Auto fill room ID from clip board upon interacting with input

desktop-client/lobby_widget.py

@@ -1,10 +1,25 @@
 import os
+import re
 from PyQt6.QtWidgets import (
     QWidget, QVBoxLayout, QHBoxLayout, QLabel, QLineEdit, QPushButton, 
-    QFileDialog, QFrame
+    QFileDialog, QFrame, QApplication
 )
 from PyQt6.QtCore import Qt, pyqtSignal
 
+class RoomCodeInput(QLineEdit):
+    """QLineEdit that auto-fills from clipboard if it looks like a room code."""
+    def focusInEvent(self, event):
+        super().focusInEvent(event)
+        if not self.text().strip():
+            self._try_paste_room_code()
+    
+    def _try_paste_room_code(self):
+        clipboard = QApplication.clipboard()
+        text = (clipboard.text() or "").strip().upper()
+        if re.match(r'^[A-Z0-9]{4,8}$', text):
+            self.setText(text)
+            self.selectAll()
+
 class LobbyWidget(QWidget):
     # Signals to communicate to VlcSyncApp
     create_requested = pyqtSignal(str, str, str, object)  # username, path, filename, size
@@ -80,7 +95,7 @@ class LobbyWidget(QWidget):
         # Join Room Panel
         join_panel = QVBoxLayout()
         join_panel.addWidget(QLabel("Join a Room"))
-        self.room_code_input = QLineEdit()
+        self.room_code_input = RoomCodeInput()
         self.room_code_input.setPlaceholderText("e.g. ABC123")
         self.join_room_btn = QPushButton("Join Room")
         self.join_room_btn.setObjectName("secondaryBtn")