Arena.ai (@arena) · 10/16/2026, 02:19:42
Meta Releases Muse Spark Open: An 816B MoE Model with 1M Context for Agentic Tasks
Meta has released Muse Spark Open, claiming it to be the most capable US open-weight model to date. Featuring an 816B total/42B active parameter MoE architecture, a 1M token context window, and native multimodality, it is optimized for long-horizon agentic tasks and complex software engineering, now available for testing on Arena.
SOURCE COVERAGEFull Original Report
Arena.ai (@arena) · 2026-10-15 18
Muse Spark Open by @AIatMeta is now in the Arena. Head to Agent Arena to test it out, scores coming soon!
In Agent Arena, we measure models on millions of real-world, long-horizon agentic tasks from a global community of users. Models can access web search, filesystem, and terminal tools to complete complex workflows. The leaderboard measures model performance on outcomes relative to the average model using a causal tracing methodology.
Muse Spark Open is also available in Code Arena: WebDev, Image-to-WebDev, Text, and Vision.
↳ 引用 @AIatMeta (AI at Meta): Today we’re releasing Muse Spark Open, the most capable US open-weight model to date.
Built for coding and agentic work, it excels at long-horizon tasks, complex software engineering, and multi-step reasoning.
Key Model Specs: → 816B total / 42B active parameters → 1M token context window → Natively multimodal across text, image, video, audio
