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Overview

The sunpeak dev command starts a local development server with a built-in ChatGPT simulator, allowing you to develop and test your MCP Resources without connecting to ChatGPT. 
sunpeak dev

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Features

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Hot Module Reload (HMR)

The dev server uses Vite’s hot reload technology for instant feedback:
  • Component changes reflect immediately without full page refresh
  • State is preserved across updates when possible
  • CSS updates apply instantly

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ChatGPT Simulator

Access the simulator at http://localhost:6767 to:
  • Test your MCP Resources in a ChatGPT-like environment
  • Simulate tool calls and responses
  • Preview your UI components with realistic styling
  • Iterate quickly without needing a tunnel or ChatGPT connection

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Automatic Discovery

The dev server automatically discovers and loads:
  • All simulations exported from src/simulations/index.ts
  • All MCP Resources from src/resources/*-resource.tsx
No manual configuration or entry point files needed!

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Configuration

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Port

Default port: 6767 To use a different port, modify your package.json script: 
{
  "scripts": {
    "dev": "sunpeak dev --port 3000"
  }
}

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Host

To expose the server on your network: 
{
  "scripts": {
    "dev": "sunpeak dev --host"
  }
}

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Usage

sunpeak dev

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When to Use

Use sunpeak dev for:
  • Local component development
  • Rapid iteration with hot reload
  • Testing UI behavior in the ChatGPT simulator
  • Debugging without ChatGPT integration
The dev server is for development only. For production, use sunpeak build to create optimized bundles.

sunpeak build

Build production bundles

sunpeak mcp

Test with real ChatGPT