fix: add output buffering to terminal connection for race condition

- Buffer WebSocket output when no handlers are registered
- Flush buffered output when message handler subscribes
- Clear buffer on reconnect to prevent stale data
- Add debug warning when sendInput fails due to closed connection

Author: devatnull

backend/src/server.ts

@@ -81,7 +81,7 @@ const sessions = new Map<string, Session>();
 
 // Connection rate limiting per IP
 const connectionAttempts = new Map<string, { count: number; resetAt: number }>();
-const MAX_CONNECTIONS_PER_IP = 3;
+const MAX_CONNECTIONS_PER_IP = 10; // Increased for dev with HMR
 const CONNECTION_WINDOW_MS = 60000; // 1 minute
 
 function getClientIP(req: http.IncomingMessage): string {

src/app/practice/page.tsx

@@ -96,7 +96,7 @@ export default function PracticePage() {
                 onReady={() => setConnected(true)}
                 onDisconnect={() => setConnected(false)}
                 onError={setError}
-                className="h-[500px] rounded-lg overflow-hidden"
+                className="h-[500px] max-w-4xl rounded-lg overflow-hidden border border-[#3b4261]"
               />
 
               {/* Key Visualizer - Always Visible */}