Harvey built an $11 billion legal-software business on top of other companies’ AI models. Now it’s trying to prove it can build one of its own.

On Tuesday, Harvey introduced Harvey Tenet, its first in-house, proprietary model for legal work. Tenet is designed to help Harvey’s software take on more of the tasks typically done by lawyers over hours or days, at a lower cost than the third-party models it relies on.

The move comes as the companies behind the biggest general-purpose models are circling the legal market. Anthropic has been chasing lawyers with plugins for document review and drafting, while OpenAI has hired Ironclad founder Jason…