LEDMatrix/docs/PLUGIN_QUICK_REFERENCE.md

LEDMatrix Plugin Architecture - Quick Reference

Overview

LEDMatrix is a modular, plugin-based system where users create, share, and install custom displays via a GitHub-based store (similar in spirit to HACS for Home Assistant). This page is a quick reference; for the full design see PLUGIN_ARCHITECTURE_SPEC.md and PLUGIN_DEVELOPMENT_GUIDE.md.

Key Decisions

✅ Plugin-First: All display features (calendar excepted) are now plugins ✅ GitHub Store: Discovery from ledmatrix-plugins registry plus any GitHub URL ✅ Plugin Location: configured by plugin_system.plugins_directory in config.json (default plugin-repos/). Plugin discovery scans only this directory — there is no loader fallback to plugins/ (only Plugin Store operations and schema lookup additionally probe plugins/)

File Structure

LEDMatrix/
├── src/
│   └── plugin_system/
│       ├── base_plugin.py          # Plugin interface
│       ├── plugin_manager.py       # Load/unload plugins
│       ├── plugin_loader.py        # Discovery + dynamic import
│       └── store_manager.py        # Install from GitHub
├── plugin-repos/                   # Default plugin install location
│   ├── clock-simple/
│   │   ├── manifest.json           # Metadata
│   │   ├── manager.py              # Main plugin class
│   │   ├── requirements.txt        # Dependencies
│   │   ├── config_schema.json      # Validation
│   │   └── README.md
│   └── hockey-scoreboard/
│       └── ... (same structure)
└── config/config.json               # Plugin configs

Creating a Plugin

1. Minimal Plugin Structure

manifest.json:

{
  "id": "my-plugin",
  "name": "My Display",
  "version": "1.0.0",
  "author": "YourName",
  "entry_point": "manager.py",
  "class_name": "MyPlugin",
  "category": "custom"
}

manager.py:

from src.plugin_system.base_plugin import BasePlugin

class MyPlugin(BasePlugin):
    def update(self):
        # Fetch data
        pass
    
    def display(self, force_clear=False):
        # Render to display
        self.display_manager.draw_text("Hello!", x=5, y=15)
        self.display_manager.update_display()

2. Configuration

config_schema.json:

{
  "type": "object",
  "properties": {
    "enabled": {"type": "boolean", "default": true},
    "message": {"type": "string", "default": "Hello"}
  }
}

User's config.json:

{
  "my-plugin": {
    "enabled": true,
    "message": "Custom text",
    "display_duration": 15
  }
}

3. Publishing

Official plugins live in the ledmatrix-plugins monorepo: add plugins/<your-plugin-id>/, bump version in its manifest.json on every change, run python update_registry.py there and open a pull request. A third-party plugin can stay in its own repository and be installed by URL. Git tags and releases are not read by the store; see PLUGIN_REGISTRY_SETUP_GUIDE.md.

Using Plugins

Web UI

1. Browse Store: Plugin Manager tab → Plugin Store section → Search/filter
2. Install: Click Install in the plugin's row
3. Configure: open the plugin's tab in the second nav row
4. Enable/Disable: toggle switch in the Installed Plugins list
5. Reorder: use the drag-and-drop Rotation Order list in the Rotation tab (saved to display.plugin_rotation_order)

REST API

The API is mounted at /api/v3 (the api_v3 blueprint in web_interface/blueprints/api_v3/, registered in web_interface/app.py).

# Install plugin from the registry
curl -X POST http://your-pi-ip:5000/api/v3/plugins/install \
  -H "Content-Type: application/json" \
  -d '{"plugin_id": "hockey-scoreboard"}'

# Install from custom URL
curl -X POST http://your-pi-ip:5000/api/v3/plugins/install-from-url \
  -H "Content-Type: application/json" \
  -d '{"repo_url": "https://github.com/User/plugin"}'

# List installed
curl http://your-pi-ip:5000/api/v3/plugins/installed

# Toggle
curl -X POST http://your-pi-ip:5000/api/v3/plugins/toggle \
  -H "Content-Type: application/json" \
  -d '{"plugin_id": "hockey-scoreboard", "enabled": true}'

See REST_API_REFERENCE.md for the full list.

Plugin Registry Structure

The official registry lives at ChuckBuilds/ledmatrix-plugins. The Plugin Store reads plugins.json at the root of that repo, which follows this shape:

{
  "plugins": [
    {
      "id": "clock-simple",
      "name": "Simple Clock",
      "author": "ChuckBuilds",
      "category": "time",
      "repo": "https://github.com/ChuckBuilds/ledmatrix-plugins",
      "branch": "main",
      "plugin_path": "plugins/clock-simple",
      "latest_version": "1.0.0",
      "verified": true
    }
  ]
}

plugin_path is empty for a third-party plugin in its own repository. The store offers an update when the installed manifest's version is older than latest_version.

Benefits

For Users

• ✅ Install only what you need
• ✅ Easy discovery of new displays
• ✅ Simple updates
• ✅ Community-created content

For Developers

• ✅ Lower barrier to contribute
• ✅ No need to fork core repo
• ✅ Faster iteration
• ✅ Clear plugin API

For Maintainers

• ✅ Smaller core codebase
• ✅ Less merge conflicts
• ✅ Community handles custom displays
• ✅ Easier to review changes

Known Limitations

The plugin system is shipped and stable, but some things are still intentionally simple:

1. Sandboxing: plugins run in the same process as the display loop; there is no isolation. Review code before installing third-party plugins.
2. Resource limits: there's a resource monitor that warns about slow plugins, but no hard CPU/memory caps.
3. Plugin ratings: not yet — the Plugin Store shows version, author, and category but no community rating system.
4. Auto-updates: off by default. Update from the Plugin Manager tab (per plugin, or Check & Update All), or turn on weekly automatic updates in the General tab (auto_update.enabled, web_interface/auto_update.py), which update LEDMatrix and then the installed plugins.
5. Dependency conflicts: each plugin's requirements.txt is installed via pip; conflicting versions across plugins are not resolved automatically.
6. Plugin testing framework: see HOW_TO_RUN_TESTS.md and DEV_PREVIEW.md — there are tools, but no mandatory test gate.

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See PLUGIN_ARCHITECTURE_SPEC.md for the full architectural specification.