{"abstract":"Global tokens are incorrectly limited by local window.","category":"Attention mask construction","checks":6,"contract":"Causal local window W; any listed global key <= query is visible at any distance.","contract_signature":"length, window, global_keys","evaluation_group":"causal_global_key_v1","failed_approach":"Shrinking the local window by one underfills ordinary rows even after global keys are admitted.","family":"w3-attention-mask-construction-global-token-window","id":"FA-98196","implementations":{"attempt":{"sha256":"c6fe4cd3455e3dbf49bbcee32f8fd09fb4655c28451d73110b5ff39c729b487d","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(length, window, global_keys):\n    return [[j<=i and (j in global_keys or 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})\ng=[0]\ncheck('old global key',solve(N+2,2,g),[[j<=i and (j in g or (2>0 and i-j<2)) for j in range(N+2)] for i in range(N+2)])\ncheck('no globals',solve(3,2,[]),[[j<=i and i-j<2 for j in range(3)] for i in range(3)])\ncheck('global future still hidden',solve(3,1,[2])[0],[True,False,False])\ncheck('zero window global only',solve(3,0,[0]),[[j==0 and j<=i for j in range(3)] for i in range(3)])\ncheck('empty sequence',solve(0,2,[]),[])\ncheck('global old key at last row',solve(4,1,[0])[3],[True,False,False,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":"adbb996f0389cad51c6f1e84bb969458c95b49dd0d04f254afdbda11ff892481","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(length, window, global_keys):\n    return [[window>0 and 0<=i-j<window 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})\ng=[0]\ncheck('old global key',solve(N+2,2,g),[[j<=i and (j in g or (2>0 and i-j<2)) for j in range(N+2)] for i in range(N+2)])\ncheck('no globals',solve(3,2,[]),[[j<=i and i-j<2 for j in range(3)] for i in range(3)])\ncheck('global future still hidden',solve(3,1,[2])[0],[True,False,False])\ncheck('zero window global only',solve(3,0,[0]),[[j==0 and j<=i for j in range(3)] for i in range(3)])\ncheck('empty sequence',solve(0,2,[]),[])\ncheck('global old key at last row',solve(4,1,[0])[3],[True,False,False,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-global-token-window","generated_at":"2026-09-30T16:48:10.194056+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":"A uniform sliding window ignores explicitly global key positions.","sha256":"cbc6ac208fd92a8f907aab6c209228744d91757e7090cff858baf31c824f2d08","title":"Global tokens are incorrectly limited by local window · 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":27.665,"exit_code":1,"observations":[{"actual":[[true,false,false],[true,true,false],[true,false,true]],"check":"old global key","expected":[[true,false,false],[true,true,false],[true,true,true]],"passed":false},{"actual":[[true,false,false],[false,true,false],[false,false,true]],"check":"no globals","expected":[[true,false,false],[true,true,false],[false,true,true]],"passed":false},{"actual":[false,false,false],"check":"global future still hidden","expected":[true,false,false],"passed":false},{"actual":[[true,false,false],[true,false,false],[true,false,false]],"check":"zero window global only","expected":[[true,false,false],[true,false,false],[true,false,false]],"passed":true},{"actual":[],"check":"empty sequence","expected":[],"passed":true},{"actual":[true,false,false,false],"check":"global old key at last row","expected":[true,false,false,true],"passed":false}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"old global key\", \"actual\": [[true, false, false], [true, true, false], [true, false, true]], \"expected\": [[true, false, false], [true, true, false], [true, true, true]], \"passed\": false}, {\"check\": \"no globals\", \"actual\": [[true, false, false], [false, true, false], [false, false, true]], \"expected\": [[true, false, false], [true, true, false], [false, true, true]], \"passed\": false}, {\"check\": \"global future still hidden\", \"actual\": [false, false, false], \"expected\": [true, false, false], \"passed\": false}, {\"check\": \"zero window global only\", \"actual\": [[true, false, false], [true, false, false], [true, false, false]], \"expected\": [[true, false, false], [true, false, false], [true, false, false]], \"passed\": true}, {\"check\": \"empty sequence\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"global old key at last row\", \"actual\": [true, false, false, false], \"expected\": [true, false, false, true], \"passed\": false}], \"passed\": false}\n"},"broken":{"elapsed_ms":26.839,"exit_code":1,"observations":[{"actual":[[true,false,false],[true,true,false],[false,true,true]],"check":"old global key","expected":[[true,false,false],[true,true,false],[true,true,true]],"passed":false},{"actual":[[true,false,false],[true,true,false],[false,true,true]],"check":"no globals","expected":[[true,false,false],[true,true,false],[false,true,true]],"passed":true},{"actual":[true,false,false],"check":"global future still hidden","expected":[true,false,false],"passed":true},{"actual":[[false,false,false],[false,false,false],[false,false,false]],"check":"zero window global only","expected":[[true,false,false],[true,false,false],[true,false,false]],"passed":false},{"actual":[],"check":"empty sequence","expected":[],"passed":true},{"actual":[false,false,false,true],"check":"global old key at last row","expected":[true,false,false,true],"passed":false}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"old global key\", \"actual\": [[true, false, false], [true, true, false], [false, true, true]], \"expected\": [[true, false, false], [true, true, false], [true, true, true]], \"passed\": false}, {\"check\": \"no globals\", \"actual\": [[true, false, false], [true, true, false], [false, true, true]], \"expected\": [[true, false, false], [true, true, false], [false, true, true]], \"passed\": true}, {\"check\": \"global future still hidden\", \"actual\": [true, false, false], \"expected\": [true, false, false], \"passed\": true}, {\"check\": \"zero window global only\", \"actual\": [[false, false, false], [false, false, false], [false, false, false]], \"expected\": [[true, false, false], [true, false, false], [true, false, false]], \"passed\": false}, {\"check\": \"empty sequence\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"global old key at last row\", \"actual\": [false, false, false, true], \"expected\": [true, false, false, 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."}}