{"abstract":"Rejection location is reported as a one-based position.","category":"Speculative decoding bookkeeping","checks":7,"contract":"Return the zero-based index of the first differing token, or the number of compared tokens when all compared pairs match.","contract_signature":"draft, verified","evaluation_group":"spec-rejection-index","failed_approach":"Returning None for complete agreement loses the useful append position.","family":"w3-speculative-decoding-bookkeeping-rejection-index","id":"FA-100646","implementations":{"attempt":{"sha256":"44484e93e4f378cd326f692f3038fb97c307329df28c4b2e5cb2d21f13ff9a24","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(draft, verified):\n    return next((i for i,(a,b) in enumerate(zip(draft,verified)) if a!=b), None)\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('first index', solve([8],[7]),0)\ncheck('later index', solve([1,2,3],[1,2,9]),2)\ncheck('all equal', solve([1,2],[1,2]),2)\ncheck('empty lists', solve([],[]),0)\ncheck('verified ends', solve([1,2],[1]),1)\ncheck('draft ends', solve([1],[1,2]),1)\ncheck('singleton equal', solve([N],[N]),1)\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":"45ac75ed0da5e207326cafc664508518e4bf4dea7bb47b1b06ab953f18a9764b","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(draft, verified):\n    return next((i+1 for i,(a,b) in enumerate(zip(draft,verified)) if a!=b), min(len(draft),len(verified)))\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('first index', solve([8],[7]),0)\ncheck('later index', solve([1,2,3],[1,2,9]),2)\ncheck('all equal', solve([1,2],[1,2]),2)\ncheck('empty lists', solve([],[]),0)\ncheck('verified ends', solve([1,2],[1]),1)\ncheck('draft ends', solve([1],[1,2]),1)\ncheck('singleton equal', solve([N],[N]),1)\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 finite toy sequences with explicit contracts; they make no claim about production decoder behavior or model quality. 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-speculative-decoding-bookkeeping-rejection-index","generated_at":"2026-09-30T16:48:38.099146+00:00","license":"CC0-1.0","python":"3.12.14","seed":1,"split":"open-access"},"relevance":"A self-contained bookkeeping model makes prefix and token-count semantics observable without a model runtime.","root_cause":"The first differing index is converted to a one-based position.","sha256":"09c49f0b85214f51bc2f012b25ead0d4a6b43e89b840b0fcfbf32e7ea01891d0","title":"Decoding: Rejection location is reported as a one-based 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":30.886,"exit_code":1,"observations":[{"actual":0,"check":"first index","expected":0,"passed":true},{"actual":2,"check":"later index","expected":2,"passed":true},{"actual":null,"check":"all equal","expected":2,"passed":false},{"actual":null,"check":"empty lists","expected":0,"passed":false},{"actual":null,"check":"verified ends","expected":1,"passed":false},{"actual":null,"check":"draft ends","expected":1,"passed":false},{"actual":null,"check":"singleton equal","expected":1,"passed":false}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"first index\", \"actual\": 0, \"expected\": 0, \"passed\": true}, {\"check\": \"later index\", \"actual\": 2, \"expected\": 2, \"passed\": true}, {\"check\": \"all equal\", \"actual\": null, \"expected\": 2, \"passed\": false}, {\"check\": \"empty lists\", \"actual\": null, \"expected\": 0, \"passed\": false}, {\"check\": \"verified ends\", \"actual\": null, \"expected\": 1, \"passed\": false}, {\"check\": \"draft ends\", \"actual\": null, \"expected\": 1, \"passed\": false}, {\"check\": \"singleton equal\", \"actual\": null, \"expected\": 1, \"passed\": false}], \"passed\": false}\n"},"broken":{"elapsed_ms":28.104,"exit_code":1,"observations":[{"actual":1,"check":"first index","expected":0,"passed":false},{"actual":3,"check":"later index","expected":2,"passed":false},{"actual":2,"check":"all equal","expected":2,"passed":true},{"actual":0,"check":"empty lists","expected":0,"passed":true},{"actual":1,"check":"verified ends","expected":1,"passed":true},{"actual":1,"check":"draft ends","expected":1,"passed":true},{"actual":1,"check":"singleton equal","expected":1,"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"first index\", \"actual\": 1, \"expected\": 0, \"passed\": false}, {\"check\": \"later index\", \"actual\": 3, \"expected\": 2, \"passed\": false}, {\"check\": \"all equal\", \"actual\": 2, \"expected\": 2, \"passed\": true}, {\"check\": \"empty lists\", \"actual\": 0, \"expected\": 0, \"passed\": true}, {\"check\": \"verified ends\", \"actual\": 1, \"expected\": 1, \"passed\": true}, {\"check\": \"draft ends\", \"actual\": 1, \"expected\": 1, \"passed\": true}, {\"check\": \"singleton equal\", \"actual\": 1, \"expected\": 1, \"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."}}