Tighten XCUI hosted preview frame contract

docs/plan/XCUI_Phase_Status_2026-04-05.md

@@ -68,12 +68,13 @@ Current gap:
 - The editor bridge layer now has smoke coverage for swapchain after-UI rendering hooks and SRV-backed ImGui texture descriptor registration.
 - `Application` no longer owns the ImGui backend directly; window presentation now routes through `IWindowUICompositor` with an `ImGuiWindowUICompositor` implementation, which currently delegates to `IEditorHostCompositor` / `ImGuiHostCompositor`.
 - The generic hosted-preview presenter contract no longer owns `ImGuiTransitionBackend`; the ImGui presenter now sits in a separate `ImGuiXCUIHostedPreviewPresenter` header while the native queue/surface registry remains XCUI-generic.
+- The generic hosted-preview frame contract no longer carries an ImGui draw-list pointer; the legacy ImGui presenter resolves its inline draw target from the active ImGui window context instead of pushing that type through the XCUI contract.
 - `XCNewEditor` builds successfully to `build/new_editor/bin/Debug/XCNewEditor.exe`.
 
 Current gap:
 
 - The shell is still ImGui-hosted.
-- The hosted-preview frame submission contract still carries an ImGui draw-list target for the legacy inline presenter path.
+- Legacy hosted preview still depends on an active ImGui window context for inline presentation.
 - Editor-specialized widgets are still incomplete at the shared-module level: the authored prototypes exist, but virtualization, selection models, command routing, property editing models, toolbar/menu chrome, and icon-atlas widgets are not yet extracted into reusable XCUI modules.
 
 ## Validated This Phase
@@ -140,6 +141,7 @@ Current gap:
 - Hosted preview contracts were tightened again:
   - generic preview surface metadata stays on XCUI-owned value types
   - `ImGuiTransitionBackend` moved behind `ImGuiXCUIHostedPreviewPresenter`
+  - generic preview frame submission no longer carries an ImGui draw-list pointer
   - panel/runtime callers still preserve the same legacy and native-preview behavior
 - `new_editor` panel/shell diagnostics improvements for hosted preview state.
 - XCUI asset document loading changed to prefer direct source compilation before `ResourceManager` fallback for the sandbox path, fixing the LayoutLab crash.

new_editor/src/XCUIBackend/ImGuiXCUIHostedPreviewPresenter.h

@@ -3,6 +3,8 @@
 #include "XCUIBackend/ImGuiTransitionBackend.h"
 #include "XCUIBackend/XCUIHostedPreviewPresenter.h"
 
+#include <imgui.h>
+
 #include <memory>
 
 namespace XCEngine {
@@ -21,7 +23,7 @@ public:
         m_backend.Submit(*frame.drawData);
         m_lastStats.submittedDrawListCount = m_backend.GetPendingDrawListCount();
         m_lastStats.submittedCommandCount = m_backend.GetPendingCommandCount();
-        m_lastStats.presented = m_backend.EndFrame(frame.targetDrawList);
+        m_lastStats.presented = m_backend.EndFrame(ImGui::GetWindowDrawList());
         m_lastStats.flushedDrawListCount = m_backend.GetLastFlushedDrawListCount();
         m_lastStats.flushedCommandCount = m_backend.GetLastFlushedCommandCount();
         return m_lastStats.presented;

new_editor/src/XCUIBackend/XCUIHostedPreviewPresenter.h

@@ -10,15 +10,12 @@
 #include <utility>
 #include <vector>
 
-struct ImDrawList;
-
 namespace XCEngine {
 namespace Editor {
 namespace XCUIBackend {
 
 struct XCUIHostedPreviewFrame {
     const ::XCEngine::UI::UIDrawData* drawData = nullptr;
-    ImDrawList* targetDrawList = nullptr;
     ::XCEngine::UI::UIRect canvasRect = {};
     ::XCEngine::UI::UISize logicalSize = {};
     const char* debugName = nullptr;

new_editor/src/panels/XCUIDemoPanel.cpp

@@ -298,7 +298,6 @@ void XCUIDemoPanel::Render() {
     if (m_hostedPreviewEnabled && m_previewPresenter != nullptr) {
         ::XCEngine::Editor::XCUIBackend::XCUIHostedPreviewFrame previewFrame = {};
         previewFrame.drawData = &frame.drawData;
-        previewFrame.targetDrawList = drawList;
         previewFrame.canvasRect = canvasRect;
         previewFrame.logicalSize = UI::UISize(canvasRect.width, canvasRect.height);
         previewFrame.debugName = kPreviewDebugName;

new_editor/src/panels/XCUILayoutLabPanel.cpp

@@ -247,7 +247,6 @@ void XCUILayoutLabPanel::Render() {
     if (m_hostedPreviewEnabled && m_previewPresenter != nullptr) {
         ::XCEngine::Editor::XCUIBackend::XCUIHostedPreviewFrame previewFrame = {};
         previewFrame.drawData = &frame.drawData;
-        previewFrame.targetDrawList = ImGui::GetWindowDrawList();
         previewFrame.canvasRect = input.canvasRect;
         previewFrame.logicalSize = UI::UISize(input.canvasRect.width, input.canvasRect.height);
         previewFrame.debugName = kPreviewDebugName;

tests/NewEditor/test_xcui_hosted_preview_presenter.cpp

@@ -103,7 +103,6 @@ TEST(XCUIHostedPreviewPresenterTest, PresentFlushesDrawDataIntoProvidedImGuiDraw
 
     XCUIHostedPreviewFrame frame = {};
     frame.drawData = &drawData;
-    frame.targetDrawList = targetDrawList;
 
     const bool presented = presenter->Present(frame);
     const XCUIHostedPreviewStats& stats = presenter->GetLastStats();
@@ -254,7 +253,6 @@ TEST(XCUIHostedPreviewPresenterTest, QueuedNativePresenterRejectsMissingDrawData
 
     XCUIHostedPreviewFrame frame = {};
     frame.debugName = "Missing DrawData";
-    frame.targetDrawList = reinterpret_cast<ImDrawList*>(1);
 
     EXPECT_FALSE(presenter->Present(frame));