refactor(editor): neutralize render surface handoff

docs/plan/editor-core-refactor-plan.md

@@ -41,7 +41,8 @@ incomplete:
 - Feature panels no longer use `Composition/EditorContext.h` directly, but the
   app include surface still needs to be narrowed before this boundary is
   build-enforced.
-- Win32 and D3D12 currently know about each other through concrete headers.
+- The direct Win32/D3D12 render-surface cross-include has been cut; broader
+  host include-surface cleanup remains.
 - App-side tests exist but are not consistently wired into CMake; some are
   stale and reference removed headers.
 
@@ -63,6 +64,9 @@ Completed boundary cuts:
   utility-window runtime contracts accept this service view instead of
   `EditorContext`, so concrete feature panels no longer depend on
   `Composition/EditorContext.h`.
+- Win32 now hands render startup a neutral
+  `Rendering::Host::EditorWindowRenderRuntimeSurface` value, and D3D12 no
+  longer includes `Platform/Win32/**` editor surface headers to obtain `HWND`.
 
 The root issue is not the existence of a single executable target by itself.
 The root issue is that shared app contracts are stored inside concrete layer
@@ -377,6 +381,17 @@ app/Host/D3D12/
 Then replace concrete Win32/D3D12 cross-includes with a neutral surface or
 factory contract.
 
+Completed first cut:
+
+- The old `Win32EditorWindowRenderRuntimeSurface` concrete adapter was removed.
+- `EditorWindowRenderRuntimeSurface` is now a value contract in
+  `Rendering/Host/EditorWindowRenderRuntime.h`.
+- Win32 fills that neutral contract during native surface capture; D3D12 reads
+  the native handle from the contract instead of including a Win32 editor
+  windowing header.
+- Remaining work in this phase is to move/rename host interface directories
+  and continue narrowing CMake include surfaces.
+
 ## Phase 6: Documentation Update
 
 Update `editor/AGENTS.md` after each completed boundary cut.

editor/AGENTS.md

@@ -245,8 +245,11 @@ inside pure shell/widget code.
   renderer and owns object-id picking state. Keep editor picking/render support
   behind `XCENGINE_ENABLE_RENDERING_EDITOR_SUPPORT`.
 - D3D12 window rendering is behind the abstract
-  `Rendering::Host::EditorWindowRenderRuntime`; use the host interfaces when
-  adding app-level features.
+  `Rendering::Host::EditorWindowRenderRuntime`; native startup surface data is
+  passed through the neutral
+  `Rendering::Host::EditorWindowRenderRuntimeSurface` value contract, not a
+  concrete Win32 adapter type. Use the host interfaces when adding app-level
+  features.
 
 ## Modification Rules
 
@@ -394,3 +397,7 @@ ownership rule.
   and `EditorProjectRuntime` now live under `app/Services/Project`, and the
   Project panel owns the widget-tree projection instead of making the service
   model depend on `UIEditorTreeViewItem`.
+- The old `Win32EditorWindowRenderRuntimeSurface` adapter was removed. Win32
+  now captures native render startup data into the neutral
+  `Rendering::Host::EditorWindowRenderRuntimeSurface` value contract, so D3D12
+  no longer includes concrete `app/Platform/Win32/**` editor surface headers.

editor/app/Platform/Win32/Windowing/EditorWindow.cpp

@@ -3,7 +3,6 @@
 #include "Platform/Win32/Chrome/EditorWindowChromeController.h"
 #include "Platform/Win32/Windowing/EditorWindowSession.h"
 #include "Platform/Win32/Windowing/EditorWindowSupport.h"
-#include "Platform/Win32/Windowing/Win32EditorWindowRenderRuntimeSurface.h"
 #include "Platform/Win32/Runtime/EditorWindowInputController.h"
 #include "Windowing/Host/EditorWindowContentBindings.h"
 #include <XCEditor/Docking/UIEditorDockHostTransfer.h>
@@ -181,8 +180,10 @@ bool EditorWindow::CaptureRuntimeSurface(
         clientHeight = 1u;
     }
 
-    outSurface.renderSurface =
-        std::make_shared<Win32EditorWindowRenderRuntimeSurface>(hwnd);
+    outSurface.renderSurface = Rendering::Host::EditorWindowRenderRuntimeSurface{
+        .kind = Rendering::Host::EditorWindowRenderRuntimeSurfaceKind::Win32Window,
+        .nativeHandle = reinterpret_cast<std::uintptr_t>(hwnd),
+    };
     outSurface.widthPixels = clientWidth;
     outSurface.heightPixels = clientHeight;
     outSurface.dpiScale = GetDpiScale();

editor/app/Platform/Win32/Windowing/Win32EditorWindowRenderRuntimeSurface.h

@@ -1,33 +0,0 @@
-#pragma once
-
-#ifndef NOMINMAX
-#define NOMINMAX
-#endif
-
-#include "Rendering/Host/EditorWindowRenderRuntime.h"
-
-#include <windows.h>
-
-namespace XCEngine::UI::Editor::App {
-
-class Win32EditorWindowRenderRuntimeSurface final
-    : public ::XCEngine::UI::Editor::Rendering::Host::EditorWindowRenderRuntimeSurface {
-public:
-    explicit Win32EditorWindowRenderRuntimeSurface(HWND hwnd)
-        : m_hwnd(hwnd) {}
-
-    ::XCEngine::UI::Editor::Rendering::Host::EditorWindowRenderRuntimeSurfaceKind
-        GetKind() const override {
-        return ::XCEngine::UI::Editor::Rendering::Host::
-            EditorWindowRenderRuntimeSurfaceKind::Win32Window;
-    }
-
-    HWND GetHwnd() const {
-        return m_hwnd;
-    }
-
-private:
-    HWND m_hwnd = nullptr;
-};
-
-} // namespace XCEngine::UI::Editor::App

editor/app/Rendering/D3D12/D3D12EditorWindowRenderRuntime.cpp

@@ -1,7 +1,5 @@
 #include "Rendering/D3D12/D3D12EditorWindowRenderRuntime.h"
 
-#include "Platform/Win32/Windowing/Win32EditorWindowRenderRuntimeSurface.h"
-
 #include <algorithm>
 #include <memory>
 
@@ -56,12 +54,10 @@ EditorWindowRenderRuntimeInitializeResult D3D12EditorWindowRenderRuntime::Initia
     const EditorWindowRenderRuntimeInitializeParams& params) {
     EditorWindowRenderRuntimeInitializeResult result = {};
 
-    const auto* surface = params.surface != nullptr
-        ? dynamic_cast<
-            const ::XCEngine::UI::Editor::App::Win32EditorWindowRenderRuntimeSurface*>(
-                params.surface.get())
-        : nullptr;
-    HWND hwnd = surface != nullptr ? surface->GetHwnd() : nullptr;
+    const HWND hwnd =
+        params.surface.kind == Rendering::Host::EditorWindowRenderRuntimeSurfaceKind::Win32Window
+            ? reinterpret_cast<HWND>(params.surface.nativeHandle)
+            : nullptr;
     if (hwnd == nullptr) {
         result.errorMessage = "window initialize skipped: hwnd is null";
         return result;

editor/app/Rendering/Host/EditorWindowRenderRuntime.h

@@ -19,20 +19,22 @@ enum class EditorWindowRenderRuntimeSurfaceKind : std::uint8_t {
     Win32Window,
 };
 
-class EditorWindowRenderRuntimeSurface {
-public:
-    virtual ~EditorWindowRenderRuntimeSurface() = default;
+struct EditorWindowRenderRuntimeSurface {
+    EditorWindowRenderRuntimeSurfaceKind kind = EditorWindowRenderRuntimeSurfaceKind::Unknown;
+    std::uintptr_t nativeHandle = 0u;
 
-    virtual EditorWindowRenderRuntimeSurfaceKind GetKind() const = 0;
+    bool IsValid() const {
+        return kind != EditorWindowRenderRuntimeSurfaceKind::Unknown && nativeHandle != 0u;
+    }
 };
 
 struct EditorWindowRenderRuntimeInitializeParams {
-    std::shared_ptr<const EditorWindowRenderRuntimeSurface> surface = {};
+    EditorWindowRenderRuntimeSurface surface = {};
     std::uint32_t widthPixels = 0u;
     std::uint32_t heightPixels = 0u;
 
     bool IsValid() const {
-        return surface != nullptr && widthPixels > 0u && heightPixels > 0u;
+        return surface.IsValid() && widthPixels > 0u && heightPixels > 0u;
     }
 };
 

editor/app/Windowing/Host/EditorWindowHostInterfaces.h

@@ -1,5 +1,6 @@
 #pragma once
 
+#include "Rendering/Host/EditorWindowRenderRuntime.h"
 #include "Windowing/EditorWindowShared.h"
 #include "Windowing/Frame/EditorWindowTransferRequests.h"
 #include "Windowing/Host/EditorWindowHostTypes.h"
@@ -29,10 +30,6 @@ namespace XCEngine::UI::Editor {
 
 struct UIEditorDockHostTabDropTarget;
 
-namespace Rendering::Host {
-class EditorWindowRenderRuntimeSurface;
-}
-
 } // namespace XCEngine::UI::Editor
 
 namespace XCEngine::UI::Editor::App {
@@ -49,13 +46,13 @@ struct EditorHostWindowRuntimeInitializationParams {
 };
 
 struct EditorNativeWindowRuntimeSurface {
-    std::shared_ptr<const Rendering::Host::EditorWindowRenderRuntimeSurface> renderSurface = {};
+    Rendering::Host::EditorWindowRenderRuntimeSurface renderSurface = {};
     std::uint32_t widthPixels = 0u;
     std::uint32_t heightPixels = 0u;
     float dpiScale = 1.0f;
 
     bool IsValid() const {
-        return renderSurface != nullptr && widthPixels > 0u && heightPixels > 0u;
+        return renderSurface.IsValid() && widthPixels > 0u && heightPixels > 0u;
     }
 };