{"abstract":"Ignored target labels mask the following position.","category":"Autoregressive target shifting","checks":6,"contract":"For labels, return one boolean per adjacent target position: true iff that target is not ignore; pair count is len(labels)-1.","contract_signature":"labels, ignore","evaluation_group":"w3-ars-loss_mask","failed_approach":"Starting target-label iteration at index one omits the first shifted target position.","family":"w3-autoregressive-target-shifting-ignore-label-mask-shift","id":"FA-98271","implementations":{"attempt":{"sha256":"8dc4d31652ddebd62dc0a76057cc1de940343a75d548e381f4b941605523a219","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(labels, ignore):\n    return [labels[i+1]!=ignore for i in range(1,len(labels)-1)]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('ignored middle target',solve([1,-1,3,4],-1),[False,True,True])\ncheck('first label ignored',solve([-1,2,3],-1),[True,True])\ncheck('last ignored',solve([1,2,-1],-1),[True,False])\ncheck('singleton',solve([-1],-1),[])\ncheck('empty',solve([],-1),[])\ncheck('all valid',solve([N,N+1,N+2],-1),[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":"48f60bc293c85c9ef89dd0301b42065b1c2839eda2b6a545e251942d9760be91","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(labels, ignore):\n    return [x!=ignore for x in labels[:-1]]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('ignored middle target',solve([1,-1,3,4],-1),[False,True,True])\ncheck('first label ignored',solve([-1,2,3],-1),[True,True])\ncheck('last ignored',solve([1,2,-1],-1),[True,False])\ncheck('singleton',solve([-1],-1),[])\ncheck('empty',solve([],-1),[])\ncheck('all valid',solve([N,N+1,N+2],-1),[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":"Inputs are toy integer token sequences; this contract says nothing about model quality, batching, sampling, or production training frameworks. 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-autoregressive-target-shifting-ignore-label-mask-shift","generated_at":"2026-09-30T16:48:11.054394+00:00","license":"CC0-1.0","python":"3.12.14","seed":1,"split":"open-access"},"relevance":"A small deterministic token-stream contract makes next-token alignment errors inspectable.","root_cause":"The ignore mask is shifted with inputs instead of being derived from target labels.","sha256":"d59f8fed9e490e8ab6d58af941e5a63a5c463cf2e7462e48123cbf4ff6b84046","title":"Ignored target labels mask the following position · 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":26.962,"exit_code":1,"observations":[{"actual":[true,true],"check":"ignored middle target","expected":[false,true,true],"passed":false},{"actual":[true],"check":"first label ignored","expected":[true,true],"passed":false},{"actual":[false],"check":"last ignored","expected":[true,false],"passed":false},{"actual":[],"check":"singleton","expected":[],"passed":true},{"actual":[],"check":"empty","expected":[],"passed":true},{"actual":[true],"check":"all valid","expected":[true,true],"passed":false}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"ignored middle target\", \"actual\": [true, true], \"expected\": [false, true, true], \"passed\": false}, {\"check\": \"first label ignored\", \"actual\": [true], \"expected\": [true, true], \"passed\": false}, {\"check\": \"last ignored\", \"actual\": [false], \"expected\": [true, false], \"passed\": false}, {\"check\": \"singleton\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"empty\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"all valid\", \"actual\": [true], \"expected\": [true, true], \"passed\": false}], \"passed\": false}\n"},"broken":{"elapsed_ms":25.348,"exit_code":1,"observations":[{"actual":[true,false,true],"check":"ignored middle target","expected":[false,true,true],"passed":false},{"actual":[false,true],"check":"first label ignored","expected":[true,true],"passed":false},{"actual":[true,true],"check":"last ignored","expected":[true,false],"passed":false},{"actual":[],"check":"singleton","expected":[],"passed":true},{"actual":[],"check":"empty","expected":[],"passed":true},{"actual":[true,true],"check":"all valid","expected":[true,true],"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"ignored middle target\", \"actual\": [true, false, true], \"expected\": [false, true, true], \"passed\": false}, {\"check\": \"first label ignored\", \"actual\": [false, true], \"expected\": [true, true], \"passed\": false}, {\"check\": \"last ignored\", \"actual\": [true, true], \"expected\": [true, false], \"passed\": false}, {\"check\": \"singleton\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"empty\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"all valid\", \"actual\": [true, true], \"expected\": [true, true], \"passed\": true}], \"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."}}