diff --git a/apps/ai-game-creator-shell/src-tauri/src/ui_editor/layout/node.rs b/apps/ai-game-creator-shell/src-tauri/src/ui_editor/layout/node.rs
index ae93e2bd2..17ecbd346 100644
--- a/apps/ai-game-creator-shell/src-tauri/src/ui_editor/layout/node.rs
+++ b/apps/ai-game-creator-shell/src-tauri/src/ui_editor/layout/node.rs
@@ -15,6 +15,8 @@ pub struct Node {
     pub component: Option<Component>,
     pub children_display_mode: ChildrenDisplayMode,
     pub children: Vec<Node>,
+    // 偏移量是后加的字段：历史设计文档没有它，默认回落到零偏移，保证旧文档仍可读。
+    #[serde(default)]
     pub offset: NodeOffset,
 }
 
diff --git a/apps/ai-game-creator-shell/src-tauri/src/ui_editor/persistence.rs b/apps/ai-game-creator-shell/src-tauri/src/ui_editor/persistence.rs
index 6c64ebdf0..a95d17803 100644
--- a/apps/ai-game-creator-shell/src-tauri/src/ui_editor/persistence.rs
+++ b/apps/ai-game-creator-shell/src-tauri/src/ui_editor/persistence.rs
@@ -832,6 +832,7 @@ fn validate_id(value: &str, label: &str) -> Result<(), String> {
 #[cfg(test)]
 mod tests {
     use super::*;
+    use crate::ui_editor::layout::offset::NodeOffset;
 
     const PROJECT_ID: &str = "ui-design-persistence-project";
 
@@ -1444,6 +1445,43 @@ mod tests {
         .is_err());
     }
 
+    /// 历史设计文档没有节点 `offset` 字段：缺字段必须按零偏移解析，不能判成缺字段损坏。
+    #[test]
+    fn legacy_nodes_without_offset_field_fall_back_to_zero_offset() {
+        let mut value = serde_json::to_value(state_with_sprite_and_dragged_transform())
+            .expect("serialize dragged UI design state");
+        strip_offset_fields(&mut value);
+        let state: State = serde_json::from_value(value).expect("节点缺 offset 时仍可解析");
+        assert_eq!(
+            state.ui_trees[0].root.offset,
+            NodeOffset::default(),
+            "根节点缺 offset 时回落零偏移"
+        );
+        assert_eq!(
+            state.ui_trees[0].root.children[0].offset,
+            NodeOffset::default(),
+            "子节点缺 offset 时回落零偏移"
+        );
+    }
+
+    /// 递归删除夹具里所有节点级 `offset` 字段，模拟该字段引入前落盘的文档。
+    fn strip_offset_fields(value: &mut serde_json::Value) {
+        match value {
+            serde_json::Value::Object(fields) => {
+                fields.remove("offset");
+                for field in fields.values_mut() {
+                    strip_offset_fields(field);
+                }
+            }
+            serde_json::Value::Array(items) => {
+                for item in items {
+                    strip_offset_fields(item);
+                }
+            }
+            _ => {}
+        }
+    }
+
     #[test]
     fn rejects_text_component_with_missing_font_asset() {
         let (directory, asset_id) = fixture();