Scene Hierarchy ET switcher + Create Sublayer via Save dialog

- Add edit-target layer combo at top of Scene Hierarchy panel (always
  visible when stage loaded — session, root, sublayers); routes through
  LayerManager::SetEditTarget so StageEditor ET checkboxes stay in sync
- Replace custom Create Sublayer modal with native SaveFile dialog;
  LayerManager::CreateNewSublayer creates the file on disk, inserts it
  at the top of the sublayer stack, and activates it as edit target

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/ui/Application.cpp

@@ -69,6 +69,7 @@ bool Application::Initialize(const std::string& windowTitle, int width, int heig
     m_sceneHierarchyPanel = std::make_unique<SceneHierarchyPanel>();
     m_sceneHierarchyPanel->SetPropertyManager(m_propertyManager.get());
     m_sceneHierarchyPanel->SetCommandHistory(&m_commandHistory);
+    m_sceneHierarchyPanel->SetLayerManager(m_layerManager.get());
     m_viewportPanel = std::make_unique<ViewportPanel>();
     m_viewportPanel->SetCommandHistory(&m_commandHistory);
     m_propertyPanel = std::make_unique<PropertyPanel>();

src/ui/SceneHierarchyPanel.cpp

@@ -119,6 +119,63 @@ void SceneHierarchyPanel::Render() {
         return;
     }
 
+    // ── Edit-target layer switcher ────────────────────────────────────
+    {
+        struct LayerEntry { SdfLayerHandle layer; std::string label; };
+        std::vector<LayerEntry> layers;
+
+        auto sessionLayer = m_stage->GetSessionLayer();
+        if (sessionLayer)
+            layers.push_back({ sessionLayer, "Session" });
+
+        auto rootLayer = m_stage->GetRootLayer();
+        if (rootLayer) {
+            std::string name = rootLayer->IsAnonymous()
+                ? "anonymous"
+                : std::filesystem::path(rootLayer->GetIdentifier()).filename().string();
+            layers.push_back({ rootLayer, "Root: " + name });
+
+            for (const auto& subPath : rootLayer->GetSubLayerPaths()) {
+                auto sub = SdfLayer::FindOrOpenRelativeToLayer(rootLayer, subPath);
+                if (!sub) continue;
+                std::string subName = sub->IsAnonymous()
+                    ? sub->GetIdentifier()
+                    : std::filesystem::path(sub->GetIdentifier()).filename().string();
+                layers.push_back({ SdfLayerHandle(sub), subName });
+            }
+        }
+
+        std::string currentLabel = "\xe2\x80\x94"; // em dash
+        auto etLayer = m_stage->GetEditTarget().GetLayer();
+        if (etLayer) {
+            for (const auto& e : layers) {
+                if (e.layer && e.layer->GetIdentifier() == etLayer->GetIdentifier()) {
+                    currentLabel = e.label;
+                    break;
+                }
+            }
+        }
+
+        ImGui::SetNextItemWidth(-1.0f);
+        if (ImGui::BeginCombo("##layerswitch", currentLabel.c_str(),
+                              ImGuiComboFlags_HeightRegular)) {
+            for (const auto& e : layers) {
+                bool isCurrent = (e.layer && etLayer &&
+                                  e.layer->GetIdentifier() == etLayer->GetIdentifier());
+                if (ImGui::Selectable(e.label.c_str(), isCurrent)) {
+                    if (m_layerManager)
+                        m_layerManager->SetEditTarget(e.layer->GetIdentifier());
+                    else
+                        m_stage->SetEditTarget(UsdEditTarget(e.layer));
+                }
+                if (isCurrent)
+                    ImGui::SetItemDefaultFocus();
+            }
+            ImGui::EndCombo();
+        }
+        ImGui::Spacing();
+    }
+
     auto paths = m_propertyManager->GetPrimPaths();
     if (paths.empty()) {
         ImGui::TextDisabled("No prims in stage");

src/ui/SceneHierarchyPanel.h

@@ -2,6 +2,7 @@
 
 #include "../core/PropertyManager.h"
 #include "../core/CommandHistory.h"
+#include "../core/LayerManager.h"
 #include "IconManager.h"
 #include <pxr/usd/usd/stage.h>
 #include <pxr/usd/sdf/path.h>
@@ -24,6 +25,7 @@ public:
     
     void SetPropertyManager(PropertyManager* manager);
     void SetCommandHistory(CommandHistory* history) { m_commandHistory = history; }
+    void SetLayerManager(LayerManager* lm) { m_layerManager = lm; }
     void SetStage(UsdStageRefPtr stage);
     void SetIconManager(IconManager* iconManager) { m_iconManager = iconManager; }
     void Render();
@@ -74,6 +76,7 @@ private:
     
     PropertyManager*             m_propertyManager;
     CommandHistory*              m_commandHistory = nullptr;
+    LayerManager*                m_layerManager   = nullptr;
     IconManager*                 m_iconManager = nullptr;
     UsdStageRefPtr               m_stage;
 

src/ui/StageEditorPanel.cpp

@@ -7,10 +7,7 @@
 
 namespace UsdLayerManager {
 
-StageEditorPanel::StageEditorPanel() {
-    m_newLayerPath[0] = '\0';
-    m_newLayerName[0] = '\0';
-}
+StageEditorPanel::StageEditorPanel() {}
 
 StageEditorPanel::~StageEditorPanel() {}
 
@@ -51,9 +48,12 @@ void StageEditorPanel::Render() {
 
     ImGui::SameLine();
     if (iconBtn("##createNew", Icon::FilePlus, "+N")) {
-        m_showCreateDialog = true;
-        m_newLayerPath[0] = '\0';
-        strcpy_s(m_newLayerName, "new_layer.usd");
+        std::string path = FileDialog::SaveFile(
+            "USD Files (*.usd;*.usda;*.usdc)\0*.usd;*.usda;*.usdc\0All Files (*.*)\0*.*\0",
+            "Create New Sublayer",
+            "usd");
+        if (!path.empty() && m_layerManager)
+            m_layerManager->CreateNewSublayer(path);
     }
     if (ImGui::IsItemHovered()) ImGui::SetTooltip("Create New Sublayer");
 
@@ -62,7 +62,6 @@ void StageEditorPanel::Render() {
     auto allLayers = m_layerManager->GetLayerStack();
     if (allLayers.empty()) {
         ImGui::TextDisabled("No stage loaded");
-        if (m_showCreateDialog) ShowCreateLayerDialog();
         return;
     }
 
@@ -82,7 +81,6 @@ void StageEditorPanel::Render() {
 
     RenderSublayerList(sublayers);
 
-    if (m_showCreateDialog) ShowCreateLayerDialog();
 }
 
 // ---------------------------------------------------------------------------
@@ -350,43 +348,5 @@ void StageEditorPanel::RenderSublayerContextMenu(int i,
     ImGui::EndPopup();
 }
 
-// ---------------------------------------------------------------------------
-void StageEditorPanel::ShowCreateLayerDialog() {
-    ImGui::SetNextWindowSize(ImVec2(400, 150), ImGuiCond_Always);
-    ImGui::OpenPopup("Create Sublayer");
-
-    if (ImGui::BeginPopupModal("Create Sublayer", &m_showCreateDialog)) {
-        ImGui::Text("Layer Name:");
-        ImGui::InputText("##name", m_newLayerName, sizeof(m_newLayerName));
-
-        ImGui::Spacing();
-        ImGui::Text("Save Path:");
-        ImGui::InputText("##path", m_newLayerPath, sizeof(m_newLayerPath));
-
-        ImGui::Spacing();
-
-        if (ImGui::Button("Create", ImVec2(120, 0))) {
-            std::string path;
-            if (m_newLayerPath[0] != '\0')
-                path = std::string(m_newLayerPath) + "/" + m_newLayerName;
-            else
-                path = m_newLayerName;
-
-            if (!path.empty()) {
-                if (m_commandHistory)
-                    m_commandHistory->Push(std::make_unique<LayerCreateCommand>(
-                        m_layerManager, "./" + path));
-                else
-                    m_layerManager->CreateSublayer("./" + path);
-                m_showCreateDialog = false;
-            }
-        }
-        ImGui::SameLine();
-        if (ImGui::Button("Cancel", ImVec2(120, 0)))
-            m_showCreateDialog = false;
-
-        ImGui::EndPopup();
-    }
-}
 
 } // namespace UsdLayerManager

src/ui/StageEditorPanel.h

@@ -23,15 +23,11 @@ private:
     void RenderFixedLayers(const std::vector<LayerInfo>& layers);
     void RenderSublayerList(const std::vector<LayerInfo>& sublayers);
     void RenderSublayerContextMenu(int i, const std::vector<LayerInfo>& sublayers);
-    void ShowCreateLayerDialog();
 
     LayerManager*   m_layerManager    = nullptr;
     CommandHistory* m_commandHistory  = nullptr;
     IconManager*    m_iconManager     = nullptr;
     int             m_selectedIdx     = -1;
-    bool            m_showCreateDialog = false;
-    char            m_newLayerPath[256];
-    char            m_newLayerName[128];
 };
 
 } // namespace UsdLayerManager