medusa-plugins

Medusa v2 Plugin Development

Before writing code

Fetch live docs:

1. Fetch https://docs.medusajs.com/learn/fundamentals/plugins for plugin overview
2. Web-search site:docs.medusajs.com plugin vs module for comparison
3. Web-search site:docs.medusajs.com create medusa plugin for plugin scaffolding
4. Web-search site:docs.medusajs.com plugin options configuration for plugin options pattern
5. Web-search site:docs.medusajs.com publish plugin npm for packaging and distribution

Plugin vs Module

| Aspect | Module | Plugin | |--------|--------|--------| | Scope | Single concern (data + service) | Full feature (modules + routes + workflows + admin) | | Location | src/modules/ in project | Separate npm package | | Distribution | Not distributable | Published to npm | | Configuration | Registered in modules array | Registered in plugins array | | Contains | Models, service, loaders | Modules, API routes, workflows, subscribers, admin, links | | Use case | Project-specific domain | Reusable across projects |

A plugin is essentially a packaged Medusa project that can contain all the same src/ directories.

Plugin Directory Structure

| Directory | Contents | |-----------|----------| | src/modules/ | Custom modules (models, services) | | src/workflows/ | Workflow definitions | | src/api/store/, src/api/admin/ | API routes + middlewares.ts | | src/subscribers/ | Event subscribers | | src/admin/widgets/, src/admin/routes/ | Admin UI extensions | | src/links/ | Module link definitions | | Root | package.json, tsconfig.json, README.md |

A plugin mirrors the standard Medusa src/ directory structure — all conventions apply.

Plugin Definition

The plugin's package.json must include specific fields:

package.json Key Fields

| Field | Value | Purpose | |-------|-------|---------| | name | medusa-plugin-my-feature | npm package name | | main | ./dist/index.js | Compiled entry point | | types | ./dist/index.d.ts | TypeScript declarations | | files | ["dist", "!dist/**/*.map"] | Included in npm package | | keywords | ["medusa-plugin"] | Discoverability | | peerDependencies | @medusajs/framework | Medusa version compatibility |

Plugin Entry Point

// src/index.ts
// Fetch live docs for plugin export shape
// Plugin entry exports nothing directly --
// Medusa discovers modules, routes, etc. by convention
export default {}

Plugin Options

Plugins receive configuration options from the consuming project:

Consuming a Plugin

// In consuming project's medusa-config.ts plugins array
// Fetch live docs for plugin registration options
{
  resolve: "medusa-plugin-my-feature",
  options: { apiKey: process.env.MY_FEATURE_API_KEY },
}

Accessing Options in Plugin Code

// In a plugin loader or service
// Fetch live docs for accessing plugin options from container
// Options are injected via the module/plugin options mechanism

Build and Compilation

| Step | Command | Purpose | |------|---------|---------| | Build | tsc or tsup | Compile TypeScript to dist/ | | Watch | tsc --watch | Development rebuild on changes | | Clean | rm -rf dist | Remove compiled output | | Pack | npm pack | Create tarball for testing |

Local Development with npm link

| Step | Command | Context | |------|---------|---------| | 1. Build plugin | npm run build | In plugin directory | | 2. Create link | npm link | In plugin directory | | 3. Link in project | npm link medusa-plugin-my-feature | In Medusa project | | 4. Register | Add to plugins in medusa-config.ts | In Medusa project | | 5. Migrate | npx medusa db:migrate | In Medusa project |

Plugin Testing

| Approach | Description | |----------|-------------| | Unit tests | Test services, workflow steps in isolation | | Integration tests | Use medusa-test-utils to spin up a test Medusa instance | | Local linking | Link plugin into a real Medusa project and test manually | | CI pipeline | Build + unit tests on every push |

Publishing to npm

Pre-publish Checklist

| Check | Why | |-------|-----| | Build succeeds | Consumers need compiled JS | | files in package.json | Only ship dist/, not src/ | | peerDependencies set | Avoid version conflicts | | README with install instructions | Developer experience | | .npmignore or files field | Exclude tests, config, etc. | | License field set | Legal clarity | | Version follows semver | Compatibility signals |

Publishing Commands

npm version patch   # or minor / major
npm publish --access public
# Fetch live docs for Medusa plugin registry conventions

Naming Conventions

| Convention | Example | |-----------|---------| | npm package name | medusa-plugin-my-feature | | Module key inside plugin | my-feature | | API route prefix | /store/my-feature, /admin/my-feature | | Admin widget files | src/admin/widgets/my-feature-widget.tsx |

Best Practices

• Follow the medusa-plugin-* naming convention for npm discoverability
• Keep peerDependencies on @medusajs/framework and @medusajs/medusa -- do not bundle them
• Ship only compiled output (dist/) -- never ship src/ or test files
• Include TypeScript declarations for consuming projects to get type safety
• Document all plugin options in your README with required vs optional markers
• Test with npm link against a real Medusa project before publishing
• Use semantic versioning -- breaking changes to options or models require a major bump

Fetch the Medusa plugin documentation for exact project structure, build configuration, and publishing requirements before implementing.