diff --git a/src/client.ts b/src/client.ts
index 8591d9a..517381b 100644
--- a/src/client.ts
+++ b/src/client.ts
@@ -69,10 +69,7 @@ async function ensureSocket(useLocalhost: boolean): Promise<WebSocket> {
     return connecting;
   }
 
-  if (socket && currentOrigin !== origin) {
-    socket.close();
-    socket = null;
-  }
+  if (socket && currentOrigin !== origin) closeClient();
 
   connecting = new Promise<WebSocket>((resolve, reject) => {
     const ws = new WebSocket(origin);
@@ -88,7 +85,7 @@ async function ensureSocket(useLocalhost: boolean): Promise<WebSocket> {
         currentOrigin = origin;
         connecting = null;
 
-        await sendUnsafe(useLocalhost, {
+        await sendUnsafe({
           type: "auth",
           cookies: authCookies,
         });
@@ -133,6 +130,10 @@ async function ensureSocket(useLocalhost: boolean): Promise<WebSocket> {
       currentOrigin = null;
       connecting = null;
     };
+
+    ws.on("ping", () => {
+      ws.pong();
+    });
   });
 
   return connecting;
@@ -142,10 +143,7 @@ async function ensureSocket(useLocalhost: boolean): Promise<WebSocket> {
    RPC helpers
 ────────────────────────── */
 
-async function sendUnsafe<T>(
-  useLocalhost: boolean,
-  payload: Record<string, any>,
-): Promise<T> {
+async function sendUnsafe<T>(payload: Record<string, any>): Promise<T> {
   if (!socket || socket.readyState !== WebSocket.OPEN) {
     throw new Error("WebSocket is not open");
   }
@@ -160,7 +158,11 @@ async function sendUnsafe<T>(
 
     pending.set(requestId, { resolve, reject, timeout });
 
-    socket?.send(JSON.stringify({ ...payload, requestId }));
+    if (!socket || socket.readyState !== WebSocket.OPEN) {
+      throw new Error("WebSocket closed while sending");
+    }
+
+    socket.send(JSON.stringify({ ...payload, requestId }));
   });
 }
 
@@ -169,13 +171,20 @@ async function send<T>(
   payload: Record<string, any>,
 ): Promise<T> {
   await ensureSocket(useLocalhost);
-  return sendUnsafe(useLocalhost, payload);
+  return sendUnsafe(payload);
 }
 
 /* ──────────────────────────
    Public API
 ────────────────────────── */
 
+export async function closeClient() {
+  if (!socket) return;
+  socket.close();
+  socket = null;
+  connecting = null;
+}
+
 export async function addRun(
   useLocalhost: boolean,
   problem: string,
diff --git a/src/extension.ts b/src/extension.ts
index 385b938..4a1e5c2 100644
--- a/src/extension.ts
+++ b/src/extension.ts
@@ -4,6 +4,7 @@ import { startServer, stopServer } from "./server";
 import os from "os";
 import { exec } from "child_process";
 import net from "net";
+import { closeClient } from "./client";
 
 var globalStatusBarItem: vscode.StatusBarItem | undefined;
 
@@ -105,6 +106,7 @@ export function activate(context: vscode.ExtensionContext) {
 
 export function deactivate() {
   stopServer(globalStatusBarItem as any);
+  closeClient();
 }
 
 export function canConnect(
diff --git a/src/move.ts b/src/move.ts
index 8b9a1a9..12db055 100644
--- a/src/move.ts
+++ b/src/move.ts
@@ -129,7 +129,7 @@ export function startMonitoring(useLocalhost: boolean, runId: string) {
           moveId: moveId++,
           changes: {
             from: 0,
-            to: serverText.length,
+            to: serverText?.length || 0,
             insert: editorText,
           },
         },