@atelier/patterns

A local MCP server that gives LLMs access to a hierarchical pattern database. Patterns are organized into domains > categories > patterns, and LLMs can discover, match, and suggest new patterns through three simple tools.

This project is intended for local use only and is not production-ready. Auth is session-based and in-memory, there's no rate limiting, and the SQLite database lives on disk alongside the code. Treat it as a personal development tool.

Quick Start

npm install

As an MCP server (stdio)

The most common way to use this. Clone the repository and then add it to your MCP client config (e.g. Claude Code, Claude Desktop):

{
  "mcpServers": {
    "patterns": {
      "command": "npx",
      "args": ["tsx", "path/to/src/stdio.ts"]
    }
  }
}

Or run directly:

npm run start:stdio

With the web UI (HTTP)

Starts both the MCP endpoint and a management web app:

ADMIN_SECRET=your-secret npm run start:http

• Web UI: http://127.0.0.1:3001
• MCP endpoint: http://127.0.0.1:3001/mcp

Set PORT to change the default port.

MCP Tools

Tool	Description
discover	Given a domain, returns its available categories
match	Given a domain + categories, returns matching patterns with templates
suggest	Submit a new pattern suggestion with source tracking

How It Works

Patterns are stored in a local SQLite database (patterns.db). Each pattern has a label, description, intention (what the user wants), and a template (structured prompt).

The typical flow:

1. LLM calls discover with a domain (e.g. "software-engineering")
2. Server returns the domain's categories
3. LLM calls match with relevant categories
4. Server returns patterns with templates the LLM can apply

The web UI provides full CRUD for managing domains, categories, and patterns, plus a review workflow for community-submitted suggestions.

Development

npm run build          # compile TypeScript
npm test               # run tests
npm run test:watch     # run tests in watch mode

Tech Stack

TypeScript, MCP SDK, Express 5, better-sqlite3, Zod, Vitest