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

build.py

@@ -4,6 +4,8 @@ from pathlib import Path
 import PyInstaller.__main__
 import typer
 from rich import print
+import time
+from datetime import datetime
 
 
 app = typer.Typer()
@@ -70,17 +72,62 @@ def build(build: bool = True, copy: bool = True, test: bool = False, dest: str |
             except Exception as e:
                 print(f"Warning: couldn't locate pythonnet runtime: {e}")
 
+            # Ensure dist/work/spec directories exist
+            dist_dir = project_root / "dist" / "test"
+            work_dir = project_root / "build" / "test"
+            spec_dir = project_root / "build" / "specs"
+            dist_dir.mkdir(parents=True, exist_ok=True)
+            work_dir.mkdir(parents=True, exist_ok=True)
+            spec_dir.mkdir(parents=True, exist_ok=True)
+
+            # Decide build name and try to remove any locked previous artifact.
+            base_name = "Uploader_test"
+            output_exe = dist_dir / f"{base_name}.exe"
+
+            def try_remove_with_retries(path: Path, retries: int = 5, delay: float = 0.5) -> bool:
+                """Try to remove a file with retries and backoff. Returns True if removed or not present."""
+                if not path.exists():
+                    return True
+                for attempt in range(retries):
+                    try:
+                        path.unlink()
+                        print(f"Removed existing file: {path}")
+                        return True
+                    except PermissionError:
+                        # Try to move/rename it out of the way
+                        try:
+                            backup = path.with_suffix(f".old.{int(time.time())}")
+                            path.rename(backup)
+                            print(f"Renamed locked file to: {backup}")
+                            return True
+                        except Exception:
+                            pass
+                        print(f"File locked, retrying in {delay} seconds ({attempt+1}/{retries})")
+                        time.sleep(delay)
+                        delay *= 1.5
+                    except Exception as e:
+                        print(f"Failed to remove existing file {path}: {e}")
+                        return False
+                return False
+
+            name_used = base_name
+            if not try_remove_with_retries(output_exe):
+                # If the previous artifact is locked, fall back to a unique name to avoid build failure
+                ts = datetime.now().strftime("%Y%m%dT%H%M%S")
+                name_used = f"{base_name}_{ts}"
+                print(f"Previous artifact appears locked; building as {name_used} to avoid PermissionError")
+
             PyInstaller.__main__.run([
                 str(project_root / "nice.py"),
                 "--onefile",
                 "--name",
-                "Uploader_test",
+                name_used,
                 "--distpath",
-                str(project_root / "dist" / "test"),
+                str(dist_dir),
                 "--workpath",
-                str(project_root / "build" / "test"),
+                str(work_dir),
                 "--specpath",
-                str(project_root / "build" / "specs"),
+                str(spec_dir),
             ] + add_data_args + add_binary_args + [
                 # add some common hidden imports that PyInstaller sometimes misses
                 "--hidden-import",

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()