{"abstract":"Range negotiation preserves preexisting Vary dimensions.","category":"HTTP ranges","checks":6,"contract":"Return sorted unique Vary names, adding accept-encoding when negotiated by encoding. Existing names are already lowercase.","evaluation_group":"s3-http_ranges-representation","failed_approach":"The partial repair uses return sorted(vary+[\"accept-encoding\"]) if selected_by_encoding else sorted(vary), which still violates the stated contract.","family":"s3-http_ranges-variant-vary-union","id":"FA-26411","implementations":{"attempt":{"sha256":"5423fbda7b286d8bc6b27c550ebb8f6b28b10e33f1c5bf5b75362b1c5824d0d1","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(vary, selected_by_encoding):\n    return sorted(vary+[\"accept-encoding\"]) if selected_by_encoding else sorted(vary)\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('variant-vary-union fixture 0', solve( [\"accept-language\"],True), [\"accept-encoding\",\"accept-language\"])\ncheck('variant-vary-union fixture 1', solve([\"accept-encoding\"],True), [\"accept-encoding\"])\ncheck('variant-vary-union fixture 2', solve([],True), [\"accept-encoding\"])\ncheck('variant-vary-union fixture 3', solve([],False), [])\ncheck('variant-vary-union fixture 4', solve([\"x-\"+str(N)],False), [\"x-\"+str(N)])\ncheck('variant-vary-union fixture 5', solve([\"accept-language\",\"accept-language\"],False), [\"accept-language\"])\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":"509ac6f44a4ae478665af300b6feeb3ae9c7dee7a3b3eb45562ba1d059c03d73","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(vary, selected_by_encoding):\n    return [\"accept-encoding\"] if selected_by_encoding else vary\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('variant-vary-union fixture 0', solve( [\"accept-language\"],True), [\"accept-encoding\",\"accept-language\"])\ncheck('variant-vary-union fixture 1', solve([\"accept-encoding\"],True), [\"accept-encoding\"])\ncheck('variant-vary-union fixture 2', solve([],True), [\"accept-encoding\"])\ncheck('variant-vary-union fixture 3', solve([],False), [])\ncheck('variant-vary-union fixture 4', solve([\"x-\"+str(N)],False), [\"x-\"+str(N)])\ncheck('variant-vary-union fixture 5', solve([\"accept-language\",\"accept-language\"],False), [\"accept-language\"])\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":"4b01da1800e1c18b4b23acf0f9e20b3468f55e0574d29b5ddad599da7aaf3836","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(vary, selected_by_encoding):\n    return sorted(set(vary+([\"accept-encoding\"] if selected_by_encoding else [])))\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('variant-vary-union fixture 0', solve( [\"accept-language\"],True), [\"accept-encoding\",\"accept-language\"])\ncheck('variant-vary-union fixture 1', solve([\"accept-encoding\"],True), [\"accept-encoding\"])\ncheck('variant-vary-union fixture 2', solve([],True), [\"accept-encoding\"])\ncheck('variant-vary-union fixture 3', solve([],False), [])\ncheck('variant-vary-union fixture 4', solve([\"x-\"+str(N)],False), [\"x-\"+str(N)])\ncheck('variant-vary-union fixture 5', solve([\"accept-language\",\"accept-language\"],False), [\"accept-language\"])\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-variant-vary-union","generated_at":"2026-09-29T14:41:15.694413+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 sorted(set(vary+([\"accept-encoding\"] if selected_by_encoding else [])))","root_cause":"The variant-vary-union decision uses return [\"accept-encoding\"] if selected_by_encoding else vary.","sha256":"d046a6ccba26cee115859bdb5d48f5197194808d2c465571297632f1dfc74359","title":"Range negotiation preserves preexisting Vary dimensions · case 01","variant":1,"variant_policy":"Five numbered records share a model and may reuse boundary fixtures.","verification":{"attempt":{"elapsed_ms":39.41,"exit_code":1,"observations":[{"actual":["accept-encoding","accept-language"],"check":"variant-vary-union fixture 0","expected":["accept-encoding","accept-language"],"passed":true},{"actual":["accept-encoding","accept-encoding"],"check":"variant-vary-union fixture 1","expected":["accept-encoding"],"passed":false},{"actual":["accept-encoding"],"check":"variant-vary-union fixture 2","expected":["accept-encoding"],"passed":true},{"actual":[],"check":"variant-vary-union fixture 3","expected":[],"passed":true},{"actual":["x-1"],"check":"variant-vary-union fixture 4","expected":["x-1"],"passed":true},{"actual":["accept-language","accept-language"],"check":"variant-vary-union fixture 5","expected":["accept-language"],"passed":false}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"variant-vary-union fixture 0\", \"actual\": [\"accept-encoding\", \"accept-language\"], \"expected\": [\"accept-encoding\", \"accept-language\"], \"passed\": true}, {\"check\": \"variant-vary-union fixture 1\", \"actual\": [\"accept-encoding\", \"accept-encoding\"], \"expected\": [\"accept-encoding\"], \"passed\": false}, {\"check\": \"variant-vary-union fixture 2\", \"actual\": [\"accept-encoding\"], \"expected\": [\"accept-encoding\"], \"passed\": true}, {\"check\": \"variant-vary-union fixture 3\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"variant-vary-union fixture 4\", \"actual\": [\"x-1\"], \"expected\": [\"x-1\"], \"passed\": true}, {\"check\": \"variant-vary-union fixture 5\", \"actual\": [\"accept-language\", \"accept-language\"], \"expected\": [\"accept-language\"], \"passed\": false}], \"passed\": false}\n"},"broken":{"elapsed_ms":39.475,"exit_code":1,"observations":[{"actual":["accept-encoding"],"check":"variant-vary-union fixture 0","expected":["accept-encoding","accept-language"],"passed":false},{"actual":["accept-encoding"],"check":"variant-vary-union fixture 1","expected":["accept-encoding"],"passed":true},{"actual":["accept-encoding"],"check":"variant-vary-union fixture 2","expected":["accept-encoding"],"passed":true},{"actual":[],"check":"variant-vary-union fixture 3","expected":[],"passed":true},{"actual":["x-1"],"check":"variant-vary-union fixture 4","expected":["x-1"],"passed":true},{"actual":["accept-language","accept-language"],"check":"variant-vary-union fixture 5","expected":["accept-language"],"passed":false}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"variant-vary-union fixture 0\", \"actual\": [\"accept-encoding\"], \"expected\": [\"accept-encoding\", \"accept-language\"], \"passed\": false}, {\"check\": \"variant-vary-union fixture 1\", \"actual\": [\"accept-encoding\"], \"expected\": [\"accept-encoding\"], \"passed\": true}, {\"check\": \"variant-vary-union fixture 2\", \"actual\": [\"accept-encoding\"], \"expected\": [\"accept-encoding\"], \"passed\": true}, {\"check\": \"variant-vary-union fixture 3\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"variant-vary-union fixture 4\", \"actual\": [\"x-1\"], \"expected\": [\"x-1\"], \"passed\": true}, {\"check\": \"variant-vary-union fixture 5\", \"actual\": [\"accept-language\", \"accept-language\"], \"expected\": [\"accept-language\"], \"passed\": false}], \"passed\": false}\n"},"fixed":{"elapsed_ms":38.014,"exit_code":0,"observations":[{"actual":["accept-encoding","accept-language"],"check":"variant-vary-union fixture 0","expected":["accept-encoding","accept-language"],"passed":true},{"actual":["accept-encoding"],"check":"variant-vary-union fixture 1","expected":["accept-encoding"],"passed":true},{"actual":["accept-encoding"],"check":"variant-vary-union fixture 2","expected":["accept-encoding"],"passed":true},{"actual":[],"check":"variant-vary-union fixture 3","expected":[],"passed":true},{"actual":["x-1"],"check":"variant-vary-union fixture 4","expected":["x-1"],"passed":true},{"actual":["accept-language"],"check":"variant-vary-union fixture 5","expected":["accept-language"],"passed":true}],"passed":true,"stderr":"","stdout":"{\"observations\": [{\"check\": \"variant-vary-union fixture 0\", \"actual\": [\"accept-encoding\", \"accept-language\"], \"expected\": [\"accept-encoding\", \"accept-language\"], \"passed\": true}, {\"check\": \"variant-vary-union fixture 1\", \"actual\": [\"accept-encoding\"], \"expected\": [\"accept-encoding\"], \"passed\": true}, {\"check\": \"variant-vary-union fixture 2\", \"actual\": [\"accept-encoding\"], \"expected\": [\"accept-encoding\"], \"passed\": true}, {\"check\": \"variant-vary-union fixture 3\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"variant-vary-union fixture 4\", \"actual\": [\"x-1\"], \"expected\": [\"x-1\"], \"passed\": true}, {\"check\": \"variant-vary-union fixture 5\", \"actual\": [\"accept-language\"], \"expected\": [\"accept-language\"], \"passed\": true}], \"passed\": true}\n"}},"verified":true,"visibility":"public"}