feat(stub): implement ADR-0047 tools/list_changed on reconnect

stub/src/main.rs

@@ -56,6 +56,7 @@ fn main() -> Result<(), Box<dyn std::error::Error>> {
         let ws_url = format!("{ws_url}/ws?client=proxy");
 
         let mut retry_count = 0;
+        let mut has_connected_once = false;
         loop {
             if *shutdown_rx.borrow() {
                 tracing::info!("Stub shutdown requested");
@@ -91,6 +92,21 @@ fn main() -> Result<(), Box<dyn std::error::Error>> {
                     tracing::info!("Successfully connected to target server");
                     let (mut write, mut read) = ws_stream.split();
 
+                    if has_connected_once {
+                        tracing::info!("Synthesizing notifications/tools/list_changed to client due to reconnect");
+                        use tokio::io::AsyncWriteExt;
+                        let mut stdout = tokio::io::BufWriter::new(tokio::io::stdout());
+                        let notification = serde_json::json!({
+                            "jsonrpc": "2.0",
+                            "method": "notifications/tools/list_changed"
+                        });
+                        let payload = notification.to_string();
+                        let _ = stdout.write_all(payload.as_bytes()).await;
+                        let _ = stdout.write_all(b"\n").await;
+                        let _ = stdout.flush().await;
+                    }
+                    has_connected_once = true;
+
                     let rx = msg_rx.clone();
                     let mut send_task = tokio::spawn(async move {
                         while let Ok(msg) = rx.recv().await {