Alexandr Wang@alexandr_wang · Apr 8, 2026

1/ today we're releasing muse spark, the first model from MSL. nine months ago we rebuilt our ai stack from scratch.…

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Summary

Meta released Muse Spark, a new multimodal AI model that powers Meta AI with support for tool-use, visual reasoning, and multi-agent orchestration. The model includes Contemplating Mode for complex reasoning tasks and Shopping Mode for recommendations, with extensive safety evaluations completed before deployment.

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#1
1/ today we're releasing muse spark, the first model from MSL. nine months ago we rebuilt our ai stack from scratch. new infrastructure, new architecture, new data pipelines. muse spark is the result of that work, and now it powers meta ai. 🧵
#2
2/ muse spark is a natively multimodal reasoning model w/ support for tool-use, visual chain of thought, & multi-agent orchestration. it's the most powerful model that meta has released. through its training process, we saw predictable scaling across pretraining, RL, & test-time reasoning.
#3
3/ we’re also releasing contemplating mode, which orchestrates multiple agents that reason in parallel designed to handle complex scientific & reasoning queries. in our testing we found it competitive w/ other extreme reasoning models such as Gemini Deep Think & GPT Pro.
#4
4/ we conducted extensive safety evaluations before deployment, both before and after applying mitigations across frontier risk categories, behavioral alignment, and adversarial robustness. we found muse spark demonstrated strong refusal behavior across high-risk domains such as biological and chemical weapons.
#5
5/ meta ai now handles quick answers and deep reasoning with instant and thinking modes. shopping mode is new too—it picks up on the creators, brands, and styling content across our apps and turns that into recommendations.
#6
6/ muse spark powers a meta ai that sees and understands the world around you, pulls from real conversations across our apps, and reasons through complex questions in health, science, and math. built for the 3 billion people already using our apps every day.
#7
7/ this is step one. bigger models are already in development with infrastructure scaling to match. private api preview open to select partners today, with plans to open-source future versions. incredibly proud of the MSL team. excited for what’s to come!
#8
8/ read more about our research and muse spark here: ai.meta.com/blog/introduci…
#9
9/ this is MSL's first model and there are certainly rough edges we will polish over time in model behavior. regardless—we are excited for everyone to try it!