AI agents need structured data, not similarity search. Graph DBs are expensive, vector stores are fuzzy.

Lithium is a storage engine on PostgreSQL ltree. Hierarchical, versioned, scoped queries. Two commands:

npx @lithium-ai/kit init

claude mcp add lithium -- npx @lithium-ai/kit serve

Your agents get tools to navigate, store, and retrieve structured data on your existing Postgres.

Open source, MIT.