{"abstract":"Continuation flags mislabel chunk boundaries.","category":"Sequence batch packing","checks":6,"contract":"Split into width-sized chunks and pair each with [continues_from_previous, continues_after], both booleans. Width is positive.","contract_signature":"tokens, width","evaluation_group":"w3-seqpack-continuation-v1","failed_approach":"Clearing the previous flag repairs the first chunk but still marks the final chunk as continuing afterward.","family":"w3-sequence-batch-packing-continuation-chunk-markers","id":"FA-98116","implementations":{"attempt":{"sha256":"8c1bcf3711348ea37c908799c150f4e7b4e225f3aa5b617dc996ebd1b9d8117a","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(tokens, width):\n    chunks=[tokens[i:i+width] for i in range(0,len(tokens),width)]\n    return [[c,[False,True]] for i,c in enumerate(chunks)]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ndata=list(range(N+1))\ncheck('tail markers', solve(data,N), [[data[:N],[False,True]],[data[N:],[True,False]]])\ncheck('single chunk', solve([N],N), [[[N],[False,False]]])\ncheck('empty', solve([],N), [])\ncheck('exact two chunks', solve(list(range(2*N)),N), [[list(range(N)),[False,True]],[list(range(N,2*N)),[True,False]]])\ncheck('width larger', solve([1],N+1), [[[1],[False,False]]])\ncheck('unit chunks', solve([4,5],1), [[[4],[False,True]],[[5],[True,False]]])\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":"269157ebfb3351fce07c5643a2044e8d4924071e7c030aa76e997676eaa148f6","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(tokens, width):\n    chunks=[tokens[i:i+width] for i in range(0,len(tokens),width)]\n    return [[c,[i>0,True]] for i,c in enumerate(chunks)]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ndata=list(range(N+1))\ncheck('tail markers', solve(data,N), [[data[:N],[False,True]],[data[N:],[True,False]]])\ncheck('single chunk', solve([N],N), [[[N],[False,False]]])\ncheck('empty', solve([],N), [])\ncheck('exact two chunks', solve(list(range(2*N)),N), [[list(range(N)),[False,True]],[list(range(N,2*N)),[True,False]]])\ncheck('width larger', solve([1],N+1), [[[1],[False,False]]])\ncheck('unit chunks', solve([4,5],1), [[[4],[False,True]],[[5],[True,False]]])\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 short integer-token lists under the stated toy contract; results do not claim compatibility with a specific training framework. 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-sequence-batch-packing-continuation-chunk-markers","generated_at":"2026-09-30T16:48:09.322766+00:00","license":"CC0-1.0","python":"3.12.14","seed":1,"split":"open-access"},"relevance":"This deterministic toy packing rule models a common boundary in preparing bounded training sequences.","root_cause":"The first chunk is marked as having a predecessor and every chunk is marked as continuing afterward.","sha256":"b8d52fa722eba691cb5a44e8381692b5dca57878645c728de91598a384a623e4","title":"Continuation flags mislabel chunk boundaries · 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":25.691,"exit_code":1,"observations":[{"actual":[[[0],[false,true]],[[1],[false,true]]],"check":"tail markers","expected":[[[0],[false,true]],[[1],[true,false]]],"passed":false},{"actual":[[[1],[false,true]]],"check":"single chunk","expected":[[[1],[false,false]]],"passed":false},{"actual":[],"check":"empty","expected":[],"passed":true},{"actual":[[[0],[false,true]],[[1],[false,true]]],"check":"exact two chunks","expected":[[[0],[false,true]],[[1],[true,false]]],"passed":false},{"actual":[[[1],[false,true]]],"check":"width larger","expected":[[[1],[false,false]]],"passed":false},{"actual":[[[4],[false,true]],[[5],[false,true]]],"check":"unit chunks","expected":[[[4],[false,true]],[[5],[true,false]]],"passed":false}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"tail markers\", \"actual\": [[[0], [false, true]], [[1], [false, true]]], \"expected\": [[[0], [false, true]], [[1], [true, false]]], \"passed\": false}, {\"check\": \"single chunk\", \"actual\": [[[1], [false, true]]], \"expected\": [[[1], [false, false]]], \"passed\": false}, {\"check\": \"empty\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"exact two chunks\", \"actual\": [[[0], [false, true]], [[1], [false, true]]], \"expected\": [[[0], [false, true]], [[1], [true, false]]], \"passed\": false}, {\"check\": \"width larger\", \"actual\": [[[1], [false, true]]], \"expected\": [[[1], [false, false]]], \"passed\": false}, {\"check\": \"unit chunks\", \"actual\": [[[4], [false, true]], [[5], [false, true]]], \"expected\": [[[4], [false, true]], [[5], [true, false]]], \"passed\": false}], \"passed\": false}\n"},"broken":{"elapsed_ms":26.767,"exit_code":1,"observations":[{"actual":[[[0],[false,true]],[[1],[true,true]]],"check":"tail markers","expected":[[[0],[false,true]],[[1],[true,false]]],"passed":false},{"actual":[[[1],[false,true]]],"check":"single chunk","expected":[[[1],[false,false]]],"passed":false},{"actual":[],"check":"empty","expected":[],"passed":true},{"actual":[[[0],[false,true]],[[1],[true,true]]],"check":"exact two chunks","expected":[[[0],[false,true]],[[1],[true,false]]],"passed":false},{"actual":[[[1],[false,true]]],"check":"width larger","expected":[[[1],[false,false]]],"passed":false},{"actual":[[[4],[false,true]],[[5],[true,true]]],"check":"unit chunks","expected":[[[4],[false,true]],[[5],[true,false]]],"passed":false}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"tail markers\", \"actual\": [[[0], [false, true]], [[1], [true, true]]], \"expected\": [[[0], [false, true]], [[1], [true, false]]], \"passed\": false}, {\"check\": \"single chunk\", \"actual\": [[[1], [false, true]]], \"expected\": [[[1], [false, false]]], \"passed\": false}, {\"check\": \"empty\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"exact two chunks\", \"actual\": [[[0], [false, true]], [[1], [true, true]]], \"expected\": [[[0], [false, true]], [[1], [true, false]]], \"passed\": false}, {\"check\": \"width larger\", \"actual\": [[[1], [false, true]]], \"expected\": [[[1], [false, false]]], \"passed\": false}, {\"check\": \"unit chunks\", \"actual\": [[[4], [false, true]], [[5], [true, true]]], \"expected\": [[[4], [false, true]], [[5], [true, false]]], \"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."}}