From efc024f7c04e780092e6f8de59948ea32873d359 Mon Sep 17 00:00:00 2001
From: maxim055 <max@bransfer.io>
Date: Mon, 24 Nov 2025 15:23:17 +0400
Subject: [PATCH] Fix blockchain fee calculation.

---
 csharp/src/Common/Common.csproj                 |  1 +
 .../Common/Extensions/Web3ClientExtensions.cs   | 17 +++++++++++++++++
 .../Helpers/EthereumEIP1559FeeEstimator.cs      |  9 +++++----
 .../src/Workflow.Solana/Workflow.Solana.csproj  |  2 +-
 4 files changed, 24 insertions(+), 5 deletions(-)
 create mode 100644 csharp/src/Common/Extensions/Web3ClientExtensions.cs

diff --git a/csharp/src/Common/Common.csproj b/csharp/src/Common/Common.csproj
index f07e35f5..e39fffaf 100644
--- a/csharp/src/Common/Common.csproj
+++ b/csharp/src/Common/Common.csproj
@@ -6,6 +6,7 @@
 	</PropertyGroup>
 
 	<ItemGroup>
+		<PackageReference Include="Nethereum.Web3" Version="4.29.0" />
 		<PackageReference Include="Temporalio.Extensions.Hosting" Version="1.5.0" />
 		<PackageReference Include="Microsoft.AspNetCore.Http.Abstractions" Version="2.3.0" />
 		<PackageReference Include="Nethereum.Util" Version="4.29.0" />
diff --git a/csharp/src/Common/Extensions/Web3ClientExtensions.cs b/csharp/src/Common/Extensions/Web3ClientExtensions.cs
new file mode 100644
index 00000000..6d7a2f62
--- /dev/null
+++ b/csharp/src/Common/Extensions/Web3ClientExtensions.cs
@@ -0,0 +1,17 @@
+using Nethereum.Hex.HexTypes;
+using Nethereum.Web3;
+using System.Numerics;
+
+namespace Train.Solver.Common.Extensions;
+
+public static class Web3ClientExtensions
+{
+    public static async Task<BigInteger> GetMaxPriorityFeePerGasAsync(this IWeb3 web3)
+    {
+        var request = new Nethereum.JsonRpc.Client.RpcRequest(Guid.NewGuid().ToString(), "eth_maxPriorityFeePerGas");
+
+        var response = await web3.Client.SendRequestAsync<string>(request);
+
+        return new HexBigInteger(response);
+    }
+}
\ No newline at end of file
diff --git a/csharp/src/Workflow.EVM/Helpers/EthereumEIP1559FeeEstimator.cs b/csharp/src/Workflow.EVM/Helpers/EthereumEIP1559FeeEstimator.cs
index 23c4c4df..fefa51a7 100644
--- a/csharp/src/Workflow.EVM/Helpers/EthereumEIP1559FeeEstimator.cs
+++ b/csharp/src/Workflow.EVM/Helpers/EthereumEIP1559FeeEstimator.cs
@@ -16,6 +16,8 @@ public class EthereumEIP1559FeeEstimator(ISmartNodeInvoker smartNodeInvoker) : F
 
     public virtual int HighPriorityBlockCount => 5;
 
+    private const string MinMaxPriorityFeePerGas = "1";
+
     public override BigInteger CalculateFee(Block block, Transaction transaction, EVMTransactionReceipt receipt)
     {
         return receipt.GasUsed * (block.BaseFeePerGas + transaction.MaxPriorityFeePerGas.Value);
@@ -66,15 +68,14 @@ async Task<Fee> GetFeeAmountAsync(
                 suggestedFees.BaseFee.Value.CompoundInterestRate(MaximumBaseFeeIncreasePerBlock, blockCount);
 
             // Node returns 0 but transfer service throws exception in case of 0
-            suggestedFees.MaxPriorityFeePerGas += 1;
-            suggestedFees.MaxPriorityFeePerGas =
-                suggestedFees.MaxPriorityFeePerGas.Value.PercentageIncrease(feePercentageIncrease);
+            var maxPriorityFeePerGas = BigInteger.Parse(MinMaxPriorityFeePerGas);
+            maxPriorityFeePerGas += (await web3.GetMaxPriorityFeePerGasAsync()).PercentageIncrease(feePercentageIncrease);
 
             return new Fee(
                 feeCurrency.Symbol,
                 feeCurrency.Decimals,
                 new EIP1559Data(
-                    suggestedFees.MaxPriorityFeePerGas.Value,
+                    maxPriorityFeePerGas,
                     increasedBaseFee,
                     gasLimit));
         }
diff --git a/csharp/src/Workflow.Solana/Workflow.Solana.csproj b/csharp/src/Workflow.Solana/Workflow.Solana.csproj
index 0f1ac094..4a66cc16 100644
--- a/csharp/src/Workflow.Solana/Workflow.Solana.csproj
+++ b/csharp/src/Workflow.Solana/Workflow.Solana.csproj
@@ -6,7 +6,7 @@
 	</PropertyGroup>
 
 	<ItemGroup>
-		<PackageReference Include="Nethereum.Web3Lite" Version="4.29.0" />
+		<PackageReference Include="Nethereum.Web3" Version="4.29.0" />
 		<PackageReference Include="Solnet.Extensions" Version="6.1.0" />
 		<PackageReference Include="Flurl.Http" Version="4.0.2" />
 	</ItemGroup>