{"abstract":"Completed byte positions count once across duplicate downloaded fragments.","category":"HTTP ranges","checks":6,"contract":"Input is a list of explicit downloaded byte-offset lists, not intervals. Return count of distinct durable byte positions.","contract_signature":"completed","evaluation_group":"s3-http_ranges-resume-client","failed_approach":"The partial repair uses return max(map(len,completed),default=0), which still violates the stated contract.","family":"s3-http_ranges-resume-progress-union-not-sum","id":"FA-26786","implementations":{"attempt":{"sha256":"1893c143cfe44f24a91601f3581b1063be177dbb83797d6cdd5bc26630b317b7","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(completed):\n    return max(map(len,completed),default=0)\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('resume-progress-union-not-sum fixture 0', solve([[0,N],[N,2*N]]), 3)\ncheck('resume-progress-union-not-sum fixture 1', solve([[0],[N]]), 2)\ncheck('resume-progress-union-not-sum fixture 2', solve([]), 0)\ncheck('resume-progress-union-not-sum fixture 3', solve([[N],[N]]), 1)\ncheck('resume-progress-union-not-sum fixture 4', solve([[],[]]), 0)\ncheck('resume-progress-union-not-sum fixture 5', solve([[0,N,2*N]]), 3)\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":"b941422c1764edd61cc76737cec744156d8d89efaeead1e5e4ce6b165f5bdab8","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(completed):\n    return sum(map(len,completed))\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('resume-progress-union-not-sum fixture 0', solve([[0,N],[N,2*N]]), 3)\ncheck('resume-progress-union-not-sum fixture 1', solve([[0],[N]]), 2)\ncheck('resume-progress-union-not-sum fixture 2', solve([]), 0)\ncheck('resume-progress-union-not-sum fixture 3', solve([[N],[N]]), 1)\ncheck('resume-progress-union-not-sum fixture 4', solve([[],[]]), 0)\ncheck('resume-progress-union-not-sum fixture 5', solve([[0,N,2*N]]), 3)\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-resume-progress-union-not-sum","generated_at":"2026-09-29T14:41:19.053968+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 resume-progress-union-not-sum decision uses return sum(map(len,completed)).","sha256":"9cc5d3a064a4e77319832f91ed77959fea8bda4dcfa818f565658cfc674ec9d8","title":"Completed byte positions count once across duplicate downloaded fragments · 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":39.367,"exit_code":1,"observations":[{"actual":2,"check":"resume-progress-union-not-sum fixture 0","expected":3,"passed":false},{"actual":1,"check":"resume-progress-union-not-sum fixture 1","expected":2,"passed":false},{"actual":0,"check":"resume-progress-union-not-sum fixture 2","expected":0,"passed":true},{"actual":1,"check":"resume-progress-union-not-sum fixture 3","expected":1,"passed":true},{"actual":0,"check":"resume-progress-union-not-sum fixture 4","expected":0,"passed":true},{"actual":3,"check":"resume-progress-union-not-sum fixture 5","expected":3,"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"resume-progress-union-not-sum fixture 0\", \"actual\": 2, \"expected\": 3, \"passed\": false}, {\"check\": \"resume-progress-union-not-sum fixture 1\", \"actual\": 1, \"expected\": 2, \"passed\": false}, {\"check\": \"resume-progress-union-not-sum fixture 2\", \"actual\": 0, \"expected\": 0, \"passed\": true}, {\"check\": \"resume-progress-union-not-sum fixture 3\", \"actual\": 1, \"expected\": 1, \"passed\": true}, {\"check\": \"resume-progress-union-not-sum fixture 4\", \"actual\": 0, \"expected\": 0, \"passed\": true}, {\"check\": \"resume-progress-union-not-sum fixture 5\", \"actual\": 3, \"expected\": 3, \"passed\": true}], \"passed\": false}\n"},"broken":{"elapsed_ms":38.089,"exit_code":1,"observations":[{"actual":4,"check":"resume-progress-union-not-sum fixture 0","expected":3,"passed":false},{"actual":2,"check":"resume-progress-union-not-sum fixture 1","expected":2,"passed":true},{"actual":0,"check":"resume-progress-union-not-sum fixture 2","expected":0,"passed":true},{"actual":2,"check":"resume-progress-union-not-sum fixture 3","expected":1,"passed":false},{"actual":0,"check":"resume-progress-union-not-sum fixture 4","expected":0,"passed":true},{"actual":3,"check":"resume-progress-union-not-sum fixture 5","expected":3,"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"resume-progress-union-not-sum fixture 0\", \"actual\": 4, \"expected\": 3, \"passed\": false}, {\"check\": \"resume-progress-union-not-sum fixture 1\", \"actual\": 2, \"expected\": 2, \"passed\": true}, {\"check\": \"resume-progress-union-not-sum fixture 2\", \"actual\": 0, \"expected\": 0, \"passed\": true}, {\"check\": \"resume-progress-union-not-sum fixture 3\", \"actual\": 2, \"expected\": 1, \"passed\": false}, {\"check\": \"resume-progress-union-not-sum fixture 4\", \"actual\": 0, \"expected\": 0, \"passed\": true}, {\"check\": \"resume-progress-union-not-sum fixture 5\", \"actual\": 3, \"expected\": 3, \"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."}}