{"abstract":"Stencil increment wraps a saturated 255 value back to zero.","category":"Rendering state","checks":4,"contract":"Increment a stencil byte using the saturating increment operation, distinct from increment-and-wrap.","evaluation_group":"xg-stencil-increment-saturates","failed_approach":"A ceiling of 254 excludes the valid maximal stencil value.","family":"xg-stencil-increment-saturates","id":"FA-10701","implementations":{"attempt":{"sha256":"6fa26c07c855310b356c0bb25a63633561654d29e02f44a8afcdf7525bc96a52","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\nimport math\nN = 1\nobservations = []\ndef solve(value):\n    return min(254,value+1)\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('fixture 1', solve(*(255,)), 255)\ncheck('fixture 2', solve(*(254,)), 255)\ncheck('fixture 3', solve(*(0,)), 1)\ncheck('fixture 4', solve(*(100,)), 101)\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":"1e9b3351dbf59c3ab9ce5e078284664dcf73c2ca4f614eb8bef2e8ff52d93778","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\nimport math\nN = 1\nobservations = []\ndef solve(value):\n    return (value+1)&255\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('fixture 1', solve(*(255,)), 255)\ncheck('fixture 2', solve(*(254,)), 255)\ncheck('fixture 3', solve(*(0,)), 1)\ncheck('fixture 4', solve(*(100,)), 101)\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":"d94141c64a494572cadd34d35ef490b41e891fe8f90b2cf1007c2a6e8848cb49","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\nimport math\nN = 1\nobservations = []\ndef solve(value):\n    return min(255,value+1)\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('fixture 1', solve(*(255,)), 255)\ncheck('fixture 2', solve(*(254,)), 255)\ncheck('fixture 3', solve(*(0,)), 1)\ncheck('fixture 4', solve(*(100,)), 101)\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":" 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":"xg-stencil-increment-saturates","generated_at":"2026-09-29T14:38:41.357607+00:00","license":"CC0-1.0","python":"3.12.14","seed":1,"split":"open-access"},"relevance":"A deterministic software graphics stage with explicit channel and coordinate conventions; no hardware, device profile or API behavior is inferred.","repair":"Use the stage contract: Increment a stencil byte using the saturating increment operation, distinct from increment-and-wrap.","root_cause":"Stencil increment wraps a saturated 255 value back to zero.","sha256":"dfb68e86ae478826b9c9064ff896b474faa7908425e8f1fc9c5b4799169d0697","title":"Stencil increment saturates · case 01","variant":1,"variant_policy":"Five numbered records share a model and may reuse boundary fixtures.","verification":{"attempt":{"elapsed_ms":51.69,"exit_code":1,"observations":[{"actual":254,"check":"fixture 1","expected":255,"passed":false},{"actual":254,"check":"fixture 2","expected":255,"passed":false},{"actual":1,"check":"fixture 3","expected":1,"passed":true},{"actual":101,"check":"fixture 4","expected":101,"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"fixture 1\", \"actual\": 254, \"expected\": 255, \"passed\": false}, {\"check\": \"fixture 2\", \"actual\": 254, \"expected\": 255, \"passed\": false}, {\"check\": \"fixture 3\", \"actual\": 1, \"expected\": 1, \"passed\": true}, {\"check\": \"fixture 4\", \"actual\": 101, \"expected\": 101, \"passed\": true}], \"passed\": false}\n"},"broken":{"elapsed_ms":43.134,"exit_code":1,"observations":[{"actual":0,"check":"fixture 1","expected":255,"passed":false},{"actual":255,"check":"fixture 2","expected":255,"passed":true},{"actual":1,"check":"fixture 3","expected":1,"passed":true},{"actual":101,"check":"fixture 4","expected":101,"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"fixture 1\", \"actual\": 0, \"expected\": 255, \"passed\": false}, {\"check\": \"fixture 2\", \"actual\": 255, \"expected\": 255, \"passed\": true}, {\"check\": \"fixture 3\", \"actual\": 1, \"expected\": 1, \"passed\": true}, {\"check\": \"fixture 4\", \"actual\": 101, \"expected\": 101, \"passed\": true}], \"passed\": false}\n"},"fixed":{"elapsed_ms":40.531,"exit_code":0,"observations":[{"actual":255,"check":"fixture 1","expected":255,"passed":true},{"actual":255,"check":"fixture 2","expected":255,"passed":true},{"actual":1,"check":"fixture 3","expected":1,"passed":true},{"actual":101,"check":"fixture 4","expected":101,"passed":true}],"passed":true,"stderr":"","stdout":"{\"observations\": [{\"check\": \"fixture 1\", \"actual\": 255, \"expected\": 255, \"passed\": true}, {\"check\": \"fixture 2\", \"actual\": 255, \"expected\": 255, \"passed\": true}, {\"check\": \"fixture 3\", \"actual\": 1, \"expected\": 1, \"passed\": true}, {\"check\": \"fixture 4\", \"actual\": 101, \"expected\": 101, \"passed\": true}], \"passed\": true}\n"}},"verified":true,"visibility":"public"}