Fix single-instance: show window immediately on IPC connection

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: Eadroma

main.py

@@ -3,16 +3,17 @@
 from pathlib import Path
 
 from PyQt6.QtGui import QIcon
+from PyQt6.QtNetwork import QLocalServer, QLocalSocket
 from PyQt6.QtWidgets import QApplication
 
 from ui.main_window import AccountManagerWindow
 
 ICON_PATH = Path(__file__).parent / "icon.ico"
-APP_ID = "RiotAccountManager.1.0"
+APP_ID    = "RiotAccountManager.1.0"
+IPC_NAME  = "RiotAccountManager-Instance"
 
 
 def _set_app_id() -> None:
-    """Tell Windows this is its own app, not pythonw.exe — fixes taskbar icon."""
     try:
         ctypes.windll.shell32.SetCurrentProcessExplicitAppUserModelID(APP_ID)
     except AttributeError:
@@ -23,11 +24,34 @@ def main() -> None:
     _set_app_id()
     app = QApplication(sys.argv)
 
+    # If another instance is running, tell it to raise and exit.
+    sock = QLocalSocket()
+    sock.connectToServer(IPC_NAME)
+    if sock.waitForConnected(300):
+        sock.write(b"raise")
+        sock.waitForBytesWritten(300)
+        sock.disconnectFromServer()
+        sys.exit(0)
+
+    # First instance: start the IPC server.
+    server = QLocalServer()
+    QLocalServer.removeServer(IPC_NAME)
+    server.listen(IPC_NAME)
+
     icon = QIcon(str(ICON_PATH)) if ICON_PATH.exists() else QIcon()
     app.setWindowIcon(icon)
 
     window = AccountManagerWindow()
     window.setWindowIcon(icon)
+
+    def _on_new_connection() -> None:
+        client = server.nextPendingConnection()
+        if client:
+            window._show_window()
+            client.disconnectFromServer()
+
+    server.newConnection.connect(_on_new_connection)
+
     window.show()
     sys.exit(app.exec())