{"abstract":"An encoded partial response carries its own representation validator.","category":"HTTP ranges","checks":6,"contract":"tags contains identity and gzip strings; return the selected tag, with no truthiness fallback for an intentionally empty opaque value.","evaluation_group":"s3-http_ranges-representation","failed_approach":"The partial repair uses return tags[coding] or tags[\"identity\"], which still violates the stated contract.","family":"s3-http_ranges-variant-etag-selection","id":"FA-26401","implementations":{"attempt":{"sha256":"429a8b414bdc970ecb966ba8a2032bc62de1bb537e4a6591bf667acf73f3ea30","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(coding, tags):\n    return tags[coding] or tags[\"identity\"]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('variant-etag-selection fixture 0', solve(\"gzip\",{\"identity\":\"i\",\"gzip\":\"g\"+str(N)}), \"g\"+str(N))\ncheck('variant-etag-selection fixture 1', solve(\"gzip\",{\"identity\":\"i\",\"gzip\":\"\"}), \"\")\ncheck('variant-etag-selection fixture 2', solve(\"identity\",{\"identity\":\"i\",\"gzip\":\"g\"}), \"i\")\ncheck('variant-etag-selection fixture 3', solve(\"gzip\",{\"identity\":\"same\",\"gzip\":\"same\"}), \"same\")\ncheck('variant-etag-selection fixture 4', solve(\"identity\",{\"identity\":\"\",\"gzip\":\"g\"}), \"\")\ncheck('variant-etag-selection fixture 5', solve(\"gzip\",{\"identity\":\"a\",\"gzip\":\"b\"}), \"b\")\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":"5b2052ff59aab6464b32b9fc0ef43f1af22a1956ca8b9b68e44f9414b0750a12","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(coding, tags):\n    return tags[\"identity\"]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('variant-etag-selection fixture 0', solve(\"gzip\",{\"identity\":\"i\",\"gzip\":\"g\"+str(N)}), \"g\"+str(N))\ncheck('variant-etag-selection fixture 1', solve(\"gzip\",{\"identity\":\"i\",\"gzip\":\"\"}), \"\")\ncheck('variant-etag-selection fixture 2', solve(\"identity\",{\"identity\":\"i\",\"gzip\":\"g\"}), \"i\")\ncheck('variant-etag-selection fixture 3', solve(\"gzip\",{\"identity\":\"same\",\"gzip\":\"same\"}), \"same\")\ncheck('variant-etag-selection fixture 4', solve(\"identity\",{\"identity\":\"\",\"gzip\":\"g\"}), \"\")\ncheck('variant-etag-selection fixture 5', solve(\"gzip\",{\"identity\":\"a\",\"gzip\":\"b\"}), \"b\")\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":"14b6bbfcc278e4ba4659b48b7c38aeb3435ce986022e52902355a38c1931a385","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(coding, tags):\n    return tags[coding]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('variant-etag-selection fixture 0', solve(\"gzip\",{\"identity\":\"i\",\"gzip\":\"g\"+str(N)}), \"g\"+str(N))\ncheck('variant-etag-selection fixture 1', solve(\"gzip\",{\"identity\":\"i\",\"gzip\":\"\"}), \"\")\ncheck('variant-etag-selection fixture 2', solve(\"identity\",{\"identity\":\"i\",\"gzip\":\"g\"}), \"i\")\ncheck('variant-etag-selection fixture 3', solve(\"gzip\",{\"identity\":\"same\",\"gzip\":\"same\"}), \"same\")\ncheck('variant-etag-selection fixture 4', solve(\"identity\",{\"identity\":\"\",\"gzip\":\"g\"}), \"\")\ncheck('variant-etag-selection fixture 5', solve(\"gzip\",{\"identity\":\"a\",\"gzip\":\"b\"}), \"b\")\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-etag-selection","generated_at":"2026-09-29T14:41:15.680587+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 tags[coding]","root_cause":"The variant-etag-selection decision uses return tags[\"identity\"].","sha256":"29803c1ccd9f7cf67a20d59a6208c38ee1e90aac1c05df8f14c4cdcafb045f93","title":"An encoded partial response carries its own representation validator · case 01","variant":1,"variant_policy":"Five numbered records share a model and may reuse boundary fixtures.","verification":{"attempt":{"elapsed_ms":40.821,"exit_code":1,"observations":[{"actual":"g1","check":"variant-etag-selection fixture 0","expected":"g1","passed":true},{"actual":"i","check":"variant-etag-selection fixture 1","expected":"","passed":false},{"actual":"i","check":"variant-etag-selection fixture 2","expected":"i","passed":true},{"actual":"same","check":"variant-etag-selection fixture 3","expected":"same","passed":true},{"actual":"","check":"variant-etag-selection fixture 4","expected":"","passed":true},{"actual":"b","check":"variant-etag-selection fixture 5","expected":"b","passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"variant-etag-selection fixture 0\", \"actual\": \"g1\", \"expected\": \"g1\", \"passed\": true}, {\"check\": \"variant-etag-selection fixture 1\", \"actual\": \"i\", \"expected\": \"\", \"passed\": false}, {\"check\": \"variant-etag-selection fixture 2\", \"actual\": \"i\", \"expected\": \"i\", \"passed\": true}, {\"check\": \"variant-etag-selection fixture 3\", \"actual\": \"same\", \"expected\": \"same\", \"passed\": true}, {\"check\": \"variant-etag-selection fixture 4\", \"actual\": \"\", \"expected\": \"\", \"passed\": true}, {\"check\": \"variant-etag-selection fixture 5\", \"actual\": \"b\", \"expected\": \"b\", \"passed\": true}], \"passed\": false}\n"},"broken":{"elapsed_ms":38.829,"exit_code":1,"observations":[{"actual":"i","check":"variant-etag-selection fixture 0","expected":"g1","passed":false},{"actual":"i","check":"variant-etag-selection fixture 1","expected":"","passed":false},{"actual":"i","check":"variant-etag-selection fixture 2","expected":"i","passed":true},{"actual":"same","check":"variant-etag-selection fixture 3","expected":"same","passed":true},{"actual":"","check":"variant-etag-selection fixture 4","expected":"","passed":true},{"actual":"a","check":"variant-etag-selection fixture 5","expected":"b","passed":false}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"variant-etag-selection fixture 0\", \"actual\": \"i\", \"expected\": \"g1\", \"passed\": false}, {\"check\": \"variant-etag-selection fixture 1\", \"actual\": \"i\", \"expected\": \"\", \"passed\": false}, {\"check\": \"variant-etag-selection fixture 2\", \"actual\": \"i\", \"expected\": \"i\", \"passed\": true}, {\"check\": \"variant-etag-selection fixture 3\", \"actual\": \"same\", \"expected\": \"same\", \"passed\": true}, {\"check\": \"variant-etag-selection fixture 4\", \"actual\": \"\", \"expected\": \"\", \"passed\": true}, {\"check\": \"variant-etag-selection fixture 5\", \"actual\": \"a\", \"expected\": \"b\", \"passed\": false}], \"passed\": false}\n"},"fixed":{"elapsed_ms":38.13,"exit_code":0,"observations":[{"actual":"g1","check":"variant-etag-selection fixture 0","expected":"g1","passed":true},{"actual":"","check":"variant-etag-selection fixture 1","expected":"","passed":true},{"actual":"i","check":"variant-etag-selection fixture 2","expected":"i","passed":true},{"actual":"same","check":"variant-etag-selection fixture 3","expected":"same","passed":true},{"actual":"","check":"variant-etag-selection fixture 4","expected":"","passed":true},{"actual":"b","check":"variant-etag-selection fixture 5","expected":"b","passed":true}],"passed":true,"stderr":"","stdout":"{\"observations\": [{\"check\": \"variant-etag-selection fixture 0\", \"actual\": \"g1\", \"expected\": \"g1\", \"passed\": true}, {\"check\": \"variant-etag-selection fixture 1\", \"actual\": \"\", \"expected\": \"\", \"passed\": true}, {\"check\": \"variant-etag-selection fixture 2\", \"actual\": \"i\", \"expected\": \"i\", \"passed\": true}, {\"check\": \"variant-etag-selection fixture 3\", \"actual\": \"same\", \"expected\": \"same\", \"passed\": true}, {\"check\": \"variant-etag-selection fixture 4\", \"actual\": \"\", \"expected\": \"\", \"passed\": true}, {\"check\": \"variant-etag-selection fixture 5\", \"actual\": \"b\", \"expected\": \"b\", \"passed\": true}], \"passed\": true}\n"}},"verified":true,"visibility":"public"}