Tighten editor scene mutation boundary

editor/app/Features/Hierarchy/HierarchyModel.cpp

@@ -163,6 +163,20 @@ HierarchyNode BuildSceneNodeRecursive(
     return node;
 }
 
+HierarchyNode BuildSnapshotNodeRecursive(
+    const EditorSceneHierarchyNode& snapshotNode) {
+    HierarchyNode node = {};
+    node.nodeId = snapshotNode.itemId;
+    node.label = snapshotNode.displayName.empty()
+        ? std::string("GameObject")
+        : snapshotNode.displayName;
+    node.children.reserve(snapshotNode.children.size());
+    for (const EditorSceneHierarchyNode& child : snapshotNode.children) {
+        node.children.push_back(BuildSnapshotNodeRecursive(child));
+    }
+    return node;
+}
+
 } // namespace
 
 HierarchyModel HierarchyModel::BuildFromScene(
@@ -184,6 +198,20 @@ HierarchyModel HierarchyModel::BuildFromScene(
     return model;
 }
 
+HierarchyModel HierarchyModel::BuildFromSnapshot(
+    const EditorSceneHierarchySnapshot& snapshot) {
+    HierarchyModel model = {};
+    model.m_roots.reserve(snapshot.roots.size());
+    for (const EditorSceneHierarchyNode& root : snapshot.roots) {
+        if (root.itemId.empty()) {
+            continue;
+        }
+
+        model.m_roots.push_back(BuildSnapshotNodeRecursive(root));
+    }
+    return model;
+}
+
 bool HierarchyModel::Empty() const {
     return m_roots.empty();
 }