{"abstract":"A supplied target prefix is aligned one token late.","category":"Autoregressive target shifting","checks":6,"contract":"Given equal length context and target lists, return zipped pairs in order; excess elements are ignored.","contract_signature":"context, target","evaluation_group":"w3-ars-target_prefix","failed_approach":"Reusing the previous target index fixes the first pair only by clamping its missing predecessor to zero.","family":"w3-autoregressive-target-shifting-prefix-target-pairing","id":"FA-98291","implementations":{"attempt":{"sha256":"0365ef19ff7a5f06d109a64f097c83eeabdd97e415a996c72de235505ee70455","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(context, target):\n    return [[context[i],target[max(0,i-1)]] for i in range(min(len(context),len(target)))]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('aligned',solve([1,2,3],[4,5,6]),[[1,4],[2,5],[3,6]])\ncheck('unequal target',solve([1,2,3],[8,9]),[[1,8],[2,9]])\ncheck('empty target',solve([1],[]),[])\ncheck('empty context',solve([],[2]),[])\ncheck('singleton',solve([N],[N+1]),[[N,N+1]])\ncheck('distinct order',solve([7,8],[9,10]),[[7,9],[8,10]])\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":"a3285c977b84cc49c170ae619d3b9a76273312dfb7b58ec02e98c94037ad63b9","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(context, target):\n    return [[context[i],target[i+1]] for i in range(min(len(context),max(0,len(target)-1)))]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('aligned',solve([1,2,3],[4,5,6]),[[1,4],[2,5],[3,6]])\ncheck('unequal target',solve([1,2,3],[8,9]),[[1,8],[2,9]])\ncheck('empty target',solve([1],[]),[])\ncheck('empty context',solve([],[2]),[])\ncheck('singleton',solve([N],[N+1]),[[N,N+1]])\ncheck('distinct order',solve([7,8],[9,10]),[[7,9],[8,10]])\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-prefix-target-pairing","generated_at":"2026-09-30T16:48:11.500144+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":"Each input is paired with the next target slot, skipping the target at the same local position.","sha256":"92cc48948a9fda65a9cb3360e6e8219c01ee04297f0e69cef8f7e0e6b9eab98f","title":"A supplied target prefix is aligned one token late · 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":28.743,"exit_code":1,"observations":[{"actual":[[1,4],[2,4],[3,5]],"check":"aligned","expected":[[1,4],[2,5],[3,6]],"passed":false},{"actual":[[1,8],[2,8]],"check":"unequal target","expected":[[1,8],[2,9]],"passed":false},{"actual":[],"check":"empty target","expected":[],"passed":true},{"actual":[],"check":"empty context","expected":[],"passed":true},{"actual":[[1,2]],"check":"singleton","expected":[[1,2]],"passed":true},{"actual":[[7,9],[8,9]],"check":"distinct order","expected":[[7,9],[8,10]],"passed":false}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"aligned\", \"actual\": [[1, 4], [2, 4], [3, 5]], \"expected\": [[1, 4], [2, 5], [3, 6]], \"passed\": false}, {\"check\": \"unequal target\", \"actual\": [[1, 8], [2, 8]], \"expected\": [[1, 8], [2, 9]], \"passed\": false}, {\"check\": \"empty target\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"empty context\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"singleton\", \"actual\": [[1, 2]], \"expected\": [[1, 2]], \"passed\": true}, {\"check\": \"distinct order\", \"actual\": [[7, 9], [8, 9]], \"expected\": [[7, 9], [8, 10]], \"passed\": false}], \"passed\": false}\n"},"broken":{"elapsed_ms":28.021,"exit_code":1,"observations":[{"actual":[[1,5],[2,6]],"check":"aligned","expected":[[1,4],[2,5],[3,6]],"passed":false},{"actual":[[1,9]],"check":"unequal target","expected":[[1,8],[2,9]],"passed":false},{"actual":[],"check":"empty target","expected":[],"passed":true},{"actual":[],"check":"empty context","expected":[],"passed":true},{"actual":[],"check":"singleton","expected":[[1,2]],"passed":false},{"actual":[[7,10]],"check":"distinct order","expected":[[7,9],[8,10]],"passed":false}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"aligned\", \"actual\": [[1, 5], [2, 6]], \"expected\": [[1, 4], [2, 5], [3, 6]], \"passed\": false}, {\"check\": \"unequal target\", \"actual\": [[1, 9]], \"expected\": [[1, 8], [2, 9]], \"passed\": false}, {\"check\": \"empty target\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"empty context\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"singleton\", \"actual\": [], \"expected\": [[1, 2]], \"passed\": false}, {\"check\": \"distinct order\", \"actual\": [[7, 10]], \"expected\": [[7, 9], [8, 10]], \"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."}}