feat: Add Plugin Button Registration API documentation and Plugin System implementation summary

- Introduced PLUGIN_BUTTON_API.md detailing button registration, UI locations, and usage examples.
- Added PLUGIN_SYSTEM_IMPLEMENTATION.md summarizing implemented features, usage examples, and API details for the plugin system.

PLUGINS.md

@@ -70,7 +70,7 @@ Plugins run with access to your Matrix client and can:
 
 ## Developing Plugins
 
-Want to create your own plugin? Check out the [Plugin Development Guide](./cinny/src/app/features/settings/plugins/PLUGIN_DEVELOPMENT.md).
+Want to create your own plugin? Check out the [Plugin API Reference](docs/PLUGIN_API.md).
 
 ### Quick Start
 
@@ -101,19 +101,19 @@ Plugins have access to:
 - **Matrix Client**: Full matrix-js-sdk client instance
 - **React**: For building UI components
 - **Commands**: Register custom slash commands
-- **UI Hooks**: Inject UI elements
+- **UI Buttons**: Inject buttons into 11 locations across the app (nav lists, toolbars, headers, sidebar)
-- **Settings**: Add custom settings sections
+- **UI Renderers**: Custom message and content renderers
-- **Utilities**: Notifications and helpers
+- **Settings**: Add custom settings sections per plugin
+- **Themes**: Register custom themes that appear in the theme selector
+- **Matrix Events**: Hook into raw Matrix events
+- **Timers**: Background intervals and timeouts, auto-cleaned on unload
+- **Notifications**: System notifications
 
-See the [Plugin Development Guide](./cinny/src/app/features/settings/plugins/PLUGIN_DEVELOPMENT.md) for complete API documentation.
+See the [Plugin API Reference](docs/PLUGIN_API.md) and [Button Registration API](docs/PLUGIN_BUTTON_API.md) for complete documentation.
 
 ## Example Plugins
 
-Check out the `example-plugin/` directory for a simple example demonstrating:
+Check out the `example-plugin/` directory for a simple example, or the `plugins/example-showcase-plugin/` for a full demonstration of all 11 UI button locations.
-- Matrix client access
-- Event listeners
-- Custom commands
-- Notifications
 
 ## Troubleshooting
 
@@ -147,7 +147,8 @@ Submit your plugins there to make them available in the marketplace!
 
 ## Support
 
-- **Documentation**: [Plugin Development Guide](./cinny/src/app/features/settings/plugins/PLUGIN_DEVELOPMENT.md)
+- **Plugin API Reference**: [docs/PLUGIN_API.md](docs/PLUGIN_API.md)
+- **Button API Reference**: [docs/PLUGIN_BUTTON_API.md](docs/PLUGIN_BUTTON_API.md)
 - **Issues**: https://github.com/Paarrot/cinny-desktop/issues
 - **Community**: Join our Matrix room for plugin development help
 

README.md

@@ -29,3 +29,50 @@ To build the app locally, run:
 
 To start local dev server, run:
 * `npm run dev`
+
+## Plugin System
+
+Paarrot includes a plugin system for extending and customising the app with JavaScript modules.
+
+### Installing Plugins
+
+1. Drop a plugin folder into your plugins directory:
+   - **Windows**: `%APPDATA%\paarrot\plugins\<plugin-name>\`
+   - **Linux**: `~/.config/Paarrot/plugins/<plugin-name>/`
+   - **macOS**: `~/Library/Application Support/Paarrot/plugins/<plugin-name>/`
+2. Enable it in **Settings → Plugins → Installed**
+
+### What Plugins Can Do
+
+- Register custom slash commands
+- Intercept and modify messages
+- Inject buttons into 11 UI locations (nav lists, toolbars, headers, sidebar, menus)
+- Register custom themes
+- Hook into raw Matrix events
+- Run background tasks
+- Show system notifications
+
+### Plugin Locations (UI Buttons)
+
+Plugins can inject buttons as **nav list rows** or **icon buttons** across the app:
+
+| Location | Style | Where |
+|---|---|---|
+| `channel-list` | Nav row | Space channel list |
+| `home-section` | Nav row | Home panel, above room list |
+| `direct-messages` | Nav row | DMs panel, below "Create Chat" |
+| `sidebar-actions` | Icon | Left sidebar — above Explore and above Search |
+| `text-composer-toolbar` | Icon | Message composer toolbar |
+| `composer-actions` | Icon | Beside the `+` attach button |
+| `room-header` | Icon | Room header bar |
+| `room-menu` | Icon | Room ⋮ dropdown |
+| `message-actions` | Icon | Message hover bar |
+| `user-menu` | Icon | Right-click on user avatar |
+| `search-notification-section` | Icon | Notifications page header |
+
+### Documentation
+
+- [Plugin System Overview](PLUGINS.md)
+- [Full Plugin API Reference](docs/PLUGIN_API.md)
+- [Button Registration API](docs/PLUGIN_BUTTON_API.md)
+- [Example Plugins](plugins/)

docs/PLUGIN_API.md

@@ -9,7 +9,8 @@ Complete reference for developing plugins for Paarrot/Cinny Desktop.
 - [Plugin Context API](#plugin-context-api)
   - [Commands](#commands)
   - [Message Interceptors](#message-interceptors)
-  - [Custom Renderers](#custom-renderers)
+  - [UI: Button Registration](#ui-button-registration)
+  - [UI: Custom Renderers](#custom-renderers)
   - [Settings](#settings)
   - [Themes](#themes)
   - [Matrix Events](#matrix-events)
@@ -322,6 +323,8 @@ ctx.ui.registerRenderer("image", (data, defaultRenderer) => {
 
 ```typescript
 interface UIAPI {
+  registerButton(button: UIButtonDefinition): void;
+  unregisterButton(id: string): void;
   registerRenderer(
     type: string,
     renderer: (data: any, defaultRenderer?: () => ReactNode) => ReactNode
@@ -336,6 +339,97 @@ type CustomRenderer = (
 
 ---
 
+### UI: Button Registration
+
+Inject buttons into various parts of the Paarrot UI. Buttons render in two visual styles depending on location — **nav list rows** (icon + label, full width) or **icon buttons** (compact, toolbar-style).
+
+See [PLUGIN_BUTTON_API.md](PLUGIN_BUTTON_API.md) for the complete reference including positioning and grouping examples.
+
+#### Register a Button
+
+```javascript
+ctx.ui.registerButton({
+  id: 'my-button',
+  location: 'text-composer-toolbar',
+  label: 'My Tool',
+  icon: '🔧',
+  onClick: () => ctx.log('clicked!')
+});
+```
+
+#### UI Locations — Nav List Rows
+
+| Location | Where it appears |
+|---|---|
+| `channel-list` | Space channel list, below Lobby and Message Search |
+| `home-section` | Home panel, inside the Rooms category above the room list |
+| `direct-messages` | DMs panel, below "Create Chat" and above the CHATS dropdown |
+
+#### UI Locations — Icon Buttons
+
+| Location | Where it appears |
+|---|---|
+| `text-composer-toolbar` | Message composer toolbar (alongside emoji, sticker buttons) |
+| `composer-actions` | Left side of the composer, beside the `+` attach button |
+| `room-header` | Top room header bar, before the ⋮ menu |
+| `room-menu` | Room ⋮ dropdown menu |
+| `message-actions` | Message hover action bar |
+| `user-menu` | Right-click popup on the user avatar |
+| `search-notification-section` | Notifications page header (right side) |
+| `sidebar-actions` | Left sidebar — above Explore Servers icon, and above Search icon in the sticky bottom section |
+
+#### Positioning
+
+```javascript
+ctx.ui.registerButton({
+  id: 'my-button',
+  location: 'text-composer-toolbar',
+  label: 'My Tool',
+  icon: '🔧',
+  position: {
+    after: 'emoji-picker-button',
+    group: 'my-tools',
+    order: 1
+  },
+  onClick: () => ctx.log('clicked!')
+});
+```
+
+#### Unregister
+
+```javascript
+ctx.ui.unregisterButton('my-button');
+// All buttons are automatically unregistered on plugin unload
+```
+
+#### API Reference
+
+```typescript
+type UILocation =
+  | 'channel-list' | 'direct-messages' | 'home-section'
+  | 'text-composer-toolbar' | 'composer-actions'
+  | 'room-header' | 'room-menu' | 'message-actions'
+  | 'user-menu' | 'search-notification-section' | 'sidebar-actions';
+
+interface UIButtonDefinition {
+  id: string;
+  location: UILocation;
+  label: string;
+  icon?: string;
+  position?: UIButtonPosition;
+  onClick?: () => void | Promise<void>;
+}
+
+interface UIButtonPosition {
+  before?: string;
+  after?: string;
+  group?: string;
+  order?: number;
+}
+```
+
+---
+
 ### Settings
 
 Define settings that users can configure in the UI.

docs/PLUGIN_BUTTON_API.md

@@ -0,0 +1,432 @@
+# Plugin Button Registration API
+
+An easy way to register plugin buttons in various UI locations with positioning and grouping support.
+
+## Example Plugins
+
+- **[example-button-plugin/](example-button-plugin/)** - Simple examples showing basic usage patterns
+- **[example-showcase-plugin/](example-showcase-plugin/)** - Complete demonstration of ALL 11 locations ⭐
+
+## UI Locations
+
+Buttons render in two visual styles depending on location — **nav list rows** (icon + label, full width) or **icon buttons** (compact, toolbar/header style).
+
+### Nav List Rows
+
+These render as full-width list entries matching the style of built-in items like "Create Room" and "Message Search":
+
+| Location | Where it appears |
+|---|---|
+| `channel-list` | Space channel list, below Lobby and Message Search |
+| `home-section` | Home panel, inside the Rooms category above the room list |
+| `direct-messages` | Direct Messages panel, below "Create Chat" and above the CHATS dropdown |
+
+### Icon Buttons
+
+These render as compact icon buttons inline with other toolbar/header controls:
+
+| Location | Where it appears |
+|---|---|
+| `text-composer-toolbar` | Message composer toolbar (alongside emoji, sticker buttons) |
+| `composer-actions` | Left side of the composer, beside the `+` attach button |
+| `room-header` | Top room header bar, before the ⋮ menu button |
+| `room-menu` | Room ⋮ dropdown menu |
+| `message-actions` | Message hover action bar |
+| `user-menu` | Right-click popup on the user avatar |
+| `search-notification-section` | Notifications page header (right side) |
+| `sidebar-actions` | Left sidebar — appears in **two** places: above the Explore Servers icon, and above the Search icon in the sticky bottom section |
+
+> 💡 **Tip:** Install the [example-showcase-plugin](example-showcase-plugin/) to see exactly where each location appears in the UI!
+
+## Basic Usage
+
+### Simple Button
+
+```javascript
+module.exports = {
+  name: 'my-plugin',
+  version: '1.0.0',
+  
+  onLoad: (context) => {
+    context.ui.registerButton({
+      id: 'my-button',
+      location: 'text-composer-toolbar',
+      label: 'My Action',
+      icon: '🎨',
+      onClick: () => {
+        context.log('Button clicked!');
+      }
+    });
+  },
+  
+  onUnload: () => {
+    // Buttons are automatically cleaned up on plugin unload
+  }
+};
+```
+
+## Positioning
+
+### Before/After Positioning
+
+Place your button before or after existing buttons:
+
+```javascript
+context.ui.registerButton({
+  id: 'my-button',
+  location: 'text-composer-toolbar',
+  label: 'My Action',
+  icon: '✨',
+  position: {
+    before: 'emoji-picker-button', // Place before emoji picker
+    // OR
+    after: 'sticker-button' // Place after sticker button
+  }
+});
+```
+
+### Grouping Buttons
+
+Group related buttons together:
+
+```javascript
+context.ui.registerButton({
+  id: 'action-1',
+  location: 'text-composer-toolbar',
+  label: 'Action 1',
+  icon: '1️⃣',
+  position: {
+    group: 'my-plugin-tools',
+    order: 1 // Lower numbers appear first
+  }
+});
+
+context.ui.registerButton({
+  id: 'action-2',
+  location: 'text-composer-toolbar',
+  label: 'Action 2',
+  icon: '2️⃣',
+  position: {
+    group: 'my-plugin-tools',
+    order: 2
+  }
+});
+```
+
+### Combined Positioning and Grouping
+
+Place a group before/after other elements:
+
+```javascript
+context.ui.registerButton({
+  id: 'tool-1',
+  location: 'text-composer-toolbar',
+  label: 'Tool 1',
+  icon: '🔧',
+  position: {
+    group: 'my-tools',
+    after: 'emoji-picker-button',
+    order: 1
+  }
+});
+
+context.ui.registerButton({
+  id: 'tool-2',
+  location: 'text-composer-toolbar',
+  label: 'Tool 2',
+  icon: '🔨',
+  position: {
+    group: 'my-tools',
+    order: 2
+  }
+});
+```
+
+## Complete Example
+
+```javascript
+module.exports = {
+  name: 'custom-tools',
+  version: '1.0.0',
+  
+  onLoad: (context) => {
+    // Nav list row — appears below "Create Chat" in the DMs panel
+    context.ui.registerButton({
+      id: 'dm-favorites',
+      location: 'direct-messages',
+      label: 'Favourites',
+      icon: '⭐',
+      onClick: () => context.log('Favourites clicked!')
+    });
+
+    // Nav list row — appears in the space channel list
+    context.ui.registerButton({
+      id: 'quick-access',
+      location: 'channel-list',
+      label: 'Quick Access',
+      icon: '⚡',
+      onClick: () => context.log('Quick access clicked!')
+    });
+
+    // Icon button — appears in the message composer toolbar
+    context.ui.registerButton({
+      id: 'format-bold',
+      location: 'text-composer-toolbar',
+      label: 'Bold',
+      icon: '𝐁',
+      position: {
+        group: 'custom-formatting',
+        order: 1
+      },
+      onClick: () => context.log('Bold clicked!')
+    });
+
+    // Icon button — appears in the room header
+    context.ui.registerButton({
+      id: 'special-search',
+      location: 'room-header',
+      label: 'Special Search',
+      icon: '🔍',
+      position: { after: 'search-button' },
+      onClick: () => context.log('Special search clicked!')
+    });
+
+    // Sidebar icon — appears above Explore and above Search
+    context.ui.registerButton({
+      id: 'plugin-panel',
+      location: 'sidebar-actions',
+      label: 'Plugin Panel',
+      icon: '🧩',
+      onClick: () => context.log('Plugin panel clicked!')
+    });
+  },
+  
+  onUnload: () => {
+    // All registered buttons are automatically cleaned up
+  }
+};
+```
+
+## Unregistering Buttons
+
+Buttons are automatically unregistered when the plugin is unloaded. To manually unregister:
+
+```javascript
+context.ui.unregisterButton('my-button-id');
+```
+
+## TypeScript Types
+
+```typescript
+import type { UIButtonDefinition, UIButtonPosition, UILocation } from '@paarrot/plugin-manager';
+
+const button: UIButtonDefinition = {
+  id: 'my-button',
+  location: 'text-composer-toolbar',
+  label: 'My Action',
+  icon: '🎨',
+  position: {
+    group: 'my-tools',
+    after: 'emoji-picker',
+    order: 1
+  },
+  onClick: () => console.log('Clicked!')
+};
+```
+
+
+## Basic Usage
+
+### Simple Button
+
+```javascript
+module.exports = {
+  name: 'my-plugin',
+  version: '1.0.0',
+  
+  onLoad: (context) => {
+    context.ui.registerButton({
+      id: 'my-button',
+      location: 'text-composer-toolbar',
+      label: 'My Action',
+      icon: '🎨',
+      onClick: () => {
+        context.log('Button clicked!');
+      }
+    });
+  },
+  
+  onUnload: () => {
+    // Buttons are automatically cleaned up on plugin unload
+  }
+};
+```
+
+## Positioning
+
+### Before/After Positioning
+
+Place your button before or after existing buttons:
+
+```javascript
+context.ui.registerButton({
+  id: 'my-button',
+  location: 'text-composer-toolbar',
+  label: 'My Action',
+  icon: '✨',
+  position: {
+    before: 'emoji-picker-button', // Place before emoji picker
+    // OR
+    after: 'sticker-button' // Place after sticker button
+  }
+});
+```
+
+### Grouping Buttons
+
+Group related buttons together:
+
+```javascript
+context.ui.registerButton({
+  id: 'action-1',
+  location: 'text-composer-toolbar',
+  label: 'Action 1',
+  icon: '1️⃣',
+  position: {
+    group: 'my-plugin-tools',
+    order: 1 // Lower numbers appear first
+  }
+});
+
+context.ui.registerButton({
+  id: 'action-2',
+  location: 'text-composer-toolbar',
+  label: 'Action 2',
+  icon: '2️⃣',
+  position: {
+    group: 'my-plugin-tools',
+    order: 2
+  }
+});
+```
+
+### Combined Positioning and Grouping
+
+Place a group before/after other elements:
+
+```javascript
+context.ui.registerButton({
+  id: 'tool-1',
+  location: 'text-composer-toolbar',
+  label: 'Tool 1',
+  icon: '🔧',
+  position: {
+    group: 'my-tools',
+    after: 'emoji-picker-button',
+    order: 1
+  }
+});
+
+context.ui.registerButton({
+  id: 'tool-2',
+  location: 'text-composer-toolbar',
+  label: 'Tool 2',
+  icon: '🔨',
+  position: {
+    group: 'my-tools',
+    order: 2
+  }
+});
+```
+
+## Complete Example
+
+```javascript
+module.exports = {
+  name: 'custom-tools',
+  version: '1.0.0',
+  
+  onLoad: (context) => {
+    // Nav list row — appears below "Create Chat" in the DMs panel
+    context.ui.registerButton({
+      id: 'dm-favorites',
+      location: 'direct-messages',
+      label: 'Favourites',
+      icon: '⭐',
+      onClick: () => context.log('Favourites clicked!')
+    });
+
+    // Nav list row — appears in the space channel list
+    context.ui.registerButton({
+      id: 'quick-access',
+      location: 'channel-list',
+      label: 'Quick Access',
+      icon: '⚡',
+      onClick: () => context.log('Quick access clicked!')
+    });
+
+    // Icon button — appears in the message composer toolbar
+    context.ui.registerButton({
+      id: 'format-bold',
+      location: 'text-composer-toolbar',
+      label: 'Bold',
+      icon: '𝐁',
+      position: {
+        group: 'custom-formatting',
+        order: 1
+      },
+      onClick: () => context.log('Bold clicked!')
+    });
+
+    // Icon button — appears in the room header
+    context.ui.registerButton({
+      id: 'special-search',
+      location: 'room-header',
+      label: 'Special Search',
+      icon: '🔍',
+      position: { after: 'search-button' },
+      onClick: () => context.log('Special search clicked!')
+    });
+
+    // Sidebar icon — appears above Explore and above Search
+    context.ui.registerButton({
+      id: 'plugin-panel',
+      location: 'sidebar-actions',
+      label: 'Plugin Panel',
+      icon: '🧩',
+      onClick: () => context.log('Plugin panel clicked!')
+    });
+  },
+  
+  onUnload: () => {
+    // All registered buttons are automatically cleaned up
+  }
+};
+```
+
+## Unregistering Buttons
+
+Buttons are automatically unregistered when the plugin is unloaded. To manually unregister:
+
+```javascript
+context.ui.unregisterButton('my-button-id');
+```
+
+## TypeScript Types
+
+```typescript
+import type { UIButtonDefinition, UIButtonPosition, UILocation } from '@paarrot/plugin-manager';
+
+const button: UIButtonDefinition = {
+  id: 'my-button',
+  location: 'text-composer-toolbar',
+  label: 'My Action',
+  icon: '🎨',
+  position: {
+    group: 'my-tools',
+    after: 'emoji-picker',
+    order: 1
+  },
+  onClick: () => console.log('Clicked!')
+};
+```

docs/PLUGIN_SYSTEM_IMPLEMENTATION.md

@@ -16,11 +16,17 @@ All requested features have been implemented! 🎉
 - Full MessageContext with content, roomId, metadata
 - Async support for interceptors
 
-### 3. ✅ Custom Renderers
+### 3. ✅ Custom Renderers & Button Registration
-- **Register**: `ctx.ui.registerRenderer("message", (msg, defaultRenderer) => { /* render */ })`
+- **Register renderer**: `ctx.ui.registerRenderer("message", (msg, defaultRenderer) => { /* render */ })`
-- **Unregister**: `ctx.ui.unregisterRenderer("message")`
+- **Unregister renderer**: `ctx.ui.unregisterRenderer("message")`
-- Fallback to default renderer support
+- **Register button**: `ctx.ui.registerButton({ id, location, label, icon, onClick })`
-- Discord-mod-tier customization enabled
+- **Unregister button**: `ctx.ui.unregisterButton(id)`
+- 11 UI locations across nav lists, toolbars, headers, sidebar, and menus
+- Nav list rows (icon + label) for `channel-list`, `home-section`, `direct-messages`
+- Icon buttons for all other locations
+- Positioning and grouping support (`before`, `after`, `group`, `order`)
+- Auto-cleanup on plugin unload
+- See [PLUGIN_BUTTON_API.md](PLUGIN_BUTTON_API.md) for full reference
 
 ### 4. ✅ Settings UI Per Plugin
 - **Define schema**: `ctx.settings.define({ theme: { type: "select", options: [...] } })`
@@ -162,6 +168,8 @@ interface PluginContext {
   };
   
   ui: {
+    registerButton: (button: UIButtonDefinition) => void;
+    unregisterButton: (id: string) => void;
     registerRenderer: (type: string, renderer: CustomRenderer) => void;
     unregisterRenderer: (type: string) => void;
   };