{"abstract":"Second expert is omitted from a top-two token dispatch.","category":"Mixture of experts dispatch","checks":6,"contract":"Return up to two (expert,weight) routes sorted by descending weight then expert ID.","contract_signature":"routes","evaluation_group":"moe-top-two","failed_approach":"Taking the first two input routes can omit the runner-up after score reordering.","family":"w3-mixture-of-experts-dispatch-top2-combine","id":"FA-100571","implementations":{"attempt":{"sha256":"52d11140bdf93ca6183a0e028ba7998c820d22f7c0dc41ef8985a1660d6ce013","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(routes):\n    return routes[:2]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\nrows=[('z',N),('a',N+1),('b',N-1)]\ncheck('ranked pair',solve(rows),[('a',N+1),('z',N)])\ncheck('two only',solve(rows[:2]),[('a',N+1),('z',N)])\ncheck('singleton',solve([('q',N)]),[('q',N)])\ncheck('empty',solve([]),[])\ncheck('tie order',solve([('z',N),('a',N)]),[('a',N),('z',N)])\ncheck('negative',solve([('x',-N),('y',-N-1)]),[('x',-N),('y',-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":"8dccbf84fdbe08d60287addfe3ca9e92b135710311cd195192b079312aaf4a5e","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(routes):\n    return sorted(routes,key=lambda x:(-x[1],x[0]))[:1]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\nrows=[('z',N),('a',N+1),('b',N-1)]\ncheck('ranked pair',solve(rows),[('a',N+1),('z',N)])\ncheck('two only',solve(rows[:2]),[('a',N+1),('z',N)])\ncheck('singleton',solve([('q',N)]),[('q',N)])\ncheck('empty',solve([]),[])\ncheck('tie order',solve([('z',N),('a',N)]),[('a',N),('z',N)])\ncheck('negative',solve([('x',-N),('y',-N-1)]),[('x',-N),('y',-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":"Inputs are finite toy scores and routes; the contract does not model a production model, accelerator, or learned routing 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-mixture-of-experts-dispatch-top2-combine","generated_at":"2026-09-30T16:48:37.194377+00:00","license":"CC0-1.0","python":"3.12.14","seed":1,"split":"open-access"},"relevance":"A deterministic toy router makes this dispatch decision independently inspectable.","root_cause":"Only the winning route is retained even when the contract requests two experts.","sha256":"4a06c52398507822036e2131079cf7a793667ff1143ca73f08e6c0c1f901d740","title":"Second expert is omitted from a top-two token dispatch · 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":33.793,"exit_code":1,"observations":[{"actual":[["z",1],["a",2]],"check":"ranked pair","expected":[["a",2],["z",1]],"passed":false},{"actual":[["z",1],["a",2]],"check":"two only","expected":[["a",2],["z",1]],"passed":false},{"actual":[["q",1]],"check":"singleton","expected":[["q",1]],"passed":true},{"actual":[],"check":"empty","expected":[],"passed":true},{"actual":[["z",1],["a",1]],"check":"tie order","expected":[["a",1],["z",1]],"passed":false},{"actual":[["x",-1],["y",-2]],"check":"negative","expected":[["x",-1],["y",-2]],"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"ranked pair\", \"actual\": [[\"z\", 1], [\"a\", 2]], \"expected\": [[\"a\", 2], [\"z\", 1]], \"passed\": false}, {\"check\": \"two only\", \"actual\": [[\"z\", 1], [\"a\", 2]], \"expected\": [[\"a\", 2], [\"z\", 1]], \"passed\": false}, {\"check\": \"singleton\", \"actual\": [[\"q\", 1]], \"expected\": [[\"q\", 1]], \"passed\": true}, {\"check\": \"empty\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"tie order\", \"actual\": [[\"z\", 1], [\"a\", 1]], \"expected\": [[\"a\", 1], [\"z\", 1]], \"passed\": false}, {\"check\": \"negative\", \"actual\": [[\"x\", -1], [\"y\", -2]], \"expected\": [[\"x\", -1], [\"y\", -2]], \"passed\": true}], \"passed\": false}\n"},"broken":{"elapsed_ms":30.245,"exit_code":1,"observations":[{"actual":[["a",2]],"check":"ranked pair","expected":[["a",2],["z",1]],"passed":false},{"actual":[["a",2]],"check":"two only","expected":[["a",2],["z",1]],"passed":false},{"actual":[["q",1]],"check":"singleton","expected":[["q",1]],"passed":true},{"actual":[],"check":"empty","expected":[],"passed":true},{"actual":[["a",1]],"check":"tie order","expected":[["a",1],["z",1]],"passed":false},{"actual":[["x",-1]],"check":"negative","expected":[["x",-1],["y",-2]],"passed":false}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"ranked pair\", \"actual\": [[\"a\", 2]], \"expected\": [[\"a\", 2], [\"z\", 1]], \"passed\": false}, {\"check\": \"two only\", \"actual\": [[\"a\", 2]], \"expected\": [[\"a\", 2], [\"z\", 1]], \"passed\": false}, {\"check\": \"singleton\", \"actual\": [[\"q\", 1]], \"expected\": [[\"q\", 1]], \"passed\": true}, {\"check\": \"empty\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"tie order\", \"actual\": [[\"a\", 1]], \"expected\": [[\"a\", 1], [\"z\", 1]], \"passed\": false}, {\"check\": \"negative\", \"actual\": [[\"x\", -1]], \"expected\": [[\"x\", -1], [\"y\", -2]], \"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."}}