fix(bitbox): recover from BLE/USB disconnect without losing wallet session

android/app/src/main/AndroidManifest.xml

@@ -2,6 +2,12 @@
     <uses-permission android:name="android.permission.CAMERA" />
     <uses-permission android:name="android.permission.USE_BIOMETRIC"/>
 
+    <!-- BitBox02 connects via USB-OTG on Android. Declared as optional so the
+         app still installs on tablets/devices without USB host support; the
+         BitBox flow simply won't be usable there. The actual per-device
+         permission is requested at runtime by bitbox_flutter. -->
+    <uses-feature android:name="android.hardware.usb.host" android:required="false" />
+
     <application
         android:label="Real Unit Wallet"
         android:name="${applicationName}"

assets/languages/strings_de.arb

@@ -19,6 +19,9 @@
   "biometricAuthenticationActivateDescription": "Verwenden Sie Face ID oder Ihren Fingerabdruck, um Ihre Wallet schnell und sicher zu entsperren.",
   "birthday": "Geburtstag",
   "bitbox": "BitBox",
+  "bitboxDisconnectedDescription": "Die Verbindung zur BitBox wurde unterbrochen. Bitte verbinden Sie Ihre BitBox erneut und versuchen Sie es noch einmal.",
+  "bitboxDisconnectedTitle": "BitBox ist nicht verbunden",
+  "bitboxReconnect": "BitBox erneut verbinden",
   "blockchain": "Blockchain",
   "buy": "Kaufen",
   "buyExecutedDescription": "Sobald Ihre Überweisung eingegangen ist, übertragen wir die REALU-Token in Ihre Wallet. Über den Fortschritt Ihrer Transaktion informieren wir Sie per E-Mail.",
@@ -306,6 +309,7 @@
   "twoFaSendCodeFailed": "Es ist ein Problem beim Senden der Mail aufgetreten",
   "twoFaWrongCode": "Der Code ist falsch",
   "userData": "Nutzerdaten",
+  "userDataLoadFailed": "Beim Laden der Nutzerdaten ist ein Fehler aufgetreten.",
   "userDataNotFound": "Zu dieser Wallet sind keine Nutzerdaten hinterlegt.",
   "verifySeedInvalid": "Die Wörter stimmen nicht überein",
   "verifySeedSubtitle": "Bitte geben Sie die folgenden Wörter aus Ihrer Wiederherstellungsphrase ein, um zu bestätigen, dass Sie sie korrekt notiert haben.",

assets/languages/strings_en.arb

@@ -19,6 +19,9 @@
   "biometricAuthenticationActivateDescription": "Use Face ID or fingerprint to unlock your wallet quickly and securely.",
   "birthday": "Birthday",
   "bitbox": "BitBox",
+  "bitboxDisconnectedDescription": "The connection to the BitBox was lost. Please reconnect your BitBox and try again.",
+  "bitboxDisconnectedTitle": "BitBox is not connected",
+  "bitboxReconnect": "Reconnect BitBox",
   "blockchain": "Blockchain",
   "buy": "Buy",
   "buyExecutedDescription": "As soon as your transfer has been received, we will transfer the REALU tokens to your wallet. We will inform you about the progress of your transaction by email.",
@@ -306,6 +309,7 @@
   "twoFaSendCodeFailed": "There was a problem sending the email",
   "twoFaWrongCode": "The Code is wrong",
   "userData": "User data",
+  "userDataLoadFailed": "An error occurred while loading user data.",
   "userDataNotFound": "No user data is stored for this wallet.",
   "verifySeedInvalid": "The words don't match",
   "verifySeedSubtitle": "Please enter the following words from your recovery phrase to confirm you've written them down correctly.",

lib/packages/hardware_wallet/bitbox.dart

@@ -1,4 +1,5 @@
 import 'dart:async';
+import 'dart:developer' as developer;
 
 import 'package:bitbox_flutter/bitbox_flutter.dart';
 import 'package:realunit_wallet/packages/hardware_wallet/bitbox_credentials.dart';
@@ -15,9 +16,9 @@ class BitboxService {
 
   BitboxCredentials getCredentials(String address) {
     final credentials = BitboxCredentials(address);
+    _credentials = credentials;
     if (_isConnected) {
       credentials.setBitbox(bitboxManager);
-      _credentials = credentials;
     }
     return credentials;
   }
@@ -27,6 +28,11 @@ class BitboxService {
     final didInit = await bitboxManager.initBitBox();
     if (!didInit) throw Exception('Failed to init');
     _isConnected = true;
+    // Restore the bitbox manager on any credentials handed out before this
+    // (re-)connect — otherwise existing wallets keep a cleared credentials
+    // instance and the next sign throws BitboxNotConnectedException even
+    // though the device is back online.
+    _credentials?.setBitbox(bitboxManager);
     return didInit;
   }
 
@@ -37,8 +43,18 @@ class BitboxService {
       if (devices.isEmpty) {
         _isConnected = false;
         _credentials?.clearBitbox();
-        _credentials = null;
+        // Keep the _credentials reference so init() can re-attach the manager
+        // on the same instance after a reconnect.
         stopConnectionStatusObserver();
+        // Close the underlying transport. Required on Android so the USB
+        // file-descriptor is released — otherwise the next connect() can
+        // fail because the OS still considers the device claimed. Safe on
+        // iOS where the BLE link is already gone at this point.
+        try {
+          await bitboxManager.disconnect();
+        } catch (e) {
+          developer.log('disconnect after device-loss failed: $e', name: '$BitboxService');
+        }
       }
     });
   }

lib/packages/hardware_wallet/bitbox_credentials.dart

@@ -61,11 +61,13 @@ class BitboxCredentials extends CredentialsWithKnownAddress {
       if (!isConnected) throw const BitboxNotConnectedException();
 
       if (isEIP1559) payload = payload.sublist(1);
-      final sig = await bitboxManager!.signETHRLPTransaction(
-        chainId ?? 1,
-        derivationPath!,
-        bytesToHex(payload),
-        isEIP1559,
+      final sig = await _runOrThrowDisconnect(
+        () => bitboxManager!.signETHRLPTransaction(
+          chainId ?? 1,
+          derivationPath!,
+          bytesToHex(payload),
+          isEIP1559,
+        ),
       );
 
       final r = bytesToHex(sig.sublist(0, 32));
@@ -101,7 +103,9 @@ class BitboxCredentials extends CredentialsWithKnownAddress {
   Future<Uint8List> signPersonalMessage(Uint8List payload, {int? chainId}) {
     return _synchronizeSign(() async {
       if (!isConnected) throw const BitboxNotConnectedException();
-      return await bitboxManager!.signETHMessage(chainId ?? 1, derivationPath!, payload);
+      return await _runOrThrowDisconnect(
+        () => bitboxManager!.signETHMessage(chainId ?? 1, derivationPath!, payload),
+      );
     });
   }
 
@@ -113,14 +117,43 @@ class BitboxCredentials extends CredentialsWithKnownAddress {
     return _synchronizeSign(() async {
       if (!isConnected) throw const BitboxNotConnectedException();
 
-      final signatureBytes = await bitboxManager!.signETHTypedMessage(
-        chainId,
-        derivationPath!,
-        Uint8List.fromList(utf8.encode(jsonData)),
+      final signatureBytes = await _runOrThrowDisconnect(
+        () => bitboxManager!.signETHTypedMessage(
+          chainId,
+          derivationPath!,
+          Uint8List.fromList(utf8.encode(jsonData)),
+        ),
       );
       return '0x${convert.hex.encode(signatureBytes)}';
     });
   }
 
+  /// Wrap a sign call so that a BLE/USB drop mid-operation surfaces as
+  /// [BitboxNotConnectedException] instead of a raw plugin error. If the
+  /// device is still reachable after the failure, the original error wins.
+  Future<T> _runOrThrowDisconnect<T>(Future<T> Function() op) async {
+    try {
+      return await op();
+    } catch (_) {
+      if (await _deviceLost()) {
+        clearBitbox();
+        throw const BitboxNotConnectedException();
+      }
+      rethrow;
+    }
+  }
+
+  Future<bool> _deviceLost() async {
+    final manager = bitboxManager;
+    if (manager == null) return true;
+    try {
+      final devices = await manager.devices;
+      return devices.isEmpty;
+    } catch (_) {
+      // Probing the device list itself failed — treat as lost.
+      return true;
+    }
+  }
+
   bool get isConnected => bitboxManager != null;
 }

lib/packages/repository/wallet_repository.dart

@@ -9,15 +9,33 @@ class WalletRepository {
 
   const WalletRepository(this._appDatabase, this._secureStorage);
 
-  Future<int> createWallet(String name, WalletType type, String seed) async {
+  Future<int> createWallet(
+    String name,
+    WalletType type,
+    String seed,
+    String address,
+  ) async {
     final encryptedSeed = await _encryptSeed(seed);
-    return _appDatabase.insertWallet(name, encryptedSeed, '', type.index);
+    return _appDatabase.insertWallet(name, encryptedSeed, address, type.index);
   }
 
   Future<int> createViewWallet(String name, WalletType type, String address) =>
       _appDatabase.insertWallet(name, '', address, type.index);
 
-  Future<WalletInfo?> getWalletById(int id) async {
+  /// Returns the wallet row with the encrypted seed *still encrypted*. Use this
+  /// at app startup so we don't pay the mnemonic-decrypt / BIP32-derivation
+  /// cost just to render the dashboard — the cached address is enough.
+  Future<WalletInfo?> getWalletInfo(int id) => _appDatabase.getWalletById(id);
+
+  /// Backfills the address column for legacy software-wallet rows that were
+  /// created before address-caching landed. After this runs once, subsequent
+  /// loads of the same row stay on the fast view-wallet path.
+  Future<void> updateAddress(int id, String address) =>
+      _appDatabase.updateWalletAddress(id, address);
+
+  /// Returns the wallet row with the seed decrypted. Only call this when the
+  /// private key is actually needed (signing a sell, revealing the seed).
+  Future<WalletInfo?> getUnlockedWalletById(int id) async {
     final info = await _appDatabase.getWalletById(id);
     if (info == null) return null;
     if (info.seed.isEmpty) return info;

lib/packages/service/app_store.dart

@@ -10,6 +10,12 @@ class AppStore {
 
   AWallet? _wallet;
 
+  /// Callback that decrypts the mnemonic and returns a fully unlocked
+  /// [SoftwareWallet]. Wired up after DI registers `WalletService`; null until
+  /// then. Used by [ensureUnlocked] so callers don't have to import the
+  /// service layer just to upgrade a view-wallet.
+  Future<AWallet> Function()? _unlocker;
+
   AppStore(this.getApiConfig, this.sessionCache);
 
   set wallet(AWallet wallet_) => _wallet = wallet_;
@@ -22,4 +28,19 @@ class AppStore {
   ApiConfig get apiConfig => getApiConfig();
 
   String get primaryAddress => wallet.currentAccount.primaryAddress.address.hex;
+
+  void attachUnlocker(Future<AWallet> Function() unlocker) {
+    _unlocker = unlocker;
+  }
+
+  /// Upgrades the current wallet from [SoftwareViewWallet] (address only) to a
+  /// fully unlocked [SoftwareWallet] (mnemonic in memory) so the next sign
+  /// operation can run. No-op for wallets that aren't locked, or when no
+  /// unlocker has been wired (e.g. tests).
+  Future<void> ensureUnlocked() async {
+    if (_wallet is! SoftwareViewWallet) return;
+    final unlocker = _unlocker;
+    if (unlocker == null) return;
+    _wallet = await unlocker();
+  }
 }

lib/packages/service/dfx/dfx_auth_service.dart

@@ -24,21 +24,42 @@ abstract class DFXAuthService {
 
   String get walletAddress => wallet.primaryAddress.address.hexEip55;
 
-  Future<String> getSignMessage() async {
-    final uri = buildUri(host, signMessagePath, {'address': walletAddress});
+  Future<String> getSignMessage() => _fetchSignMessage(walletAddress);
+
+  /// Create-and-persist the auth signature for [account] without going through
+  /// `appStore.wallet`. Used during the BitBox pairing flow so the signature is
+  /// captured while the hardware wallet is guaranteed connected — every
+  /// subsequent buy / KYC / user-data call can then run off the cached
+  /// signature without needing the BitBox.
+  ///
+  /// No-op if a signature for this address is already in the cache.
+  Future<void> ensureSignatureFor(AWalletAccount account) async {
+    final address = account.primaryAddress.address.hexEip55;
+    await appStore.sessionCache.loadSignature();
+    if (appStore.sessionCache.signature != null &&
+        appStore.sessionCache.signatureAddress == address) {
+      return;
+    }
 
+    final message = await _fetchSignMessage(address);
+    final signature = await account.signMessage(message).timeout(_signMessageTimeout);
+    if (signature.isEmpty || signature == '0x') {
+      throw const SigningCancelledException();
+    }
+    await appStore.sessionCache.saveSignature(address, signature);
+  }
+
+  Future<String> _fetchSignMessage(String address) async {
+    final uri = buildUri(host, signMessagePath, {'address': address});
     final response = await appStore.httpClient
         .get(uri, headers: {'accept': 'application/json'})
         .timeout(_httpTimeout);
-
-    if (response.statusCode == 200) {
-      final responseBody = jsonDecode(response.body);
-      return responseBody['message'] as String;
-    } else {
+    if (response.statusCode != 200) {
       throw Exception(
         'Failed to get sign message. Status: ${response.statusCode} ${response.body}',
       );
     }
+    return (jsonDecode(response.body) as Map<String, dynamic>)['message'] as String;
   }
 
   // Exceptions this method can throw on the BitBox path:
@@ -54,6 +75,9 @@ abstract class DFXAuthService {
       return cached;
     }
 
+    // Cache miss — we actually need the private key. Decrypt the mnemonic on
+    // demand if the currently loaded wallet is a view-only software wallet.
+    await appStore.ensureUnlocked();
     final signature = await wallet.signMessage(message).timeout(_signMessageTimeout);
     if (signature.isEmpty || signature == '0x') {
       throw const SigningCancelledException();

lib/packages/service/dfx/exceptions/bitbox_exception.dart

@@ -1,3 +1,6 @@
 class BitboxNotConnectedException implements Exception {
   const BitboxNotConnectedException();
+
+  @override
+  String toString() => 'BitBox is not connected';
 }

lib/packages/service/dfx/models/payment/payment_info_error.dart

@@ -2,5 +2,6 @@ enum PaymentInfoError {
   registrationRequired,
   kycRequired,
   minAmountNotMet,
+  bitboxDisconnected,
   unknown,
 }

lib/packages/service/dfx/real_unit_registration_service.dart

@@ -51,6 +51,9 @@ class RealUnitRegistrationService extends DFXAuthService {
 
   /// registers a wallet and and adds the wallet to the new user
   Future<RegistrationStatus> completeRegistration(Registration registration) async {
+    // EIP-712 registration signature requires the private key — promote the
+    // view-wallet (if any) to a fully unlocked SoftwareWallet first.
+    await appStore.ensureUnlocked();
     final credentials = appStore.wallet.primaryAccount.primaryAddress;
     // BitBox firmware rejects non-ASCII bytes in EIP-712 string fields.
     // Transliterate everything that goes into the signed envelope AND the

lib/packages/service/dfx/real_unit_sell_payment_info_service.dart

@@ -78,6 +78,10 @@ class RealUnitSellPaymentInfoService extends DFXAuthService {
 
   /// Confirms payment for Software Wallet
   Future<void> confirmPayment(SellPaymentInfo paymentInfo) async {
+    // EIP-712 + EIP-7702 typed-data signing requires the private key; promote
+    // the view-wallet to a fully unlocked SoftwareWallet before reading
+    // credentials.
+    await appStore.ensureUnlocked();
     final credentials = appStore.wallet.currentAccount.primaryAddress;
     _validateEip7702Data(paymentInfo.eip7702, credentials.address.hexEip55, paymentInfo.amount);