fix: fit main window within screen on startup

app/gui/main_window.py

@@ -8,11 +8,72 @@ from .tabs.collect import CollectTab
 from .tabs.generate import GenerateTab
 from .tabs.settings import SettingsTab
 from .widgets import *
+
+PREFERRED_WINDOW_SIZE = (1180, 760)
+MIN_WINDOW_SIZE = (960, 640)
+WINDOW_SCREEN_MARGIN = 40
+
+
+def _screen_available_geometry():
+    app = QApplication.instance()
+    if app is None:
+        return None
+    screen = app.primaryScreen()
+    if screen is None:
+        return None
+    return screen.availableGeometry()
+
+
+def _bounded_dimension(available_size, preferred_size, minimum_size, margin):
+    if available_size <= 0:
+        return preferred_size
+    if available_size > margin * 2:
+        maximum = available_size - margin * 2
+    else:
+        maximum = available_size
+    if maximum >= minimum_size:
+        return max(minimum_size, min(preferred_size, maximum))
+    return max(1, min(preferred_size, maximum))
+
+
+def _fit_and_center_window(
+    window,
+    available_geometry=None,
+    preferred_size=PREFERRED_WINDOW_SIZE,
+    minimum_size=MIN_WINDOW_SIZE,
+    margin=WINDOW_SCREEN_MARGIN,
+):
+    available = available_geometry if available_geometry is not None else _screen_available_geometry()
+    if available is None or available.width() <= 0 or available.height() <= 0:
+        window.resize(*preferred_size)
+        return
+
+    width = _bounded_dimension(
+        available.width(),
+        preferred_size[0],
+        minimum_size[0],
+        margin,
+    )
+    height = _bounded_dimension(
+        available.height(),
+        preferred_size[1],
+        minimum_size[1],
+        margin,
+    )
+    window.resize(width, height)
+
+    x = available.x() + max(0, (available.width() - width) // 2)
+    y = available.y() + max(0, (available.height() - height) // 2)
+    max_x = available.x() + max(0, available.width() - width)
+    max_y = available.y() + max(0, available.height() - height)
+    window.move(min(max(x, available.x()), max_x), min(max(y, available.y()), max_y))
+
 class MainWindow(QMainWindow):
     """Main application window with the fixed five-tab workflow."""
 
     def __init__(self, db_path=None, config=None, config_path=None, ai_models_path=None):
         super().__init__()
+        self._initial_window_fit_applied_after_show = False
         self.config = appconfig.load_config(config_path or appconfig.CONFIG_PATH) if config is None else config
         self.config_path = (
             config_path
@@ -26,7 +87,7 @@ class MainWindow(QMainWindow):
             or appconfig.AI_MODELS_PATH
         )
         self.setWindowTitle("蝦皮圈優化助手")
-        self.resize(1180, 760)
+        _fit_and_center_window(self)
         self.setStyleSheet(BUTTON_BASE_STYLE)
         self._settings_tab_index = TAB_TITLES.index("⑤ 设置")
         self._last_tab_index = 0
@@ -41,6 +102,12 @@ class MainWindow(QMainWindow):
         self.setCentralWidget(self.tabs)
         self.statusBar().showMessage("就绪")
 
+    def showEvent(self, event):
+        super().showEvent(event)
+        if not self._initial_window_fit_applied_after_show:
+            _fit_and_center_window(self)
+            self._initial_window_fit_applied_after_show = True
+
     def _build_tab(self, title):
         if title == "① 导入采集":
             return CollectTab(