{"abstract":"Preamble bytes before the first delimiter do not form a range part.","category":"HTTP ranges","checks":6,"contract":"Return only explicitly parsed part bodies; preamble is ignored even when nonempty.","contract_signature":"preamble, parts","evaluation_group":"s3-http_ranges-multipart-client","failed_approach":"The partial repair uses return [preamble]+parts if preamble else parts, which still violates the stated contract.","family":"s3-http_ranges-multipart-client-preamble-not-part","id":"FA-26831","implementations":{"attempt":{"sha256":"2ccebcd1b0c6df355b3f13a3923ee64b3a288bdcdc7e33220f06783f0ba89380","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(preamble, parts):\n    return [preamble]+parts if preamble else parts\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('multipart-client-preamble-not-part fixture 0', solve(\"banner\"*N,[\"p\"]), [\"p\"])\ncheck('multipart-client-preamble-not-part fixture 1', solve(\"\",[\"p\"]), [\"p\"])\ncheck('multipart-client-preamble-not-part fixture 2', solve(\"banner\",[]), [])\ncheck('multipart-client-preamble-not-part fixture 3', solve(\"\",[]), [])\ncheck('multipart-client-preamble-not-part fixture 4', solve(\"x\",[\"a\",\"b\"]), [\"a\",\"b\"])\ncheck('multipart-client-preamble-not-part fixture 5', solve(\"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":"084f5b6da971c02e7c866ea4b6c5a3016de0942358ec1309f4e82fd656ea2414","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(preamble, parts):\n    return [preamble]+parts\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('multipart-client-preamble-not-part fixture 0', solve(\"banner\"*N,[\"p\"]), [\"p\"])\ncheck('multipart-client-preamble-not-part fixture 1', solve(\"\",[\"p\"]), [\"p\"])\ncheck('multipart-client-preamble-not-part fixture 2', solve(\"banner\",[]), [])\ncheck('multipart-client-preamble-not-part fixture 3', solve(\"\",[]), [])\ncheck('multipart-client-preamble-not-part fixture 4', solve(\"x\",[\"a\",\"b\"]), [\"a\",\"b\"])\ncheck('multipart-client-preamble-not-part fixture 5', solve(\"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-multipart-client-preamble-not-part","generated_at":"2026-09-29T14:41:19.424107+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.","root_cause":"The multipart-client-preamble-not-part decision uses return [preamble]+parts.","sha256":"ca1a951afb417c61980ac5aaff754604d27f46941ff3ce03d2205fa9aa5c2f70","title":"Preamble bytes before the first delimiter do not form a range part · 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":38.438,"exit_code":1,"observations":[{"actual":["banner","p"],"check":"multipart-client-preamble-not-part fixture 0","expected":["p"],"passed":false},{"actual":["p"],"check":"multipart-client-preamble-not-part fixture 1","expected":["p"],"passed":true},{"actual":["banner"],"check":"multipart-client-preamble-not-part fixture 2","expected":[],"passed":false},{"actual":[],"check":"multipart-client-preamble-not-part fixture 3","expected":[],"passed":true},{"actual":["x","a","b"],"check":"multipart-client-preamble-not-part fixture 4","expected":["a","b"],"passed":false},{"actual":["x",""],"check":"multipart-client-preamble-not-part fixture 5","expected":[""],"passed":false}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"multipart-client-preamble-not-part fixture 0\", \"actual\": [\"banner\", \"p\"], \"expected\": [\"p\"], \"passed\": false}, {\"check\": \"multipart-client-preamble-not-part fixture 1\", \"actual\": [\"p\"], \"expected\": [\"p\"], \"passed\": true}, {\"check\": \"multipart-client-preamble-not-part fixture 2\", \"actual\": [\"banner\"], \"expected\": [], \"passed\": false}, {\"check\": \"multipart-client-preamble-not-part fixture 3\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"multipart-client-preamble-not-part fixture 4\", \"actual\": [\"x\", \"a\", \"b\"], \"expected\": [\"a\", \"b\"], \"passed\": false}, {\"check\": \"multipart-client-preamble-not-part fixture 5\", \"actual\": [\"x\", \"\"], \"expected\": [\"\"], \"passed\": false}], \"passed\": false}\n"},"broken":{"elapsed_ms":38.988,"exit_code":1,"observations":[{"actual":["banner","p"],"check":"multipart-client-preamble-not-part fixture 0","expected":["p"],"passed":false},{"actual":["","p"],"check":"multipart-client-preamble-not-part fixture 1","expected":["p"],"passed":false},{"actual":["banner"],"check":"multipart-client-preamble-not-part fixture 2","expected":[],"passed":false},{"actual":[""],"check":"multipart-client-preamble-not-part fixture 3","expected":[],"passed":false},{"actual":["x","a","b"],"check":"multipart-client-preamble-not-part fixture 4","expected":["a","b"],"passed":false},{"actual":["x",""],"check":"multipart-client-preamble-not-part fixture 5","expected":[""],"passed":false}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"multipart-client-preamble-not-part fixture 0\", \"actual\": [\"banner\", \"p\"], \"expected\": [\"p\"], \"passed\": false}, {\"check\": \"multipart-client-preamble-not-part fixture 1\", \"actual\": [\"\", \"p\"], \"expected\": [\"p\"], \"passed\": false}, {\"check\": \"multipart-client-preamble-not-part fixture 2\", \"actual\": [\"banner\"], \"expected\": [], \"passed\": false}, {\"check\": \"multipart-client-preamble-not-part fixture 3\", \"actual\": [\"\"], \"expected\": [], \"passed\": false}, {\"check\": \"multipart-client-preamble-not-part fixture 4\", \"actual\": [\"x\", \"a\", \"b\"], \"expected\": [\"a\", \"b\"], \"passed\": false}, {\"check\": \"multipart-client-preamble-not-part fixture 5\", \"actual\": [\"x\", \"\"], \"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."}}