add native mode checks and fallback for pywebview in UI launch process; create new pywebview module

nice.py

@@ -133,6 +133,7 @@ async def read_nng_messages():
         # This shouldn't be necessary
         global SHUTDOWN
         SHUTDOWN = True
+        logger.debug("Triggering shutdown due to socket in use")
         return
 
     # asyncio.create_task(read_nng_messages())
@@ -752,8 +753,56 @@ def launch_app(
         port = native.find_open_port()
         #port = 8001
         logger.debug(f"Run on port {port}")
-        #ui.run(reload=False, show=True, port=port, native=native_mode, favicon="icon/icon1.ico")
-        ui.run(reload=False, show=True, port=port, native=native_mode)
+
+        # If native mode was requested, ensure pywebview has a usable GUI
+        # backend (Qt or GTK). If not present, disable native mode to avoid
+        # runtime WebViewException errors when webview.initialize() runs.
+        if native_mode:
+            try:
+                import webview
+
+                backend_available = False
+                # Check common backends: PyQt5/PySide6 or GTK (gi)
+                try:
+                    import PyQt5  # type: ignore
+                    backend_available = True
+                except Exception:
+                    try:
+                        import PySide6  # type: ignore
+                        backend_available = True
+                    except Exception:
+                        pass
+
+                if not backend_available:
+                    try:
+                        # GTK
+                        from gi.repository import Gtk  # type: ignore
+
+                        backend_available = True
+                    except Exception:
+                        backend_available = False
+
+                if not backend_available:
+                    logger.debug(
+                        "pywebview backend (Qt/GTK) not available; disabling native mode"
+                    )
+                    native_mode = False
+            except Exception as e:
+                logger.debug(f"pywebview import/check failed: {e}; disabling native mode")
+                native_mode = False
+
+        # Try to run with the requested mode. If native startup fails at
+        # runtime, catch and fall back to browser mode so the app stays usable.
+        try:
+            ui.run(reload=False, show=True, port=port, native=native_mode)
+        except Exception as e:
+            logger.error(f"Failed to start UI in native mode: {e}")
+            if native_mode:
+                logger.debug("Retrying without native mode (browser fallback)")
+                try:
+                    ui.run(reload=False, show=True, port=port, native=False)
+                except Exception as e2:
+                    logger.error(f"Fallback to browser mode failed: {e2}")
     except Exception as e:
         logger.error(e)
         pass

pywebview.py

@@ -0,0 +1,3 @@
+import webview
+webview.create_window('Hello world', 'https://pywebview.flowrl.com/hello')
+webview.start()