Add OP_RETURN support required for rosen bridge

diff --git a/lib/pages/send_view/send_view.dart b/lib/pages/send_view/send_view.dart
index a2dd4f4..48f3290 100644
--- a/lib/pages/send_view/send_view.dart
+++ b/lib/pages/send_view/send_view.dart
@@ -160,7 +160,6 @@ class _SendViewState extends ConsumerState<SendView> {
     try {
       // auto fill address
       _address = paymentData.address.trim();
-      sendToController.text = _address!;
 
       // autofill notes field
       if (paymentData.message != null) {
@@ -180,7 +179,25 @@ class _SendViewState extends ConsumerState<SendView> {
         ref.read(pSendAmount.notifier).state = amount;
       }
 
+      // Extract OP_RETURN data if present (for Rosen Bridge and other protocols)
+      // Must be set BEFORE sendToController.text to avoid re-entrant
+      // onChanged handler reading stale null value.
+      if (paymentData.additionalParams.containsKey('op_return')) {
+        final data = paymentData.additionalParams['op_return'];
+        ref.read(pOpReturnData.notifier).state = data;
+        Logging.instance.i(
+          "Extracted OP_RETURN data from URI, length: ${data!.length ~/ 2} bytes",
+        );
+      } else {
+        ref.read(pOpReturnData.notifier).state = null;
+      }
+
       _setValidAddressProviders(_address);
+
+      // Assign controller.text last — it triggers onChanged which depends
+      // on pOpReturnData already being set above.
+      sendToController.text = _address!;
+
       setState(() {
         _addressToggleFlag = sendToController.text.isNotEmpty;
       });
@@ -923,6 +940,7 @@ class _SendViewState extends ConsumerState<SendView> {
                     selectedUTXOs.isNotEmpty)
                 ? selectedUTXOs
                 : null,
+            opReturnData: ref.read(pOpReturnData),
           ),
         );
       } else if (wallet is FiroWallet) {
@@ -964,6 +982,7 @@ class _SendViewState extends ConsumerState<SendView> {
                   utxos: (coinControlEnabled && selectedUTXOs.isNotEmpty)
                       ? selectedUTXOs
                       : null,
+                  opReturnData: ref.read(pOpReturnData),
                 ),
               );
             }
@@ -1136,6 +1155,7 @@ class _SendViewState extends ConsumerState<SendView> {
     memoController.text = "";
     _address = "";
     _addressToggleFlag = false;
+    ref.read(pOpReturnData.notifier).state = null;
     if (mounted) {
       setState(() {});
     }
@@ -1726,9 +1746,10 @@ class _SendViewState extends ConsumerState<SendView> {
                                     final trimmed = newValue.trim();
 
                                     if ((trimmed.length -
-                                                (_address?.length ?? 0))
-                                            .abs() >
-                                        1) {
+                                                    (_address?.length ?? 0))
+                                                .abs() >
+                                            1 ||
+                                        trimmed.contains(':')) {
                                       final parsed =
                                           AddressUtils.parsePaymentUri(
                                             trimmed,
@@ -1737,6 +1758,8 @@ class _SendViewState extends ConsumerState<SendView> {
                                       if (parsed != null) {
                                         _applyUri(parsed);
                                       } else {
+                                        ref.read(pOpReturnData.notifier).state =
+                                            null;
                                         await _checkSparkNameAndOrSetAddress(
                                           newValue,
                                         );
@@ -1949,6 +1972,38 @@ class _SendViewState extends ConsumerState<SendView> {
                                       ),
                                 ),
                               ),
+                            if (ref.watch(pOpReturnData) != null &&
+                                _address != null &&
+                                _address!.isNotEmpty &&
+                                (ref.watch(pValidSendToAddress) ||
+                                    ref.watch(pValidSparkSendToAddress)) &&
+                                balType == BalanceType.public)
+                              Align(
+                                alignment: Alignment.topLeft,
+                                child: Padding(
+                                  padding: const EdgeInsets.only(
+                                    left: 12.0,
+                                    top: 4.0,
+                                  ),
+                                  child: Tooltip(
+                                    message: AddressUtils.formatOpReturnTooltip(
+                                      ref.watch(pOpReturnData)!,
+                                    ),
+                                    child: Text(
+                                      "Transaction includes metadata "
+                                      "(${ref.watch(pOpReturnData)!.length ~/ 2} bytes) "
+                                      "\u2014 tap for details",
+                                      textAlign: TextAlign.left,
+                                      style: STextStyles.label(context)
+                                          .copyWith(
+                                            color: Theme.of(context)
+                                                .extension<StackColors>()!
+                                                .accentColorGreen,
+                                          ),
+                                    ),
+                                  ),
+                                ),
+                              ),
                             Builder(
                               builder: (_) {
                                 final String? error;
@@ -2666,16 +2721,42 @@ class _SendViewState extends ConsumerState<SendView> {
                               ),
                             const Spacer(),
                             const SizedBox(height: 12),
+                            if (ref.watch(pOpReturnData) != null &&
+                                balType == BalanceType.private)
+                              Padding(
+                                padding: const EdgeInsets.only(
+                                  left: 12.0,
+                                  right: 12.0,
+                                  bottom: 12.0,
+                                ),
+                                child: Text(
+                                  "Bridge data detected but Spark (private) "
+                                  "transactions cannot carry OP_RETURN data. "
+                                  "Switch to public balance to complete the "
+                                  "bridge transaction.",
+                                  textAlign: TextAlign.left,
+                                  style: STextStyles.label(context).copyWith(
+                                    color: Theme.of(
+                                      context,
+                                    ).extension<StackColors>()!.textError,
+                                  ),
+                                ),
+                              ),
                             TextButton(
                               onPressed:
-                                  ref.watch(pPreviewTxButtonEnabled(coin))
+                                  ref.watch(pPreviewTxButtonEnabled(coin)) &&
+                                      (ref.watch(pOpReturnData) == null ||
+                                          balType != BalanceType.private)
                                   ? isMwcSlatepack
                                         ? _createSlatepack
                                         : isEpicSlatepack
                                         ? _createEpicSlatepack
                                         : _previewTransaction
                                   : null,
-                              style: ref.watch(pPreviewTxButtonEnabled(coin))
+                              style:
+                                  ref.watch(pPreviewTxButtonEnabled(coin)) &&
+                                      (ref.watch(pOpReturnData) == null ||
+                                          balType != BalanceType.private)
                                   ? Theme.of(context)
                                         .extension<StackColors>()!
                                         .getPrimaryEnabledButtonStyle(context)
diff --git a/lib/pages_desktop_specific/my_stack_view/wallet_view/sub_widgets/desktop_send.dart b/lib/pages_desktop_specific/my_stack_view/wallet_view/sub_widgets/desktop_send.dart
index efc02f6..72b646e 100644
--- a/lib/pages_desktop_specific/my_stack_view/wallet_view/sub_widgets/desktop_send.dart
+++ b/lib/pages_desktop_specific/my_stack_view/wallet_view/sub_widgets/desktop_send.dart
@@ -650,6 +650,7 @@ class _DesktopSendState extends ConsumerState<DesktopSend> {
                           ref.read(pDesktopUseUTXOs).isNotEmpty)
                       ? ref.read(pDesktopUseUTXOs)
                       : null,
+                  opReturnData: ref.read(pOpReturnData),
                 ),
               );
             }
@@ -920,8 +921,11 @@ class _DesktopSendState extends ConsumerState<DesktopSend> {
 
       if (paymentData != null &&
           paymentData.coin?.uriScheme == coin.uriScheme) {
+        ref.read(pOpReturnData.notifier).state =
+            paymentData.additionalParams['op_return'];
         _applyUri(paymentData);
       } else {
+        ref.read(pOpReturnData.notifier).state = null;
         _address = qrCodeData.split("\n").first.trim();
         sendToController.text = _address ?? "";
 
@@ -1050,8 +1054,11 @@ class _DesktopSendState extends ConsumerState<DesktopSend> {
         );
         if (paymentData != null &&
             paymentData.coin?.uriScheme == coin.uriScheme) {
+          ref.read(pOpReturnData.notifier).state =
+              paymentData.additionalParams['op_return'];
           _applyUri(paymentData);
         } else {
+          ref.read(pOpReturnData.notifier).state = null;
           if (coin is Epiccash) {
             content = AddressUtils().formatEpicCashAddress(content);
           }
@@ -1068,6 +1075,7 @@ class _DesktopSendState extends ConsumerState<DesktopSend> {
           });
         }
       } catch (e) {
+        ref.read(pOpReturnData.notifier).state = null;
         // If parsing fails, treat it as a plain address.
         if (coin is Epiccash) {
           // strip http:// and https:// if content contains @
@@ -1754,14 +1762,18 @@ class _DesktopSendState extends ConsumerState<DesktopSend> {
               onChanged: (newValue) async {
                 final trimmed = newValue;
 
-                if ((trimmed.length - (_address?.length ?? 0)).abs() > 1) {
+                if ((trimmed.length - (_address?.length ?? 0)).abs() > 1 ||
+                    trimmed.contains(':')) {
                   final parsed = AddressUtils.parsePaymentUri(
                     trimmed,
                     logging: Logging.instance,
                   );
                   if (parsed != null) {
+                    ref.read(pOpReturnData.notifier).state =
+                        parsed.additionalParams['op_return'];
                     _applyUri(parsed);
                   } else {
+                    ref.read(pOpReturnData.notifier).state = null;
                     await _checkSparkNameAndOrSetAddress(newValue);
                   }
                 } else {
@@ -1815,6 +1827,8 @@ class _DesktopSendState extends ConsumerState<DesktopSend> {
                                     onTap: () {
                                       sendToController.text = "";
                                       _address = "";
+                                      ref.read(pOpReturnData.notifier).state =
+                                          null;
                                       _setValidAddressProviders(_address);
                                       setState(() {
                                         _addressToggleFlag = false;
@@ -1960,6 +1974,66 @@ class _DesktopSendState extends ConsumerState<DesktopSend> {
               }
             },
           ),
+        // OP_RETURN metadata info (green, public mode only, with tooltip)
+        Builder(
+          builder: (context) {
+            final opData = ref.watch(pOpReturnData);
+            final balType = ref.watch(publicPrivateBalanceStateProvider);
+            if (opData == null ||
+                opData.isEmpty ||
+                balType != BalanceType.public) {
+              return Container();
+            }
+            return Align(
+              alignment: Alignment.topLeft,
+              child: Padding(
+                padding: const EdgeInsets.only(left: 12.0, top: 4.0),
+                child: Tooltip(
+                  message: AddressUtils.formatOpReturnTooltip(opData),
+                  child: Text(
+                    "Transaction includes metadata "
+                    "(${opData.length ~/ 2} bytes)",
+                    textAlign: TextAlign.left,
+                    style: STextStyles.label(context).copyWith(
+                      color: Theme.of(
+                        context,
+                      ).extension<StackColors>()!.accentColorGreen,
+                    ),
+                  ),
+                ),
+              ),
+            );
+          },
+        ),
+        // OP_RETURN bridge warning (red, private mode only)
+        Builder(
+          builder: (context) {
+            final opData = ref.watch(pOpReturnData);
+            final balType = ref.watch(publicPrivateBalanceStateProvider);
+            if (opData == null ||
+                opData.isEmpty ||
+                balType != BalanceType.private) {
+              return Container();
+            }
+            return Align(
+              alignment: Alignment.topLeft,
+              child: Padding(
+                padding: const EdgeInsets.only(left: 12.0, top: 4.0),
+                child: Text(
+                  "Bridge data detected but Spark (private) transactions "
+                  "cannot carry OP_RETURN data. Switch to public balance "
+                  "to complete the bridge transaction.",
+                  textAlign: TextAlign.left,
+                  style: STextStyles.label(context).copyWith(
+                    color: Theme.of(
+                      context,
+                    ).extension<StackColors>()!.textError,
+                  ),
+                ),
+              ),
+            );
+          },
+        ),
         if (hasOptionalMemo || ref.watch(pValidSparkSendToAddress))
           const SizedBox(height: 10),
         if (hasOptionalMemo || ref.watch(pValidSparkSendToAddress))
diff --git a/lib/providers/ui/preview_tx_button_state_provider.dart b/lib/providers/ui/preview_tx_button_state_provider.dart
index fcb77fe..1ad75aa 100644
--- a/lib/providers/ui/preview_tx_button_state_provider.dart
+++ b/lib/providers/ui/preview_tx_button_state_provider.dart
@@ -23,6 +23,8 @@ final pValidSparkSendToAddress = StateProvider.autoDispose<bool>((_) => false);
 
 final pIsExchangeAddress = StateProvider<bool>((_) => false);
 
+final pOpReturnData = StateProvider<String?>((_) => null);
+
 // MWC Transaction Method Provider.
 final pSelectedMwcTransactionMethod = StateProvider<MwcTransactionMethod>(
   (_) => MwcTransactionMethod.slatepack,
@@ -47,42 +49,44 @@ final pIsSlatepack = Provider.family<bool, String>((ref, walletId) {
   return false;
 });
 
-final pPreviewTxButtonEnabled = Provider.autoDispose
-    .family<bool, CryptoCurrency>((ref, coin) {
-      final amount = ref.watch(pSendAmount) ?? Amount.zero;
+final pPreviewTxButtonEnabled = Provider.autoDispose.family<bool, CryptoCurrency>(
+  (ref, coin) {
+    final amount = ref.watch(pSendAmount) ?? Amount.zero;
 
-      // For MWC slatepack transactions, address validation is not required.
-      if (coin is Mimblewimblecoin) {
-        final selectedMethod = ref.watch(pSelectedMwcTransactionMethod);
-        if (selectedMethod == MwcTransactionMethod.slatepack) {
-          return amount > Amount.zero;
-        }
+    // For MWC slatepack transactions, address validation is not required.
+    if (coin is Mimblewimblecoin) {
+      final selectedMethod = ref.watch(pSelectedMwcTransactionMethod);
+      if (selectedMethod == MwcTransactionMethod.slatepack) {
+        return amount > Amount.zero;
       }
+    }
 
-      // For Epic Cash slatepack transactions, address validation is not required.
-      if (coin is Epiccash) {
-        final selectedMethod = ref.watch(pSelectedEpicTransactionMethod);
-        if (selectedMethod == EpicTransactionMethod.slatepack) {
-          return amount > Amount.zero;
-        }
+    // For Epic Cash slatepack transactions, address validation is not required.
+    if (coin is Epiccash) {
+      final selectedMethod = ref.watch(pSelectedEpicTransactionMethod);
+      if (selectedMethod == EpicTransactionMethod.slatepack) {
+        return amount > Amount.zero;
       }
+    }
 
-      if (coin is Firo) {
-        final firoType = ref.watch(publicPrivateBalanceStateProvider);
-        switch (firoType) {
-          case BalanceType.private:
-            return (ref.watch(pValidSendToAddress) ||
-                    ref.watch(pValidSparkSendToAddress)) &&
-                !ref.watch(pIsExchangeAddress) &&
-                amount > Amount.zero;
+    if (coin is Firo) {
+      final firoType = ref.watch(publicPrivateBalanceStateProvider);
+      switch (firoType) {
+        case BalanceType.private:
+          return (ref.watch(pValidSendToAddress) ||
+                  ref.watch(pValidSparkSendToAddress)) &&
+              !ref.watch(pIsExchangeAddress) &&
+              ref.watch(pOpReturnData) == null &&
+              amount > Amount.zero;
 
-          case BalanceType.public:
-            return ref.watch(pValidSendToAddress) && amount > Amount.zero;
-        }
-      } else {
-        return ref.watch(pValidSendToAddress) && amount > Amount.zero;
+        case BalanceType.public:
+          return ref.watch(pValidSendToAddress) && amount > Amount.zero;
       }
-    });
+    } else {
+      return ref.watch(pValidSendToAddress) && amount > Amount.zero;
+    }
+  },
+);
 
 final previewTokenTxButtonStateProvider = StateProvider.autoDispose<bool>((_) {
   return false;
diff --git a/lib/utilities/address_utils.dart b/lib/utilities/address_utils.dart
index ff0880c..43e72b6 100644
--- a/lib/utilities/address_utils.dart
+++ b/lib/utilities/address_utils.dart
@@ -23,6 +23,7 @@ class AddressUtils {
     'tx_payment_id',
     'recipient_name',
     'tx_description',
+    'op_return', // For Rosen Bridge and other OP_RETURN protocols.
     // TODO [prio=med]: Add more recognized params for other coins.
   };
 
@@ -268,24 +269,85 @@ class AddressUtils {
     if ((mimblewimblecoinAddress.startsWith("http://") ||
             mimblewimblecoinAddress.startsWith("https://")) &&
         mimblewimblecoinAddress.contains("@")) {
-      mimblewimblecoinAddress =
-          mimblewimblecoinAddress.replaceAll("http://", "");
-      mimblewimblecoinAddress =
-          mimblewimblecoinAddress.replaceAll("https://", "");
+      mimblewimblecoinAddress = mimblewimblecoinAddress.replaceAll(
+        "http://",
+        "",
+      );
+      mimblewimblecoinAddress = mimblewimblecoinAddress.replaceAll(
+        "https://",
+        "",
+      );
     }
     // strip mailto: prefix
     if (mimblewimblecoinAddress.startsWith("mailto:")) {
-      mimblewimblecoinAddress =
-          mimblewimblecoinAddress.replaceAll("mailto:", "");
+      mimblewimblecoinAddress = mimblewimblecoinAddress.replaceAll(
+        "mailto:",
+        "",
+      );
     }
     // strip / suffix if the address contains an @ symbol (and is thus an mwcmqs address)
     if (mimblewimblecoinAddress.endsWith("/") &&
         mimblewimblecoinAddress.contains("@")) {
       mimblewimblecoinAddress = mimblewimblecoinAddress.substring(
-          0, mimblewimblecoinAddress.length - 1);
+        0,
+        mimblewimblecoinAddress.length - 1,
+      );
     }
     return mimblewimblecoinAddress;
   }
+
+  /// Formats OP_RETURN hex data for display in tooltip.
+  /// If data matches Rosen Bridge format, shows structured fields.
+  /// Otherwise returns the raw hex with a generic description.
+  static String formatOpReturnTooltip(String hex) {
+    // Rosen Bridge OP_RETURN format:
+    // toChain(1B) + bridgeFee(8B) + networkFee(8B) + addrLen(1B) + toAddress(var)
+    const minRosenLen = 36; // minimum 18 bytes
+    if (hex.length < minRosenLen) {
+      return "Raw OP_RETURN data:\n$hex";
+    }
+
+    try {
+      const chains = [
+        'ergo',
+        'cardano',
+        'bitcoin',
+        'ethereum',
+        'binance',
+        'doge',
+        'bitcoin-runes',
+        'firo',
+      ];
+
+      final toChainCode = int.parse(hex.substring(0, 2), radix: 16);
+      if (toChainCode >= chains.length) {
+        return "Raw OP_RETURN data:\n$hex";
+      }
+
+      final bridgeFee = BigInt.parse(
+        hex.substring(2, 18),
+        radix: 16,
+      ).toString();
+      final networkFee = BigInt.parse(
+        hex.substring(18, 34),
+        radix: 16,
+      ).toString();
+      final addrLen = int.parse(hex.substring(34, 36), radix: 16);
+      final addrEnd = 36 + addrLen * 2;
+      if (hex.length < addrEnd) {
+        return "Raw OP_RETURN data:\n$hex";
+      }
+      final toAddressHex = hex.substring(36, addrEnd);
+
+      return "Rosen Bridge data\n"
+          "  To chain: ${chains[toChainCode]}\n"
+          "  Bridge fee: $bridgeFee\n"
+          "  Network fee: $networkFee\n"
+          "  To address (hex): $toAddressHex";
+    } catch (_) {
+      return "Raw OP_RETURN data:\n$hex";
+    }
+  }
 }
 
 class PaymentUriData {
diff --git a/lib/wallets/models/tx_data.dart b/lib/wallets/models/tx_data.dart
index 14c7186..bdff31c 100644
--- a/lib/wallets/models/tx_data.dart
+++ b/lib/wallets/models/tx_data.dart
@@ -112,6 +112,9 @@ class TxData {
 
   final bool salviumStakeTx;
 
+  // Generic OP_RETURN data (hex string) - for Rosen Bridge and other protocols
+  final String? opReturnData;
+
   TxData({
     this.feeRateType,
     this.feeRateAmount,
@@ -149,6 +152,7 @@ class TxData {
     this.sparkNameInfo,
     this.vExtraData,
     this.overrideVersion,
+    this.opReturnData,
     this.type = TxType.regular,
     this.salviumStakeTx = false,
   });
@@ -263,6 +267,7 @@ class TxData {
     String? noteOnChain,
     String? memo,
     String? otherData,
+    String? opReturnData,
     Set<BaseInput>? utxos,
     List<BaseInput>? usedUTXOs,
     List<TxRecipient>? recipients,
@@ -341,6 +346,7 @@ class TxData {
       sparkNameInfo: sparkNameInfo ?? this.sparkNameInfo,
       vExtraData: vExtraData ?? this.vExtraData,
       overrideVersion: overrideVersion ?? this.overrideVersion,
+      opReturnData: opReturnData ?? this.opReturnData,
       type: type ?? this.type,
     );
   }
@@ -383,6 +389,7 @@ class TxData {
       'sparkNameInfo: $sparkNameInfo, '
       'vExtraData: ${vExtraData?.toHex}, '
       'overrideVersion: $overrideVersion, '
+      'opReturnData: $opReturnData, '
       'type: $type, '
       '}';
 }
diff --git a/lib/wallets/wallet/wallet_mixin_interfaces/electrumx_interface.dart b/lib/wallets/wallet/wallet_mixin_interfaces/electrumx_interface.dart
index e963566..91496e7 100644
--- a/lib/wallets/wallet/wallet_mixin_interfaces/electrumx_interface.dart
+++ b/lib/wallets/wallet/wallet_mixin_interfaces/electrumx_interface.dart
@@ -852,6 +852,63 @@ mixin ElectrumXInterface<T extends ElectrumXCurrencyInterface>
       );
     }
 
+    // Add OP_RETURN output if provided (for Rosen Bridge and other protocols)
+    // Currently only supported for Firo
+    if (cryptoCurrency is Firo &&
+        txData.opReturnData != null &&
+        txData.opReturnData!.isNotEmpty) {
+      try {
+        final opReturnBytes = txData.opReturnData!.toUint8ListFromHex;
+
+        // Validate OP_RETURN size (Bitcoin/Firo limit is 80 bytes)
+        if (opReturnBytes.length > 80) {
+          throw Exception(
+            "OP_RETURN data exceeds 80 byte limit: ${opReturnBytes.length} bytes",
+          );
+        }
+
+        // Encode push data: OP_PUSHDATA1 (0x4c) for 76-80 bytes, direct length otherwise
+        final pushData = opReturnBytes.length <= 75
+            ? Uint8List.fromList([opReturnBytes.length, ...opReturnBytes])
+            : Uint8List.fromList([
+                0x4c,
+                opReturnBytes.length,
+                ...opReturnBytes,
+              ]);
+
+        final opReturnScript = Uint8List.fromList([
+          0x6a, // OP_RETURN opcode
+          ...pushData,
+        ]);
+
+        final opReturnOutput = coinlib.Output.fromScriptBytes(
+          BigInt.zero, // OP_RETURN outputs have 0 value
+          opReturnScript,
+        );
+
+        clTx = clTx.addOutput(opReturnOutput);
+
+        Logging.instance.i(
+          "Added OP_RETURN output with ${opReturnBytes.length} bytes of data",
+        );
+
+        tempOutputs.add(
+          OutputV2.isarCantDoRequiredInDefaultConstructor(
+            scriptPubKeyHex: opReturnScript.toHex,
+            valueStringSats: "0",
+            addresses: [],
+            walletOwns: false,
+          ),
+        );
+      } catch (e, s) {
+        Logging.instance.e(
+          "Failed to add OP_RETURN output",
+          error: e,
+          stackTrace: s,
+        );
+        throw Exception("Invalid OP_RETURN data: $e");
+      }
+    }
     if (isMweb) {
       if (hasNonWitnessInput) {
         throw Exception("Found non witness input in mweb tx");