{"abstract":"A special separator token is predicted as ordinary content.","category":"Autoregressive target shifting","checks":6,"contract":"For tokens and sep, return adjacent pairs except any pair whose target equals sep.","contract_signature":"tokens, sep","evaluation_group":"w3-ars-special_token","failed_approach":"Filtering pairs by input token drops predictions after the separator as well.","family":"w3-autoregressive-target-shifting-paired-special-token","id":"FA-98331","implementations":{"attempt":{"sha256":"1c171e0b8d01e2638b866fce8eff6812d6201112be533e7367799016368c43a2","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(tokens, sep):\n    return [[tokens[i],tokens[i+1]] for i in range(len(tokens)-1) if tokens[i]!=sep]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('separator target skipped',solve([1,9,2],9),[[9,2]])\ncheck('ordinary pairs',solve([1,2,3],9),[[1,2],[2,3]])\ncheck('separator first',solve([9,2,3],9),[[9,2],[2,3]])\ncheck('terminal separator',solve([1,2,9],9),[[1,2]])\ncheck('singleton',solve([9],9),[])\ncheck('empty',solve([],9),[])\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":"784af3fb9b212df0a9517fc765e1d9a9e682e6d3f884200c0b1d0f3a0fdf0f7f","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(tokens, sep):\n    return [[tokens[i],tokens[i+1]] for i in range(len(tokens)-1)]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('separator target skipped',solve([1,9,2],9),[[9,2]])\ncheck('ordinary pairs',solve([1,2,3],9),[[1,2],[2,3]])\ncheck('separator first',solve([9,2,3],9),[[9,2],[2,3]])\ncheck('terminal separator',solve([1,2,9],9),[[1,2]])\ncheck('singleton',solve([9],9),[])\ncheck('empty',solve([],9),[])\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-paired-special-token","generated_at":"2026-09-30T16:48:11.933363+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":"A separator is included as a target despite the contract assigning it only as context boundary.","sha256":"61028dbbf2a6b691529a4b5a913c6d170d5f7becf18d1f7d8d39e4a21d429bd8","title":"A special separator token is predicted as ordinary content · case 01","variant":1,"variant_policy":"The same explicitly authored fixtures repeat across all five numbered records; runtime N is unused. These records share one mechanism and must remain together in evaluation splits.","verified":true,"visibility":"public","verification":{"attempt":{"elapsed_ms":28.838,"exit_code":1,"observations":[{"actual":[[1,9]],"check":"separator target skipped","expected":[[9,2]],"passed":false},{"actual":[[1,2],[2,3]],"check":"ordinary pairs","expected":[[1,2],[2,3]],"passed":true},{"actual":[[2,3]],"check":"separator first","expected":[[9,2],[2,3]],"passed":false},{"actual":[[1,2],[2,9]],"check":"terminal separator","expected":[[1,2]],"passed":false},{"actual":[],"check":"singleton","expected":[],"passed":true},{"actual":[],"check":"empty","expected":[],"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"separator target skipped\", \"actual\": [[1, 9]], \"expected\": [[9, 2]], \"passed\": false}, {\"check\": \"ordinary pairs\", \"actual\": [[1, 2], [2, 3]], \"expected\": [[1, 2], [2, 3]], \"passed\": true}, {\"check\": \"separator first\", \"actual\": [[2, 3]], \"expected\": [[9, 2], [2, 3]], \"passed\": false}, {\"check\": \"terminal separator\", \"actual\": [[1, 2], [2, 9]], \"expected\": [[1, 2]], \"passed\": false}, {\"check\": \"singleton\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"empty\", \"actual\": [], \"expected\": [], \"passed\": true}], \"passed\": false}\n"},"broken":{"elapsed_ms":28.219,"exit_code":1,"observations":[{"actual":[[1,9],[9,2]],"check":"separator target skipped","expected":[[9,2]],"passed":false},{"actual":[[1,2],[2,3]],"check":"ordinary pairs","expected":[[1,2],[2,3]],"passed":true},{"actual":[[9,2],[2,3]],"check":"separator first","expected":[[9,2],[2,3]],"passed":true},{"actual":[[1,2],[2,9]],"check":"terminal separator","expected":[[1,2]],"passed":false},{"actual":[],"check":"singleton","expected":[],"passed":true},{"actual":[],"check":"empty","expected":[],"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"separator target skipped\", \"actual\": [[1, 9], [9, 2]], \"expected\": [[9, 2]], \"passed\": false}, {\"check\": \"ordinary pairs\", \"actual\": [[1, 2], [2, 3]], \"expected\": [[1, 2], [2, 3]], \"passed\": true}, {\"check\": \"separator first\", \"actual\": [[9, 2], [2, 3]], \"expected\": [[9, 2], [2, 3]], \"passed\": true}, {\"check\": \"terminal separator\", \"actual\": [[1, 2], [2, 9]], \"expected\": [[1, 2]], \"passed\": false}, {\"check\": \"singleton\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"empty\", \"actual\": [], \"expected\": [], \"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."}}