The Policy Belongs in the Prompt

Mistral's Shieldstral is a 3B open-weights multimodal safety classifier that accepts plain-language policy descriptions at inference time, framing each moderation call as binary QA against whatever policy you provide — no retraining needed when policies change. It matches or outperforms guard models up to 7× its size and ships under Apache 2.0.

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miniF2F Hits the Ceiling

Mistral's Leanstral 1.5 scores 100% on miniF2F and solves 587 of 672 Putnam Competition problems using a 6B-active-parameter MoE. The model saturates the main formal-proof benchmark and finds real bugs in production code — at roughly $4 per Putnam problem versus competitors charging $300.

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