# LED Strip Test Device Auto-Refresh Implementation

## Overview
Implemented automatic refresh functionality for the device dropdown in the LED strip test interface. The device list now updates in real-time when devices are discovered, connected, or disconnected.

## Changes Made

### 1. Frontend Changes (`src/components/led-strip-test/led-strip-test.tsx`)

#### Added Event Listener Import
```typescript
import { listen } from '@tauri-apps/api/event';
```

#### Enhanced Device Loading Logic
- **Initial Load**: Still loads devices on component mount using `get_boards()`
- **Real-time Updates**: Added listener for `boards_changed` events from backend
- **Smart Selection**: Automatically handles device selection when devices are added/removed:
  - If current device disconnects, automatically selects first available device
  - If no device was selected and devices become available, selects the first one
  - Properly cleans up event listeners on component unmount

#### Improved UI Display
- **Device Count**: Shows number of devices found in label
- **Connection Status**: Each device option shows:
  - Status icon (🟢 Connected, 🟡 Connecting, 🔴 Disconnected)
  - Device name and address
  - Connection status text
- **Empty State**: Shows "Searching..." when no devices found

#### Type Safety Improvements
- Updated `BoardInfo` interface to match backend types
- Proper handling of `connect_status` union type
- Type-safe status checking functions

### 2. Backend Integration
The implementation leverages existing backend infrastructure:
- **UdpRpc Manager**: Continuously searches for devices via mDNS
- **Device Monitoring**: Checks device connectivity every second
- **Event Broadcasting**: Sends `boards_changed` events to frontend
- **Status Tracking**: Maintains real-time connection status for each device

## Technical Details

### Event Flow
1. Backend `UdpRpc` discovers devices via mDNS service discovery
2. Backend monitors device connectivity with periodic health checks
3. Backend broadcasts `boards_changed` events when device list changes
4. Frontend listens for events and updates UI automatically
5. Frontend handles device selection logic intelligently

### Connection Status Types
- `Connected`: Device is responding to ping requests
- `Connecting`: Device is in retry state (with retry count)
- `Disconnected`: Device is not responding

### Error Handling
- Graceful fallback if initial device load fails
- Proper cleanup of event listeners
- Maintains UI state consistency during device changes

## Benefits
1. **Real-time Updates**: No need to manually refresh device list
2. **Better UX**: Visual indicators for device status
3. **Automatic Recovery**: Handles device disconnections gracefully
4. **Type Safety**: Proper TypeScript types prevent runtime errors
5. **Performance**: Efficient event-driven updates instead of polling

## Implementation Status
✅ **Completed**: LED Strip Test device dropdown auto-refresh
✅ **Already Implemented**: Board Index page auto-refresh (was already working)
✅ **Type Safety**: Fixed TypeScript type definitions for BoardInfo
✅ **UI Improvements**: Added status indicators and device count display

## Testing
To test the functionality:
1. Start the application with `npm run tauri dev`
2. Navigate to LED Strip Test page
3. Observe device list updates as devices come online/offline
4. Verify status indicators show correct connection states:
   - 🟢 Connected devices
   - 🟡 Connecting devices (with retry count)
   - 🔴 Disconnected devices
5. Test device selection behavior when devices disconnect
6. Check that device count is displayed in the label

## Code Quality
- ✅ No TypeScript errors
- ✅ Proper event listener cleanup
- ✅ Type-safe status checking
- ✅ Consistent with existing codebase patterns
- ✅ Follows SolidJS best practices

## Future Enhancements
- Add device refresh button for manual refresh
- Show device discovery progress indicator
- Add device connection retry controls
- Display device ping latency information
- Add device connection history/logs