Course 2: Building with MIFY — Chapter 4

Chapter 4: Creating a Plugin

Extend MIFY with your own custom nodes and publish them to the marketplace.

What You’ll Learn

• How to scaffold a plugin project
• How to implement a custom node
• How to test and publish

Step 1: Initialize

npx mify-plugin init my-weather-node
cd my-weather-node

Creates:

my-weather-node/
├── manifest.json      # Plugin metadata
├── src/
│   └── nodes/
│       └── WeatherNode.ts  # Your custom node
├── tests/
└── package.json

Step 2: Define Your Manifest

{
  "name": "my-weather-node",
  "version": "1.0.0",
  "description": "Fetches weather data for any city",
  "mifyVersion": ">=1.0.0",
  "extensionPoints": {
    "nodes": ["src/nodes/WeatherNode.ts"]
  },
  "permissions": ["network"],
  "runtime": "v8"
}

Step 3: Implement Your Node

export class WeatherNode implements NodeImplementation {
  static definition = {
    type: "weather.current",
    name: "Current Weather",
    category: "io",
    description: "Get current weather for a city",
    inputs: { city: { type: "string", required: true } },
    outputs: { temperature: { type: "number" }, condition: { type: "string" } },
  };

  async execute(input: { city: string }) {
    const response = await fetch(
      `https://api.weatherapi.com/v1/current.json?q=${input.city}`
    );
    const data = await response.json();
    return {
      temperature: data.current.temp_c,
      condition: data.current.condition.text,
    };
  }
}

Step 4: Test

npx mify-plugin dev    # Hot reload dev server
npx mify-plugin test   # Run unit tests
npx mify-plugin validate  # Check manifest

Step 5: Publish

npx mify-plugin publish

Your plugin appears in the Plugin Marketplace at /plugins/marketplace.

Exercise

1. Initialize a plugin project
2. Implement a node that takes text input and returns a word count
3. Test it with npx mify-plugin dev
4. Use it in a workflow on the canvas

Previous: Chapter 3 — Content Generation | Next: Chapter 5 — Advanced Patterns