[fix] withdraw

lib/mm2/mm2_api/rpc/rpc_extras.dart

@@ -0,0 +1,30 @@
+/// Provides coin-specific RPC parameter extensions for MM2 API calls.
+///
+/// This adapter centralizes coin-specific requirements that need to be added
+/// to RPC requests, preventing duplication and keeping coin logic isolated.
+class RpcExtras {
+  /// Default amount value for KMD rewards when claiming.
+  static const String kDefaultKmdRewardsAmount = '0';
+
+  /// Returns coin-specific extra parameters for withdrawal requests.
+  ///
+  /// These parameters are merged into the 'params' section of the RPC request.
+  /// Currently handles:
+  /// - KMD: Adds kmd_rewards object with claimed_by_me flag
+  ///
+  /// Returns an empty map if no coin-specific parameters are needed.
+  static Map<String, dynamic> withdrawForCoin(String coin) {
+    final normalizedCoin = coin.toUpperCase();
+
+    if (normalizedCoin == 'KMD') {
+      return {
+        'kmd_rewards': {
+          'amount': kDefaultKmdRewardsAmount,
+          'claimed_by_me': true,
+        },
+      };
+    }
+
+    return const {};
+  }
+}

lib/mm2/mm2_api/rpc/withdraw/withdraw_request.dart

@@ -1,5 +1,6 @@
 import 'package:web_dex/app_config/app_config.dart';
 import 'package:web_dex/mm2/mm2_api/rpc/base.dart';
+import 'package:web_dex/mm2/mm2_api/rpc/rpc_extras.dart';
 import 'package:web_dex/mm2/mm2_api/rpc/withdraw/fee/fee_request.dart';
 
 class WithdrawRequestParams {
@@ -48,6 +49,7 @@ class WithdrawRequest
   @override
   Map<String, dynamic> toJson() {
     final FeeRequest? fee = params.fee;
+    final extras = RpcExtras.withdrawForCoin(params.coin);
 
     return <String, dynamic>{
       'method': method,
@@ -60,7 +62,7 @@ class WithdrawRequest
         if (params.memo != null) 'memo': params.memo,
         if (params.amount != null) 'amount': params.amount,
         if (fee != null) 'fee': fee.toJson(),
-      },
+      }..addAll(extras),
     };
   }
 }