feat: Implement lazy-loading for SearchFilterWidget to improve performance and resource management

src/main.py

@@ -24,7 +24,6 @@ from pathology_management_window import PathologyManagementWindow
 from pathology_manager import PathologyManager
 from preferences import get_config_dir, get_pref, save_preferences, set_pref
 from search_filter import DataFilter
-from search_filter_ui import SearchFilterWidget
 from settings_window import SettingsWindow
 from theme_manager import ThemeManager
 from ui_manager import UIManager
@@ -346,6 +345,8 @@ class MedTrackerApp:
         # --- Main Frame ---
         main_frame: ttk.Frame = ttk.Frame(self.root, padding="10", style="Card.TFrame")
         main_frame.grid(row=0, column=0, sticky="nsew")
+        # Store for lazy child creation (search panel)
+        self.main_frame = main_frame
 
         # Configure root window grid
         self.root.grid_rowconfigure(0, weight=1)
@@ -400,19 +401,14 @@ class MedTrackerApp:
         self.tree: ttk.Treeview = table_ui["tree"]
         self.tree.bind("<Double-1>", self.handle_double_click)
 
-        # --- Create Search/Filter Widget ---
+        # --- Search/Filter Widget (lazy-loaded) ---
-        self.search_filter_widget = SearchFilterWidget(
+        self.search_filter_widget = None  # Created on demand
-            main_frame,
+        # Restore prior visibility preference, but only create when needed
-            self.data_filter,
-            self._on_filter_update,
-            self.medicine_manager,
-            self.pathology_manager,
-            logger,
-        )
-        # Restore prior visibility state from preferences
         self.search_filter_visible = bool(get_pref("search_panel_visible", False))
         if self.search_filter_visible:
-            self.search_filter_widget.show()
+            self._ensure_search_widget()
+            # mypy: widget ensured above
+            self.search_filter_widget.show()  # type: ignore[union-attr]
 
         # --- Create Status Bar ---
         self.status_bar = self.ui_manager.create_status_bar(main_frame)
@@ -426,9 +422,8 @@ class MedTrackerApp:
             # Force one-time restoration in refresh and reflect in the UI if visible
             try:
                 self.refresh_data_display(apply_filters=True)
-                if self.search_filter_visible and hasattr(
+                if self.search_filter_visible and self.search_filter_widget is not None:
-                    self.search_filter_widget, "sync_ui_from_filter"
+                    # Keep UI in sync only if panel is actually instantiated
-                ):
                     self.search_filter_widget.sync_ui_from_filter()
             except Exception:
                 self.refresh_data_display()
@@ -1169,18 +1164,44 @@ Use Ctrl+S to save entries and Ctrl+Q to quit."""
     def _toggle_search_filter(self) -> None:
         """Toggle the search and filter panel."""
         if self.search_filter_visible:
+            if self.search_filter_widget is not None:
                 self.search_filter_widget.hide()
             self.search_filter_visible = False
             self.ui_manager.update_status("Search panel hidden", "info")
             set_pref("search_panel_visible", False)
             save_preferences()
         else:
-            self.search_filter_widget.show()
+            self._ensure_search_widget()
+            # mypy: widget ensured above
+            self.search_filter_widget.show()  # type: ignore[union-attr]
             self.search_filter_visible = True
             self.ui_manager.update_status("Search panel shown", "info")
             set_pref("search_panel_visible", True)
             save_preferences()
 
+    def _ensure_search_widget(self) -> None:
+        """Create the search widget on demand to support lazy-loading."""
+        if getattr(self, "search_filter_widget", None) is not None:
+            return
+        try:
+            # Local import to defer module load cost until first use
+            from search_filter_ui import SearchFilterWidget  # type: ignore
+
+            self.search_filter_widget = SearchFilterWidget(
+                self.main_frame,
+                self.data_filter,
+                self._on_filter_update,
+                self.medicine_manager,
+                self.pathology_manager,
+                logger,
+            )
+            # If filters were restored earlier, reflect state in UI now
+            with contextlib.suppress(Exception):
+                self.search_filter_widget.sync_ui_from_filter()
+        except Exception as exc:
+            logger.error(f"Failed to initialize search panel: {exc}")
+            self.ui_manager.update_status("Search panel unavailable", "error")
+
     def _on_filter_update(self) -> None:
         """Handle filter updates from the search widget."""
         # Debounce rapid filter changes to avoid repeated heavy refresh.
@@ -1608,6 +1629,10 @@ Use Ctrl+S to save entries and Ctrl+Q to quit."""
                 if current_scroll_top > 0:
                     self.tree.yview_moveto(current_scroll_top)
 
+            # Ensure alternating stripes are normalized after any update
+            with contextlib.suppress(Exception):
+                self.ui_manager.normalize_tree_stripes(self.tree)
+
         except Exception as e:
             logger.error(f"Error updating tree efficiently: {e}")