97, \"passed\": false}, {\"check\": \"stream-checksum-body-only fixture 2\", \"actual\": 103, \"expected\": 0, \"passed\": false}, {\"check\": \"stream-checksum-body-only fixture 3\", \"actual\": 0, \"expected\": 0, \"passed\": true}, {\"check\": \"stream-checksum-body-only fixture 4\", \"actual\": 195, \"expected\": 195, \"passed\": true}, {\"check\": \"stream-checksum-body-only fixture 5\", \"actual\": 109, \"expected\": 109, \"passed\": true}], \"passed\": false}\n"},"fixed":{"elapsed_ms":36.192,"exit_code":0,"observations":[{"actual":231,"check":"stream-checksum-body-only fixture 0","expected":231,"passed":true},{"actual":97,"check":"stream-checksum-body-only fixture 1","expected":97,"passed":true},{"actual":0,"check":"stream-checksum-body-only fixture 2","expected":0,"passed":true},{"actual":0,"check":"stream-checksum-body-only fixture 3","expected":0,"passed":true},{"actual":195,"check":"stream-checksum-body-only fixture 4","expected":195,"passed":true},{"actual":109,"check":"stream-checksum-body-only fixture 5","expected":109,"passed":true}],"passed":true,"stderr":"","stdout":"{\"observations\": [{\"check\": \"stream-checksum-body-only fixture 0\", \"actual\": 231, \"expected\": 231, \"passed\": true}, {\"check\": \"stream-checksum-body-only fixture 1\", \"actual\": 97, \"expected\": 97, \"passed\": true}, {\"check\": \"stream-checksum-body-only fixture 2\", \"actual\": 0, \"expected\": 0, \"passed\": true}, {\"check\": \"stream-checksum-body-only fixture 3\", \"actual\": 0, \"expected\": 0, \"passed\": true}, {\"check\": \"stream-checksum-body-only fixture 4\", \"actual\": 195, \"expected\": 195, \"passed\": true}, {\"check\": \"stream-checksum-body-only fixture 5\", \"actual\": 109, \"expected\": 109, \"passed\": true}], \"passed\": true}\n"}},"verified":true,"visibility":"public"}