修复分离树合成根节点 ID 冲突

避免单图根节点重复进入重做计数
补充根图片构造回归测试

apps/ai-game-creator-shell/src-tauri/src/ui_editor/commands/separation/mod.rs

@@ -92,6 +92,21 @@ mod tests {
             "image"
         );
     }
+
+    #[test]
+    fn construction_uses_distinct_root_id_for_root_image() {
+        let image = Component::Image(ImageComponent {
+            target_graphic: None,
+            image_type: ImageType::Simple {
+                preserve_aspect: false,
+            },
+        });
+        let root = node("root-image", vec![image], vec![]);
+        let result = construct_separation_state(&state(root));
+        let tree = &result.unprocessed_trees[0];
+        assert_ne!(tree.root.id, tree.root.children[0].id);
+        assert_eq!(tree.root.children[0].id.as_str(), "root-image");
+    }
     #[test]
     fn binding_validation_requires_exact_batch_coverage() {
         let node = SeparationNode {

apps/ai-game-creator-shell/src-tauri/src/ui_editor/commands/separation/tree.rs

@@ -85,7 +85,14 @@ pub fn construct_separation_state(state: &State) -> SeparationState {
             (!children.is_empty()).then(|| SeparationTree {
                 src_ui_design: tree.src_ui_design.clone(),
                 root: SeparationNode {
-                    id: tree.root.id.clone(),
+                    // The synthetic root must never share an ID with a real
+                    // UI node. A single-image design may use the original
+                    // tree root as an eligible separation leaf.
+                    id: NodeId::new(format!(
+                        "separation-root-{}",
+                        uuid::Uuid::new_v4().simple()
+                    ))
+                    .expect("synthetic separation root id is valid"),
                     global_pos_x_px: 0,
                     global_pos_y_px: 0,
                     width_px: image.pixel_size.x.max(0.0).round() as u32,