WIP: Fix attempt

Author: lionel-

crates/ark/src/dap/dap_server.rs

@@ -95,6 +95,14 @@ pub fn start_dap(
             Ok((stream, addr)) => {
                 log::info!("DAP: Connected to client {addr:?}");
 
+                // Disable Nagle's algorithm to ensure events are sent immediately.
+                // Without this, small writes may be buffered at the TCP level,
+                // causing events to not reach the client until more data is sent.
+                // This was observed to cause hangs on Windows ARM.
+                if let Err(err) = stream.set_nodelay(true) {
+                    log::warn!("DAP: Failed to set TCP_NODELAY: {err:?}");
+                }
+
                 let mut state = state.lock().unwrap();
                 state.is_connected = true;
 

crates/ark_test/src/dap_client.rs

@@ -69,6 +69,10 @@ impl DapClient {
         stream.set_read_timeout(Some(DEFAULT_TIMEOUT))?;
         stream.set_write_timeout(Some(DEFAULT_TIMEOUT))?;
 
+        // Disable Nagle's algorithm to ensure messages are sent immediately.
+        // This matches the server-side setting and prevents buffering delays.
+        stream.set_nodelay(true)?;
+
         let reader = BufReader::new(stream.try_clone()?);
         let writer = BufWriter::new(stream);