Mistral AI releases Leanstral 1.5 in June 2026; 119B-parameter model engineered for automated theorem proving with 256k context window at $0 cost

Leanstral 1.5 - Mistral AI

June 30, 2026v1.5An updated Lean 4 formal proof engineering model optimised for automated theorem proving and autoformalization. 119B total parameters, 6.5B active.SpeedPerformanceModalitiesContext256kPrice$0SpeedPerformanceModalitiesContext256kPrice$0FeaturesChat CompletionsFunction CallingAgents & ConversationsBuilt-In ToolsStructured OutputsPredicted OutputsPrefixOCRAnnotations - StructuredBBox ExtractionDocument QnAFIMEmbeddingsModerationsChat ModerationsTranscriptionsText to SpeechTimestamp...