Milestone alpha3

main.py

@@ -14,7 +14,7 @@ import time
 import customtkinter as ctk
 from tkinter import messagebox
 
-from async_loop_singleton import get_global_loop
+from async_loop_singleton import get_global_loop, stop_global_loop
 from async_msssql_query import AsyncMSSQLClient
 from audit_log import log_session_event
 from db_config import build_dsn_from_config, ensure_db_config
@@ -45,12 +45,6 @@ BYPASS_LOGIN_USER = {
     "codice_unita": "U1",
 }
 
-if sys.platform.startswith("win"):
-    try:
-        asyncio.set_event_loop_policy(asyncio.WindowsSelectorEventLoopPolicy())
-    except Exception:
-        pass
-
 # Create one global loop and make it the default everywhere.
 _loop = get_global_loop()
 asyncio.set_event_loop(_loop)
@@ -71,6 +65,51 @@ _APP_MUTEX = None
 _APP_MUTEX_NAME = "Local\\WarehousePythonAppSingleton"
 
 
+def _dispose_db_client() -> None:
+    """Best-effort disposal of the shared DB client."""
+
+    global db_app
+    if db_app is None:
+        return
+    try:
+        fut = asyncio.run_coroutine_threadsafe(db_app.dispose(), _loop)
+        try:
+            fut.result(timeout=2)
+        except Exception:
+            pass
+    finally:
+        db_app = None
+
+
+def _destroy_tk_root(root: tk.Misc | None) -> None:
+    """Destroy a hidden bootstrap root without leaking a Tk interpreter."""
+
+    if root is None:
+        return
+    try:
+        root.quit()
+    except Exception:
+        pass
+    try:
+        root.destroy()
+    except Exception:
+        pass
+
+
+def _shutdown_runtime(*, bootstrap: tk.Misc | None = None, dispose_db: bool = True) -> None:
+    """Release temporary Tk resources, DB client and background loop."""
+
+    try:
+        _destroy_tk_root(bootstrap)
+    finally:
+        if dispose_db:
+            _dispose_db_client()
+        try:
+            stop_global_loop()
+        except Exception:
+            pass
+
+
 def _acquire_single_instance_mutex() -> bool:
     """Return ``True`` only for the first running instance of the application."""
 
@@ -435,14 +474,19 @@ if __name__ == "__main__":
             ),
             parent=root,
         )
+        _destroy_tk_root(root)
         try:
-            root.destroy()
+            stop_global_loop()
         except Exception:
             pass
         raise SystemExit(0)
 
     db_cfg = ensure_db_config(_loop)
     if db_cfg is None:
+        try:
+            stop_global_loop()
+        except Exception:
+            pass
         raise SystemExit(0)
 
     db_app = AsyncMSSQLClient(build_dsn_from_config(db_cfg))
@@ -466,23 +510,12 @@ if __name__ == "__main__":
         session = prompt_login(bootstrap, db_app)
 
     if session is None:
-        if db_app is not None:
-            fut = asyncio.run_coroutine_threadsafe(db_app.dispose(), _loop)
-            try:
-                fut.result(timeout=2)
-            except Exception:
-                pass
-        try:
-            if bootstrap is not None:
-                bootstrap.destroy()
-        except Exception:
-            pass
+        _shutdown_runtime(bootstrap=bootstrap, dispose_db=True)
         raise SystemExit(0)
 
-    try:
-        if bootstrap is not None:
-            bootstrap.destroy()
-    except Exception:
-        pass
+    _destroy_tk_root(bootstrap)
 
-    Launcher(session, db_app).mainloop()
+    try:
+        Launcher(session, db_app).mainloop()
+    finally:
+        _shutdown_runtime(bootstrap=None, dispose_db=True)