diff --git a/README.md b/README.md
index 52da745..45e0ecf 100644
--- a/README.md
+++ b/README.md
@@ -35,16 +35,11 @@ Allows authorized users to create, edit, and manage document pages. Support for
 
 ---
 
-## 💡 What's New (v0.2.1) - Stability & Profile Improvements
+## 🛠 What's New (v0.2.16)
 
-This patch release improves reliability and profile editing behavior.
-
-### 🛠 Improved
-
-- Fixed a crash when opening the profile window for accounts without a filled display name.
-- Improved reliability of profile data updates after backend deployment updates.
-- Improved handling of empty values in document and page names.
-- Improved stability of search and document loading in edge cases.
+- Improved toolbar behavior in document edit/create windows.
+- `Duplicate` and `Delete` now only mark a document as changed when pages were actually modified.
+- Reduced accidental “unsaved changes” state when pressing toolbar actions with no selected pages.
 
 ---
 
diff --git a/README_RU.md b/README_RU.md
index 7797807..e7e5d44 100644
--- a/README_RU.md
+++ b/README_RU.md
@@ -35,16 +35,11 @@
 
 ---
 
-## 💡 Что нового (v0.2.1) - Стабильность и профиль
+## 🛠 Что нового (v0.2.16)
 
-Это патч-обновление повышает надежность и улучшает поведение при работе с профилем.
-
-### 🛠 Улучшено
-
-- Исправлен сбой при открытии профиля для аккаунтов без заполненного отображаемого имени.
-- Повышена надежность обновления данных профиля после обновлений backend-сервиса.
-- Улучшена обработка пустых значений в названиях документов и страниц.
-- Повышена стабильность поиска и загрузки документов в пограничных сценариях.
+- Улучшено поведение панели инструментов в окнах создания и редактирования документа.
+- `Дублировать` и `Удалить` теперь помечают документ как изменённый только при реальном изменении страниц.
+- Снижен риск ложного состояния “есть несохранённые изменения” при нажатии действий без выбранных страниц.
 
 ---
 
diff --git a/api/api_client.py b/api/api_client.py
index fb446ab..37bb925 100644
--- a/api/api_client.py
+++ b/api/api_client.py
@@ -539,4 +539,10 @@ def _request(self, method: str, url: str, timeout: int = 10, **kwargs) -> dict:
         request.raise_for_status()
         if request.status_code == 204 or not request.content:
             return {}
-        return request.json()
+        try:
+            return request.json()
+        except ValueError:
+            # Some backends may return 200 with an empty/whitespace body.
+            if not (request.text or "").strip():
+                return {}
+            raise
diff --git a/app.py b/app.py
index d277c84..d0addf1 100644
--- a/app.py
+++ b/app.py
@@ -27,7 +27,7 @@
 os.environ.setdefault("QT_SCALE_FACTOR_ROUNDING_POLICY", "PassThrough")
 
 
-APP_VERSION = "0.2.1"
+APP_VERSION = "0.2.16"
 
 class Application:
     """
diff --git a/core/updater.py b/core/updater.py
index 020b95f..bfd6fb9 100644
--- a/core/updater.py
+++ b/core/updater.py
@@ -78,6 +78,7 @@ class UpdateDownloader(QThread):
     """Thread for downloading the update file."""
     progress = pyqtSignal(int, int) # downloaded_bytes, total_bytes
     finished = pyqtSignal(str)  # путь к скачанному файлу
+    canceled = pyqtSignal()
     error = pyqtSignal(str)
 
     def __init__(self, url: str, expected_size: int = 0):
@@ -91,6 +92,7 @@ def stop(self):
         self._is_running = False
 
     def run(self):
+        path = None
         try:
             # Use requests context manager to ensure connection closure
             with requests.get(self.url, stream=True, timeout=30, allow_redirects=True) as response:
@@ -121,6 +123,7 @@ def run(self):
                                 os.remove(path)
                             except OSError:
                                 pass
+                            self.canceled.emit()
                             return
 
                         if chunk:
@@ -138,10 +141,24 @@ def run(self):
                                     self.progress.emit(downloaded_size, total_size)
                                     last_emitted_size = downloaded_size
 
-                if self._is_running:
-                    self.finished.emit(path)
+                if not self._is_running:
+                    try:
+                        os.remove(path)
+                    except OSError:
+                        pass
+                    self.canceled.emit()
+                    return
+
+                self.finished.emit(path)
 
         except Exception as e:
+            if path and not self._is_running:
+                try:
+                    os.remove(path)
+                except OSError:
+                    pass
+                self.canceled.emit()
+                return
             logger.error(f"Download failed: {e}")
             self.error.emit(str(e))
 
@@ -193,6 +210,7 @@ def _start_download(self, url, size):
         self._downloader = UpdateDownloader(url, size)
         self._downloader.progress.connect(self.progress_dialog.set_progress)
         self._downloader.finished.connect(self._on_download_finished)
+        self._downloader.canceled.connect(self._on_download_canceled)
         self._downloader.error.connect(self._on_download_error)
         
         self.progress_dialog.canceled.connect(self._downloader.stop)
@@ -201,6 +219,7 @@ def _start_download(self, url, size):
 
     def _on_download_error(self, error_msg):
         self.progress_dialog.close()
+        self._downloader = None
         # If main window is not created yet (check on startup), NotificationService won't work
         if NotificationService().main_window:
             NotificationService().show_toast("error", "Ошибка", f"Ошибка скачивания: {error_msg}")
@@ -208,6 +227,12 @@ def _on_download_error(self, error_msg):
             # Use standard QMessageBox as a fallback
             QMessageBox.critical(self.parent_widget, "Ошибка", f"Ошибка скачивания:\n{error_msg}")
 
+    def _on_download_canceled(self):
+        self.progress_dialog.close()
+        self._downloader = None
+        if NotificationService().main_window:
+            NotificationService().show_toast("info", "Обновление", "Скачивание обновления отменено.")
+
     def _on_download_finished(self, file_path):
         # Force set 100% so user sees completion
         self.progress_dialog.set_progress(100, 100)
@@ -216,6 +241,7 @@ def _on_download_finished(self, file_path):
 
     def _show_install_confirmation(self, file_path):
         self.progress_dialog.close()
+        self._downloader = None
         dialog = InstallConfirmDialog(self.parent_widget)
         if dialog.exec_() == QDialog.Accepted:
             self._install_update(file_path)
diff --git a/modules/auth/mvc/auth_controller.py b/modules/auth/mvc/auth_controller.py
index 5a19bdd..c807016 100644
--- a/modules/auth/mvc/auth_controller.py
+++ b/modules/auth/mvc/auth_controller.py
@@ -96,6 +96,13 @@ def login_user(self, data: dict) -> None:
         try:
             auto_login = self.view.login_page.get_auto_login_state()
             user_id = self.model.save_user(user_data=data, auto_login=auto_login)
+            if not isinstance(user_id, int):
+                NotificationService().show_toast(
+                    "error",
+                    "Ошибка входа",
+                    "Не удалось сохранить сессию. Попробуйте войти снова."
+                )
+                return
 
             self.view.login_page.clear_lineedits()
             self.login_successful.emit("auth", user_id)
@@ -120,6 +127,13 @@ def signup_user(self, user_data: dict) -> None:
         try:
             auto_login = self.view.signup_page.get_auto_login_state()
             user_id = self.model.save_user(user_data=user_data, auto_login=auto_login)
+            if not isinstance(user_id, int):
+                NotificationService().show_toast(
+                    "error",
+                    "Ошибка регистрации",
+                    "Не удалось сохранить сессию. Попробуйте войти снова."
+                )
+                return
 
             self.view.signup_page.clear_lineedits()
 
@@ -154,6 +168,13 @@ def signup(self, data: dict, email: str, password: str) -> None:
             message=f"Код подтверждения отправлен на {email}"
         )
         code = EmailConfirmDialog.get_code(parent=self.auth_window)
+        if not code:
+            NotificationService().show_toast(
+                notification_type="info",
+                title="Подтверждение отменено",
+                message="Регистрация не завершена: код подтверждения не введён."
+            )
+            return
 
         # Create success callback
         success_cb = lambda data: self.signup_user(user_data=data)
@@ -228,6 +249,13 @@ def open_email_confirm_modal_window(self, data, email: str) -> None:
         """
         logging.info(f"Reset password data received: {data}")
         code = EmailConfirmDialog.get_code(parent=self.auth_window)
+        if not code:
+            NotificationService().show_toast(
+                notification_type="info",
+                title="Подтверждение отменено",
+                message="Сброс пароля не завершён: код подтверждения не введён."
+            )
+            return
 
         # Create success callback
         success_cb = lambda data: self.switch_to_reset_password_page(data=data)
@@ -328,10 +356,12 @@ def on_login_page_lineedits_changed(self) -> None:
 
         # Validate email
         if not self.field_validator.validate_email(email=email):
+            self.view.login_page.update_submit_button_state(state=False)
             return
         
         # Validate password
         if not self.field_validator.validate_password(password=password):
+            self.view.login_page.update_submit_button_state(state=False)
             return
 
         # Defining login button state (True if both lineedits has text, else False)
@@ -400,10 +430,12 @@ def on_signup_page_lineedits_changed(self) -> None:
         
         # Validate email
         if not self.field_validator.validate_email(email=email):
+            self.view.signup_page.update_submit_button_state(state=False)
             return
         
         # Validate password
         if not self.field_validator.validate_password(password=password):
+            self.view.signup_page.update_submit_button_state(state=False)
             return
 
         # Check password matching
@@ -491,6 +523,7 @@ def on_reset_password_page_lineedits_changed(self) -> None:
         
         # Validate password
         if not self.field_validator.validate_password(password=password):
+            self.view.forgot_page_reset_password.update_submit_button_state(state=False)
             return
         
         # Check password matching
diff --git a/modules/auth/mvc/auth_model.py b/modules/auth/mvc/auth_model.py
index ecf4bd5..ab4c7cf 100644
--- a/modules/auth/mvc/auth_model.py
+++ b/modules/auth/mvc/auth_model.py
@@ -138,6 +138,9 @@ def save_user(self, user_data: dict, auto_login: bool) -> int | None:
             return None
 
         user_id = user.get("id", None)
+        if not isinstance(user_id, int):
+            logging.error("Cannot save user session: invalid or missing user id.")
+            return None
 
         # Save access and refresh tokens
         self.save_token(token_name=f"access_token_{user_id}", token="access_token", data=user_data)
diff --git a/modules/document_editor/mvc/document_editor_controller.py b/modules/document_editor/mvc/document_editor_controller.py
index 7e06425..e0271f3 100644
--- a/modules/document_editor/mvc/document_editor_controller.py
+++ b/modules/document_editor/mvc/document_editor_controller.py
@@ -129,8 +129,10 @@ def _on_add_page_button_clicked(self) -> None:
 
     def _on_duplicate_page_button_clicked(self) -> None:
         """Handles the duplicate page button click event."""
-        self.view.duplicate_selected_pages()
-        self._on_document_data_changed()
+        changed = self.view.duplicate_selected_pages()
+        if changed:
+            self._on_document_data_changed()
+        self._on_table_selection_changed()
 
 
     def _on_print_button_clicked(self) -> None:
@@ -250,8 +252,9 @@ def _on_export_button_clicked(self) -> None:
 
     def _on_delete_page_button_clicked(self) -> None:
         """Handles the delete page button click event."""
-        self.view.delete_selected_pages()
-        self._on_document_data_changed()
+        changed = self.view.delete_selected_pages()
+        if changed:
+            self._on_document_data_changed()
         self._on_table_selection_changed()
 
 
diff --git a/modules/document_editor/mvc/document_editor_model.py b/modules/document_editor/mvc/document_editor_model.py
index 303f9ec..db6fead 100644
--- a/modules/document_editor/mvc/document_editor_model.py
+++ b/modules/document_editor/mvc/document_editor_model.py
@@ -190,11 +190,12 @@ def save_document(self, data: dict) -> None:
     
     def _get_user_token(self) -> str | None:
         last_logged = read_json(self.LOCAL_DIR_LAST_LOGGED)
-
-        if not last_logged:
+        if not isinstance(last_logged, dict):
             return None
 
-        user_id = last_logged["user_id"]
+        user_id = last_logged.get("user_id")
+        if user_id in (None, ""):
+            return None
 
         access_token = keyring.get_password(
             service_name="Documents Exp",
@@ -222,10 +223,12 @@ def _refresh_tokens(self) -> bool:
         """Refreshes tokens using the stored refresh token."""
         try:
             last_logged = read_json(self.LOCAL_DIR_LAST_LOGGED)
-            if not last_logged:
+            if not isinstance(last_logged, dict):
                 return False
             
             user_id = last_logged.get("user_id")
+            if user_id in (None, ""):
+                return False
             refresh_token = keyring.get_password("Documents Exp", f"refresh_token_{user_id}")
             
             if not refresh_token:
@@ -237,4 +240,4 @@ def _refresh_tokens(self) -> bool:
             return True
         except Exception as e:
             logging.error(f"Failed to refresh tokens: {e}")
-            return False
\ No newline at end of file
+            return False
diff --git a/modules/document_editor/mvc/document_editor_view.py b/modules/document_editor/mvc/document_editor_view.py
index 813b8fa..19d1712 100644
--- a/modules/document_editor/mvc/document_editor_view.py
+++ b/modules/document_editor/mvc/document_editor_view.py
@@ -292,8 +292,12 @@ def add_new_page(self) -> None:
         self.table_view.edit(index)
 
 
-    def delete_selected_pages(self) -> None:
-        """Deletes selected or checked pages from the table."""
+    def delete_selected_pages(self) -> bool:
+        """Deletes selected or checked pages from the table.
+
+        Returns:
+            bool: True if any page was deleted, otherwise False.
+        """
         model = self.table_view.model()
         rows_to_delete = set()
 
@@ -313,10 +317,15 @@ def delete_selected_pages(self) -> None:
             model.removeRow(row)
         
         self.table_view.clearSelection()
+        return bool(rows_to_delete)
 
 
-    def duplicate_selected_pages(self) -> None:
-        """Duplicates selected or checked pages."""
+    def duplicate_selected_pages(self) -> bool:
+        """Duplicates selected or checked pages.
+
+        Returns:
+            bool: True if any page was duplicated, otherwise False.
+        """
         model = self.table_view.model()
         rows_to_duplicate = set()
 
@@ -375,6 +384,7 @@ def duplicate_selected_pages(self) -> None:
                 model.index(insert_row, 0), 
                 QItemSelectionModel.Select | QItemSelectionModel.Rows
             )
+        return bool(rows_to_duplicate)
 
 
     def has_selection_or_checks(self) -> bool:
@@ -561,14 +571,22 @@ def has_selected_pages(self) -> bool:
         return self.pages_table.has_selection_or_checks()
 
 
-    def delete_selected_pages(self) -> None:
-        """Deletes selected or checked pages."""
-        self.pages_table.delete_selected_pages()
+    def delete_selected_pages(self) -> bool:
+        """Deletes selected or checked pages.
+
+        Returns:
+            bool: True if any page was deleted, otherwise False.
+        """
+        return self.pages_table.delete_selected_pages()
 
     
-    def duplicate_selected_pages(self) -> None:
-        """Duplicates selected or checked pages."""
-        self.pages_table.duplicate_selected_pages()
+    def duplicate_selected_pages(self) -> bool:
+        """Duplicates selected or checked pages.
+
+        Returns:
+            bool: True if any page was duplicated, otherwise False.
+        """
+        return self.pages_table.duplicate_selected_pages()
 
 
     def get_document_data(self) -> dict:
@@ -811,4 +829,4 @@ def switch_to_files_tab(self) -> None:
         self.ui.tabs_tabWidget.setCurrentIndex(1)
 
     def set_file_drop_active(self, active: bool) -> None:
-        self.files_tab.file_drop_widget.setDragActive(active)
\ No newline at end of file
+        self.files_tab.file_drop_widget.setDragActive(active)
diff --git a/modules/main/mvc/main_controller.py b/modules/main/mvc/main_controller.py
index 964f014..9c407d3 100644
--- a/modules/main/mvc/main_controller.py
+++ b/modules/main/mvc/main_controller.py
@@ -98,10 +98,14 @@ def __init__(
     # Controller Handlers
     # ====================
 
+    def _normalized_search_text(self) -> str:
+        """Returns trimmed search text to avoid treating whitespace as active search."""
+        return (self.view.get_search_text() or "").strip()
+
 
     def _on_search_lineedit_text_changed(self) -> None:
         """Handles the search line edit text change."""
-        search_text = self.view.get_search_text()
+        search_text = self._normalized_search_text()
         
         # If empty, update immediately without delay
         if not search_text:
@@ -129,7 +133,7 @@ def _on_search_filters_changed(self, checked: bool) -> None:
 
     def _perform_search(self) -> None:
         """Executes the search request after delay."""
-        search_text = self.view.get_search_text()
+        search_text = self._normalized_search_text()
         filters = self.view.get_search_filters()
         if not search_text:
             return
@@ -455,7 +459,7 @@ def _on_department_selected(self, selected, deselected) -> None:
 
                 # With active search keep previous table until new results arrive.
                 # This avoids a blank table if the first request after idle fails.
-                if self.view.get_search_text():
+                if self._normalized_search_text():
                     self._on_search_lineedit_text_changed()
                 else:
                     # No search active: clear stale documents and load current category data.
@@ -477,13 +481,13 @@ def _on_category_selected(self, selected, deselected) -> None:
 
             if cat_id is not None and cat_id != self.model.current_category_id:
                 self.model.current_category_id = cat_id
-                if self.view.get_search_text():
+                if self._normalized_search_text():
                     self._on_search_lineedit_text_changed()
                 else:
                     self._update_documents_list()
         else:
             self.model.current_category_id = None
-            if self.view.get_search_text():
+            if self._normalized_search_text():
                 self._on_search_lineedit_text_changed()
             else:
                 self._update_documents_list()
@@ -495,9 +499,13 @@ def _on_category_selected(self, selected, deselected) -> None:
     def _on_update_button_clicked(self) -> None:
         """Handles the update button click."""
         try:
+            saved_dept_id = self.model.current_department_id
+            saved_cat_id = self.model.current_category_id
             self.model.refresh_data()
-            self._update_app_data()
-            self._update_documents_list() # Reload list
+            self._update_app_data(
+                preferred_dept_id=saved_dept_id,
+                preferred_cat_id=saved_cat_id
+            )
             NotificationService().show_toast(
                 notification_type="success",
                 title="Обновлено",
@@ -541,9 +549,13 @@ def _on_edit_button_clicked(self) -> None:
                 logger.error(f"Error fetching document details: {e}")
 
         # Get selected document pages list
-        pages = self.model.get_document_pages(
-            document_id=document_id
-        )
+        try:
+            pages = self.model.get_document_pages(
+                document_id=document_id
+            )
+        except Exception as e:
+            self._handle_error(e, "Ошибка загрузки документа")
+            return
 
         # Show document editor window
         self.editor_window = EditorWindow(
@@ -691,7 +703,7 @@ def _on_table_scroll(self, value: int) -> None:
         if not at_bottom:
             return
 
-        if self.view.get_search_text():
+        if self._normalized_search_text():
             # Search results are held fully in memory — paginate client-side
             self._load_more_search_results()
         elif not self.is_loading and self.has_more:
@@ -763,7 +775,7 @@ def _on_search_finished(self, data: list) -> None:
 
         # If the user cleared the search field while the worker was running,
         # discard the result — _update_documents_list already took over.
-        search_text = self.view.get_search_text()
+        search_text = self._normalized_search_text()
         if not search_text:
             return
 
@@ -1018,7 +1030,7 @@ def _update_documents_list(self) -> None:
     def _load_more_documents(self) -> None:
         """Loads the next page of documents."""
         # Do not load more if loading, no category selected, or SEARCH IS ACTIVE
-        if self.is_loading or self.model.current_category_id is None or self.view.get_search_text():
+        if self.is_loading or self.model.current_category_id is None or self._normalized_search_text():
             return
 
         self.is_loading = True
@@ -1070,7 +1082,7 @@ def _on_load_more_finished(self, docs: list) -> None:
         self.search_results_all = []
 
         # Prevent updating UI if search is active (stale request)
-        if self.view.get_search_text():
+        if self._normalized_search_text():
             return
 
         # With a large limit, we assume we've fetched all documents.
@@ -1119,25 +1131,46 @@ def _on_load_more_error(self, error: Exception) -> None:
         self._handle_error(error, "Ошибка загрузки документов")
 
     
-    def _update_app_data(self):
+    def _update_app_data(self, preferred_dept_id=None, preferred_cat_id=None):
         """Updates the application data."""
         self.is_updating_data = True
+        dept_exists = False
         
         try:
             # Save current selection to restore it after reload
-            saved_dept_id = self.model.current_department_id
-            saved_cat_id = self.model.current_category_id
-
-            self._load_sidebar_data()
+            saved_dept_id = (
+                preferred_dept_id
+                if preferred_dept_id is not None
+                else self.model.current_department_id
+            )
+            saved_cat_id = (
+                preferred_cat_id
+                if preferred_cat_id is not None
+                else self.model.current_category_id
+            )
             
             # Check if saved department exists
-            dept_exists = any(d["id"] == saved_dept_id for d in self.model.departments)
+            matched_dept = next(
+                (d for d in self.model.departments if str(d.get("id")) == str(saved_dept_id)),
+                None
+            )
+            dept_exists = matched_dept is not None
+            self.model.current_department_id = matched_dept.get("id") if matched_dept else (
+                self.model.departments[0]["id"] if self.model.departments else None
+            )
+
+            # Rebuild sidebar/categories for the resolved current department.
+            self._load_sidebar_data()
 
             if dept_exists:
-                self.view.select_department(saved_dept_id)
+                self.view.select_department(self.model.current_department_id)
                 
                 # Restore category
-                cat_exists = any(c["id"] == saved_cat_id for c in self.model.categories)
+                matched_cat = next(
+                    (c for c in self.model.categories if str(c.get("id")) == str(saved_cat_id)),
+                    None
+                )
+                cat_exists = matched_cat is not None
                 
                 if not cat_exists and isinstance(
                     saved_cat_id, str
@@ -1145,12 +1178,15 @@ def _update_app_data(self):
                     cat_exists = True
 
                 if cat_exists:
-                    self.view.select_category(saved_cat_id)
+                    self.model.current_category_id = (
+                        matched_cat.get("id") if matched_cat is not None else saved_cat_id
+                    )
+                    self.view.select_category(self.model.current_category_id)
                 else:
                     # If category was deleted or not selected, select the first one if available
                     # to match SidebarBlock behavior (which selects first item on reset)
                     dept_cats = [c for c in self.model.categories 
-                                 if c.get("group_id") == saved_dept_id]
+                                 if str(c.get("group_id")) == str(self.model.current_department_id)]
                     if dept_cats:
                         self.model.current_category_id = dept_cats[0]["id"]
                         self.view.select_category(self.model.current_category_id)
@@ -1161,11 +1197,14 @@ def _update_app_data(self):
 
         # Trigger update manually after state is restored
         if dept_exists:
-            if self.view.get_search_text():
+            if self._normalized_search_text():
                 # Perform search immediately, bypassing debounce timer
                 self._perform_search()
             else:
                 self._update_documents_list()
+        else:
+            self.model.current_category_id = None
+            self._update_documents_list()
 
         self._update_create_category_state()
         self._update_create_document_state()
diff --git a/modules/main/mvc/main_model.py b/modules/main/mvc/main_model.py
index c0afe35..2136bd5 100644
--- a/modules/main/mvc/main_model.py
+++ b/modules/main/mvc/main_model.py
@@ -342,11 +342,12 @@ def _get_user_token(self) -> str | None:
             return None
 
         last_logged = read_json(self.LOCAL_DIR_LAST_LOGGED)
-
-        if not last_logged:
+        if not isinstance(last_logged, dict):
             return None
 
-        user_id = last_logged["user_id"]
+        user_id = last_logged.get("user_id")
+        if user_id in (None, ""):
+            return None
 
         access_token = keyring.get_password(
             service_name="Documents Exp",
diff --git a/tests/test_apiclient.py b/tests/test_apiclient.py
index 5c078a7..a24acc8 100644
--- a/tests/test_apiclient.py
+++ b/tests/test_apiclient.py
@@ -170,6 +170,33 @@ def test_request_returns_empty_dict_for_empty_body(self, client):
 
             assert result == {}
 
+    def test_request_returns_empty_dict_for_whitespace_json_body(self, client):
+        with patch.object(client.session, "request") as mock_request:
+            mock_response = Mock()
+            mock_response.status_code = 200
+            mock_response.content = b"   \n\t  "
+            mock_response.text = "   \n\t  "
+            mock_response.raise_for_status = Mock()
+            mock_response.json.side_effect = ValueError("No JSON object could be decoded")
+            mock_request.return_value = mock_response
+
+            result = client._request("GET", f"{self.BASE_URL}/app/search")
+
+            assert result == {}
+
+    def test_request_raises_for_non_json_non_empty_body(self, client):
+        with patch.object(client.session, "request") as mock_request:
+            mock_response = Mock()
+            mock_response.status_code = 200
+            mock_response.content = b"<html>error</html>"
+            mock_response.text = "<html>error</html>"
+            mock_response.raise_for_status = Mock()
+            mock_response.json.side_effect = ValueError("No JSON object could be decoded")
+            mock_request.return_value = mock_response
+
+            with pytest.raises(ValueError):
+                client._request("GET", f"{self.BASE_URL}/app/search")
+
     def test_search_data(self, client):
         token = "auth_token"
         query = "test query"
diff --git a/tests/test_auth.py b/tests/test_auth.py
index c77ca76..efd3fae 100644
--- a/tests/test_auth.py
+++ b/tests/test_auth.py
@@ -59,6 +59,21 @@ def test_save_user(self, model):
             # Check file writing (user data and last logged)
             assert mock_open.call_count >= 2
 
+    def test_save_user_returns_none_for_invalid_user_id(self, model):
+        user_data = {
+            "user": {"id": None, "email": "test@test.com"},
+            "access_token": "acc",
+            "refresh_token": "ref",
+        }
+
+        with patch("modules.auth.mvc.auth_model.keyring.set_password") as mock_keyring, \
+             patch("builtins.open", new_callable=MagicMock) as mock_open:
+            result = model.save_user(user_data, True)
+
+        assert result is None
+        mock_keyring.assert_not_called()
+        mock_open.assert_not_called()
+
     def test_save_token_raises_when_keyring_write_fails(self, model):
         with patch("modules.auth.mvc.auth_model.keyring.set_password", side_effect=Exception("keyring fail")):
             with pytest.raises(RuntimeError):
@@ -169,6 +184,21 @@ def test_login_success_callback_handles_save_error(self, controller):
         controller.view.login_page.clear_lineedits.assert_not_called()
         MockNotify.return_value.show_toast.assert_called_once()
 
+    def test_login_success_callback_handles_invalid_user_id(self, controller):
+        data = {"user": {"id": None}}
+        controller.view.login_page.get_auto_login_state.return_value = True
+        controller.model.save_user.return_value = None
+
+        mock_signal = Mock()
+        controller.login_successful.connect(mock_signal)
+
+        with patch("modules.auth.mvc.auth_controller.NotificationService") as MockNotify:
+            controller.login_user(data)
+
+        mock_signal.assert_not_called()
+        controller.view.login_page.clear_lineedits.assert_not_called()
+        MockNotify.return_value.show_toast.assert_called_once()
+
     def test_reset_password_page_switch_handles_save_error(self, controller):
         controller.view.pages = {"change_password_change_page": Mock()}
         controller.model.save_token.side_effect = RuntimeError("keyring fail")
@@ -215,4 +245,68 @@ def test_validation_login_invalid(self, controller):
         controller.view.login_page.get_email.return_value = "invalid"
         controller.on_login_page_lineedits_changed()
         
-        controller.view.login_page.update_submit_button_state.assert_not_called()
+        controller.view.login_page.update_submit_button_state.assert_called_once_with(state=False)
+
+    def test_validation_login_invalid_password_disables_submit(self, controller):
+        controller.field_validator.validate_email.return_value = True
+        controller.field_validator.validate_password.return_value = False
+        controller.view.login_page.get_email.return_value = "valid@test.com"
+        controller.view.login_page.get_password.return_value = "short"
+
+        controller.on_login_page_lineedits_changed()
+
+        controller.view.login_page.update_submit_button_state.assert_called_once_with(state=False)
+
+    def test_validation_signup_invalid_email_disables_submit(self, controller):
+        controller.field_validator.validate_email.return_value = False
+        controller.view.signup_page.get_email.return_value = "invalid"
+
+        controller.on_signup_page_lineedits_changed()
+
+        controller.view.signup_page.update_submit_button_state.assert_called_once_with(state=False)
+
+    def test_validation_reset_password_invalid_disables_submit(self, controller):
+        controller.field_validator.validate_password.return_value = False
+        controller.view.forgot_page_reset_password.get_password.return_value = "123"
+        controller.view.forgot_page_reset_password.get_confirm_password.return_value = "123"
+
+        controller.on_reset_password_page_lineedits_changed()
+
+        controller.view.forgot_page_reset_password.update_submit_button_state.assert_called_once_with(state=False)
+
+    def test_signup_skips_worker_when_confirmation_code_cancelled(self, controller):
+        with patch("modules.auth.mvc.auth_controller.EmailConfirmDialog.get_code", return_value=None), \
+             patch.object(controller, "_create_worker") as mock_create_worker, \
+             patch("modules.auth.mvc.auth_controller.NotificationService") as MockNotify:
+            controller.signup(data={}, email="new@test.com", password="StrongPass123")
+
+        mock_create_worker.assert_not_called()
+        MockNotify.return_value.show_toast.assert_any_call(
+            notification_type="info",
+            title="Подтверждение отменено",
+            message="Регистрация не завершена: код подтверждения не введён."
+        )
+
+    def test_reset_confirm_skips_worker_when_confirmation_code_cancelled(self, controller):
+        with patch("modules.auth.mvc.auth_controller.EmailConfirmDialog.get_code", return_value=""), \
+             patch.object(controller, "_create_worker") as mock_create_worker, \
+             patch("modules.auth.mvc.auth_controller.NotificationService") as MockNotify:
+            controller.open_email_confirm_modal_window(data={}, email="new@test.com")
+
+        mock_create_worker.assert_not_called()
+        MockNotify.return_value.show_toast.assert_called_once()
+
+    def test_signup_success_callback_handles_invalid_user_id(self, controller):
+        data = {"user": {"id": None}}
+        controller.view.signup_page.get_auto_login_state.return_value = True
+        controller.model.save_user.return_value = None
+
+        mock_signal = Mock()
+        controller.login_successful.connect(mock_signal)
+
+        with patch("modules.auth.mvc.auth_controller.NotificationService") as MockNotify:
+            controller.signup_user(data)
+
+        mock_signal.assert_not_called()
+        controller.view.signup_page.clear_lineedits.assert_not_called()
+        MockNotify.return_value.show_toast.assert_called_once()
diff --git a/tests/test_document_editor.py b/tests/test_document_editor.py
index 7b29c40..8730229 100644
--- a/tests/test_document_editor.py
+++ b/tests/test_document_editor.py
@@ -92,6 +92,22 @@ def test_export_to_docx(self, model, tmp_path):
             mock_doc.add_table.assert_called()
             mock_doc.save.assert_called_with(str(tmp_path / "export.docx"))
 
+    def test_get_user_token_returns_none_for_non_dict_last_logged(self, model):
+        with patch("modules.document_editor.mvc.document_editor_model.read_json", return_value=[]):
+            assert model._get_user_token() is None
+
+    def test_get_user_token_returns_none_for_missing_user_id(self, model):
+        with patch("modules.document_editor.mvc.document_editor_model.read_json", return_value={}), \
+             patch("modules.document_editor.mvc.document_editor_model.keyring.get_password") as mock_get_password:
+            assert model._get_user_token() is None
+            mock_get_password.assert_not_called()
+
+    def test_refresh_tokens_returns_false_for_missing_user_id(self, model):
+        with patch("modules.document_editor.mvc.document_editor_model.read_json", return_value={}), \
+             patch("modules.document_editor.mvc.document_editor_model.keyring.get_password") as mock_get_password:
+            assert model._refresh_tokens() is False
+            mock_get_password.assert_not_called()
+
 
 
 class TestDocumentEditorController:
@@ -207,3 +223,23 @@ def test_delete_document_clicked(self, controller):
             controller.model.delete_document.assert_called_once()
             controller.window.document_deleted.emit.assert_called_once()
             controller.window.close.assert_called_once()
+
+    def test_duplicate_without_selection_does_not_mark_document_edited(self, controller):
+        controller.model.is_document_edited = False
+        controller.view.duplicate_selected_pages.return_value = False
+
+        with patch.object(controller, "_on_document_data_changed") as mock_changed:
+            controller._on_duplicate_page_button_clicked()
+
+        mock_changed.assert_not_called()
+        controller.view.update_delete_page_button_state.assert_called()
+
+    def test_delete_without_selection_does_not_mark_document_edited(self, controller):
+        controller.model.is_document_edited = False
+        controller.view.delete_selected_pages.return_value = False
+
+        with patch.object(controller, "_on_document_data_changed") as mock_changed:
+            controller._on_delete_page_button_clicked()
+
+        mock_changed.assert_not_called()
+        controller.view.update_delete_page_button_state.assert_called()
diff --git a/tests/test_main.py b/tests/test_main.py
index cdbed17..06c4c2a 100644
--- a/tests/test_main.py
+++ b/tests/test_main.py
@@ -144,6 +144,20 @@ def test_load_more_documents(self, controller):
             assert kwargs['offset'] == 0
             assert kwargs['limit'] == controller.limit
 
+    def test_load_more_documents_when_search_has_only_whitespace(self, controller):
+        """Whitespace-only search text should be treated as empty and must not block loading."""
+        controller.model.current_category_id = 10
+        controller.is_loading = False
+        controller.has_more = True
+        controller.offset = 0
+        controller.view.get_search_text.return_value = "   "
+
+        with patch("modules.main.mvc.main_controller.APIWorker") as MockWorker:
+            controller._load_more_documents()
+
+            assert controller.is_loading is True
+            MockWorker.assert_called_once()
+
     def test_update_documents_list_keeps_previous_table_until_success(self, controller):
         """Reloading the table should not clear the old data before the new response arrives."""
         controller.model.current_category_id = 10
@@ -284,3 +298,58 @@ def test_search_task_handles_invalid_virtual_category_id(self, controller):
             group_id=None,
             filters={},
         )
+
+    def test_edit_button_handles_pages_loading_error(self, controller):
+        """Editor opening should fail safely when pages loading raises."""
+        controller.model.selected_document = (55, False)
+        controller.model.get_document.return_value = {"id": 55}
+        controller.model.get_document_pages.side_effect = RuntimeError("pages failed")
+
+        with patch.object(controller, "_handle_error") as mock_handle_error, \
+             patch("modules.main.mvc.main_controller.EditorWindow") as MockEditor:
+            controller._on_edit_button_clicked()
+
+        mock_handle_error.assert_called_once()
+        MockEditor.assert_not_called()
+
+    def test_update_button_keeps_selected_department_and_category(self, controller):
+        """Update must preserve current dept/category selection when new departments are added."""
+        controller.model.current_department_id = 2
+        controller.model.current_category_id = "20"
+        controller.model.departments = [
+            {"id": 1, "name": "Dept 1", "documents_count": 5},
+            {"id": 2, "name": "Dept 2", "documents_count": 3},
+        ]
+        controller.model.categories = [
+            {"id": 10, "name": "Cat 1", "group_id": 1, "documents_count": 2},
+            {"id": 20, "name": "Cat 2", "group_id": 2, "documents_count": 4},
+        ]
+        controller.view.get_search_text.return_value = ""
+
+        def refresh_side_effect():
+            # Simulate model refresh behavior that resets current department
+            controller.model.departments = [
+                {"id": 1, "name": "Dept 1", "documents_count": 5},
+                {"id": 2, "name": "Dept 2", "documents_count": 3},
+                {"id": 3, "name": "New Dept", "documents_count": 1},
+            ]
+            controller.model.categories = [
+                {"id": 10, "name": "Cat 1", "group_id": 1, "documents_count": 2},
+                {"id": 20, "name": "Cat 2", "group_id": 2, "documents_count": 4},
+                {"id": 30, "name": "Cat 3", "group_id": 3, "documents_count": 1},
+            ]
+            controller.model.current_department_id = 1
+            controller.model.current_category_id = None
+
+        controller.model.refresh_data.side_effect = refresh_side_effect
+
+        with patch.object(controller, "_update_documents_list") as mock_update_docs:
+            controller._on_update_button_clicked()
+
+        assert controller.model.current_department_id == 2
+        assert controller.model.current_category_id == 20
+        categories_payload = controller.view.update_categories.call_args[0][0]
+        assert any(getattr(item, "id", None) == 20 for item in categories_payload)
+        controller.view.select_department.assert_any_call(2)
+        controller.view.select_category.assert_any_call(20)
+        mock_update_docs.assert_called_once()
diff --git a/tests/test_main_model.py b/tests/test_main_model.py
index d5c3c22..f147af4 100644
--- a/tests/test_main_model.py
+++ b/tests/test_main_model.py
@@ -32,3 +32,17 @@ def test_normalize_user_data_keeps_flat_payload(self):
         flat = {"id": 1, "email": "flat@x.test"}
         assert MainModel._normalize_user_data(flat) == flat
 
+    def test_get_user_token_returns_none_for_non_dict_last_logged(self):
+        model = self._build_model()
+
+        with patch("modules.main.mvc.main_model.read_json", return_value=[]):
+            assert model._get_user_token() is None
+
+    def test_get_user_token_returns_none_for_missing_user_id(self):
+        model = self._build_model()
+
+        with patch("modules.main.mvc.main_model.read_json", return_value={}), \
+             patch("modules.main.mvc.main_model.keyring.get_password") as mock_get_password:
+            assert model._get_user_token() is None
+            mock_get_password.assert_not_called()
+
diff --git a/tests/test_notifications.py b/tests/test_notifications.py
index 2128bf3..e5ea942 100644
--- a/tests/test_notifications.py
+++ b/tests/test_notifications.py
@@ -39,6 +39,8 @@ def test_show_toast(self, mock_toast_class, mock_tm):
         mock_toast_instance = Mock()
         mock_toast_instance.height.return_value = 100
         mock_toast_instance.width.return_value = 300
+        mock_toast_instance.destroyed = Mock()
+        mock_toast_instance.destroyed.connect = Mock()
         mock_toast_class.return_value = mock_toast_instance
         
         # Call method
@@ -54,11 +56,41 @@ def test_show_toast(self, mock_toast_class, mock_tm):
         
         # Verify that toast is added to list and shown
         assert mock_toast_instance in service.active_toasts
+        mock_toast_instance.destroyed.connect.assert_called_once()
         mock_toast_instance.show_animated.assert_called_once()
 
+    @patch("utils.notifications.notification_service.ThemeManagerInstance")
+    def test_destroyed_toast_is_removed_from_stack(self, mock_tm):
+        service = NotificationService()
+        service.main_window = Mock(spec=QWidget)
+
+        toast = Mock()
+        service.active_toasts = [toast]
+
+        with patch.object(service, "_reposition_toasts") as mock_reposition:
+            service._on_toast_destroyed(toast)
+
+        assert toast not in service.active_toasts
+        mock_reposition.assert_called_once()
+
     def test_singleton_behavior(self):
         """Test Singleton pattern."""
         with patch("utils.notifications.notification_service.ThemeManagerInstance"):
             s1 = NotificationService()
             s2 = NotificationService()
-            assert s1 is s2
\ No newline at end of file
+            assert s1 is s2
+
+    @patch("utils.notifications.notification_service.ThemeManagerInstance")
+    def test_set_main_window_accepts_none_without_crash(self, mock_tm):
+        service = NotificationService()
+        old_window = Mock(spec=QWidget)
+        old_toast = Mock()
+        service.main_window = old_window
+        service.active_toasts = [old_toast]
+
+        service.set_main_window(None)
+
+        old_window.removeEventFilter.assert_called_once()
+        old_toast.close.assert_called_once()
+        assert service.main_window is None
+        assert service.active_toasts == []
diff --git a/tests/test_settings_manager.py b/tests/test_settings_manager.py
index 9eeedab..befe329 100644
--- a/tests/test_settings_manager.py
+++ b/tests/test_settings_manager.py
@@ -1,3 +1,5 @@
+import json
+
 from unittest.mock import MagicMock, patch
 
 from utils.settings_manager import SettingsManager
@@ -11,3 +13,66 @@ def test_default_settings_include_whats_new_version(self):
             manager = SettingsManager(user_id=1)
 
             assert manager.get_default_settings()["last_seen_whats_new_version"] == ""
+
+    def test_default_search_filters_schema(self):
+        with patch("utils.settings_manager.get_app_data_dir") as mock_app_dir:
+            mock_app_dir.return_value = MagicMock()
+            manager = SettingsManager(user_id=1)
+
+            assert manager.get_default_settings()["search_filters"] == {
+                "include_pages": True,
+                "search_by_name": True,
+                "search_by_code": True,
+                "exact_match": False,
+            }
+
+    def test_load_settings_migrates_legacy_search_filters(self, tmp_path):
+        settings_file = tmp_path / "Profiles" / "user_settings_1.json"
+        settings_file.parent.mkdir(parents=True, exist_ok=True)
+        settings_file.write_text(
+            json.dumps(
+                {
+                    "search_filters": {
+                        "search_in_pages": False,
+                        "search_field": "code",
+                        "match_mode": "exact",
+                    }
+                }
+            ),
+            encoding="utf-8",
+        )
+
+        with patch("utils.settings_manager.get_app_data_dir", return_value=tmp_path):
+            manager = SettingsManager(user_id=1)
+            assert manager.get_setting("search_filters") == {
+                "include_pages": False,
+                "search_by_name": False,
+                "search_by_code": True,
+                "exact_match": True,
+            }
+
+    def test_load_settings_keeps_current_schema(self, tmp_path):
+        settings_file = tmp_path / "Profiles" / "user_settings_1.json"
+        settings_file.parent.mkdir(parents=True, exist_ok=True)
+        settings_file.write_text(
+            json.dumps(
+                {
+                    "search_filters": {
+                        "include_pages": False,
+                        "search_by_name": True,
+                        "search_by_code": False,
+                        "exact_match": True,
+                    }
+                }
+            ),
+            encoding="utf-8",
+        )
+
+        with patch("utils.settings_manager.get_app_data_dir", return_value=tmp_path):
+            manager = SettingsManager(user_id=1)
+            assert manager.get_setting("search_filters") == {
+                "include_pages": False,
+                "search_by_name": True,
+                "search_by_code": False,
+                "exact_match": True,
+            }
diff --git a/tests/test_updater.py b/tests/test_updater.py
index 35d6c21..09c38b1 100644
--- a/tests/test_updater.py
+++ b/tests/test_updater.py
@@ -1,7 +1,7 @@
 import pytest
 import requests
 from unittest.mock import Mock, patch, MagicMock
-from core.updater import GitHubUpdateChecker, UpdateDownloader
+from core.updater import GitHubUpdateChecker, UpdateDownloader, UpdateManager
 
 
 
@@ -147,3 +147,80 @@ def test_download_error(self):
             
             downloader.error.emit.assert_called_once()
             assert "Fail" in downloader.error.emit.call_args[0][0]
+
+    def test_download_canceled_emits_signal(self, tmp_path):
+        """Stopping download should emit canceled and not emit finished."""
+        url = "http://test.com/file.exe"
+        downloader = UpdateDownloader(url, 10)
+        downloader.finished = Mock()
+        downloader.progress = Mock()
+        downloader.error = Mock()
+        downloader.canceled = Mock()
+
+        with patch("requests.get") as mock_get:
+            mock_response = Mock()
+            mock_response.headers = {"content-length": "10"}
+
+            def chunks():
+                yield b"12345"
+                downloader.stop()
+                yield b"67890"
+
+            mock_response.iter_content.return_value = chunks()
+            mock_response.raise_for_status = Mock()
+            mock_get.return_value.__enter__.return_value = mock_response
+
+            target_file = tmp_path / "update.exe"
+            with patch("core.updater.tempfile.mkstemp", return_value=(123, str(target_file))), \
+                 patch("core.updater.os.close"):
+                downloader.run()
+
+        downloader.canceled.emit.assert_called_once()
+        downloader.finished.emit.assert_not_called()
+
+    def test_download_canceled_after_last_chunk_still_emits_signal(self, tmp_path):
+        """Cancel at the end of streaming should still emit canceled and clean temp file."""
+        url = "http://test.com/file.exe"
+        downloader = UpdateDownloader(url, 5)
+        downloader.finished = Mock()
+        downloader.progress = Mock()
+        downloader.error = Mock()
+        downloader.canceled = Mock()
+
+        with patch("requests.get") as mock_get:
+            mock_response = Mock()
+            mock_response.headers = {"content-length": "5"}
+
+            def chunks():
+                yield b"12345"
+                downloader.stop()
+
+            mock_response.iter_content.return_value = chunks()
+            mock_response.raise_for_status = Mock()
+            mock_get.return_value.__enter__.return_value = mock_response
+
+            target_file = tmp_path / "update.exe"
+            with patch("core.updater.tempfile.mkstemp", return_value=(123, str(target_file))), \
+                 patch("core.updater.os.close"):
+                downloader.run()
+
+        downloader.canceled.emit.assert_called_once()
+        downloader.finished.emit.assert_not_called()
+        assert not target_file.exists()
+
+
+class TestUpdateManager:
+    def test_on_download_canceled_cleans_state(self):
+        manager = UpdateManager(current_version="0.2.0", repo_name="owner/repo")
+        manager.progress_dialog = Mock()
+        manager._downloader = Mock()
+
+        with patch("core.updater.NotificationService") as mock_notification_service:
+            service_instance = mock_notification_service.return_value
+            service_instance.main_window = Mock()
+
+            manager._on_download_canceled()
+
+        manager.progress_dialog.close.assert_called_once()
+        assert manager._downloader is None
+        service_instance.show_toast.assert_called_once()
diff --git a/tests/test_utils.py b/tests/test_utils.py
index fec1950..9c39e55 100644
--- a/tests/test_utils.py
+++ b/tests/test_utils.py
@@ -113,6 +113,25 @@ def test_http_errors(self, status_code, json_data, expected_part):
         exception = requests.exceptions.HTTPError(response=mock_response)
         assert expected_part in get_friendly_error_message(exception)
 
+    def test_http_error_detail_list_is_rendered(self):
+        mock_response = Mock(spec=requests.Response)
+        mock_response.status_code = 422
+        mock_response.json.return_value = {"detail": ["field A invalid", "field B required"]}
+
+        exception = requests.exceptions.HTTPError(response=mock_response)
+        message = get_friendly_error_message(exception)
+        assert "field A invalid" in message
+        assert "field B required" in message
+
+    def test_http_error_non_json_response_fallback(self):
+        mock_response = Mock(spec=requests.Response)
+        mock_response.status_code = 418
+        mock_response.json.side_effect = ValueError("not json")
+
+        exception = requests.exceptions.HTTPError(response=mock_response)
+        message = get_friendly_error_message(exception)
+        assert "HTTP 418" in message
+
 
 
 class TestValidators:
@@ -197,6 +216,24 @@ def test_load_config_yaml_error(self, tmp_path):
             config = load_config()
             assert config == {}
 
+    def test_load_config_empty_yaml_returns_empty_dict(self, tmp_path):
+        """Empty YAML should not return None to callers."""
+        config_file = tmp_path / "config.yaml"
+        config_file.write_text("", encoding="utf-8")
+
+        with patch("utils.file_utils.get_app_root", return_value=tmp_path):
+            config = load_config()
+            assert config == {}
+
+    def test_load_config_non_mapping_root_returns_empty_dict(self, tmp_path):
+        """Only mapping root is supported for config structure."""
+        config_file = tmp_path / "config.yaml"
+        config_file.write_text("- item1\n- item2\n", encoding="utf-8")
+
+        with patch("utils.file_utils.get_app_root", return_value=tmp_path):
+            config = load_config()
+            assert config == {}
+
 
     def test_read_json_success(self, tmp_path):
         """Test successful reading of a JSON file."""
diff --git a/utils/error_messages.py b/utils/error_messages.py
index a5d65f8..b5dc192 100644
--- a/utils/error_messages.py
+++ b/utils/error_messages.py
@@ -1,5 +1,23 @@
 import requests
 
+
+def _extract_http_detail(response) -> str | None:
+    """Extracts API error detail from JSON response payload."""
+    try:
+        payload = response.json()
+    except ValueError:
+        return None
+
+    detail = payload.get("detail") if isinstance(payload, dict) else payload
+    if detail is None:
+        return None
+    if isinstance(detail, str):
+        return detail
+    if isinstance(detail, list):
+        return "; ".join(str(item) for item in detail if item is not None) or None
+    return str(detail)
+
+
 def get_friendly_error_message(exception: Exception) -> str:
     """
     Translates exceptions into user-friendly Russian messages.
@@ -22,10 +40,7 @@ def get_friendly_error_message(exception: Exception) -> str:
             status_code = exception.response.status_code
             
             # Try to get detail from JSON response
-            try:
-                detail = exception.response.json().get("detail")
-            except:
-                detail = None
+            detail = _extract_http_detail(exception.response)
 
             if status_code == 400:
                 return f"Ошибка запроса: {detail}" if detail else "Некорректный запрос."
@@ -50,5 +65,9 @@ def get_friendly_error_message(exception: Exception) -> str:
             
             if status_code >= 500:
                 return f"Внутренняя ошибка сервера ({status_code}). Попробуйте позже."
+
+            if detail:
+                return f"HTTP {status_code}: {detail}"
+            return f"Ошибка запроса (HTTP {status_code})."
     
     return str(exception)
diff --git a/utils/file_utils.py b/utils/file_utils.py
index 99975d4..64bea33 100644
--- a/utils/file_utils.py
+++ b/utils/file_utils.py
@@ -13,8 +13,17 @@ def load_config() -> dict:
     """
     try:
         config_path = get_app_root() / "config.yaml"
-        with open(config_path, 'r') as file:
-            return yaml.safe_load(file)
+        with open(config_path, "r", encoding="utf-8") as file:
+            data = yaml.safe_load(file)
+            if data is None:
+                return {}
+            if not isinstance(data, dict):
+                logging.error(
+                    "Configuration file has invalid root type: expected mapping, got %s.",
+                    type(data).__name__,
+                )
+                return {}
+            return data
     except FileNotFoundError:
         logging.error("Configuration file not found.", exc_info=True)
         return {}
diff --git a/utils/notifications/notification_service.py b/utils/notifications/notification_service.py
index 7c1a66b..3132349 100644
--- a/utils/notifications/notification_service.py
+++ b/utils/notifications/notification_service.py
@@ -63,11 +63,13 @@ def set_main_window(self, main_window: QWidget):
             self.main_window.removeEventFilter(self.resize_filter)
 
         # Clear active toasts from the previous window to prevent positioning issues
-        for toast in self.active_toasts:
+        for toast in list(self.active_toasts):
             toast.close()
         self.active_toasts.clear()
 
         self.main_window = main_window
+        if not self.main_window:
+            return
         self.main_window.installEventFilter(self.resize_filter)
 
     def show_toast(
@@ -108,6 +110,7 @@ def show_toast(
             position_y -= active_toast.height() + self.SPACING
 
         self.active_toasts.append(toast)
+        toast.destroyed.connect(lambda *_: self._on_toast_destroyed(toast))
         toast.show_animated(position_y)
 
         # Schedule closing
@@ -121,7 +124,16 @@ def _close_toast(self, toast_to_close: ToastNotification):
         """
         if toast_to_close in self.active_toasts:
             toast_to_close.close_animated()
-            self.active_toasts.remove(toast_to_close)
+            self._remove_toast_from_stack(toast_to_close)
+
+    def _on_toast_destroyed(self, toast: ToastNotification) -> None:
+        """Keeps the stack consistent when a toast is closed manually."""
+        self._remove_toast_from_stack(toast)
+
+    def _remove_toast_from_stack(self, toast: ToastNotification) -> None:
+        """Removes a toast reference from active stack and repositions others."""
+        if toast in self.active_toasts:
+            self.active_toasts.remove(toast)
             self._reposition_toasts()
 
     def _reposition_toasts(self):
@@ -147,4 +159,4 @@ def show_modal(self):
         (Not yet implemented)
         """
         # TODO: Implement modal dialog logic
-        pass
\ No newline at end of file
+        pass
diff --git a/utils/settings_manager.py b/utils/settings_manager.py
index fdb3786..5cec1fc 100644
--- a/utils/settings_manager.py
+++ b/utils/settings_manager.py
@@ -32,12 +32,47 @@ def get_default_settings(self) -> Dict[str, Any]:
             "theme": 1,  # 0 for light, 1 for dark
             "last_seen_whats_new_version": "",
             "search_filters": {
-                "search_in_pages": True,
-                "search_field": "name",
-                "match_mode": "contains"
+                "include_pages": True,
+                "search_by_name": True,
+                "search_by_code": True,
+                "exact_match": False,
             }
         }
 
+    @staticmethod
+    def _normalize_search_filters(filters: Any, default_filters: Dict[str, Any]) -> Dict[str, Any]:
+        """Normalizes legacy and current search filter schemas to the current format."""
+        normalized = dict(default_filters)
+        if not isinstance(filters, dict):
+            return normalized
+
+        # Legacy schema migration.
+        if "search_in_pages" in filters:
+            normalized["include_pages"] = bool(filters.get("search_in_pages", normalized["include_pages"]))
+
+        if "search_field" in filters:
+            field = str(filters.get("search_field", "")).strip().lower()
+            if field == "name":
+                normalized["search_by_name"] = True
+                normalized["search_by_code"] = False
+            elif field == "code":
+                normalized["search_by_name"] = False
+                normalized["search_by_code"] = True
+            elif field == "both":
+                normalized["search_by_name"] = True
+                normalized["search_by_code"] = True
+
+        if "match_mode" in filters:
+            mode = str(filters.get("match_mode", "")).strip().lower()
+            normalized["exact_match"] = mode in {"exact", "equals", "strict"}
+
+        # Current schema overrides.
+        for key in ("include_pages", "search_by_name", "search_by_code", "exact_match"):
+            if key in filters:
+                normalized[key] = bool(filters[key])
+
+        return normalized
+
     def load_settings(self) -> Dict[str, Any]:
         """
         Loads settings from the user's settings file.
@@ -51,10 +86,16 @@ def load_settings(self) -> Dict[str, Any]:
         try:
             with open(self.settings_file, "r", encoding="utf-8") as f:
                 loaded_settings = json.load(f)
-            
+             
             # Merge loaded settings with defaults to ensure all keys are present
             settings = default_settings.copy()
-            settings.update(loaded_settings)
+            if isinstance(loaded_settings, dict):
+                settings.update(loaded_settings)
+
+            settings["search_filters"] = self._normalize_search_filters(
+                settings.get("search_filters"),
+                default_settings.get("search_filters", {}),
+            )
             return settings
 
         except (json.JSONDecodeError, IOError) as e:
diff --git a/utils/whats_new_modal.py b/utils/whats_new_modal.py
index e5d9145..a0f6daa 100644
--- a/utils/whats_new_modal.py
+++ b/utils/whats_new_modal.py
@@ -17,14 +17,13 @@
 
 
 RELEASE_NOTES = {
-    "0.2.1": [
+    "0.2.16": [
         {
-            "title": "Стабильность и профиль",
+            "title": "Улучшения панели инструментов",
             "items": [
-                "Исправлен сбой при открытии профиля для аккаунтов без заполненного отображаемого имени.",
-                "Повышена надежность обновления данных профиля после обновлений backend-сервиса.",
-                "Улучшена обработка пустых значений в названиях документов и страниц.",
-                "Повышена стабильность поиска и загрузки документов в пограничных сценариях.",
+                "Улучшено поведение панели инструментов в окнах создания и редактирования документа.",
+                "`Дублировать` и `Удалить` теперь помечают документ как изменённый только при реальном изменении страниц.",
+                "Снижен риск ложного состояния `есть несохранённые изменения` при нажатии действий без выбранных страниц.",
             ],
         },
     ],