diff --git a/engine/include/XCEngine/Resources/Shader/Shader.h b/engine/include/XCEngine/Resources/Shader/Shader.h
index 13f58db8..9a2cd01f 100644
--- a/engine/include/XCEngine/Resources/Shader/Shader.h
+++ b/engine/include/XCEngine/Resources/Shader/Shader.h
@@ -22,6 +22,13 @@ enum class ShaderLanguage : Core::uint8 {
     SPIRV
 };
 
+enum class ShaderBackend : Core::uint8 {
+    Generic = 0,
+    D3D12,
+    OpenGL,
+    Vulkan
+};
+
 struct ShaderUniform {
     Containers::String name;
     Core::uint32 location;
@@ -36,6 +43,27 @@ struct ShaderAttribute {
     Core::uint32 type;
 };
 
+struct ShaderPassTagEntry {
+    Containers::String name;
+    Containers::String value;
+};
+
+struct ShaderStageVariant {
+    ShaderType stage = ShaderType::Fragment;
+    ShaderLanguage language = ShaderLanguage::GLSL;
+    ShaderBackend backend = ShaderBackend::Generic;
+    Containers::String entryPoint;
+    Containers::String profile;
+    Containers::String sourceCode;
+    Containers::Array<Core::uint8> compiledBinary;
+};
+
+struct ShaderPass {
+    Containers::String name;
+    Containers::Array<ShaderPassTagEntry> tags;
+    Containers::Array<ShaderStageVariant> variants;
+};
+
 class Shader : public IResource {
 public:
     Shader();
@@ -49,10 +77,10 @@ public:
     size_t GetMemorySize() const override { return m_memorySize; }
     void Release() override;
     
-    void SetShaderType(ShaderType type) { m_shaderType = type; }
+    void SetShaderType(ShaderType type);
     ShaderType GetShaderType() const { return m_shaderType; }
     
-    void SetShaderLanguage(ShaderLanguage lang) { m_language = lang; }
+    void SetShaderLanguage(ShaderLanguage lang);
     ShaderLanguage GetShaderLanguage() const { return m_language; }
     
     void SetSourceCode(const Containers::String& source);
@@ -66,11 +94,33 @@ public:
     
     void AddAttribute(const ShaderAttribute& attribute);
     const Containers::Array<ShaderAttribute>& GetAttributes() const { return m_attributes; }
+
+    void AddPass(const ShaderPass& pass);
+    void ClearPasses();
+    Core::uint32 GetPassCount() const { return static_cast<Core::uint32>(m_passes.Size()); }
+    const Containers::Array<ShaderPass>& GetPasses() const { return m_passes; }
+
+    void AddPassVariant(const Containers::String& passName, const ShaderStageVariant& variant);
+    void SetPassTag(
+        const Containers::String& passName,
+        const Containers::String& tagName,
+        const Containers::String& tagValue);
+    bool HasPass(const Containers::String& passName) const;
+    const ShaderPass* FindPass(const Containers::String& passName) const;
+    ShaderPass* FindPass(const Containers::String& passName);
+    const ShaderStageVariant* FindVariant(
+        const Containers::String& passName,
+        ShaderType stage,
+        ShaderBackend backend = ShaderBackend::Generic) const;
     
     class IRHIShader* GetRHIResource() const { return m_rhiResource; }
     void SetRHIResource(class IRHIShader* resource);
 
 private:
+    ShaderPass& GetOrCreatePass(const Containers::String& passName);
+    ShaderStageVariant& GetOrCreateLegacyVariant();
+    void SyncLegacyVariant();
+
     ShaderType m_shaderType = ShaderType::Fragment;
     ShaderLanguage m_language = ShaderLanguage::GLSL;
     
@@ -79,6 +129,7 @@ private:
     
     Containers::Array<ShaderUniform> m_uniforms;
     Containers::Array<ShaderAttribute> m_attributes;
+    Containers::Array<ShaderPass> m_passes;
     
     class IRHIShader* m_rhiResource = nullptr;
 };
diff --git a/engine/src/Resources/Shader/Shader.cpp b/engine/src/Resources/Shader/Shader.cpp
index c11032f2..d8249eaa 100644
--- a/engine/src/Resources/Shader/Shader.cpp
+++ b/engine/src/Resources/Shader/Shader.cpp
@@ -3,25 +3,46 @@
 namespace XCEngine {
 namespace Resources {
 
+namespace {
+
+const char* kLegacyShaderPassName = "Default";
+
+} // namespace
+
 Shader::Shader() = default;
 
 Shader::~Shader() = default;
 
 void Shader::Release() {
+    m_shaderType = ShaderType::Fragment;
+    m_language = ShaderLanguage::GLSL;
     m_sourceCode.Clear();
     m_compiledBinary.Clear();
     m_uniforms.Clear();
     m_attributes.Clear();
+    m_passes.Clear();
     m_rhiResource = nullptr;
     m_isValid = false;
 }
 
+void Shader::SetShaderType(ShaderType type) {
+    m_shaderType = type;
+    SyncLegacyVariant();
+}
+
+void Shader::SetShaderLanguage(ShaderLanguage lang) {
+    m_language = lang;
+    SyncLegacyVariant();
+}
+
 void Shader::SetSourceCode(const Containers::String& source) {
     m_sourceCode = source;
+    SyncLegacyVariant();
 }
 
 void Shader::SetCompiledBinary(const Containers::Array<Core::uint8>& binary) {
     m_compiledBinary = binary;
+    SyncLegacyVariant();
 }
 
 void Shader::AddUniform(const ShaderUniform& uniform) {
@@ -32,9 +53,123 @@ void Shader::AddAttribute(const ShaderAttribute& attribute) {
     m_attributes.PushBack(attribute);
 }
 
+void Shader::AddPass(const ShaderPass& pass) {
+    m_passes.PushBack(pass);
+}
+
+void Shader::ClearPasses() {
+    m_passes.Clear();
+}
+
+void Shader::AddPassVariant(
+    const Containers::String& passName,
+    const ShaderStageVariant& variant) {
+    ShaderPass& pass = GetOrCreatePass(passName);
+    pass.variants.PushBack(variant);
+}
+
+void Shader::SetPassTag(
+    const Containers::String& passName,
+    const Containers::String& tagName,
+    const Containers::String& tagValue) {
+    ShaderPass& pass = GetOrCreatePass(passName);
+    for (ShaderPassTagEntry& tag : pass.tags) {
+        if (tag.name == tagName) {
+            tag.value = tagValue;
+            return;
+        }
+    }
+
+    ShaderPassTagEntry& tag = pass.tags.EmplaceBack();
+    tag.name = tagName;
+    tag.value = tagValue;
+}
+
+bool Shader::HasPass(const Containers::String& passName) const {
+    return FindPass(passName) != nullptr;
+}
+
+const ShaderPass* Shader::FindPass(const Containers::String& passName) const {
+    for (const ShaderPass& pass : m_passes) {
+        if (pass.name == passName) {
+            return &pass;
+        }
+    }
+
+    return nullptr;
+}
+
+ShaderPass* Shader::FindPass(const Containers::String& passName) {
+    for (ShaderPass& pass : m_passes) {
+        if (pass.name == passName) {
+            return &pass;
+        }
+    }
+
+    return nullptr;
+}
+
+const ShaderStageVariant* Shader::FindVariant(
+    const Containers::String& passName,
+    ShaderType stage,
+    ShaderBackend backend) const {
+    const ShaderPass* pass = FindPass(passName);
+    if (pass == nullptr) {
+        return nullptr;
+    }
+
+    const ShaderStageVariant* genericVariant = nullptr;
+    for (const ShaderStageVariant& variant : pass->variants) {
+        if (variant.stage != stage) {
+            continue;
+        }
+
+        if (variant.backend == backend) {
+            return &variant;
+        }
+
+        if (variant.backend == ShaderBackend::Generic && genericVariant == nullptr) {
+            genericVariant = &variant;
+        }
+    }
+
+    return genericVariant;
+}
+
 void Shader::SetRHIResource(class IRHIShader* resource) {
     m_rhiResource = resource;
 }
 
+ShaderPass& Shader::GetOrCreatePass(const Containers::String& passName) {
+    if (ShaderPass* pass = FindPass(passName)) {
+        return *pass;
+    }
+
+    ShaderPass& pass = m_passes.EmplaceBack();
+    pass.name = passName;
+    return pass;
+}
+
+ShaderStageVariant& Shader::GetOrCreateLegacyVariant() {
+    ShaderPass& pass = GetOrCreatePass(kLegacyShaderPassName);
+    for (ShaderStageVariant& variant : pass.variants) {
+        if (variant.backend == ShaderBackend::Generic) {
+            return variant;
+        }
+    }
+
+    ShaderStageVariant& variant = pass.variants.EmplaceBack();
+    variant.backend = ShaderBackend::Generic;
+    return variant;
+}
+
+void Shader::SyncLegacyVariant() {
+    ShaderStageVariant& variant = GetOrCreateLegacyVariant();
+    variant.stage = m_shaderType;
+    variant.language = m_language;
+    variant.sourceCode = m_sourceCode;
+    variant.compiledBinary = m_compiledBinary;
+}
+
 } // namespace Resources
 } // namespace XCEngine
diff --git a/tests/Resources/Shader/test_shader.cpp b/tests/Resources/Shader/test_shader.cpp
index 4caf44dd..7bd49fca 100644
--- a/tests/Resources/Shader/test_shader.cpp
+++ b/tests/Resources/Shader/test_shader.cpp
@@ -100,4 +100,78 @@ TEST(Shader, AddGetAttributes) {
     EXPECT_EQ(attributes[0].name, "aPosition");
 }
 
+TEST(Shader, LegacySingleStageStateSyncsIntoDefaultPassVariant) {
+    Shader shader;
+    shader.SetShaderType(ShaderType::Vertex);
+    shader.SetShaderLanguage(ShaderLanguage::HLSL);
+    shader.SetSourceCode("float4 MainVS() : SV_POSITION { return 0; }");
+
+    ASSERT_EQ(shader.GetPassCount(), 1u);
+    const ShaderPass* pass = shader.FindPass("Default");
+    ASSERT_NE(pass, nullptr);
+    ASSERT_EQ(pass->variants.Size(), 1u);
+    EXPECT_EQ(pass->variants[0].stage, ShaderType::Vertex);
+    EXPECT_EQ(pass->variants[0].language, ShaderLanguage::HLSL);
+    EXPECT_EQ(pass->variants[0].backend, ShaderBackend::Generic);
+    EXPECT_EQ(pass->variants[0].sourceCode, "float4 MainVS() : SV_POSITION { return 0; }");
+}
+
+TEST(Shader, FindsBackendSpecificVariantAndFallsBackToGeneric) {
+    Shader shader;
+
+    ShaderStageVariant genericFragment = {};
+    genericFragment.stage = ShaderType::Fragment;
+    genericFragment.language = ShaderLanguage::GLSL;
+    genericFragment.backend = ShaderBackend::Generic;
+    genericFragment.sourceCode = "generic fragment";
+    shader.AddPassVariant("ForwardLit", genericFragment);
+
+    ShaderStageVariant d3d12Fragment = {};
+    d3d12Fragment.stage = ShaderType::Fragment;
+    d3d12Fragment.language = ShaderLanguage::HLSL;
+    d3d12Fragment.backend = ShaderBackend::D3D12;
+    d3d12Fragment.sourceCode = "d3d12 fragment";
+    shader.AddPassVariant("ForwardLit", d3d12Fragment);
+
+    const ShaderStageVariant* d3d12Variant =
+        shader.FindVariant("ForwardLit", ShaderType::Fragment, ShaderBackend::D3D12);
+    ASSERT_NE(d3d12Variant, nullptr);
+    EXPECT_EQ(d3d12Variant->sourceCode, "d3d12 fragment");
+
+    const ShaderStageVariant* openglVariant =
+        shader.FindVariant("ForwardLit", ShaderType::Fragment, ShaderBackend::OpenGL);
+    ASSERT_NE(openglVariant, nullptr);
+    EXPECT_EQ(openglVariant->sourceCode, "generic fragment");
+}
+
+TEST(Shader, StoresPerPassTags) {
+    Shader shader;
+    shader.SetPassTag("ForwardLit", "LightMode", "ForwardBase");
+    shader.SetPassTag("ForwardLit", "Queue", "Geometry");
+
+    const ShaderPass* pass = shader.FindPass("ForwardLit");
+    ASSERT_NE(pass, nullptr);
+    ASSERT_EQ(pass->tags.Size(), 2u);
+    EXPECT_EQ(pass->tags[0].name, "LightMode");
+    EXPECT_EQ(pass->tags[0].value, "ForwardBase");
+    EXPECT_EQ(pass->tags[1].name, "Queue");
+    EXPECT_EQ(pass->tags[1].value, "Geometry");
+}
+
+TEST(Shader, ReleaseClearsPassRuntimeData) {
+    Shader shader;
+    shader.SetSourceCode("void main() {}");
+    ShaderStageVariant variant = {};
+    variant.stage = ShaderType::Fragment;
+    variant.sourceCode = "fragment";
+    shader.AddPassVariant("ForwardLit", variant);
+
+    shader.Release();
+
+    EXPECT_EQ(shader.GetPassCount(), 0u);
+    EXPECT_EQ(shader.GetSourceCode(), "");
+    EXPECT_EQ(shader.GetCompiledBinary().Size(), 0u);
+    EXPECT_FALSE(shader.IsValid());
+}
+
 } // namespace
diff --git a/tests/Resources/Shader/test_shader_loader.cpp b/tests/Resources/Shader/test_shader_loader.cpp
index c43abe5e..02f4b32e 100644
--- a/tests/Resources/Shader/test_shader_loader.cpp
+++ b/tests/Resources/Shader/test_shader_loader.cpp
@@ -3,6 +3,10 @@
 #include <XCEngine/Core/Asset/ResourceTypes.h>
 #include <XCEngine/Core/Containers/Array.h>
 
+#include <cstdio>
+#include <filesystem>
+#include <fstream>
+
 using namespace XCEngine::Resources;
 using namespace XCEngine::Containers;
 
@@ -35,4 +39,35 @@ TEST(ShaderLoader, LoadInvalidPath) {
     EXPECT_FALSE(result);
 }
 
+TEST(ShaderLoader, LoadLegacySingleStageShaderBuildsDefaultPassVariant) {
+    namespace fs = std::filesystem;
+
+    const fs::path shaderPath = fs::temp_directory_path() / "xc_shader_loader_stage.vert";
+    {
+        std::ofstream shaderFile(shaderPath);
+        ASSERT_TRUE(shaderFile.is_open());
+        shaderFile << "#version 430\nvoid main() {}";
+    }
+
+    ShaderLoader loader;
+    LoadResult result = loader.Load(shaderPath.string().c_str());
+    ASSERT_TRUE(result);
+    ASSERT_NE(result.resource, nullptr);
+
+    Shader* shader = static_cast<Shader*>(result.resource);
+    ASSERT_NE(shader, nullptr);
+    EXPECT_EQ(shader->GetShaderType(), ShaderType::Vertex);
+    ASSERT_EQ(shader->GetPassCount(), 1u);
+
+    const ShaderPass* pass = shader->FindPass("Default");
+    ASSERT_NE(pass, nullptr);
+    ASSERT_EQ(pass->variants.Size(), 1u);
+    EXPECT_EQ(pass->variants[0].stage, ShaderType::Vertex);
+    EXPECT_EQ(pass->variants[0].backend, ShaderBackend::Generic);
+    EXPECT_EQ(pass->variants[0].sourceCode, shader->GetSourceCode());
+
+    delete shader;
+    std::remove(shaderPath.string().c_str());
+}
+
 } // namespace