AI / Full Stack
Open Brain (OB1)
Self-hosted knowledge system with pgvector semantic search and an MCP server.
DenoHonoPostgreSQL + pgvectorMCPNext.jsOpenAI embeddings
Problem
No unified, self-hosted, semantically searchable store for thoughts, contacts, and work that also handles dedup and secret-safety.
What I built
A production knowledge system: pgvector + embeddings (1536-dim, HNSW) for sub-100ms retrieval, an MCP server exposing ~12 REST and 12 MCP tools, five ingestion sources with automatic metadata extraction and dedup, and a dashboard for timeline, stats, contacts, and job pipeline.
Engineering highlights
Cosine similarity over HNSW; SHA256 content-hash dedup with upsert returning duplicate/orphan status; LLM-powered metadata extraction; a multi-table schema with expression indexes; regex secret detection to block credential storage; a dual REST + MCP API on Hono.