Mistral · coding line · open weights
The newest Devstral & Leanstral model is Leanstral 1.5, released on June 30, 2026. Mistral officially discontinued the line on September 30, 2026.
How long it has been since the last release against the line's usual gap and its recent ones — the rhythm, not a date.
Latest: Leanstral 1.5 · Jun 30, 2026
Every Monday, only when something shipped: the AI models that came out, what each one changed, and which lines are due next.
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Newest first — what each version changed versus the one before, in Mistral's own numbers.
Apache 2.0 model for Lean 4 proof engineering with 119B parameters and 6B active, solving 587 of 672 PutnamBench problems.
An open-weight (Apache 2.0) code agent for the Lean 4 proof assistant that generates code and formally proves implementations against specifications.