fix(t8n): serialize receipt root/status as mutually exclusive

src/Nethermind/Nethermind.JsonRpc.Test/Data/ReceiptsForRpcTests.cs

@@ -132,6 +132,56 @@ public void Error_field_is_not_deserialized()
             Assert.That(receiptForRpc!.ToReceipt().Error, Is.Null);
         }
 
+        [Test]
+        public void Post_byzantium_receipt_serializes_status_without_root()
+        {
+            TxReceipt receipt = new()
+            {
+                Bloom = Bloom.Empty,
+                Index = 0,
+                Recipient = TestItem.AddressA,
+                Sender = TestItem.AddressB,
+                BlockHash = TestItem.KeccakA,
+                BlockNumber = 1,
+                GasUsed = 1000,
+                TxHash = Keccak.OfAnEmptyString,
+                StatusCode = 1,
+                GasUsedTotal = 1000,
+                Logs = []
+            };
+
+            using JsonDocument document = JsonDocument.Parse(SerializeReceipt(receipt));
+            JsonElement root = document.RootElement;
+
+            Assert.That(root.TryGetProperty("root", out _), Is.False);
+            Assert.That(root.GetProperty("status").GetString(), Is.EqualTo("0x1"));
+        }
+
+        [Test]
+        public void Pre_byzantium_receipt_serializes_root_without_status()
+        {
+            TxReceipt receipt = new()
+            {
+                Bloom = Bloom.Empty,
+                Index = 0,
+                Recipient = TestItem.AddressA,
+                Sender = TestItem.AddressB,
+                BlockHash = TestItem.KeccakA,
+                BlockNumber = 1,
+                GasUsed = 1000,
+                TxHash = Keccak.OfAnEmptyString,
+                PostTransactionState = TestItem.KeccakB,
+                GasUsedTotal = 1000,
+                Logs = []
+            };
+
+            using JsonDocument document = JsonDocument.Parse(SerializeReceipt(receipt));
+            JsonElement root = document.RootElement;
+
+            Assert.That(root.TryGetProperty("status", out _), Is.False);
+            Assert.That(root.GetProperty("root").GetString(), Is.EqualTo(TestItem.KeccakB.ToString()));
+        }
+
         private static TxReceipt CreateDiagnosticReceipt()
             => new()
             {

src/Nethermind/Nethermind.JsonRpc/Converters/TxReceiptConverter.cs

@@ -30,10 +30,19 @@ public override void Write(Utf8JsonWriter writer, TxReceipt value, JsonSerialize
                 writer.WritePropertyName("type");
                 JsonSerializer.Serialize(writer, receipt.Type, options);
             }
-            writer.WritePropertyName("root");
-            ByteArrayConverter.Convert(writer, (receipt.Root ?? Keccak.Zero).Bytes);
-            writer.WritePropertyName("status");
-            JsonSerializer.Serialize(writer, receipt.Status, options);
+            // Pre-Byzantium receipts carry a post-state root; from Byzantium onwards they carry a status
+            // code. The two are mutually exclusive (EIP-658), matching the receipt schema in
+            // ethereum/execution-apis and go-ethereum's marshalReceipt.
+            if (receipt.Root is not null)
+            {
+                writer.WritePropertyName("root");
+                ByteArrayConverter.Convert(writer, receipt.Root.Bytes);
+            }
+            else
+            {
+                writer.WritePropertyName("status");
+                JsonSerializer.Serialize(writer, receipt.Status, options);
+            }
 
             writer.WritePropertyName("cumulativeGasUsed");
             JsonSerializer.Serialize(writer, receipt.CumulativeGasUsed, options);