feat(ai): generate covers without new titles

app/gui/tabs/generate.py

@@ -945,7 +945,7 @@ class GenerateTab(QWidget):
             self.empty_state_button.clicked.connect(self.open_accounts_callback)
         self.task_table = QTableView()
         self.model = GenerateTaskTableModel(self.task_table, db_path=self.db_path, status_callback=self._set_status)
-        self.model.set_generate_cover_enabled(self._current_generate_mode_includes_cover())
+        self.model.set_generate_mode(self._current_generate_mode())
         self.task_table.setModel(self.model)
         self.task_table.setSelectionBehavior(QAbstractItemView.SelectRows)
         self.task_table.setSelectionMode(QAbstractItemView.ExtendedSelection)
@@ -1159,13 +1159,13 @@ class GenerateTab(QWidget):
         previous = appconfig.ai_generate_mode(self.config)
         current = self._current_generate_mode()
         if self._save_generate_mode_setting(show_status=True):
-            self.model.set_generate_cover_enabled(appconfig.generate_mode_includes_cover(current))
+            self.model.set_generate_mode(current)
             self.refresh_tasks()
             return
         self.generate_mode_combo.blockSignals(True)
         self._set_combo_by_data(self.generate_mode_combo, previous)
         self.generate_mode_combo.blockSignals(False)
-        self.model.set_generate_cover_enabled(appconfig.generate_mode_includes_cover(previous))
+        self.model.set_generate_mode(previous)
 
     def _apply_task_table_column_widths(self):
         if self.model.columnCount() != len(self.TABLE_COLUMN_WEIGHTS):
@@ -1524,7 +1524,7 @@ class GenerateTab(QWidget):
         ]
         if not tasks:
             if generate_mode == "cover":
-                self._set_status("当前筛选结果没有可生成封面的任务，请先生成标题。")
+                self._set_status("当前筛选结果没有可生成的封面；请确认商品已完成采集且尚未生成新封面。")
             else:
                 self._set_status("当前筛选结果没有可生成的缺失内容；请先在①导入采集完成采集，或调整生成内容")
             return
@@ -2081,9 +2081,12 @@ class GenerateTab(QWidget):
         return None
 
     def _prompt_context(self, task):
+        new_title = task.new_title
+        if self._current_generate_mode() == "cover":
+            new_title = ai.cover_title_context(task)
         return {
             "old_title": task.old_title,
-            "new_title": task.new_title,
+            "new_title": new_title,
             "item_id": task.item_id,
             "account_name": self.model.account_name_for(task),
             "alias": task.alias,
@@ -2133,7 +2136,7 @@ class GenerateTab(QWidget):
             _set_empty_state(self.empty_state_card, self.empty_state_label, self.empty_state_button)
             self._set_status(f"AI 生成任务读取失败：{exc}")
             return
-        self.model.set_generate_cover_enabled(self._current_generate_mode_includes_cover())
+        self.model.set_generate_mode(self._current_generate_mode())
         self.model.set_tasks(filtered_tasks, accounts_rows)
         self._apply_task_table_column_widths()
         self.summary_label.setText(