Leanstral: Open-Source foundation for trustworthy vibe-coding | Mistral AI

What this post added

Introduces Leanstral, an open-source code agent specifically for Lean 4. Details its sparse architecture (6B active parameters), evaluation methodology using the FLTEval suite, and comparative performance against other coding agents and open-source models. Provides case studies demonstrating its ability to answer Stack Exchange questions about Lean 4 changes and translate/reason about programs from Rocq. Highlights its availability through Mistral Vibe, a free API, and as downloadable weights.