Initial project scaffold: Open Brain self-hosted knowledge infrastructure

Node.js/TypeScript server with MCP endpoint for AI assistant integration,
Discord bot for thought capture and slash commands, PostgreSQL + pgvector
for semantic search, and OpenRouter for embeddings/metadata extraction.
Dockerized for deployment behind Caddy.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

sql/schema.sql

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+CREATE EXTENSION IF NOT EXISTS vector;
+
+CREATE TABLE IF NOT EXISTS thoughts (
+  id UUID DEFAULT gen_random_uuid() PRIMARY KEY,
+  user_id TEXT NOT NULL DEFAULT 'default',
+  content TEXT NOT NULL,
+  embedding VECTOR(1536),
+  metadata JSONB DEFAULT '{}'::jsonb,
+  source TEXT NOT NULL DEFAULT 'mcp',
+  created_at TIMESTAMPTZ DEFAULT now(),
+  updated_at TIMESTAMPTZ DEFAULT now()
+);
+
+CREATE INDEX IF NOT EXISTS thoughts_embedding_idx ON thoughts USING hnsw (embedding vector_cosine_ops);
+CREATE INDEX IF NOT EXISTS thoughts_metadata_idx ON thoughts USING gin (metadata);
+CREATE INDEX IF NOT EXISTS thoughts_created_at_idx ON thoughts (created_at DESC);
+CREATE INDEX IF NOT EXISTS thoughts_user_id_idx ON thoughts (user_id);
+
+-- Auto-update trigger for updated_at
+CREATE OR REPLACE FUNCTION update_updated_at() RETURNS TRIGGER AS $$
+BEGIN
+  NEW.updated_at = now();
+  RETURN NEW;
+END;
+$$ LANGUAGE plpgsql;
+
+DROP TRIGGER IF EXISTS thoughts_updated_at ON thoughts;
+CREATE TRIGGER thoughts_updated_at
+  BEFORE UPDATE ON thoughts
+  FOR EACH ROW EXECUTE FUNCTION update_updated_at();
+
+-- Semantic search function
+CREATE OR REPLACE FUNCTION match_thoughts(
+  query_embedding VECTOR(1536),
+  match_threshold FLOAT DEFAULT 0.7,
+  match_count INT DEFAULT 10,
+  filter JSONB DEFAULT '{}'::jsonb
+) RETURNS TABLE (
+  id UUID,
+  content TEXT,
+  metadata JSONB,
+  similarity FLOAT,
+  created_at TIMESTAMPTZ
+) LANGUAGE plpgsql AS $$
+BEGIN
+  RETURN QUERY
+  SELECT
+    t.id,
+    t.content,
+    t.metadata,
+    (1 - (t.embedding <=> query_embedding))::FLOAT AS similarity,
+    t.created_at
+  FROM thoughts t
+  WHERE 1 - (t.embedding <=> query_embedding) > match_threshold
+  ORDER BY t.embedding <=> query_embedding
+  LIMIT match_count;
+END;
+$$;