{"abstract":"Sliding window omits the oldest key within its span.","category":"Attention mask construction","checks":6,"contract":"Return square causal visibility with window W counting the current position; W<=0 yields no visible keys.","contract_signature":"length, window","evaluation_group":"causal_sliding_window_v1","failed_approach":"Using i-window as the inclusive lower bound admits one extra older key.","family":"w3-attention-mask-construction-causal-window","id":"FA-98156","implementations":{"attempt":{"sha256":"5fee6f8d96fe86deed7e8dcc2b5123fc869fd7f741b675c7b93cef68a8cb81fe","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(length, window):\n    return [[max(0,i-window)<=j<=i for j in range(length)] for i in range(length)]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('window edge',solve(N+2,N),[[N>0 and max(0,i-N+1)<=j<=i for j in range(N+2)] for i in range(N+2)])\ncheck('window one',solve(3,1),[[True,False,False],[False,True,False],[False,False,True]])\ncheck('window zero',solve(3,0),[[False]*3 for _ in range(3)])\ncheck('window exceeds length',solve(2,5),[[True,False],[True,True]])\ncheck('empty',solve(0,2),[])\ncheck('last query',solve(4,2)[3],[False,False,True,True])\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":"6c32f1f69c1ab08ee7a6807f1d175bbec8644421402688f68e260d4a44373578","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(length, window):\n    return [[0<=i-j<window-1 for j in range(length)] for i in range(length)]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('window edge',solve(N+2,N),[[N>0 and max(0,i-N+1)<=j<=i for j in range(N+2)] for i in range(N+2)])\ncheck('window one',solve(3,1),[[True,False,False],[False,True,False],[False,False,True]])\ncheck('window zero',solve(3,0),[[False]*3 for _ in range(3)])\ncheck('window exceeds length',solve(2,5),[[True,False],[True,True]])\ncheck('empty',solve(0,2),[])\ncheck('last query',solve(4,2)[3],[False,False,True,True])\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":"These are toy Boolean matrix contracts; they do not define a production model architecture or tensor library behavior. 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":"w3-attention-mask-construction-causal-window","generated_at":"2026-09-30T16:48:09.758468+00:00","license":"CC0-1.0","python":"3.12.14","seed":1,"split":"open-access"},"relevance":"A small explicit visibility matrix makes sequence-attention boundary behavior reviewable.","root_cause":"The lower bound is shifted one position too far.","sha256":"ca2f49020e6e87c5bd7ac409bda38e050c69b88777a107a522e4b975b817cc8c","title":"Sliding window omits the oldest key within its span · case 01","variant":1,"variant_policy":"The fixture code references N, supplied as 1 through 5. Fixed boundary checks may repeat. These records share one mechanism and must remain together in evaluation splits.","verified":true,"visibility":"public","verification":{"attempt":{"elapsed_ms":27.939,"exit_code":1,"observations":[{"actual":[[true,false,false],[true,true,false],[false,true,true]],"check":"window edge","expected":[[true,false,false],[false,true,false],[false,false,true]],"passed":false},{"actual":[[true,false,false],[true,true,false],[false,true,true]],"check":"window one","expected":[[true,false,false],[false,true,false],[false,false,true]],"passed":false},{"actual":[[true,false,false],[false,true,false],[false,false,true]],"check":"window zero","expected":[[false,false,false],[false,false,false],[false,false,false]],"passed":false},{"actual":[[true,false],[true,true]],"check":"window exceeds length","expected":[[true,false],[true,true]],"passed":true},{"actual":[],"check":"empty","expected":[],"passed":true},{"actual":[false,true,true,true],"check":"last query","expected":[false,false,true,true],"passed":false}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"window edge\", \"actual\": [[true, false, false], [true, true, false], [false, true, true]], \"expected\": [[true, false, false], [false, true, false], [false, false, true]], \"passed\": false}, {\"check\": \"window one\", \"actual\": [[true, false, false], [true, true, false], [false, true, true]], \"expected\": [[true, false, false], [false, true, false], [false, false, true]], \"passed\": false}, {\"check\": \"window zero\", \"actual\": [[true, false, false], [false, true, false], [false, false, true]], \"expected\": [[false, false, false], [false, false, false], [false, false, false]], \"passed\": false}, {\"check\": \"window exceeds length\", \"actual\": [[true, false], [true, true]], \"expected\": [[true, false], [true, true]], \"passed\": true}, {\"check\": \"empty\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"last query\", \"actual\": [false, true, true, true], \"expected\": [false, false, true, true], \"passed\": false}], \"passed\": false}\n"},"broken":{"elapsed_ms":25.746,"exit_code":1,"observations":[{"actual":[[false,false,false],[false,false,false],[false,false,false]],"check":"window edge","expected":[[true,false,false],[false,true,false],[false,false,true]],"passed":false},{"actual":[[false,false,false],[false,false,false],[false,false,false]],"check":"window one","expected":[[true,false,false],[false,true,false],[false,false,true]],"passed":false},{"actual":[[false,false,false],[false,false,false],[false,false,false]],"check":"window zero","expected":[[false,false,false],[false,false,false],[false,false,false]],"passed":true},{"actual":[[true,false],[true,true]],"check":"window exceeds length","expected":[[true,false],[true,true]],"passed":true},{"actual":[],"check":"empty","expected":[],"passed":true},{"actual":[false,false,false,true],"check":"last query","expected":[false,false,true,true],"passed":false}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"window edge\", \"actual\": [[false, false, false], [false, false, false], [false, false, false]], \"expected\": [[true, false, false], [false, true, false], [false, false, true]], \"passed\": false}, {\"check\": \"window one\", \"actual\": [[false, false, false], [false, false, false], [false, false, false]], \"expected\": [[true, false, false], [false, true, false], [false, false, true]], \"passed\": false}, {\"check\": \"window zero\", \"actual\": [[false, false, false], [false, false, false], [false, false, false]], \"expected\": [[false, false, false], [false, false, false], [false, false, false]], \"passed\": true}, {\"check\": \"window exceeds length\", \"actual\": [[true, false], [true, true]], \"expected\": [[true, false], [true, true]], \"passed\": true}, {\"check\": \"empty\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"last query\", \"actual\": [false, false, false, true], \"expected\": [false, false, true, true], \"passed\": false}], \"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."}}