Split new_editor compat sources into static library

docs/plan/XCUI_Phase_Status_2026-04-05.md

@@ -30,6 +30,9 @@ Old `editor` replacement is explicitly out of scope for this phase.
 - The default native shell path now also has a cleaner translation-unit seam:
   - legacy ImGui shell chrome / HUD rendering now lives in a dedicated legacy-only `Application` translation unit instead of keeping direct `ImGui::*` calls inside the main native host TU
   - `Application.cpp` no longer directly includes `<imgui.h>`, even though the compatibility host path is still compiled into `new_editor`
+- The `new_editor` build now also has an explicit compatibility-source slice:
+  - legacy ImGui shell sources and vendored ImGui backend sources are now grouped into a dedicated compatibility static library instead of being compiled directly as part of the main `XCNewEditor` source list
+  - the main `XCNewEditor` target still sees ImGui headers through older editor bridge headers, but its default implementation source list is now narrower than the compatibility source list
 - Old `editor` replacement remains deferred; all active execution still stays inside XCUI shared code and `new_editor`.
 
 ## Three-Layer Status
@@ -282,6 +285,9 @@ Current gap:
 - Legacy shell chrome / HUD rendering is now split out of the main `Application.cpp` translation unit:
   - the direct `ImGui::*` shell rendering path now lives in a dedicated legacy-only `Application` implementation file
   - the main `Application.cpp` native host path no longer directly includes `<imgui.h>`, reducing default-path compile-time coupling before the larger compat-target split
+- `new_editor` build composition is now split into main/native and compatibility slices:
+  - the main `XCNewEditor` target no longer compiles legacy ImGui shell/panel/backend source files directly
+  - legacy ImGui shell/panel/backend sources plus vendored ImGui sources now build behind a dedicated compatibility static library that the main executable links
 
 ## Phase Risks Still Open
 

new_editor/CMakeLists.txt

@@ -44,17 +44,10 @@ endif()
 set(NEW_EDITOR_SOURCES
     src/main.cpp
     src/Application.cpp
-    src/ApplicationLegacyImGui.cpp
     src/panels/Panel.cpp
-    src/panels/XCUIDemoPanel.cpp
-    src/panels/XCUILayoutLabPanel.cpp
     src/Rendering/MainWindowBackdropPass.cpp
     src/Rendering/MainWindowNativeBackdropRenderer.cpp
-    src/XCUIBackend/ImGuiXCUIInputAdapter.cpp
-    src/XCUIBackend/LegacyImGuiHostInterop.cpp
-    src/XCUIBackend/ImGuiHostCompositor.cpp
     src/XCUIBackend/NativeWindowUICompositor.cpp
-    src/XCUIBackend/XCUIEditorFontSetup.cpp
     src/XCUIBackend/XCUIAssetDocumentSource.cpp
     src/XCUIBackend/XCUIEditorCommandRouter.cpp
     src/XCUIBackend/XCUIInputBridge.cpp
@@ -64,6 +57,16 @@ set(NEW_EDITOR_SOURCES
     src/XCUIBackend/XCUIStandaloneTextAtlasProvider.cpp
     src/XCUIBackend/XCUIDemoRuntime.cpp
     src/XCUIBackend/XCUILayoutLabRuntime.cpp
+)
+
+set(NEW_EDITOR_IMGUI_COMPAT_SOURCES
+    src/ApplicationLegacyImGui.cpp
+    src/panels/XCUIDemoPanel.cpp
+    src/panels/XCUILayoutLabPanel.cpp
+    src/XCUIBackend/ImGuiXCUIInputAdapter.cpp
+    src/XCUIBackend/LegacyImGuiHostInterop.cpp
+    src/XCUIBackend/ImGuiHostCompositor.cpp
+    src/XCUIBackend/XCUIEditorFontSetup.cpp
     ${IMGUI_SOURCE_DIR}/imgui.cpp
     ${IMGUI_SOURCE_DIR}/imgui_demo.cpp
     ${IMGUI_SOURCE_DIR}/imgui_draw.cpp
@@ -73,8 +76,17 @@ set(NEW_EDITOR_SOURCES
     ${IMGUI_SOURCE_DIR}/backends/imgui_impl_dx12.cpp
 )
 
+add_library(XCNewEditorImGuiCompat STATIC ${NEW_EDITOR_IMGUI_COMPAT_SOURCES})
 add_executable(${PROJECT_NAME} WIN32 ${NEW_EDITOR_SOURCES})
 
+target_include_directories(XCNewEditorImGuiCompat PRIVATE
+    ${CMAKE_CURRENT_SOURCE_DIR}/src
+    ${XCENGINE_ROOT_DIR}/engine/include
+    ${XCENGINE_ROOT_DIR}/editor/src
+    ${IMGUI_SOURCE_DIR}
+    ${IMGUI_SOURCE_DIR}/backends
+)
+
 target_include_directories(${PROJECT_NAME} PRIVATE
     ${CMAKE_CURRENT_SOURCE_DIR}/src
     ${XCENGINE_ROOT_DIR}/engine/include
@@ -85,6 +97,13 @@ target_include_directories(${PROJECT_NAME} PRIVATE
 
 file(TO_CMAKE_PATH "${XCENGINE_ROOT_DIR}" XCENGINE_ROOT_DIR_CMAKE)
 
+target_compile_definitions(XCNewEditorImGuiCompat PRIVATE
+    UNICODE
+    _UNICODE
+    XCENGINE_NEW_EDITOR_REPO_ROOT="${XCENGINE_ROOT_DIR_CMAKE}"
+)
+target_compile_options(XCNewEditorImGuiCompat PRIVATE /utf-8)
+
 target_compile_definitions(${PROJECT_NAME} PRIVATE
     UNICODE
     _UNICODE
@@ -93,7 +112,18 @@ target_compile_definitions(${PROJECT_NAME} PRIVATE
 target_compile_options(${PROJECT_NAME} PRIVATE /utf-8)
 
 if(MSVC)
+    target_compile_options(XCNewEditorImGuiCompat PRIVATE /FS)
     target_compile_options(${PROJECT_NAME} PRIVATE /FS)
+    set_property(TARGET XCNewEditorImGuiCompat PROPERTY
+        MSVC_RUNTIME_LIBRARY "MultiThreaded$<$<CONFIG:Debug>:Debug>DLL")
+    set_target_properties(XCNewEditorImGuiCompat PROPERTIES
+        MSVC_DEBUG_INFORMATION_FORMAT "$<$<CONFIG:Debug,RelWithDebInfo>:Embedded>"
+        COMPILE_PDB_NAME "XCNewEditorImGuiCompat-compile"
+        COMPILE_PDB_OUTPUT_DIRECTORY "${CMAKE_BINARY_DIR}/new_editor/compile-pdb-compat"
+        COMPILE_PDB_OUTPUT_DIRECTORY_DEBUG "${CMAKE_BINARY_DIR}/new_editor/compile-pdb-compat/Debug"
+        COMPILE_PDB_OUTPUT_DIRECTORY_RELEASE "${CMAKE_BINARY_DIR}/new_editor/compile-pdb-compat/Release"
+        COMPILE_PDB_OUTPUT_DIRECTORY_MINSIZEREL "${CMAKE_BINARY_DIR}/new_editor/compile-pdb-compat/MinSizeRel"
+        COMPILE_PDB_OUTPUT_DIRECTORY_RELWITHDEBINFO "${CMAKE_BINARY_DIR}/new_editor/compile-pdb-compat/RelWithDebInfo")
     target_link_options(${PROJECT_NAME} PRIVATE
         $<$<CONFIG:Debug,RelWithDebInfo>:/INCREMENTAL:NO>)
     set_property(TARGET ${PROJECT_NAME} PROPERTY
@@ -110,8 +140,17 @@ if(MSVC)
     )
 endif()
 
+target_link_libraries(XCNewEditorImGuiCompat PRIVATE
+    XCEngine
+    d3d12.lib
+    dxgi.lib
+    user32
+    gdi32
+)
+
 target_link_libraries(${PROJECT_NAME} PRIVATE
     XCEngine
+    XCNewEditorImGuiCompat
     d3d12.lib
     dxgi.lib
     user32