diff --git a/Windows/Rust/CubeLib/src/websocket/client.rs b/Windows/Rust/CubeLib/src/websocket/client.rs
index 0b4373c..b71203f 100644
--- a/Windows/Rust/CubeLib/src/websocket/client.rs
+++ b/Windows/Rust/CubeLib/src/websocket/client.rs
@@ -637,7 +637,7 @@ impl WebSocketClient {
     /// Send a text message
     pub async fn send(&self, msg_type: &str, data: Value) -> Result<(), WebSocketError> {
         let message = WebSocketMessage::new(msg_type, data);
-        let json = serde_json::to_string(&message)?;
+        let json = message.to_json_string()?;
         self.send_raw_text(json).await
     }
 
diff --git a/Windows/Rust/CubeLib/src/websocket/message.rs b/Windows/Rust/CubeLib/src/websocket/message.rs
index 01b92eb..adf6cd2 100644
--- a/Windows/Rust/CubeLib/src/websocket/message.rs
+++ b/Windows/Rust/CubeLib/src/websocket/message.rs
@@ -45,6 +45,26 @@ impl WebSocketMessage {
         let data = serde_json::to_value(data)?;
         Ok(Self::new(msg_type, data))
     }
+
+    /// Serialize to JSON string with Type field first (required by MasterSuite protocol)
+    /// Note: serde's default serialization order follows field definition order,
+    /// but this method guarantees Type comes first regardless of any future changes
+    pub fn to_json_string(&self) -> Result<String, serde_json::Error> {
+        let mut map = serde_json::Map::new();
+        
+        // Type is always first
+        map.insert("Type".to_string(), serde_json::Value::String(self.msg_type.clone()));
+        
+        // Data field
+        map.insert("Data".to_string(), self.data.clone());
+        
+        // MessageId (optional, skip if None)
+        if let Some(ref id) = self.id {
+            map.insert("MessageId".to_string(), serde_json::Value::String(id.clone()));
+        }
+        
+        serde_json::to_string(&map)
+    }
 }
 
 /// Client type enumeration