Cairn

A self-hosted memory platform that runs as four Docker containers: MCP server, web UI, PostgreSQL with pgvector, and Neo4j for knowledge graphs. Exposes 16 MCP tools including store, search, recall for persistent memory across sessions, plus beliefs for tracking epistemic state, work_items for task management, and code_query for structural analysis of 30 languages via tree-sitter. Memory search fuses vector similarity, recency, keyword matching, and tags through Reciprocal Rank Fusion. Includes bi-temporal tracking to separate event time from creation time, automatic memory consolidation, and optional auto-enrichment via local LLMs or hosted APIs. Auth off by default but supports JWT and OIDC when needed. Built for people who need memory that works across projects and sessions without reinventing it per runtime.