fix(build): move generated assets to per-build binary dir

assets_data.cc was shared in src/generated/ across all builds. When a
native debug build regenerated it with --disk_load (file paths), then
build_win compiled with STRIP_ALL=ON, the disk-load fopen() path was
compiled out, leaving raw macOS paths as shader source content — causing
wgpu WGSL parse errors on Wine.

Fix: GEN_DEMO_H/CC and all stamps now live in CMAKE_CURRENT_BINARY_DIR/
src/generated/ so each build dir independently generates assets in the
correct mode (embedded vs disk-load). Added CMAKE_CURRENT_BINARY_DIR/src
to CORE_INCLUDES so the binary-dir assets.h is resolved first.

handoff(Gemini): build system fix — assets are now per-build-dir; tests
35/35 pass; build_win produces embedded shaders.

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

2 files changed, 9 insertions, 5 deletions

diff --git a/cmake/DemoCodegen.cmake b/cmake/DemoCodegen.cmake
index a353fc7..7fc7f98 100644
--- a/cmake/DemoCodegen.cmake
+++ b/cmake/DemoCodegen.cmake
@@ -198,13 +198,14 @@ parse_asset_list(${FILTERED_AUDIO} AUDIO_DEPS)
 parse_asset_list(${FILTERED_MODELS} MODELS_DEPS)
 parse_asset_list(${FILTERED_DATA} DATA_DEPS)
 
-# Single unified output (avoids duplicate symbols)
-set(GEN_DEMO_H ${CMAKE_CURRENT_SOURCE_DIR}/src/generated/assets.h)
-set(GEN_DEMO_CC ${CMAKE_CURRENT_SOURCE_DIR}/src/generated/assets_data.cc)
+# Single unified output (per-build-dir to avoid disk_load vs embedded conflicts)
+set(GEN_DEMO_H ${CMAKE_CURRENT_BINARY_DIR}/src/generated/assets.h)
+set(GEN_DEMO_CC ${CMAKE_CURRENT_BINARY_DIR}/src/generated/assets_data.cc)
 
 # Category-specific targets for granular rebuilds
 add_custom_command(
     OUTPUT ${GEN_DEMO_H}.shaders_stamp
+    COMMAND ${CMAKE_COMMAND} -E make_directory ${CMAKE_CURRENT_BINARY_DIR}/src/generated
     COMMAND ${CMAKE_COMMAND} -E touch ${GEN_DEMO_H}.shaders_stamp
     DEPENDS ${ASSET_PACKER_DEPENDS} ${WORKSPACE_ASSETS} ${SHADERS_DEPS}
     COMMENT "Checking shader assets..."
@@ -213,6 +214,7 @@ add_custom_target(generate_demo_shaders DEPENDS ${GEN_DEMO_H}.shaders_stamp)
 
 add_custom_command(
     OUTPUT ${GEN_DEMO_H}.audio_stamp
+    COMMAND ${CMAKE_COMMAND} -E make_directory ${CMAKE_CURRENT_BINARY_DIR}/src/generated
     COMMAND ${CMAKE_COMMAND} -E touch ${GEN_DEMO_H}.audio_stamp
     DEPENDS ${ASSET_PACKER_DEPENDS} ${WORKSPACE_ASSETS} ${AUDIO_DEPS}
     COMMENT "Checking audio assets..."
@@ -221,6 +223,7 @@ add_custom_target(generate_demo_audio DEPENDS ${GEN_DEMO_H}.audio_stamp)
 
 add_custom_command(
     OUTPUT ${GEN_DEMO_H}.models_stamp
+    COMMAND ${CMAKE_COMMAND} -E make_directory ${CMAKE_CURRENT_BINARY_DIR}/src/generated
     COMMAND ${CMAKE_COMMAND} -E touch ${GEN_DEMO_H}.models_stamp
     DEPENDS ${ASSET_PACKER_DEPENDS} ${WORKSPACE_ASSETS} ${MODELS_DEPS}
     COMMENT "Checking model assets..."
@@ -229,6 +232,7 @@ add_custom_target(generate_demo_models DEPENDS ${GEN_DEMO_H}.models_stamp)
 
 add_custom_command(
     OUTPUT ${GEN_DEMO_H}.data_stamp
+    COMMAND ${CMAKE_COMMAND} -E make_directory ${CMAKE_CURRENT_BINARY_DIR}/src/generated
     COMMAND ${CMAKE_COMMAND} -E touch ${GEN_DEMO_H}.data_stamp
     DEPENDS ${ASSET_PACKER_DEPENDS} ${WORKSPACE_ASSETS} ${DATA_DEPS}
     COMMENT "Checking data assets..."
@@ -255,7 +259,7 @@ endif()
 set(GEN_DEMO_H_STAMP ${GEN_DEMO_H}.gen_stamp)
 add_custom_command(
     OUTPUT ${GEN_DEMO_H_STAMP} ${GEN_DEMO_CC}
-    COMMAND ${CMAKE_COMMAND} -E make_directory ${CMAKE_CURRENT_SOURCE_DIR}/src/generated
+    COMMAND ${CMAKE_COMMAND} -E make_directory ${CMAKE_CURRENT_BINARY_DIR}/src/generated
     COMMAND ${ASSET_PACKER_CMD} ${WORKSPACE_ASSETS} ${GEN_DEMO_H}.new ${GEN_DEMO_CC} ${ASSET_PACKER_FLAGS}
     COMMAND ${CMAKE_COMMAND} -E copy_if_different ${GEN_DEMO_H}.new ${GEN_DEMO_H}
     COMMAND ${CMAKE_COMMAND} -E touch ${GEN_DEMO_H_STAMP}
diff --git a/cmake/DemoDependencies.cmake b/cmake/DemoDependencies.cmake
index daac571..55cc180 100644
--- a/cmake/DemoDependencies.cmake
+++ b/cmake/DemoDependencies.cmake
@@ -1,7 +1,7 @@
 # External Dependencies and Includes
 # Finds and configures external libraries (WGPU, GLFW, platform libs)
 
-set(CORE_INCLUDES src third_party)
+set(CORE_INCLUDES ${CMAKE_CURRENT_BINARY_DIR}/src src third_party)
 
 if(DEMO_CROSS_COMPILE_WIN32)
     add_definitions(-DDEMO_CROSS_COMPILE_WIN32)