diff --git a/CMakeLists.txt b/CMakeLists.txt
index 3385614..8dde4af 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -61,6 +61,12 @@ add_custom_target(panopainter_modernization_status
     COMMAND "${CMAKE_COMMAND}" -E echo "Debt log: docs/modernization/debt.md"
     VERBATIM)
 
+add_custom_target(panopainter_validate_shaders
+    COMMAND "${CMAKE_COMMAND}"
+        "-DPP_SHADER_DIR=${CMAKE_CURRENT_SOURCE_DIR}/data/shaders"
+        -P "${CMAKE_CURRENT_SOURCE_DIR}/cmake/ValidatePanoPainterShaders.cmake"
+    VERBATIM)
+
 add_library(pp_foundation STATIC
     src/foundation/binary_stream.cpp
     src/foundation/parse.cpp
diff --git a/cmake/ValidatePanoPainterShaders.cmake b/cmake/ValidatePanoPainterShaders.cmake
new file mode 100644
index 0000000..5df22f6
--- /dev/null
+++ b/cmake/ValidatePanoPainterShaders.cmake
@@ -0,0 +1,75 @@
+if(NOT DEFINED PP_SHADER_DIR)
+    message(FATAL_ERROR "PP_SHADER_DIR is required")
+endif()
+
+file(REAL_PATH "${PP_SHADER_DIR}" pp_shader_dir)
+if(NOT IS_DIRECTORY "${pp_shader_dir}")
+    message(FATAL_ERROR "Shader directory does not exist: ${pp_shader_dir}")
+endif()
+
+file(GLOB_RECURSE pp_shader_files
+    "${pp_shader_dir}/*.glsl")
+
+if(NOT pp_shader_files)
+    message(FATAL_ERROR "No shader files found under: ${pp_shader_dir}")
+endif()
+
+set(pp_shader_errors "")
+set(pp_top_level_count 0)
+set(pp_include_count 0)
+
+foreach(pp_shader_file IN LISTS pp_shader_files)
+    file(RELATIVE_PATH pp_shader_rel "${pp_shader_dir}" "${pp_shader_file}")
+    file(READ "${pp_shader_file}" pp_shader_contents)
+
+    string(REGEX MATCHALL "#[ \t]*include[ \t]+\"[^\"]+\"" pp_include_lines "${pp_shader_contents}")
+    foreach(pp_include_line IN LISTS pp_include_lines)
+        string(REGEX REPLACE ".*\"([^\"]+)\".*" "\\1" pp_include_path "${pp_include_line}")
+        if(pp_include_path MATCHES "^/")
+            list(APPEND pp_shader_errors "${pp_shader_rel}: include path must be relative: ${pp_include_path}")
+        endif()
+        if(pp_include_path MATCHES "^[A-Za-z]:")
+            list(APPEND pp_shader_errors "${pp_shader_rel}: include path must not be drive-absolute: ${pp_include_path}")
+        endif()
+        if(pp_include_path MATCHES "\\.\\.")
+            list(APPEND pp_shader_errors "${pp_shader_rel}: include path must not traverse parent directories: ${pp_include_path}")
+        endif()
+        if(NOT EXISTS "${pp_shader_dir}/${pp_include_path}")
+            list(APPEND pp_shader_errors "${pp_shader_rel}: missing include: ${pp_include_path}")
+        endif()
+    endforeach()
+
+    if(pp_shader_rel MATCHES "^include/")
+        math(EXPR pp_include_count "${pp_include_count} + 1")
+        if(pp_shader_contents MATCHES "\\[\\[(vertex|fragment)\\]\\]")
+            list(APPEND pp_shader_errors "${pp_shader_rel}: include shaders must not declare stage markers")
+        endif()
+    else()
+        math(EXPR pp_top_level_count "${pp_top_level_count} + 1")
+
+        string(REGEX MATCHALL "\\[\\[vertex\\]\\]" pp_vertex_markers "${pp_shader_contents}")
+        string(REGEX MATCHALL "\\[\\[fragment\\]\\]" pp_fragment_markers "${pp_shader_contents}")
+        list(LENGTH pp_vertex_markers pp_vertex_count)
+        list(LENGTH pp_fragment_markers pp_fragment_count)
+
+        if(NOT pp_vertex_count EQUAL 1)
+            list(APPEND pp_shader_errors "${pp_shader_rel}: expected exactly one [[vertex]] marker")
+        endif()
+        if(NOT pp_fragment_count EQUAL 1)
+            list(APPEND pp_shader_errors "${pp_shader_rel}: expected exactly one [[fragment]] marker")
+        endif()
+
+        string(FIND "${pp_shader_contents}" "[[vertex]]" pp_vertex_pos)
+        string(FIND "${pp_shader_contents}" "[[fragment]]" pp_fragment_pos)
+        if(pp_vertex_pos GREATER_EQUAL 0 AND pp_fragment_pos GREATER_EQUAL 0 AND NOT pp_vertex_pos LESS pp_fragment_pos)
+            list(APPEND pp_shader_errors "${pp_shader_rel}: [[vertex]] marker must appear before [[fragment]]")
+        endif()
+    endif()
+endforeach()
+
+if(pp_shader_errors)
+    list(JOIN pp_shader_errors "\n" pp_shader_error_text)
+    message(FATAL_ERROR "Shader validation failed:\n${pp_shader_error_text}")
+endif()
+
+message(STATUS "Validated ${pp_top_level_count} shader programs and ${pp_include_count} shader includes under ${pp_shader_dir}")
diff --git a/docs/modernization/build-inventory.md b/docs/modernization/build-inventory.md
index 9898b4d..74347f5 100644
--- a/docs/modernization/build-inventory.md
+++ b/docs/modernization/build-inventory.md
@@ -63,6 +63,8 @@ cmake --build --preset windows-msvc-default --config Debug --target PanoPainter
 ctest --preset desktop-fast --build-config Debug
 powershell -ExecutionPolicy Bypass -File scripts\automation\test.ps1 -Preset desktop-fast -Configuration Debug
 powershell -ExecutionPolicy Bypass -File scripts\automation\build.ps1 -Preset windows-msvc-default -Configuration Debug -Target pano_cli
+cmake --build --preset windows-msvc-default --target panopainter_validate_shaders
+powershell -ExecutionPolicy Bypass -File scripts\automation\analyze.ps1 -Preset windows-msvc-default -NoApp
 cmake --preset android-arm64
 powershell -ExecutionPolicy Bypass -File scripts\automation\platform-build.ps1 -Presets android-arm64
 powershell -ExecutionPolicy Bypass -File scripts\automation\package-smoke.ps1 -Preset windows-msvc-default -Configuration Debug
@@ -79,6 +81,9 @@ Known local toolchain state:
   `pp_paint`, `pp_document`, `pp_renderer_api`, `pp_paint_renderer`,
   `pp_ui_core`, `pano_cli`, and their current headless test binaries,
   including PPI header and layout XML parse coverage.
+- `panopainter_validate_shaders` validates the current combined GLSL shader
+  files for one vertex stage marker, one fragment stage marker, valid marker
+  order, and existing relative includes.
 - `vcpkg` is not on PATH yet; see DEBT-0007.
 
 Known warnings after the current CMake app build:
diff --git a/docs/modernization/roadmap.md b/docs/modernization/roadmap.md
index 648a8d9..b3a0f77 100644
--- a/docs/modernization/roadmap.md
+++ b/docs/modernization/roadmap.md
@@ -188,9 +188,10 @@ Gate:
 
 Goal: turn the build into an error-finding system before deep refactors.
 
-Status: in progress. Initial warning/sanitizer option targets and `vcpkg.json`
-exist. Dependency migration is not complete until component targets consume
-vcpkg packages and platform triplets are validated.
+Status: in progress. Initial warning/sanitizer option targets, `vcpkg.json`,
+and a headless `panopainter_validate_shaders` target exist. Dependency
+migration is not complete until component targets consume vcpkg packages and
+platform triplets are validated.
 
 Implementation tasks:
 
@@ -524,6 +525,8 @@ cmake --build --preset windows-msvc-default --config Debug --target pp_foundatio
 ctest --preset desktop-fast --build-config Debug
 powershell -ExecutionPolicy Bypass -File scripts\automation\test.ps1 -Preset desktop-fast -Configuration Debug
 powershell -ExecutionPolicy Bypass -File scripts\automation\build.ps1 -Preset windows-msvc-default -Configuration Debug -Target pano_cli
+cmake --build --preset windows-msvc-default --target panopainter_validate_shaders
+powershell -ExecutionPolicy Bypass -File scripts\automation\analyze.ps1 -Preset windows-msvc-default -NoApp
 cmake --preset android-arm64
 powershell -ExecutionPolicy Bypass -File scripts\automation\platform-build.ps1 -Presets android-arm64
 powershell -ExecutionPolicy Bypass -File scripts\automation\package-smoke.ps1 -Preset windows-msvc-default -Configuration Debug
@@ -546,6 +549,10 @@ Results:
 - `pano_cli_inspect_image_rejects_unsupported` passed as an expected failure
   test.
 - `pano_cli_parse_layout_smoke` passed.
+- `panopainter_validate_shaders` passed, validating 25 shader programs and 7
+  shader includes for stage markers and include graph integrity.
+- PowerShell analyze automation returns JSON summaries and includes the shader
+  validation target.
 - `PanoPainter.exe` built through CMake at
   `out/build/windows-msvc-default/Debug/PanoPainter.exe`.
 - PowerShell build/test automation wrappers return JSON summaries and passed
diff --git a/scripts/automation/analyze.ps1 b/scripts/automation/analyze.ps1
index bb34a97..01551fb 100644
--- a/scripts/automation/analyze.ps1
+++ b/scripts/automation/analyze.ps1
@@ -17,14 +17,36 @@ if ($NoApp) {
 }
 
 & cmake @argsList
-$exitCode = $LASTEXITCODE
+$configureExitCode = $LASTEXITCODE
+$shaderExitCode = 0
+
+if ($configureExitCode -eq 0) {
+    & cmake --build --preset $Preset --target panopainter_validate_shaders
+    $shaderExitCode = $LASTEXITCODE
+}
+
+$exitCode = $configureExitCode
+if ($exitCode -eq 0 -and $shaderExitCode -ne 0) {
+    $exitCode = $shaderExitCode
+}
+
 $elapsed = [int]((Get-Date) - $started).TotalMilliseconds
 
 [ordered]@{
-    command = "analyze-configure"
+    command = "analyze"
     preset = $Preset
     exitCode = $exitCode
+    checks = @(
+        [ordered]@{
+            name = "configure"
+            exitCode = $configureExitCode
+        },
+        [ordered]@{
+            name = "shader-validation"
+            exitCode = $shaderExitCode
+        }
+    )
     elapsedMs = $elapsed
-} | ConvertTo-Json -Compress
+} | ConvertTo-Json -Compress -Depth 4
 
 exit $exitCode
diff --git a/scripts/automation/analyze.sh b/scripts/automation/analyze.sh
index d3098bc..d81b811 100644
--- a/scripts/automation/analyze.sh
+++ b/scripts/automation/analyze.sh
@@ -4,8 +4,17 @@ set -u
 preset="${1:-linux-clang}"
 start="$(date +%s)"
 cmake --preset "$preset" -DPP_ENABLE_CLANG_TIDY=ON -DPP_ENABLE_CPPCHECK=ON
-exit_code="$?"
+configure_exit_code="$?"
+shader_exit_code="0"
+if [ "$configure_exit_code" -eq 0 ]; then
+    cmake --build --preset "$preset" --target panopainter_validate_shaders
+    shader_exit_code="$?"
+fi
+exit_code="$configure_exit_code"
+if [ "$exit_code" -eq 0 ] && [ "$shader_exit_code" -ne 0 ]; then
+    exit_code="$shader_exit_code"
+fi
 end="$(date +%s)"
 elapsed_ms="$(( (end - start) * 1000 ))"
-printf '{"command":"analyze-configure","preset":"%s","exitCode":%s,"elapsedMs":%s}\n' "$preset" "$exit_code" "$elapsed_ms"
+printf '{"command":"analyze","preset":"%s","exitCode":%s,"checks":[{"name":"configure","exitCode":%s},{"name":"shader-validation","exitCode":%s}],"elapsedMs":%s}\n' "$preset" "$exit_code" "$configure_exit_code" "$shader_exit_code" "$elapsed_ms"
 exit "$exit_code"