Implement short-lived stellar event handling and optimize batch processing; add tests for new functionality

stage/stage.gd

@@ -312,6 +312,7 @@ func _page_action_pressed(page_id: int, action_amount: float) -> void:
 
 
 func _ready() -> void:
+    get_tree().auto_accept_quit = false
     var inited_result = init_enitities()
     locked_items = inited_result.locked_items
     load_data()
@@ -420,15 +421,33 @@ func save_data() -> void:
     var page: int = pending_page
     if page < 0:
         page = clampi(roundi(float(stage_page_scroller.scroll_horizontal) / PAGE_WIDTH), 0, PAGE_COUNT - 1)
-    SaveManager.save_data("owniverse", "qwerty", {
+    SaveManager.request_save("owniverse", "qwerty", {
         "state": owniverse.state,
         "ui": {"current_page": page},
     })
 
 
+var closing: bool = false
+
+
 func _notification(what: int) -> void:
-    if is_node_ready() and (what == NOTIFICATION_WM_CLOSE_REQUEST or what == NOTIFICATION_APPLICATION_PAUSED):
+    if not is_node_ready() or closing:
+        return
+    if what == NOTIFICATION_WM_CLOSE_REQUEST:
+        _close_after_save()
+    elif what == NOTIFICATION_APPLICATION_PAUSED:
         save_data()
+        # The OS may suspend frames immediately; finish the queued write now.
+        SaveManager.flush_saves()
+
+
+func _close_after_save() -> void:
+    closing = true
+    process_mode = Node.PROCESS_MODE_DISABLED
+    save_data()
+    if SaveManager.is_saving():
+        await SaveManager.saves_drained
+    get_tree().quit()
 
 
 func init_enitities() -> Dictionary: