{"abstract":"Queued partial payloads preserve FIFO order under backpressure.","category":"HTTP ranges","checks":6,"contract":"Append new complete byte chunk to FIFO queue; empty chunks carry no payload and are not added.","evaluation_group":"s3-http_ranges-stream-transfer","failed_approach":"The partial repair uses return queued+[new], which still violates the stated contract.","family":"s3-http_ranges-stream-buffer-retains-order","id":"FA-26616","implementations":{"attempt":{"sha256":"5bdb8b0f8801dc676e01f06ace8562194eb2e4f699f17c93aad60948fbad46c9","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(queued, new):\n    return queued+[new]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('stream-buffer-retains-order fixture 0', solve( [\"a\"*N],\"b\"*N), [\"a\"*N,\"b\"*N])\ncheck('stream-buffer-retains-order fixture 1', solve([\"a\"],\"\"), [\"a\"])\ncheck('stream-buffer-retains-order fixture 2', solve([],\"x\"), [\"x\"])\ncheck('stream-buffer-retains-order fixture 3', solve([],\"\"), [])\ncheck('stream-buffer-retains-order fixture 4', solve([\"a\",\"b\"],\"c\"), [\"a\",\"b\",\"c\"])\ncheck('stream-buffer-retains-order fixture 5', solve([\"\"],\"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":"0c819cdb6518552859bcceac71c30e5764ec8c1f694f1d495c8c37ed0ba3e027","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(queued, new):\n    return ([new] if new else [])+queued\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('stream-buffer-retains-order fixture 0', solve( [\"a\"*N],\"b\"*N), [\"a\"*N,\"b\"*N])\ncheck('stream-buffer-retains-order fixture 1', solve([\"a\"],\"\"), [\"a\"])\ncheck('stream-buffer-retains-order fixture 2', solve([],\"x\"), [\"x\"])\ncheck('stream-buffer-retains-order fixture 3', solve([],\"\"), [])\ncheck('stream-buffer-retains-order fixture 4', solve([\"a\",\"b\"],\"c\"), [\"a\",\"b\",\"c\"])\ncheck('stream-buffer-retains-order fixture 5', solve([\"\"],\"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":"c59e892744922b3270b62e1bcf93e183c48dc735b5e2c2787113f32528ab85cb","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(queued, new):\n    return queued+([new] if new else [])\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('stream-buffer-retains-order fixture 0', solve( [\"a\"*N],\"b\"*N), [\"a\"*N,\"b\"*N])\ncheck('stream-buffer-retains-order fixture 1', solve([\"a\"],\"\"), [\"a\"])\ncheck('stream-buffer-retains-order fixture 2', solve([],\"x\"), [\"x\"])\ncheck('stream-buffer-retains-order fixture 3', solve([],\"\"), [])\ncheck('stream-buffer-retains-order fixture 4', solve([\"a\",\"b\"],\"c\"), [\"a\",\"b\",\"c\"])\ncheck('stream-buffer-retains-order fixture 5', solve([\"\"],\"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-stream-buffer-retains-order","generated_at":"2026-09-29T14:41:17.580372+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 queued+([new] if new else [])","root_cause":"The stream-buffer-retains-order decision uses return ([new] if new else [])+queued.","sha256":"52837cb6cf10ff049726ae215e0c1921590e640d605ee83419efc85dc8f2ed77","title":"Queued partial payloads preserve FIFO order under backpressure · case 01","variant":1,"variant_policy":"Five numbered records share a model and may reuse boundary fixtures.","verification":{"attempt":{"elapsed_ms":47.624,"exit_code":1,"observations":[{"actual":["a","b"],"check":"stream-buffer-retains-order fixture 0","expected":["a","b"],"passed":true},{"actual":["a",""],"check":"stream-buffer-retains-order fixture 1","expected":["a"],"passed":false},{"actual":["x"],"check":"stream-buffer-retains-order fixture 2","expected":["x"],"passed":true},{"actual":[""],"check":"stream-buffer-retains-order fixture 3","expected":[],"passed":false},{"actual":["a","b","c"],"check":"stream-buffer-retains-order fixture 4","expected":["a","b","c"],"passed":true},{"actual":["","x"],"check":"stream-buffer-retains-order fixture 5","expected":["","x"],"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"stream-buffer-retains-order fixture 0\", \"actual\": [\"a\", \"b\"], \"expected\": [\"a\", \"b\"], \"passed\": true}, {\"check\": \"stream-buffer-retains-order fixture 1\", \"actual\": [\"a\", \"\"], \"expected\": [\"a\"], \"passed\": false}, {\"check\": \"stream-buffer-retains-order fixture 2\", \"actual\": [\"x\"], \"expected\": [\"x\"], \"passed\": true}, {\"check\": \"stream-buffer-retains-order fixture 3\", \"actual\": [\"\"], \"expected\": [], \"passed\": false}, {\"check\": \"stream-buffer-retains-order fixture 4\", \"actual\": [\"a\", \"b\", \"c\"], \"expected\": [\"a\", \"b\", \"c\"], \"passed\": true}, {\"check\": \"stream-buffer-retains-order fixture 5\", \"actual\": [\"\", \"x\"], \"expected\": [\"\", \"x\"], \"passed\": true}], \"passed\": false}\n"},"broken":{"elapsed_ms":39.978,"exit_code":1,"observations":[{"actual":["b","a"],"check":"stream-buffer-retains-order fixture 0","expected":["a","b"],"passed":false},{"actual":["a"],"check":"stream-buffer-retains-order fixture 1","expected":["a"],"passed":true},{"actual":["x"],"check":"stream-buffer-retains-order fixture 2","expected":["x"],"passed":true},{"actual":[],"check":"stream-buffer-retains-order fixture 3","expected":[],"passed":true},{"actual":["c","a","b"],"check":"stream-buffer-retains-order fixture 4","expected":["a","b","c"],"passed":false},{"actual":["x",""],"check":"stream-buffer-retains-order fixture 5","expected":["","x"],"passed":false}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"stream-buffer-retains-order fixture 0\", \"actual\": [\"b\", \"a\"], \"expected\": [\"a\", \"b\"], \"passed\": false}, {\"check\": \"stream-buffer-retains-order fixture 1\", \"actual\": [\"a\"], \"expected\": [\"a\"], \"passed\": true}, {\"check\": \"stream-buffer-retains-order fixture 2\", \"actual\": [\"x\"], \"expected\": [\"x\"], \"passed\": true}, {\"check\": \"stream-buffer-retains-order fixture 3\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"stream-buffer-retains-order fixture 4\", \"actual\": [\"c\", \"a\", \"b\"], \"expected\": [\"a\", \"b\", \"c\"], \"passed\": false}, {\"check\": \"stream-buffer-retains-order fixture 5\", \"actual\": [\"x\", \"\"], \"expected\": [\"\", \"x\"], \"passed\": false}], \"passed\": false}\n"},"fixed":{"elapsed_ms":42.553,"exit_code":0,"observations":[{"actual":["a","b"],"check":"stream-buffer-retains-order fixture 0","expected":["a","b"],"passed":true},{"actual":["a"],"check":"stream-buffer-retains-order fixture 1","expected":["a"],"passed":true},{"actual":["x"],"check":"stream-buffer-retains-order fixture 2","expected":["x"],"passed":true},{"actual":[],"check":"stream-buffer-retains-order fixture 3","expected":[],"passed":true},{"actual":["a","b","c"],"check":"stream-buffer-retains-order fixture 4","expected":["a","b","c"],"passed":true},{"actual":["","x"],"check":"stream-buffer-retains-order fixture 5","expected":["","x"],"passed":true}],"passed":true,"stderr":"","stdout":"{\"observations\": [{\"check\": \"stream-buffer-retains-order fixture 0\", \"actual\": [\"a\", \"b\"], \"expected\": [\"a\", \"b\"], \"passed\": true}, {\"check\": \"stream-buffer-retains-order fixture 1\", \"actual\": [\"a\"], \"expected\": [\"a\"], \"passed\": true}, {\"check\": \"stream-buffer-retains-order fixture 2\", \"actual\": [\"x\"], \"expected\": [\"x\"], \"passed\": true}, {\"check\": \"stream-buffer-retains-order fixture 3\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"stream-buffer-retains-order fixture 4\", \"actual\": [\"a\", \"b\", \"c\"], \"expected\": [\"a\", \"b\", \"c\"], \"passed\": true}, {\"check\": \"stream-buffer-retains-order fixture 5\", \"actual\": [\"\", \"x\"], \"expected\": [\"\", \"x\"], \"passed\": true}], \"passed\": true}\n"}},"verified":true,"visibility":"public"}