AI Coding Live News

Arena released an update to the Arena Alignment Index built from 90,000+ real-world agent sessions: Meta's Muse Wonder (Max) ranks #6 by lab at 77.5% (2.09% unauthorized action rate, 14.41% deceptive completion rate), Reflection AI's open-weight Beam-1.0-501B-A23B debuts at #7 with 75.3% (4.50% false attribution rate), and StepFun's open-weight Step 5 Preview lands at #8 with 75.1% (2.11% unauthorized action rate).

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On 2026-10-15 StepFun released open weights for Step 5 Preview as promised: a 600B-total / 27B-active sparse MoE with up to 1M-token context and vision input, aimed at agentic software engineering and knowledge work. Checkpoints are on Hugging Face (FP8, BF16, NVFP4) and ModelScope. Official scores include StepCodeBench 49.0%, FrontierFinance 66.4%, and Artificial Analysis Intelligence Index 44. September coverage was API/index only; this is the first public weight drop.

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StepFun (@StepFun_ai) released Step Code v0.1.0 as MIT open source. The company says one CLI covers the full loop from reading and editing code to running tests and shipping, with fast execution, high token efficiency, and long-horizon reliability. Reported scores: about 80.9% on Terminal-Bench 2.1 and 73.3% on their 150-task Multi-Frame benchmark, plus one-command static publishing via StepPage. Repo: https://github.com/stepfun-ai/Step-Code

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@ArtificialAnlys evaluated StepFun Step 5 Preview (600B-total / 27B-active MoE): Artificial Analysis Intelligence Index 44, matching Kimi K3 (max) at about $0.72 per Index task (~2.8x cheaper). Pricing is about $1/$2.70 per 1M input/output tokens with $0.05/M cached input; 1M context; open weights planned for October 15. It still lags peers on agentic evals such as GDPval-AA and Terminal-Bench 4.0.

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