feat: implement native UDP ping/pong health check pattern

server/src/lib.rs

@@ -368,11 +368,13 @@ pub async fn run_server(state: Arc<MemoryState>) -> Result<(), Box<dyn std::erro
                                 for tx in senders {
                                     let _ = tx.try_send(msg_str.clone());
                                 }
-                            } else if let Ok(gate_wait) = serde_json::from_slice::<serde_json::Value>(&buf[..len]) {
+                            } else if let Ok(json_payload) = serde_json::from_slice::<serde_json::Value>(&buf[..len]) {
-                                if gate_wait.get("type").and_then(|t| t.as_str()) == Some("gate_wait") {
+                                if json_payload.get("type").and_then(|t| t.as_str()) == Some("ping") {
+                                    let _ = socket.send_to(b"pong", addr).await;
+                                } else if json_payload.get("type").and_then(|t| t.as_str()) == Some("gate_wait") {
                                     if let (Some(action), Some(target)) = (
-                                        gate_wait.get("action").and_then(|a| a.as_str()),
+                                        json_payload.get("action").and_then(|a| a.as_str()),
-                                        gate_wait.get("target").and_then(|t| t.as_str())
+                                        json_payload.get("target").and_then(|t| t.as_str())
                                     ) {
                                         subscribers.insert((action.to_string(), target.to_string()), addr);
                                     }

server/src/udp-test.rs

@@ -0,0 +1 @@
+test

server/src/udp-test2.rs

@@ -0,0 +1 @@
+test