feat: fw-update recovery flow

lib/main.dart

@@ -1,6 +1,7 @@
 import 'dart:async';
 
 import 'package:abawo_bt_app/controller/bluetooth.dart';
+import 'package:abawo_bt_app/pages/bootloader_recovery_update_page.dart';
 import 'package:abawo_bt_app/pages/devices_page.dart';
 import 'package:abawo_bt_app/pages/devices_tab_page.dart';
 import 'package:abawo_bt_app/src/rust/frb_generated.dart';
@@ -125,6 +126,18 @@ final _router = GoRouter(
         return DeviceDetailsPage(deviceAddress: deviceAddress);
       },
     ),
+    GoRoute(
+      path: '/bootloader_recovery_update',
+      builder: (context, state) {
+        final args = state.extra;
+        if (args is! BootloaderRecoveryUpdateArgs) {
+          return const Scaffold(
+            body: Center(child: Text('Missing bootloader recovery data.')),
+          );
+        }
+        return BootloaderRecoveryUpdatePage(args: args);
+      },
+    ),
   ],
 );
 

lib/pages/bootloader_recovery_update_page.dart

@@ -0,0 +1,196 @@
+import 'dart:async';
+
+import 'package:abawo_bt_app/controller/bluetooth.dart';
+import 'package:abawo_bt_app/model/firmware_file_selection.dart';
+import 'package:abawo_bt_app/model/shifter_types.dart';
+import 'package:abawo_bt_app/service/firmware_update_service.dart';
+import 'package:abawo_bt_app/widgets/firmware_update_fullscreen.dart';
+import 'package:flutter/material.dart';
+import 'package:flutter_riverpod/flutter_riverpod.dart';
+import 'package:go_router/go_router.dart';
+
+class BootloaderRecoveryUpdateArgs {
+  const BootloaderRecoveryUpdateArgs({
+    required this.bootloaderDeviceId,
+    required this.firmware,
+  });
+
+  final String bootloaderDeviceId;
+  final BootloaderDfuPreparedFirmware firmware;
+}
+
+class BootloaderRecoveryUpdatePage extends ConsumerStatefulWidget {
+  const BootloaderRecoveryUpdatePage({
+    required this.args,
+    super.key,
+  });
+
+  final BootloaderRecoveryUpdateArgs args;
+
+  @override
+  ConsumerState<BootloaderRecoveryUpdatePage> createState() =>
+      _BootloaderRecoveryUpdatePageState();
+}
+
+class _BootloaderRecoveryUpdatePageState
+    extends ConsumerState<BootloaderRecoveryUpdatePage> {
+  FirmwareUpdateService? _firmwareUpdateService;
+  StreamSubscription<DfuUpdateProgress>? _firmwareProgressSubscription;
+  DfuUpdateProgress _dfuProgress = const DfuUpdateProgress(
+    state: DfuUpdateState.idle,
+    totalBytes: 0,
+    sentBytes: 0,
+    expectedOffset: 0,
+    sessionId: 0,
+    flags: DfuUpdateFlags(),
+  );
+  String? _firmwareUserMessage = 'Preparing US-DFU recovery update...';
+  bool _hasStarted = false;
+
+  @override
+  void initState() {
+    super.initState();
+    WidgetsBinding.instance.addPostFrameCallback((_) {
+      if (mounted) {
+        unawaited(_startUpdate());
+      }
+    });
+  }
+
+  @override
+  void dispose() {
+    unawaited(_firmwareProgressSubscription?.cancel());
+    unawaited(_firmwareUpdateService?.dispose() ?? Future<void>.value());
+    super.dispose();
+  }
+
+  Future<FirmwareUpdateService?> _ensureFirmwareUpdateService() async {
+    if (_firmwareUpdateService != null) {
+      return _firmwareUpdateService;
+    }
+
+    final bluetooth = ref.read(bluetoothProvider).valueOrNull;
+    if (bluetooth == null) {
+      return null;
+    }
+
+    final service = FirmwareUpdateService(
+      verifyAfterFinish: false,
+      transport: ShifterFirmwareUpdateTransport(
+        shifterService: null,
+        bluetoothController: bluetooth,
+        buttonDeviceId: widget.args.bootloaderDeviceId,
+      ),
+    );
+    _firmwareProgressSubscription = service.progressStream.listen((progress) {
+      if (!mounted) {
+        return;
+      }
+      setState(() {
+        _dfuProgress = progress;
+        if (progress.state == DfuUpdateState.failed &&
+            progress.errorMessage != null) {
+          _firmwareUserMessage = progress.errorMessage;
+        } else if (progress.state == DfuUpdateState.completed) {
+          _firmwareUserMessage =
+              'Firmware update completed. The bootloader accepted FINISH and reset; reconnect to the device when it starts advertising again.';
+        } else if (progress.state == DfuUpdateState.aborted) {
+          _firmwareUserMessage = 'Firmware update canceled.';
+        } else if (progress.errorMessage != null) {
+          _firmwareUserMessage = progress.errorMessage;
+        }
+      });
+    });
+    _firmwareUpdateService = service;
+    return service;
+  }
+
+  Future<void> _startUpdate() async {
+    if (_hasStarted) {
+      return;
+    }
+    _hasStarted = true;
+
+    final updater = await _ensureFirmwareUpdateService();
+    if (!mounted) {
+      return;
+    }
+    if (updater == null) {
+      setState(() {
+        _dfuProgress = DfuUpdateProgress(
+          state: DfuUpdateState.failed,
+          totalBytes: widget.args.firmware.fileBytes.length,
+          sentBytes: 0,
+          expectedOffset: 0,
+          sessionId: widget.args.firmware.metadata.sessionId,
+          flags: DfuUpdateFlags.fromRaw(widget.args.firmware.metadata.flags),
+          errorMessage:
+              'Firmware updater is not ready. Reconnect to US-DFU and retry.',
+        );
+        _firmwareUserMessage = _dfuProgress.errorMessage;
+      });
+      return;
+    }
+
+    final firmware = widget.args.firmware;
+    final result = await updater.startUpdate(
+      imageBytes: firmware.fileBytes,
+      sessionId: firmware.metadata.sessionId,
+      appStart: firmware.metadata.appStart,
+      imageVersion: firmware.metadata.imageVersion,
+      flags: DfuUpdateFlags.fromRaw(firmware.metadata.flags),
+    );
+
+    if (!mounted || result.isOk()) {
+      return;
+    }
+    setState(() {
+      _firmwareUserMessage = result.unwrapErr().toString();
+    });
+  }
+
+  String _dfuPhaseText(DfuUpdateState state) {
+    return switch (state) {
+      DfuUpdateState.idle => 'Preparing recovery update',
+      DfuUpdateState.starting => 'Preparing update',
+      DfuUpdateState.enteringBootloader => 'Checking bootloader mode',
+      DfuUpdateState.connectingBootloader => 'Connecting to bootloader',
+      DfuUpdateState.waitingForStatus => 'Waiting for bootloader status',
+      DfuUpdateState.erasing => 'Starting destructive bootloader update',
+      DfuUpdateState.transferring => 'Transferring firmware image',
+      DfuUpdateState.finishing => 'Finalizing bootloader update',
+      DfuUpdateState.rebooting => 'Waiting for bootloader reset',
+      DfuUpdateState.verifying => 'Verifying updated app',
+      DfuUpdateState.completed => 'Update completed',
+      DfuUpdateState.aborted => 'Update canceled',
+      DfuUpdateState.failed => 'Update failed',
+    };
+  }
+
+  String _formatBytes(int bytes) {
+    if (bytes < 1024) {
+      return '$bytes B';
+    }
+    if (bytes < 1024 * 1024) {
+      return '${(bytes / 1024).toStringAsFixed(1)} KB';
+    }
+    return '${(bytes / (1024 * 1024)).toStringAsFixed(2)} MB';
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    return FirmwareUpdateFullscreen(
+      progress: _dfuProgress,
+      selectedFirmware: widget.args.firmware,
+      phaseText: _dfuPhaseText(_dfuProgress.state),
+      statusText: _firmwareUserMessage,
+      formattedProgressBytes:
+          '${_formatBytes(_dfuProgress.sentBytes)} / ${_formatBytes(_dfuProgress.totalBytes)}',
+      expectedOffsetHex:
+          '0x${_dfuProgress.expectedOffset.toRadixString(16).padLeft(8, '0').toUpperCase()}',
+      doneLabel: 'Back to devices',
+      failedLabel: 'Back to devices',
+      onDismiss: () => context.go('/devices'),
+    );
+  }
+}

lib/pages/device_details_page.dart

@@ -8,6 +8,7 @@ import 'package:abawo_bt_app/service/firmware_update_service.dart';
 import 'package:abawo_bt_app/service/shifter_service.dart';
 import 'package:abawo_bt_app/util/bluetooth_settings.dart';
 import 'package:abawo_bt_app/widgets/bike_scan_dialog.dart';
+import 'package:abawo_bt_app/widgets/firmware_update_fullscreen.dart';
 import 'package:abawo_bt_app/widgets/gear_ratio_editor_card.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
@@ -904,7 +905,7 @@ class _DeviceDetailsPageState extends ConsumerState<DeviceDetailsPage> {
         (_dfuProgress.state != DfuUpdateState.idle &&
             _dfuProgress.state != DfuUpdateState.completed &&
             _dfuProgress.state != DfuUpdateState.failed)) {
-      return _FirmwareUpdateFullscreen(
+      return FirmwareUpdateFullscreen(
         progress: _dfuProgress,
         selectedFirmware: _selectedFirmware,
         phaseText: _dfuPhaseText(_dfuProgress.state),
@@ -1956,244 +1957,3 @@ class _OverviewMetricTile extends StatelessWidget {
     );
   }
 }
-
-class _FirmwareUpdateFullscreen extends StatelessWidget {
-  const _FirmwareUpdateFullscreen({
-    required this.progress,
-    required this.selectedFirmware,
-    required this.phaseText,
-    required this.statusText,
-    required this.formattedProgressBytes,
-    required this.expectedOffsetHex,
-    required this.onDismiss,
-  });
-
-  final DfuUpdateProgress progress;
-  final BootloaderDfuPreparedFirmware? selectedFirmware;
-  final String phaseText;
-  final String? statusText;
-  final String formattedProgressBytes;
-  final String expectedOffsetHex;
-  final VoidCallback onDismiss;
-
-  bool get _isTerminal =>
-      progress.state == DfuUpdateState.completed ||
-      progress.state == DfuUpdateState.failed;
-
-  bool get _isRunning => !_isTerminal && progress.state != DfuUpdateState.idle;
-
-  String? get _bootloaderStatusText {
-    final status = progress.bootloaderStatus;
-    if (status == null) {
-      return null;
-    }
-    final codeLabel = switch (status.code) {
-      DfuBootloaderStatusCode.ok => 'OK',
-      DfuBootloaderStatusCode.parseError => 'parse error',
-      DfuBootloaderStatusCode.stateError => 'state error',
-      DfuBootloaderStatusCode.boundsError => 'bounds error',
-      DfuBootloaderStatusCode.crcError => 'CRC error',
-      DfuBootloaderStatusCode.flashError => 'flash error',
-      DfuBootloaderStatusCode.unsupportedError => 'unsupported flags',
-      DfuBootloaderStatusCode.vectorError => 'vector table error',
-      DfuBootloaderStatusCode.queueFull => 'queue full',
-      DfuBootloaderStatusCode.bootMetadataError => 'boot metadata error',
-      DfuBootloaderStatusCode.unknown =>
-        'unknown 0x${status.rawCode.toRadixString(16).padLeft(2, '0').toUpperCase()}',
-    };
-    return '$codeLabel  •  session ${status.sessionId}  •  offset 0x${status.expectedOffset.toRadixString(16).padLeft(8, '0').toUpperCase()}';
-  }
-
-  @override
-  Widget build(BuildContext context) {
-    final theme = Theme.of(context);
-    final colorScheme = theme.colorScheme;
-    final isFailed = progress.state == DfuUpdateState.failed;
-
-    return PopScope(
-      canPop: false,
-      child: Scaffold(
-        backgroundColor: colorScheme.surface,
-        body: SafeArea(
-          child: Column(
-            children: [
-              if (_isRunning)
-                Container(
-                  width: double.infinity,
-                  padding:
-                      const EdgeInsets.symmetric(horizontal: 20, vertical: 12),
-                  color: colorScheme.errorContainer,
-                  child: Row(
-                    children: [
-                      Icon(Icons.warning_amber_rounded,
-                          color: colorScheme.onErrorContainer, size: 20),
-                      const SizedBox(width: 10),
-                      Expanded(
-                        child: Text(
-                          'Do not close the app, lock the phone, or move away from the button.',
-                          style: theme.textTheme.bodySmall?.copyWith(
-                            color: colorScheme.onErrorContainer,
-                            fontWeight: FontWeight.w600,
-                          ),
-                        ),
-                      ),
-                    ],
-                  ),
-                ),
-              Expanded(
-                child: SingleChildScrollView(
-                  padding: const EdgeInsets.fromLTRB(24, 32, 24, 24),
-                  child: Column(
-                    crossAxisAlignment: CrossAxisAlignment.center,
-                    children: [
-                      Icon(
-                        _isTerminal
-                            ? (isFailed
-                                ? Icons.error_outline_rounded
-                                : Icons.check_circle_outline_rounded)
-                            : Icons.system_update_alt_rounded,
-                        size: 56,
-                        color: _isTerminal
-                            ? (isFailed
-                                ? colorScheme.error
-                                : colorScheme.primary)
-                            : colorScheme.primary,
-                      ),
-                      const SizedBox(height: 16),
-                      Text(
-                        _isTerminal
-                            ? (isFailed ? 'Update failed' : 'Update completed')
-                            : 'Updating firmware',
-                        style: theme.textTheme.headlineSmall?.copyWith(
-                          fontWeight: FontWeight.w700,
-                        ),
-                      ),
-                      const SizedBox(height: 8),
-                      Text(
-                        phaseText,
-                        style: theme.textTheme.bodyLarge?.copyWith(
-                          color: colorScheme.onSurface.withValues(alpha: 0.72),
-                        ),
-                      ),
-                      if (selectedFirmware != null) ...[
-                        const SizedBox(height: 12),
-                        Text(
-                          '${selectedFirmware!.fileName}  •  ${_formatBytes(selectedFirmware!.fileBytes.length)}',
-                          style: theme.textTheme.bodySmall,
-                        ),
-                      ],
-                      const SizedBox(height: 24),
-                      if (_isRunning) ...[
-                        LinearProgressIndicator(
-                          value: progress.totalBytes > 0
-                              ? progress.fractionComplete
-                              : null,
-                          minHeight: 12,
-                          borderRadius: BorderRadius.circular(999),
-                        ),
-                        const SizedBox(height: 12),
-                        Text(
-                          '${progress.percentComplete}%  •  $formattedProgressBytes',
-                          style: theme.textTheme.bodyMedium?.copyWith(
-                            fontWeight: FontWeight.w600,
-                          ),
-                        ),
-                      ],
-                      if (progress.state == DfuUpdateState.finishing ||
-                          progress.state == DfuUpdateState.rebooting ||
-                          progress.state == DfuUpdateState.verifying) ...[
-                        const SizedBox(height: 20),
-                        Container(
-                          width: double.infinity,
-                          padding: const EdgeInsets.all(14),
-                          decoration: BoxDecoration(
-                            color: colorScheme.primaryContainer
-                                .withValues(alpha: 0.36),
-                            borderRadius: BorderRadius.circular(14),
-                          ),
-                          child: Row(
-                            children: [
-                              SizedBox(
-                                width: 18,
-                                height: 18,
-                                child: CircularProgressIndicator(
-                                    strokeWidth: 2, color: colorScheme.primary),
-                              ),
-                              const SizedBox(width: 10),
-                              Expanded(
-                                child: Text(
-                                  'Bootloader is verifying, resetting, and booting the new app. Keep the screen open.',
-                                  style: theme.textTheme.bodySmall?.copyWith(
-                                    color: colorScheme.primary,
-                                    fontWeight: FontWeight.w600,
-                                  ),
-                                ),
-                              ),
-                            ],
-                          ),
-                        ),
-                      ],
-                      if (_bootloaderStatusText != null) ...[
-                        const SizedBox(height: 12),
-                        Text(
-                          _bootloaderStatusText!,
-                          style: theme.textTheme.bodySmall?.copyWith(
-                            color:
-                                colorScheme.onSurface.withValues(alpha: 0.56),
-                          ),
-                        ),
-                      ],
-                      if (statusText != null &&
-                          statusText!.trim().isNotEmpty) ...[
-                        const SizedBox(height: 20),
-                        Container(
-                          width: double.infinity,
-                          padding: const EdgeInsets.all(14),
-                          decoration: BoxDecoration(
-                            color: isFailed
-                                ? colorScheme.errorContainer
-                                : colorScheme.surfaceContainerHighest,
-                            borderRadius: BorderRadius.circular(14),
-                          ),
-                          child: Text(
-                            statusText!,
-                            style: theme.textTheme.bodyMedium?.copyWith(
-                              color: isFailed
-                                  ? colorScheme.onErrorContainer
-                                  : null,
-                            ),
-                          ),
-                        ),
-                      ],
-                      if (_isTerminal) ...[
-                        const SizedBox(height: 32),
-                        SizedBox(
-                          width: double.infinity,
-                          child: FilledButton.icon(
-                            onPressed: onDismiss,
-                            icon: Icon(isFailed
-                                ? Icons.arrow_back_rounded
-                                : Icons.check_rounded),
-                            label: Text(
-                              isFailed ? 'Back to device' : 'Done',
-                            ),
-                          ),
-                        ),
-                      ],
-                    ],
-                  ),
-                ),
-              ),
-            ],
-          ),
-        ),
-      ),
-    );
-  }
-
-  String _formatBytes(int bytes) {
-    if (bytes < 1024) return '$bytes B';
-    if (bytes < 1024 * 1024) return '${(bytes / 1024).toStringAsFixed(1)} KB';
-    return '${(bytes / (1024 * 1024)).toStringAsFixed(2)} MB';
-  }
-}

lib/pages/devices_tab_page.dart

@@ -1,18 +1,145 @@
+import 'dart:async';
+
 import 'package:abawo_bt_app/controller/bluetooth.dart';
 import 'package:abawo_bt_app/controller/shifter_device_telemetry.dart';
 import 'package:abawo_bt_app/database/database.dart';
 import 'package:abawo_bt_app/model/bluetooth_device_model.dart';
+import 'package:abawo_bt_app/model/firmware_file_selection.dart';
+import 'package:abawo_bt_app/model/shifter_types.dart';
+import 'package:abawo_bt_app/pages/bootloader_recovery_update_page.dart';
+import 'package:abawo_bt_app/service/firmware_file_selection_service.dart';
 import 'package:flutter/material.dart';
+import 'package:flutter_reactive_ble/flutter_reactive_ble.dart'
+    show DiscoveredDevice, ScanMode, Uuid;
 import 'package:flutter_riverpod/flutter_riverpod.dart';
 import 'package:go_router/go_router.dart';
 
-class DevicesTabPage extends ConsumerWidget {
+class DevicesTabPage extends ConsumerStatefulWidget {
   const DevicesTabPage({super.key});
 
   @override
-  Widget build(BuildContext context, WidgetRef ref) {
+  ConsumerState<DevicesTabPage> createState() => _DevicesTabPageState();
+}
+
+class _DevicesTabPageState extends ConsumerState<DevicesTabPage> {
+  static const Duration _bootloaderScanTimeout = Duration(seconds: 10);
+
+  StreamSubscription<List<DiscoveredDevice>>? _scanSubscription;
+  DiscoveredDevice? _dfuDevice;
+  bool _isBootloaderScanStarting = false;
+
+  @override
+  void initState() {
+    super.initState();
+    unawaited(_startBootloaderBackgroundScan());
+  }
+
+  @override
+  void dispose() {
+    final bluetooth = ref.read(bluetoothProvider).valueOrNull;
+    unawaited(_scanSubscription?.cancel());
+    unawaited(_stopBootloaderScan(bluetooth));
+    super.dispose();
+  }
+
+  Future<void> _startBootloaderBackgroundScan() async {
+    if (_isBootloaderScanStarting || _scanSubscription != null) {
+      return;
+    }
+    _isBootloaderScanStarting = true;
+
+    try {
+      final bluetooth = await ref.read(bluetoothProvider.future);
+      if (!mounted) {
+        return;
+      }
+
+      final scanResult = await bluetooth.startScan(
+        timeout: _bootloaderScanTimeout,
+        scanMode: ScanMode.lowLatency,
+      );
+      if (scanResult.isErr()) {
+        return;
+      }
+
+      _updateBootloaderDevice(bluetooth.scanResults);
+      _scanSubscription = bluetooth.scanResultsStream.listen(
+        _updateBootloaderDevice,
+      );
+    } finally {
+      _isBootloaderScanStarting = false;
+    }
+  }
+
+  Future<void> _stopBootloaderScan([BluetoothController? bluetooth]) async {
+    await _scanSubscription?.cancel();
+    _scanSubscription = null;
+
+    await bluetooth?.stopScan();
+  }
+
+  void _updateBootloaderDevice(List<DiscoveredDevice> devices) {
+    final dfuDevice = devices.cast<DiscoveredDevice?>().firstWhere(
+          (device) => device != null && _isBootloaderAdvertisement(device),
+          orElse: () => null,
+        );
+    if (!mounted || dfuDevice == null || dfuDevice.id == _dfuDevice?.id) {
+      return;
+    }
+
+    setState(() {
+      _dfuDevice = dfuDevice;
+    });
+  }
+
+  bool _isBootloaderAdvertisement(DiscoveredDevice device) {
+    final name = device.name.trim();
+    if (name == 'US-DFU' || name == 'UniversalShifters DFU') {
+      return true;
+    }
+    return name.toLowerCase().contains('dfu') &&
+        device.serviceUuids.any(
+          (uuid) =>
+              uuid.expanded ==
+              Uuid.parse(universalShifterControlServiceUuid).expanded,
+        );
+  }
+
+  Future<void> _openBootloaderRecovery() async {
+    final device = _dfuDevice;
+    if (device == null) {
+      return;
+    }
+
+    final firmware =
+        await Navigator.of(context).push<BootloaderDfuPreparedFirmware>(
+      MaterialPageRoute(
+        fullscreenDialog: true,
+        builder: (_) => _BootloaderRecoverySetupPage(device: device),
+      ),
+    );
+    if (!mounted || firmware == null) {
+      return;
+    }
+
+    await _stopBootloaderScan();
+    if (!mounted) {
+      return;
+    }
+    context.push(
+      '/bootloader_recovery_update',
+      extra: BootloaderRecoveryUpdateArgs(
+        bootloaderDeviceId: device.id,
+        firmware: firmware,
+      ),
+    );
+  }
+
+  @override
+  Widget build(BuildContext context) {
     final devicesAsync = ref.watch(nConnectedDevicesProvider);
     final connectionData = ref.watch(connectionStatusProvider).valueOrNull;
+    final dfuDevice = _dfuDevice;
 
     return ListView(
       padding: const EdgeInsets.fromLTRB(20, 16, 20, 24),
@@ -50,6 +177,13 @@ class DevicesTabPage extends ConsumerWidget {
           ],
         ),
         const SizedBox(height: 20),
+        if (dfuDevice != null) ...[
+          _BootloaderRecoveryCard(
+            device: dfuDevice,
+            onStartRecovery: _openBootloaderRecovery,
+          ),
+          const SizedBox(height: 20),
+        ],
         devicesAsync.when(
           loading: () => const _LoadingCard(),
           error: (error, _) => _MessageCard(
@@ -86,6 +220,259 @@ class DevicesTabPage extends ConsumerWidget {
   }
 }
 
+class _BootloaderRecoveryCard extends StatelessWidget {
+  const _BootloaderRecoveryCard({
+    required this.device,
+    required this.onStartRecovery,
+  });
+
+  final DiscoveredDevice device;
+  final VoidCallback onStartRecovery;
+
+  @override
+  Widget build(BuildContext context) {
+    final colorScheme = Theme.of(context).colorScheme;
+
+    return Card(
+      color: colorScheme.errorContainer.withValues(alpha: 0.45),
+      child: Padding(
+        padding: const EdgeInsets.all(18),
+        child: Column(
+          crossAxisAlignment: CrossAxisAlignment.start,
+          children: [
+            Row(
+              crossAxisAlignment: CrossAxisAlignment.start,
+              children: [
+                Icon(Icons.system_update_alt, color: colorScheme.error),
+                const SizedBox(width: 12),
+                Expanded(
+                  child: Column(
+                    crossAxisAlignment: CrossAxisAlignment.start,
+                    children: [
+                      Text(
+                        'US-DFU Device Detected',
+                        style: Theme.of(context).textTheme.titleLarge?.copyWith(
+                              fontWeight: FontWeight.w700,
+                            ),
+                      ),
+                      const SizedBox(height: 4),
+                      const Text(
+                        'US-DFU (Universal Shifters Firmware Update) device detected. Maybe a previous update failed?',
+                      ),
+                    ],
+                  ),
+                ),
+              ],
+            ),
+            const SizedBox(height: 12),
+            Text(
+              device.name.isEmpty ? device.id : '${device.name} - ${device.id}',
+              style: Theme.of(context).textTheme.bodySmall?.copyWith(
+                    color: colorScheme.onSurface.withValues(alpha: 0.68),
+                  ),
+            ),
+            const SizedBox(height: 12),
+            FilledButton.icon(
+              onPressed: onStartRecovery,
+              icon: const Icon(Icons.build_circle_outlined),
+              label: const Text('Start Recovery'),
+            ),
+          ],
+        ),
+      ),
+    );
+  }
+}
+
+class _BootloaderRecoverySetupPage extends ConsumerStatefulWidget {
+  const _BootloaderRecoverySetupPage({required this.device});
+
+  final DiscoveredDevice device;
+
+  @override
+  ConsumerState<_BootloaderRecoverySetupPage> createState() =>
+      _BootloaderRecoverySetupPageState();
+}
+
+class _BootloaderRecoverySetupPageState
+    extends ConsumerState<_BootloaderRecoverySetupPage> {
+  final FirmwareFileSelectionService _firmwareFileSelectionService =
+      FirmwareFileSelectionService(filePicker: LocalFirmwareFilePicker());
+
+  BootloaderDfuPreparedFirmware? _selectedFirmware;
+  bool _isSelectingFirmware = false;
+  String? _message;
+
+  Future<void> _selectFirmwareFile() async {
+    if (_isSelectingFirmware) {
+      return;
+    }
+
+    setState(() {
+      _isSelectingFirmware = true;
+      _message = null;
+    });
+
+    final suppressionCount = ref.read(
+      backgroundBluetoothDisconnectSuppressionCountProvider.notifier,
+    );
+    suppressionCount.state += 1;
+
+    final FirmwareFileSelectionResult result;
+    try {
+      result =
+          await _firmwareFileSelectionService.selectAndPrepareBootloaderDfu();
+    } finally {
+      suppressionCount.state =
+          suppressionCount.state <= 0 ? 0 : suppressionCount.state - 1;
+    }
+
+    if (!mounted) {
+      return;
+    }
+
+    setState(() {
+      _isSelectingFirmware = false;
+      if (result.isSuccess) {
+        _selectedFirmware = result.firmware;
+        _message =
+            'Validated ${result.firmware!.fileName}. Ready to start recovery.';
+      } else if (!result.isCanceled) {
+        _message = result.failure?.message;
+      }
+    });
+  }
+
+  void _startRecovery() {
+    final firmware = _selectedFirmware;
+    if (firmware == null) {
+      setState(() {
+        _message = 'Select a firmware .bin file before starting recovery.';
+      });
+      return;
+    }
+
+    Navigator.of(context).pop(firmware);
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    final theme = Theme.of(context);
+    final colorScheme = theme.colorScheme;
+    final selectedFirmware = _selectedFirmware;
+
+    return Scaffold(
+      appBar: AppBar(
+        title: const Text('US-DFU Recovery'),
+        leading: IconButton(
+          icon: const Icon(Icons.close),
+          onPressed: () => Navigator.of(context).pop(),
+        ),
+      ),
+      body: SafeArea(
+        child: ListView(
+          padding: const EdgeInsets.all(20),
+          children: [
+            Card(
+              child: Padding(
+                padding: const EdgeInsets.all(18),
+                child: Column(
+                  crossAxisAlignment: CrossAxisAlignment.start,
+                  children: [
+                    Row(
+                      children: [
+                        Icon(Icons.system_update_alt_rounded,
+                            color: colorScheme.primary),
+                        const SizedBox(width: 10),
+                        Text(
+                          'Recover Firmware Update',
+                          style: theme.textTheme.titleLarge?.copyWith(
+                            fontWeight: FontWeight.w700,
+                          ),
+                        ),
+                      ],
+                    ),
+                    const SizedBox(height: 10),
+                    Text(
+                      'Select a raw app image for the detected US-DFU bootloader. Starting recovery opens the firmware update screen.',
+                      style: theme.textTheme.bodyMedium?.copyWith(
+                        color: colorScheme.onSurface.withValues(alpha: 0.68),
+                      ),
+                    ),
+                    const SizedBox(height: 14),
+                    Text(
+                      widget.device.name.isEmpty
+                          ? widget.device.id
+                          : '${widget.device.name} - ${widget.device.id}',
+                      style: theme.textTheme.bodySmall,
+                    ),
+                  ],
+                ),
+              ),
+            ),
+            const SizedBox(height: 16),
+            Card(
+              child: Padding(
+                padding: const EdgeInsets.all(18),
+                child: Column(
+                  crossAxisAlignment: CrossAxisAlignment.start,
+                  children: [
+                    Text(
+                      selectedFirmware == null
+                          ? 'Selected file: none'
+                          : 'Selected file: ${selectedFirmware.fileName}',
+                      style: theme.textTheme.bodyMedium?.copyWith(
+                        fontWeight: FontWeight.w600,
+                      ),
+                    ),
+                    if (selectedFirmware != null) ...[
+                      const SizedBox(height: 6),
+                      Text(
+                        'Size: ${selectedFirmware.fileBytes.length} bytes  |  Session: ${selectedFirmware.metadata.sessionId}  |  CRC32: 0x${selectedFirmware.metadata.crc32.toRadixString(16).padLeft(8, '0').toUpperCase()}',
+                        style: theme.textTheme.bodySmall,
+                      ),
+                    ],
+                    const SizedBox(height: 14),
+                    Wrap(
+                      spacing: 8,
+                      runSpacing: 8,
+                      children: [
+                        OutlinedButton.icon(
+                          onPressed:
+                              _isSelectingFirmware ? null : _selectFirmwareFile,
+                          icon: _isSelectingFirmware
+                              ? const SizedBox(
+                                  width: 16,
+                                  height: 16,
+                                  child:
+                                      CircularProgressIndicator(strokeWidth: 2),
+                                )
+                              : const Icon(Icons.upload_file),
+                          label: const Text('Select Firmware'),
+                        ),
+                        FilledButton.icon(
+                          onPressed:
+                              selectedFirmware == null ? null : _startRecovery,
+                          icon: const Icon(Icons.system_update_alt),
+                          label: const Text('Start Update'),
+                        ),
+                      ],
+                    ),
+                    if (_message != null && _message!.isNotEmpty) ...[
+                      const SizedBox(height: 12),
+                      Text(_message!),
+                    ],
+                  ],
+                ),
+              ),
+            ),
+          ],
+        ),
+      ),
+    );
+  }
+}
+
 class _SavedDevicesList extends ConsumerStatefulWidget {
   const _SavedDevicesList();
 

lib/pages/home_page.dart

@@ -30,7 +30,6 @@ class HomePage extends StatelessWidget {
               style: TextStyle(fontSize: 20),
             ),
             const SizedBox(height: 20),
-            // Devices Section
             Container(
               padding: const EdgeInsets.only(left: 16, right: 16),
               child: Column(
@@ -84,7 +83,7 @@ class DevicesList extends ConsumerStatefulWidget {
 }
 
 class _DevicesListState extends ConsumerState<DevicesList> {
-  String? _connectingDeviceId; // ID of device currently being connected
+  String? _connectingDeviceId;
 
   Future<void> _removeDevice(ConnectedDevice device) async {
     final shouldRemove = await showDialog<bool>(
@@ -197,10 +196,10 @@ class _DevicesListState extends ConsumerState<DevicesList> {
                     context.go('/device/${device.deviceAddress}');
                   } else {
                     ScaffoldMessenger.of(context).showSnackBar(
-                      SnackBar(
+                      const SnackBar(
                         content: Text(
                             'Connection failed. Is the device turned on and in range?'),
-                        duration: const Duration(seconds: 3),
+                        duration: Duration(seconds: 3),
                       ),
                     );
                   }

lib/service/firmware_update_service.dart

@@ -11,6 +11,7 @@ import 'package:flutter_reactive_ble/flutter_reactive_ble.dart'
 class FirmwareUpdateService {
   FirmwareUpdateService({
     required FirmwareUpdateTransport transport,
+    this.verifyAfterFinish = true,
     this.defaultStatusTimeout = const Duration(seconds: 2),
     this.defaultBootloaderConnectTimeout = const Duration(seconds: 60),
     this.defaultPostFinishResetTimeout = const Duration(seconds: 8),
@@ -22,6 +23,7 @@ class FirmwareUpdateService {
   }) : _transport = transport;
 
   final FirmwareUpdateTransport _transport;
+  final bool verifyAfterFinish;
   final Duration defaultStatusTimeout;
   final Duration defaultBootloaderConnectTimeout;
   final Duration defaultPostFinishResetTimeout;
@@ -220,6 +222,15 @@ class FirmwareUpdateService {
         );
       }
 
+      if (!verifyAfterFinish) {
+        _emitProgress(
+          state: DfuUpdateState.completed,
+          sentBytes: imageBytes.length,
+          expectedOffset: imageBytes.length,
+        );
+        return Ok(null);
+      }
+
       _emitProgress(state: DfuUpdateState.verifying);
       final reconnectResult = await _transport.reconnectForVerification(
         timeout: effectiveReconnectTimeout,
@@ -831,6 +842,14 @@ class ShifterFirmwareUpdateTransport implements FirmwareUpdateTransport {
       return Ok(null);
     }
 
+    if (shifterService == null) {
+      _bootloaderDeviceId = buttonDeviceId;
+      return bluetoothController.connectById(
+        buttonDeviceId,
+        timeout: timeout,
+      );
+    }
+
     final scanResult = await _scanForBootloader(timeout: timeout);
     if (scanResult.isErr()) {
       return Err(scanResult.unwrapErr());

lib/widgets/firmware_update_fullscreen.dart

@@ -0,0 +1,247 @@
+import 'package:abawo_bt_app/model/firmware_file_selection.dart';
+import 'package:abawo_bt_app/model/shifter_types.dart';
+import 'package:flutter/material.dart';
+
+class FirmwareUpdateFullscreen extends StatelessWidget {
+  const FirmwareUpdateFullscreen({
+    super.key,
+    required this.progress,
+    required this.selectedFirmware,
+    required this.phaseText,
+    required this.statusText,
+    required this.formattedProgressBytes,
+    required this.expectedOffsetHex,
+    required this.onDismiss,
+    this.doneLabel = 'Done',
+    this.failedLabel = 'Back to device',
+  });
+
+  final DfuUpdateProgress progress;
+  final BootloaderDfuPreparedFirmware? selectedFirmware;
+  final String phaseText;
+  final String? statusText;
+  final String formattedProgressBytes;
+  final String expectedOffsetHex;
+  final VoidCallback onDismiss;
+  final String doneLabel;
+  final String failedLabel;
+
+  bool get _isTerminal =>
+      progress.state == DfuUpdateState.completed ||
+      progress.state == DfuUpdateState.failed;
+
+  bool get _isRunning => !_isTerminal && progress.state != DfuUpdateState.idle;
+
+  String? get _bootloaderStatusText {
+    final status = progress.bootloaderStatus;
+    if (status == null) {
+      return null;
+    }
+    final codeLabel = switch (status.code) {
+      DfuBootloaderStatusCode.ok => 'OK',
+      DfuBootloaderStatusCode.parseError => 'parse error',
+      DfuBootloaderStatusCode.stateError => 'state error',
+      DfuBootloaderStatusCode.boundsError => 'bounds error',
+      DfuBootloaderStatusCode.crcError => 'CRC error',
+      DfuBootloaderStatusCode.flashError => 'flash error',
+      DfuBootloaderStatusCode.unsupportedError => 'unsupported flags',
+      DfuBootloaderStatusCode.vectorError => 'vector table error',
+      DfuBootloaderStatusCode.queueFull => 'queue full',
+      DfuBootloaderStatusCode.bootMetadataError => 'boot metadata error',
+      DfuBootloaderStatusCode.unknown =>
+        'unknown 0x${status.rawCode.toRadixString(16).padLeft(2, '0').toUpperCase()}',
+    };
+    return '$codeLabel  •  session ${status.sessionId}  •  offset 0x${status.expectedOffset.toRadixString(16).padLeft(8, '0').toUpperCase()}';
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    final theme = Theme.of(context);
+    final colorScheme = theme.colorScheme;
+    final isFailed = progress.state == DfuUpdateState.failed;
+
+    return PopScope(
+      canPop: false,
+      child: Scaffold(
+        backgroundColor: colorScheme.surface,
+        body: SafeArea(
+          child: Column(
+            children: [
+              if (_isRunning)
+                Container(
+                  width: double.infinity,
+                  padding:
+                      const EdgeInsets.symmetric(horizontal: 20, vertical: 12),
+                  color: colorScheme.errorContainer,
+                  child: Row(
+                    children: [
+                      Icon(Icons.warning_amber_rounded,
+                          color: colorScheme.onErrorContainer, size: 20),
+                      const SizedBox(width: 10),
+                      Expanded(
+                        child: Text(
+                          'Do not close the app, lock the phone, or move away from the button.',
+                          style: theme.textTheme.bodySmall?.copyWith(
+                            color: colorScheme.onErrorContainer,
+                            fontWeight: FontWeight.w600,
+                          ),
+                        ),
+                      ),
+                    ],
+                  ),
+                ),
+              Expanded(
+                child: SingleChildScrollView(
+                  padding: const EdgeInsets.fromLTRB(24, 32, 24, 24),
+                  child: Column(
+                    crossAxisAlignment: CrossAxisAlignment.center,
+                    children: [
+                      Icon(
+                        _isTerminal
+                            ? (isFailed
+                                ? Icons.error_outline_rounded
+                                : Icons.check_circle_outline_rounded)
+                            : Icons.system_update_alt_rounded,
+                        size: 56,
+                        color: _isTerminal
+                            ? (isFailed
+                                ? colorScheme.error
+                                : colorScheme.primary)
+                            : colorScheme.primary,
+                      ),
+                      const SizedBox(height: 16),
+                      Text(
+                        _isTerminal
+                            ? (isFailed ? 'Update failed' : 'Update completed')
+                            : 'Updating firmware',
+                        style: theme.textTheme.headlineSmall?.copyWith(
+                          fontWeight: FontWeight.w700,
+                        ),
+                      ),
+                      const SizedBox(height: 8),
+                      Text(
+                        phaseText,
+                        style: theme.textTheme.bodyLarge?.copyWith(
+                          color: colorScheme.onSurface.withValues(alpha: 0.72),
+                        ),
+                      ),
+                      if (selectedFirmware != null) ...[
+                        const SizedBox(height: 12),
+                        Text(
+                          '${selectedFirmware!.fileName}  •  ${_formatBytes(selectedFirmware!.fileBytes.length)}',
+                          style: theme.textTheme.bodySmall,
+                        ),
+                      ],
+                      const SizedBox(height: 24),
+                      if (_isRunning) ...[
+                        LinearProgressIndicator(
+                          value: progress.totalBytes > 0
+                              ? progress.fractionComplete
+                              : null,
+                          minHeight: 12,
+                          borderRadius: BorderRadius.circular(999),
+                        ),
+                        const SizedBox(height: 12),
+                        Text(
+                          '${progress.percentComplete}%  •  $formattedProgressBytes',
+                          style: theme.textTheme.bodyMedium?.copyWith(
+                            fontWeight: FontWeight.w600,
+                          ),
+                        ),
+                      ],
+                      if (progress.state == DfuUpdateState.finishing ||
+                          progress.state == DfuUpdateState.rebooting ||
+                          progress.state == DfuUpdateState.verifying) ...[
+                        const SizedBox(height: 20),
+                        Container(
+                          width: double.infinity,
+                          padding: const EdgeInsets.all(14),
+                          decoration: BoxDecoration(
+                            color: colorScheme.primaryContainer
+                                .withValues(alpha: 0.36),
+                            borderRadius: BorderRadius.circular(14),
+                          ),
+                          child: Row(
+                            children: [
+                              SizedBox(
+                                width: 18,
+                                height: 18,
+                                child: CircularProgressIndicator(
+                                    strokeWidth: 2, color: colorScheme.primary),
+                              ),
+                              const SizedBox(width: 10),
+                              Expanded(
+                                child: Text(
+                                  'Bootloader is verifying, resetting, and booting the new app. Keep the screen open.',
+                                  style: theme.textTheme.bodySmall?.copyWith(
+                                    color: colorScheme.primary,
+                                    fontWeight: FontWeight.w600,
+                                  ),
+                                ),
+                              ),
+                            ],
+                          ),
+                        ),
+                      ],
+                      if (_bootloaderStatusText != null) ...[
+                        const SizedBox(height: 12),
+                        Text(
+                          _bootloaderStatusText!,
+                          style: theme.textTheme.bodySmall?.copyWith(
+                            color:
+                                colorScheme.onSurface.withValues(alpha: 0.56),
+                          ),
+                        ),
+                      ],
+                      if (statusText != null &&
+                          statusText!.trim().isNotEmpty) ...[
+                        const SizedBox(height: 20),
+                        Container(
+                          width: double.infinity,
+                          padding: const EdgeInsets.all(14),
+                          decoration: BoxDecoration(
+                            color: isFailed
+                                ? colorScheme.errorContainer
+                                : colorScheme.surfaceContainerHighest,
+                            borderRadius: BorderRadius.circular(14),
+                          ),
+                          child: Text(
+                            statusText!,
+                            style: theme.textTheme.bodyMedium?.copyWith(
+                              color: isFailed
+                                  ? colorScheme.onErrorContainer
+                                  : null,
+                            ),
+                          ),
+                        ),
+                      ],
+                      if (_isTerminal) ...[
+                        const SizedBox(height: 32),
+                        SizedBox(
+                          width: double.infinity,
+                          child: FilledButton.icon(
+                            onPressed: onDismiss,
+                            icon: Icon(isFailed
+                                ? Icons.arrow_back_rounded
+                                : Icons.check_rounded),
+                            label: Text(isFailed ? failedLabel : doneLabel),
+                          ),
+                        ),
+                      ],
+                    ],
+                  ),
+                ),
+              ),
+            ],
+          ),
+        ),
+      ),
+    );
+  }
+
+  String _formatBytes(int bytes) {
+    if (bytes < 1024) return '$bytes B';
+    if (bytes < 1024 * 1024) return '${(bytes / 1024).toStringAsFixed(1)} KB';
+    return '${(bytes / (1024 * 1024)).toStringAsFixed(2)} MB';
+  }
+}