Leanstral 1.5 (labs-leanstral-1-5) Lean 4 proof engineering model
UpdateVerifiedAdded Sep 22, 2026
Leanstral 1.5 is an updated Lean 4 formal proof engineering model with improved SFT mixture quality and extended long-context reasoning. The model will be retired on September 30, 2026.
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More Mistral AI Studio and API releases
Every Mistral AI Studio and API release| Date | Release | Type |
|---|---|---|
| Jul 2 | Leanstral 1.5: Proof Abundance for All Update | Update |
| Jun 24 | Bringing more control over your connectors Update | Update |
| Jul 8 | Introducing Robostral Navigate Update | Update |
| Jul 9 | Your Prompts and Skills need a system of record Update | Update |
| Jul 16 | Mistral OCR 4.1 (mistral-ocr-4-1) released Update | Update |
| Jul 16 | OCR API confidence_scores_granularity adds block granularity Update | Update |
| Aug 4 | Introducing Shieldstral Update | Update |
| Aug 11 | In-region inference, open models, and new European infrastructure for sovereign AI Update | Update |
