{"abstract":"A late position fix pulls the present estimate backwards along the trajectory.","category":"Sensor fusion consistency","checks":6,"contract":"Constant known velocity model: x is current position, age nonnegative delay, z delayed position measurement. Return current position after a half-gain historical update and replay, as a fraction string.","contract_signature":"x, velocity, age, z","evaluation_group":"model-ead9cff33aae7961","failed_approach":"Updating at acquisition time without replay returns an estimate at the wrong epoch.","family":"z-sensor_fusion-delayed-state-update","id":"FA-12081","implementations":{"attempt":{"sha256":"37650692af86a23a34ede70fb5c399653eefe318df7ee327e48d41440464a53f","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\nfrom fractions import Fraction\nN = 1\nobservations = []\ndef solve(x, velocity, age, z):\n    return str(Fraction(x-velocity*age+z,2))\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('consistent delayed fix', solve(10*N,N,2,8*N), str(10*N))\ncheck('delayed correction', solve(10*N,N,2,6*N), str(9*N))\ncheck('no delay', solve(10*N,N,0,8*N), str(9*N))\ncheck('stationary target', solve(10*N,0,2,8*N), str(9*N))\ncheck('reverse trajectory', solve(10*N,-N,2,12*N), str(10*N))\ncheck('fractional update', solve(N,1,1,0), str(Fraction(N+1,2)))\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":"82273291edc729e252916e92997f928e892c5a17fea28d8d563135ce95cef2f3","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\nfrom fractions import Fraction\nN = 1\nobservations = []\ndef solve(x, velocity, age, z):\n    return str(Fraction(x+z,2))\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('consistent delayed fix', solve(10*N,N,2,8*N), str(10*N))\ncheck('delayed correction', solve(10*N,N,2,6*N), str(9*N))\ncheck('no delay', solve(10*N,N,0,8*N), str(9*N))\ncheck('stationary target', solve(10*N,0,2,8*N), str(9*N))\ncheck('reverse trajectory', solve(10*N,-N,2,12*N), str(10*N))\ncheck('fractional update', solve(N,1,1,0), str(Fraction(N+1,2)))\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":"Exact small scalar or two-axis models; no nonlinear dynamics, numerical conditioning, or real sensor noise simulation. 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":"z-sensor_fusion-delayed-state-update","generated_at":"2026-09-29T14:38:53.676236+00:00","license":"CC0-1.0","python":"3.12.14","seed":1,"split":"open-access"},"relevance":"Deterministic sensor-fusion model isolating one consistency contract; no hardware or production estimator is simulated.","root_cause":"Residual uses current position for an older acquisition timestamp.","sha256":"ae5a551750dc52fcd48059a46eb5ccf8002e06fb876fa78d8e7b8ce5aa27a173","title":"Delayed measurement is applied at the current state epoch · case 01","variant":1,"variant_policy":"Five numbered records share a model and may reuse boundary fixtures.","verified":true,"visibility":"public","verification":{"attempt":{"elapsed_ms":43.828,"exit_code":1,"observations":[{"actual":"8","check":"consistent delayed fix","expected":"10","passed":false},{"actual":"7","check":"delayed correction","expected":"9","passed":false},{"actual":"9","check":"no delay","expected":"9","passed":true},{"actual":"9","check":"stationary target","expected":"9","passed":true},{"actual":"12","check":"reverse trajectory","expected":"10","passed":false},{"actual":"0","check":"fractional update","expected":"1","passed":false}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"consistent delayed fix\", \"actual\": \"8\", \"expected\": \"10\", \"passed\": false}, {\"check\": \"delayed correction\", \"actual\": \"7\", \"expected\": \"9\", \"passed\": false}, {\"check\": \"no delay\", \"actual\": \"9\", \"expected\": \"9\", \"passed\": true}, {\"check\": \"stationary target\", \"actual\": \"9\", \"expected\": \"9\", \"passed\": true}, {\"check\": \"reverse trajectory\", \"actual\": \"12\", \"expected\": \"10\", \"passed\": false}, {\"check\": \"fractional update\", \"actual\": \"0\", \"expected\": \"1\", \"passed\": false}], \"passed\": false}\n"},"broken":{"elapsed_ms":41.584,"exit_code":1,"observations":[{"actual":"9","check":"consistent delayed fix","expected":"10","passed":false},{"actual":"8","check":"delayed correction","expected":"9","passed":false},{"actual":"9","check":"no delay","expected":"9","passed":true},{"actual":"9","check":"stationary target","expected":"9","passed":true},{"actual":"11","check":"reverse trajectory","expected":"10","passed":false},{"actual":"1/2","check":"fractional update","expected":"1","passed":false}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"consistent delayed fix\", \"actual\": \"9\", \"expected\": \"10\", \"passed\": false}, {\"check\": \"delayed correction\", \"actual\": \"8\", \"expected\": \"9\", \"passed\": false}, {\"check\": \"no delay\", \"actual\": \"9\", \"expected\": \"9\", \"passed\": true}, {\"check\": \"stationary target\", \"actual\": \"9\", \"expected\": \"9\", \"passed\": true}, {\"check\": \"reverse trajectory\", \"actual\": \"11\", \"expected\": \"10\", \"passed\": false}, {\"check\": \"fractional update\", \"actual\": \"1/2\", \"expected\": \"1\", \"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."}}