feat: 优化部分代码及提示词

app/actions/add.py

@@ -0,0 +1,42 @@
+"""在大屏 JSON 副本上新增组件，用于后端校验动作能否执行"""
+
+from app.actions.base import BaseActionHandler
+from app.schemas.actions import AddAction
+from app.schemas.screen import Screen, ScreenNode
+
+
+class AddHandler(BaseActionHandler[AddAction]):
+    def apply(self, screen: Screen, action: AddAction) -> Screen:
+        # 重新校验节点，避免模型创建后被修改成无效内容
+        node = ScreenNode.model_validate(action.node.model_dump())
+        if any(existing.id == node.id for existing in screen.nodes):
+            raise ValueError(f"新增组件 ID 已存在: {node.id}")
+        result = screen.model_copy(deep=True)
+        # 追加到末尾，不共享动作中的嵌套配置
+        result.nodes.append(node.model_copy(deep=True))
+        return result
+
+
+if __name__ == "__main__":
+    screen = Screen.model_validate(
+        {"canvas": {"width": 1920, "height": 1080}, "nodes": []}
+    )
+    action = AddAction.model_validate(
+        {
+            "type": "add",
+            "node": {
+                "id": "screen-title",
+                "type": "text",
+                "layout": {"x": 100, "y": 50, "width": 400, "height": 60},
+                "props": {},
+            },
+        }
+    )
+    handler = AddHandler()
+    final_screen = handler.apply(screen, action)
+    print(final_screen.model_dump_json(indent=2))
+    print("原始组件数:", len(screen.nodes))
+    try:
+        handler.apply(final_screen, action)
+    except ValueError as error:
+        print("重复新增:", error)