diff --git a/Shaders/Private/ShaderLabCommon.ush b/Shaders/Private/ShaderLabCommon.ush
index 036886a..d738ea2 100644
--- a/Shaders/Private/ShaderLabCommon.ush
+++ b/Shaders/Private/ShaderLabCommon.ush
@@ -7,6 +7,40 @@
 // Per-pixel/vertex inputs are read through `UE_NodeName(...)` intrinsics (resolved by the graph
 // builder to real material expression nodes), not through a context struct.
 
+// ---------------------------------------------------------------------------
+// Read-only project/engine-driven permutation macros. The graph builder leaks SHADERLAB_QUALITY /
+// SHADERLAB_FEATURELEVEL / SHADERLAB_SHADINGPATH (via a before-attributes QualitySwitch/FeatureLevelSwitch/
+// ShadingPathSwitch, same mechanism as static switches) so a body can `#if` on them to adapt per permutation.
+// These are NOT author-settable — the engine picks the permutation. Compare against the ordered constants
+// below (ordered low->high so `<=`/`>=` are meaningful).
+// ---------------------------------------------------------------------------
+#define QUALITY_LOW          0
+#define QUALITY_MEDIUM       1
+#define QUALITY_HIGH         2
+#define QUALITY_EPIC         3
+
+#define FEATURELEVEL_ES31    0
+#define FEATURELEVEL_SM5     1
+#define FEATURELEVEL_SM6     2
+
+#define SHADINGPATH_DEFERRED 0
+#define SHADINGPATH_FORWARD  1
+#define SHADINGPATH_MOBILE   2
+
+#ifdef SHADERLAB_IDE
+	// IDE only: give the leaked macros a default so `#if SHADERLAB_QUALITY ...` completes/checks. At real
+	// compile these come from the graph's before-attributes switch nodes (SHADERLAB_IDE is never defined then).
+	#ifndef SHADERLAB_QUALITY
+		#define SHADERLAB_QUALITY QUALITY_HIGH
+	#endif
+	#ifndef SHADERLAB_FEATURELEVEL
+		#define SHADERLAB_FEATURELEVEL FEATURELEVEL_SM6
+	#endif
+	#ifndef SHADERLAB_SHADINGPATH
+		#define SHADERLAB_SHADINGPATH SHADINGPATH_DEFERRED
+	#endif
+#endif
+
 // Surface description filled by the Surface(...) body. Defaults mirror the
 // UMaterialExpressionSubstrateSlabBSDF pin defaults so that fields the body does not
 // touch keep Substrate's native behavior.
@@ -32,8 +66,204 @@ struct FShaderLabSurface
 	float2 GlintUV;
 	float  Opacity;
 	float  OpacityMask;
+	// Material-level outputs (single-Surface sugar): wired to the main node's Refraction / PixelDepthOffset pins.
+	float  Refraction;       // scalar IOR (RefractionMethod = IndexOfRefraction); 1.0 = no bending
+	float  PixelDepthOffset; // world-unit depth push toward camera
 };
 
+// --- Additional Substrate BSDF output structs. Each mirrors the pins of its engine BSDF node; the graph
+// builder wires only the fields a body writes, leaving the rest at the node's native default. ---
+
+// Unlit BSDF (SL_UNLIT): pure emissive / transmittance, no lighting.
+struct FShaderLabUnlit
+{
+	float3 EmissiveColor;
+	float3 TransmittanceColor;
+	float3 Normal;
+};
+
+// Hair BSDF (SL_HAIR): hair-fiber shading.
+struct FShaderLabHair
+{
+	float3 BaseColor;
+	float  Scatter;
+	float  Specular;
+	float  Roughness;
+	float3 Backlit;
+	float3 Tangent;
+	float3 EmissiveColor;
+};
+
+// Eye BSDF (SL_EYE): cornea / iris / sclera shading.
+struct FShaderLabEye
+{
+	float3 DiffuseColor;
+	float  Roughness;
+	float3 CorneaNormal;
+	float3 IrisNormal;
+	float3 IrisPlaneNormal;
+	float  IrisMask;
+	float  IrisDistance;
+	float3 EmissiveColor;
+};
+
+// Single Layer Water BSDF (SL_WATER): water surface + underwater scattering.
+struct FShaderLabWater
+{
+	float3 BaseColor;
+	float  Metallic;
+	float  Specular;
+	float  Roughness;
+	float3 Normal;
+	float3 EmissiveColor;
+	float3 TopMaterialOpacity;
+	float3 WaterAlbedo;
+	float3 WaterExtinction;
+	float  WaterPhaseG;
+	float3 ColorScaleBehindWater;
+};
+
+// Volumetric-Fog-Cloud BSDF (SL_VOLUME, Domain = Volume): participating media.
+struct FShaderLabVolume
+{
+	float3 Albedo;
+	float3 Extinction;
+	float3 EmissiveColor;
+	float  AmbientOcclusion;
+};
+
+// Simple Clear Coat BSDF (SL_CLEARCOAT): bottom layer + clear coat top.
+struct FShaderLabClearCoat
+{
+	float3 DiffuseAlbedo;
+	float3 F0;
+	float  Roughness;
+	float  ClearCoatCoverage;
+	float  ClearCoatRoughness;
+	float3 Normal;
+	float3 EmissiveColor;
+	float3 BottomNormal;
+};
+
+// Toon BSDF (SL_TOON, experimental): stylized shading.
+struct FShaderLabToon
+{
+	float3 BaseColor;
+	float  Metallic;
+	float  Specular;
+	float  Roughness;
+	float3 Normal;
+	float3 EmissiveColor;
+	float2 PatternUVs;
+	float  Anisotropy;
+	float3 Tangent;
+};
+
+// Light Function (SL_LIGHTFUNCTION, Domain = LightFunction): per-light modulation color.
+struct FShaderLabLightFunction
+{
+	float3 Color;
+};
+
+FShaderLabUnlit ShaderLabDefaultUnlit()
+{
+	FShaderLabUnlit U;
+	U.EmissiveColor = float3(0, 0, 0);
+	U.TransmittanceColor = float3(1, 1, 1);
+	U.Normal = float3(0, 0, 1);
+	return U;
+}
+
+FShaderLabHair ShaderLabDefaultHair()
+{
+	FShaderLabHair H;
+	H.BaseColor = float3(0, 0, 0);
+	H.Scatter = 0;
+	H.Specular = 0.5;
+	H.Roughness = 0.5;
+	H.Backlit = float3(0, 0, 0);
+	H.Tangent = float3(1, 0, 0);
+	H.EmissiveColor = float3(0, 0, 0);
+	return H;
+}
+
+FShaderLabEye ShaderLabDefaultEye()
+{
+	FShaderLabEye E;
+	E.DiffuseColor = float3(0, 0, 0);
+	E.Roughness = 0.5;
+	E.CorneaNormal = float3(0, 0, 1);
+	E.IrisNormal = float3(0, 0, 1);
+	E.IrisPlaneNormal = float3(0, 0, 1);
+	E.IrisMask = 0;
+	E.IrisDistance = 0;
+	E.EmissiveColor = float3(0, 0, 0);
+	return E;
+}
+
+FShaderLabWater ShaderLabDefaultWater()
+{
+	FShaderLabWater W;
+	W.BaseColor = float3(0, 0, 0);
+	W.Metallic = 0;
+	W.Specular = 0.5;
+	W.Roughness = 0.5;
+	W.Normal = float3(0, 0, 1);
+	W.EmissiveColor = float3(0, 0, 0);
+	W.TopMaterialOpacity = float3(0, 0, 0);
+	W.WaterAlbedo = float3(0, 0, 0);
+	W.WaterExtinction = float3(0, 0, 0);
+	W.WaterPhaseG = 0;
+	W.ColorScaleBehindWater = float3(1, 1, 1);
+	return W;
+}
+
+FShaderLabVolume ShaderLabDefaultVolume()
+{
+	FShaderLabVolume V;
+	V.Albedo = float3(0, 0, 0);
+	V.Extinction = float3(0, 0, 0);
+	V.EmissiveColor = float3(0, 0, 0);
+	V.AmbientOcclusion = 1;
+	return V;
+}
+
+FShaderLabClearCoat ShaderLabDefaultClearCoat()
+{
+	FShaderLabClearCoat C;
+	C.DiffuseAlbedo = float3(0.18, 0.18, 0.18);
+	C.F0 = float3(0.04, 0.04, 0.04);
+	C.Roughness = 0.5;
+	C.ClearCoatCoverage = 0.5;
+	C.ClearCoatRoughness = 0.5;
+	C.Normal = float3(0, 0, 1);
+	C.EmissiveColor = float3(0, 0, 0);
+	C.BottomNormal = float3(0, 0, 1);
+	return C;
+}
+
+FShaderLabToon ShaderLabDefaultToon()
+{
+	FShaderLabToon T;
+	T.BaseColor = float3(0.18, 0.18, 0.18);
+	T.Metallic = 0;
+	T.Specular = 0.5;
+	T.Roughness = 0.5;
+	T.Normal = float3(0, 0, 1);
+	T.EmissiveColor = float3(0, 0, 0);
+	T.PatternUVs = float2(0, 0);
+	T.Anisotropy = 0;
+	T.Tangent = float3(1, 0, 0);
+	return T;
+}
+
+FShaderLabLightFunction ShaderLabDefaultLightFunction()
+{
+	FShaderLabLightFunction L;
+	L.Color = float3(1, 1, 1);
+	return L;
+}
+
 // Output for the PostProcess(...) entry (Domain = PostProcess). Color feeds the material EmissiveColor.
 struct FShaderLabPostProcess
 {
@@ -82,6 +312,8 @@ FShaderLabSurface ShaderLabDefaultSurface()
 	S.GlintUV = float2(0, 0);
 	S.Opacity = 1;
 	S.OpacityMask = 1;
+	S.Refraction = 1.0;
+	S.PixelDepthOffset = 0.0;
 	return S;
 }
 
diff --git a/Shaders/Private/ShaderLabDSL.ush b/Shaders/Private/ShaderLabDSL.ush
index fe56b2e..8d56d60 100644
--- a/Shaders/Private/ShaderLabDSL.ush
+++ b/Shaders/Private/ShaderLabDSL.ush
@@ -32,6 +32,12 @@
 //   #include "/Project/Lib/DetailLib.uslfunc"
 #define SL_IMPORT(...)
 
+// Material Parameter Collection read. Precedes a `floatN <Name>;` declaration; reads a global MPC value
+// (not a per-instance knob). Path is the collection asset; optional Parameter overrides the in-collection name.
+//   SL_COLLECTION(Path = "/Game/MPC/MPC_Weather", Parameter = "WindVector")
+//   float3 WindVector;
+#define SL_COLLECTION(...)
+
 // Library function (`.uslfunc` files only). Precedes a normal HLSL function; it may use UE_ intrinsics,
 // reference the library's own properties, and call other library functions.
 //   SL_FUNCTION()
@@ -39,20 +45,40 @@
 #define SL_FUNCTION(...)
 
 // Pixel/vertex entry points. Precede a `void Name(inout F... X) { ... }` (Vertex takes FShaderLabVertex).
+// Optional material context: to call the UE_Transform* helpers (which need the material `Parameters`), add
+// a leading `FMaterialPixelParameters Parameters` (pixel entries) or `FMaterialVertexParameters Parameters`
+// (SL_VERTEX) BEFORE the output-struct parameter, named literally `Parameters`, e.g.
+//   SL_SURFACE() void Surface(FMaterialPixelParameters Parameters, inout FShaderLabSurface S) { ... }
 #define SL_SURFACE(...)
 #define SL_POSTPROCESS(...)
 #define SL_UI(...)
 #define SL_VERTEX(...)
 
+// Additional Substrate BSDF entries. Each precedes a `void Name(inout F<Bsdf> X) { ... }` whose output struct
+// is the matching FShaderLab<Bsdf> (see ShaderLabCommon.ush). Used either as the sole entry (whole material =
+// that BSDF) or as a named block referenced by SL_FRONTMATERIAL. Composition legality is enforced by the
+// builder (mirroring Substrate's operator allow-lists). SL_VOLUME requires Domain = Volume; SL_LIGHTFUNCTION
+// requires Domain = LightFunction; the rest are Surface-domain BSDFs.
+#define SL_UNLIT(...)          // void Name(inout FShaderLabUnlit U)
+#define SL_HAIR(...)           // void Name(inout FShaderLabHair H)
+#define SL_EYE(...)            // void Name(inout FShaderLabEye E)
+#define SL_WATER(...)          // void Name(inout FShaderLabWater W)
+#define SL_CLEARCOAT(...)      // void Name(inout FShaderLabClearCoat C)
+#define SL_TOON(...)           // void Name(inout FShaderLabToon T)
+#define SL_VOLUME(...)         // void Name(inout FShaderLabVolume V)   — Domain = Volume
+#define SL_LIGHTFUNCTION(...)  // void Name(inout FShaderLabLightFunction L)  — Domain = LightFunction
+
 // Multi-slab building blocks.
-#define SL_SLAB(...)              // precedes `void Name(inout FShaderLabSurface S) { ... }`
-#define SL_VALUE(...)             // precedes `float Name() { return <float>; }`
+#define SL_SLAB(...)              // precedes `void Name([FMaterialPixelParameters Parameters,] inout FShaderLabSurface S) { ... }`
+#define SL_VALUE(...)             // precedes `float Name([FMaterialPixelParameters Parameters]) { return <float>; }`
 #define SL_FRONTMATERIAL(...)     // standalone: SL_FRONTMATERIAL(VerticalLayer(Coat, Metal, Thickness))
 #define SL_OPACITY(...)           // standalone: SL_OPACITY(SomeValueName)
 #define SL_OPACITY_MASK(...)      // standalone: SL_OPACITY_MASK(SomeValueName)
+#define SL_REFRACTION(...)        // standalone: SL_REFRACTION(SomeValueName)  — feeds the material Refraction pin
+#define SL_PIXEL_DEPTH_OFFSET(...)// standalone: SL_PIXEL_DEPTH_OFFSET(SomeValueName) — feeds the material PixelDepthOffset pin
 
-// Vertex Interpolator: precedes `floatN Name() { return <vertex-frequency HLSL>; }` — a value computed
-// per-vertex and interpolated to the pixel shader (backed by a UMaterialExpressionVertexInterpolator).
+// Vertex Interpolator: precedes `floatN Name([FMaterialVertexParameters Parameters]) { return <vertex HLSL>; }`
+// — a value computed per-vertex and interpolated to the pixel shader (backed by a UMaterialExpressionVertexInterpolator).
 // Read it in a pixel body with `UE_Interpolator(Name)`, or use a scalar one as a topology mix factor.
 #define SL_INTERPOLATOR(...)
 
@@ -70,7 +96,10 @@
 //   SL_SETTINGS : Domain, BlendMode, TwoSided, OpacityMaskClipValue, <reflection-allowlist keys...>
 //                 Domain    = Surface | PostProcess | UI | Decal
 //                 BlendMode = Opaque | Masked | Translucent | Additive | Modulate
-//   SL_PROPERTY : DisplayName, Category, SortPriority, Range (Scalar only), DefaultTexture (textures only)
+//   SL_PROPERTY : Category, SortPriority, DefaultTexture (textures only),
+//                 ClampMin / ClampMax (Scalar slider bounds; each independent),
+//                 CustomPrimitiveData = <index> (Scalar/Vector only; per-instance via Custom Primitive Data;
+//                                                mutually exclusive with ClampMin/ClampMax)
 //
 // Topology operators (used inside SL_FRONTMATERIAL):
 //   VerticalLayer(Top, Base, Thickness) | HorizontalMix(Background, Foreground, Mix)
diff --git a/Shaders/Private/ShaderLabUEFunctions.ush b/Shaders/Private/ShaderLabUEFunctions.ush
index 93ee784..74a7e21 100644
--- a/Shaders/Private/ShaderLabUEFunctions.ush
+++ b/Shaders/Private/ShaderLabUEFunctions.ush
@@ -8,5 +8,6 @@
 
 #include "/Plugin/ShaderLab/Private/UEFunctions/Noise.ush"
 #include "/Plugin/ShaderLab/Private/UEFunctions/Rotation.ush"
+#include "/Plugin/ShaderLab/Private/UEFunctions/SceneTexture.ush"
 #include "/Plugin/ShaderLab/Private/UEFunctions/Transform.ush"          // generated (UE_Transform*VectorTo*)
 #include "/Plugin/ShaderLab/Private/UEFunctions/TransformPosition.ush"  // generated (UE_Transform*PositionTo*)
diff --git a/Shaders/Private/UEFunctions/SceneTexture.ush b/Shaders/Private/UEFunctions/SceneTexture.ush
new file mode 100644
index 0000000..1b2a253
--- /dev/null
+++ b/Shaders/Private/UEFunctions/SceneTexture.ush
@@ -0,0 +1,57 @@
+// Copyright UShaderLab. All Rights Reserved.
+//
+// UE_ scene-texture reads — forward to the engine's SceneTextureLookup (MaterialTemplate.ush). Because
+// these take a dynamic UV they are emitted as HLSL helpers (like Noise), NOT wired intrinsics. The graph
+// builder places a hidden UMaterialExpressionSceneTexture node (wired to the ParameterAnchor) whenever a
+// body uses one of these, so the engine sets bNeedsSceneTextures and binds the scene-texture SRVs.
+//
+// Enum scheme B (see Noise.ush): under SHADERLAB_IDE the id is a real HLSL `enum` for completion/semantics;
+// at real compile it degrades to `int` + `#define`s aliasing the engine's PPI_* ids (defined in the material
+// environment), so no magic numbers are hard-coded here.
+//
+// Domain rules (enforced by the builder, mirroring the engine): SceneDepth/CustomDepth/CustomStencil work in
+// a translucent Surface, Decal, or PostProcess material; the full GBuffer / PostProcessInput ids require the
+// PostProcess (or Decal) domain. (Scene-color-behind-translucency uses a different engine path and is not
+// exposed here yet — read it as PostProcessInput0 in a PostProcess material instead.)
+
+#pragma once
+
+#ifdef SHADERLAB_IDE
+	enum ESLSceneTexture
+	{
+		SL_ST_SceneColor,
+		SL_ST_SceneDepth,
+		SL_ST_CustomDepth,
+		SL_ST_CustomStencil,
+		SL_ST_WorldNormal,
+		SL_ST_PostProcessInput0,
+		SL_ST_PostProcessInput1,
+		SL_ST_PostProcessInput2,
+		SL_ST_PostProcessInput3,
+		SL_ST_PostProcessInput4,
+	};
+	float4 SceneTextureLookup(float2 UV, int SceneTextureIndex, bool bFiltered) { return (float4)0; }
+#else
+	#define ESLSceneTexture int
+	#define SL_ST_SceneColor         PPI_SceneColor
+	#define SL_ST_SceneDepth         PPI_SceneDepth
+	#define SL_ST_CustomDepth        PPI_CustomDepth
+	#define SL_ST_CustomStencil      PPI_CustomStencil
+	#define SL_ST_WorldNormal        PPI_WorldNormal
+	#define SL_ST_PostProcessInput0  PPI_PostProcessInput0
+	#define SL_ST_PostProcessInput1  PPI_PostProcessInput1
+	#define SL_ST_PostProcessInput2  PPI_PostProcessInput2
+	#define SL_ST_PostProcessInput3  PPI_PostProcessInput3
+	#define SL_ST_PostProcessInput4  PPI_PostProcessInput4
+#endif
+
+// Full-control lookup: read any scene-texture id at UV (id is an ESLSceneTexture token).
+float4 UE_SceneTexture(ESLSceneTexture Id, float2 UV)
+{
+	return SceneTextureLookup(UV, Id, false);
+}
+
+// Convenience wrappers for the common reads.
+float  UE_SceneDepth(float2 UV)    { return SceneTextureLookup(UV, SL_ST_SceneDepth, false).r; }
+float  UE_CustomDepth(float2 UV)   { return SceneTextureLookup(UV, SL_ST_CustomDepth, false).r; }
+float  UE_CustomStencil(float2 UV) { return SceneTextureLookup(UV, SL_ST_CustomStencil, false).r; }
diff --git a/Source/UShaderLab/Private/ShaderLabModel.cpp b/Source/UShaderLab/Private/ShaderLabModel.cpp
index 6c40fc8..93d8f4c 100644
--- a/Source/UShaderLab/Private/ShaderLabModel.cpp
+++ b/Source/UShaderLab/Private/ShaderLabModel.cpp
@@ -2,6 +2,8 @@
 
 #include "ShaderLabModel.h"
 
+#include "Templates/Function.h"
+
 const FShaderLabProperty* FShaderLabModel::FindProperty(FName InName) const
 {
 	return Properties.FindByPredicate([InName](const FShaderLabProperty& P) { return P.Name == InName; });
@@ -22,3 +24,114 @@ bool FShaderLabModel::HasStaticSwitches() const
 	return Properties.ContainsByPredicate(
 		[](const FShaderLabProperty& P) { return P.Type == EShaderLabPropertyType::StaticBool; });
 }
+
+namespace
+{
+	// One-hot flag per BSDF type; a subtree's flowing-type set is the OR of its leaves.
+	uint32 BsdfTypeFlag(EShaderLabBsdfType T) { return 1u << static_cast<uint32>(T); }
+
+	const TCHAR* BsdfTypeName(EShaderLabBsdfType T)
+	{
+		switch (T)
+		{
+		case EShaderLabBsdfType::Slab: return TEXT("Slab");
+		case EShaderLabBsdfType::Unlit: return TEXT("Unlit");
+		case EShaderLabBsdfType::Hair: return TEXT("Hair");
+		case EShaderLabBsdfType::Eye: return TEXT("Eye");
+		case EShaderLabBsdfType::Water: return TEXT("Water");
+		case EShaderLabBsdfType::Volume: return TEXT("Volume");
+		case EShaderLabBsdfType::ClearCoat: return TEXT("ClearCoat");
+		case EShaderLabBsdfType::Toon: return TEXT("Toon");
+		case EShaderLabBsdfType::LightFunction: return TEXT("LightFunction");
+		default: return TEXT("?");
+		}
+	}
+
+	const TCHAR* OpName(EShaderLabOp Op)
+	{
+		switch (Op)
+		{
+		case EShaderLabOp::VerticalLayer: return TEXT("VerticalLayer");
+		case EShaderLabOp::HorizontalMix: return TEXT("HorizontalMix");
+		case EShaderLabOp::Add: return TEXT("Add");
+		case EShaderLabOp::Weight: return TEXT("Weight");
+		case EShaderLabOp::Select: return TEXT("Select");
+		default: return TEXT("SlabRef");
+		}
+	}
+
+	// Allowed flowing-type mask per operator (mirrors SubstrateTranslatorCommon.cpp allow-lists).
+	uint32 AllowedMask(EShaderLabOp Op)
+	{
+		const uint32 Slab = BsdfTypeFlag(EShaderLabBsdfType::Slab);
+		const uint32 Unlit = BsdfTypeFlag(EShaderLabBsdfType::Unlit);
+		const uint32 Toon = BsdfTypeFlag(EShaderLabBsdfType::Toon);
+		const uint32 Hair = BsdfTypeFlag(EShaderLabBsdfType::Hair);
+		const uint32 Eye = BsdfTypeFlag(EShaderLabBsdfType::Eye);
+		switch (Op)
+		{
+		case EShaderLabOp::VerticalLayer:
+		case EShaderLabOp::HorizontalMix:
+		case EShaderLabOp::Add:      return Slab;
+		case EShaderLabOp::Weight:   return Unlit | Slab | Toon;
+		case EShaderLabOp::Select:   return Slab | Hair | Eye | Toon;
+		default:                     return 0xFFFFFFFFu; // SlabRef: leaf, unconstrained here
+		}
+	}
+}
+
+bool FShaderLabModel::ValidateTopology(TArray<FString>& OutErrors) const
+{
+	if (TopologyRoot == INDEX_NONE || Topology.Num() == 0)
+	{
+		return true; // Single-Surface sugar / non-Substrate entries: nothing to validate.
+	}
+
+	auto SlabTypeByName = [this](FName SlabName, EShaderLabBsdfType& OutType) -> bool
+	{
+		for (const FShaderLabSlab& S : Slabs)
+		{
+			if (S.Name == SlabName) { OutType = S.BsdfType; return true; }
+		}
+		return false;
+	};
+
+	bool bOk = true;
+	// Recursively compute a subtree's flowing-type mask and validate each operator against its allow-list.
+	TFunction<uint32(int32)> Visit = [&](int32 Index) -> uint32
+	{
+		if (!Topology.IsValidIndex(Index)) { return 0; }
+		const FShaderLabTopoNode& Node = Topology[Index];
+		if (Node.Op == EShaderLabOp::SlabRef)
+		{
+			EShaderLabBsdfType T;
+			return SlabTypeByName(Node.SlabRef, T) ? BsdfTypeFlag(T) : 0;
+		}
+		uint32 Mask = 0;
+		if (Node.ChildA != INDEX_NONE) { Mask |= Visit(Node.ChildA); }
+		if (Node.ChildB != INDEX_NONE) { Mask |= Visit(Node.ChildB); }
+
+		const uint32 Allowed = AllowedMask(Node.Op);
+		const uint32 Illegal = Mask & ~Allowed;
+		if (Illegal != 0)
+		{
+			// List the offending flowing types.
+			FString Types;
+			for (uint32 i = 0; i <= static_cast<uint32>(EShaderLabBsdfType::LightFunction); ++i)
+			{
+				if (Illegal & (1u << i))
+				{
+					if (!Types.IsEmpty()) { Types += TEXT(", "); }
+					Types += BsdfTypeName(static_cast<EShaderLabBsdfType>(i));
+				}
+			}
+			OutErrors.Add(FString::Printf(
+				TEXT("%s(%d): Substrate error: operator '%s' cannot combine BSDF type(s) {%s} (only Slab layers/mixes/adds; Weight allows Unlit/Slab/Toon; Select allows Slab/Hair/Eye/Toon)."),
+				*SourceFilePath, Node.SourceLine, OpName(Node.Op), *Types));
+			bOk = false;
+		}
+		return Mask;
+	};
+	Visit(TopologyRoot);
+	return bOk;
+}
diff --git a/Source/UShaderLab/Private/ShaderLabParser.cpp b/Source/UShaderLab/Private/ShaderLabParser.cpp
index 74db248..6c3fd89 100644
--- a/Source/UShaderLab/Private/ShaderLabParser.cpp
+++ b/Source/UShaderLab/Private/ShaderLabParser.cpp
@@ -384,6 +384,8 @@ namespace ShaderLabParser_Private
 		if (Token == TEXT("PostProcess")) { Out = EShaderLabDomain::PostProcess; return true; }
 		if (Token == TEXT("UI")) { Out = EShaderLabDomain::UI; return true; }
 		if (Token == TEXT("Decal")) { Out = EShaderLabDomain::Decal; return true; }
+		if (Token == TEXT("Volume")) { Out = EShaderLabDomain::Volume; return true; }
+		if (Token == TEXT("LightFunction")) { Out = EShaderLabDomain::LightFunction; return true; }
 		return false;
 	}
 
@@ -394,6 +396,8 @@ namespace ShaderLabParser_Private
 		if (Token == TEXT("Translucent")) { Out = EShaderLabBlendMode::Translucent; return true; }
 		if (Token == TEXT("Additive")) { Out = EShaderLabBlendMode::Additive; return true; }
 		if (Token == TEXT("Modulate")) { Out = EShaderLabBlendMode::Modulate; return true; }
+		if (Token == TEXT("AlphaComposite")) { Out = EShaderLabBlendMode::AlphaComposite; return true; }
+		if (Token == TEXT("AlphaHoldout")) { Out = EShaderLabBlendMode::AlphaHoldout; return true; }
 		return false;
 	}
 
@@ -404,6 +408,23 @@ namespace ShaderLabParser_Private
 		return false;
 	}
 
+	/** True if Token is a non-empty run of ASCII digits (a non-negative integer literal). */
+	static bool IsNonNegativeInteger(const FString& Token)
+	{
+		if (Token.IsEmpty())
+		{
+			return false;
+		}
+		for (const TCHAR C : Token)
+		{
+			if (!FChar::IsDigit(C))
+			{
+				return false;
+			}
+		}
+		return true;
+	}
+
 	/** Map an HLSL declaration type token to a DSL property type. */
 	static bool InferPropertyType(const FString& HlslType, EShaderLabPropertyType& Out)
 	{
@@ -412,6 +433,9 @@ namespace ShaderLabParser_Private
 		if (HlslType == TEXT("float4")) { Out = EShaderLabPropertyType::Vector; return true; }
 		if (HlslType == TEXT("Texture2D")) { Out = EShaderLabPropertyType::Texture2D; return true; }
 		if (HlslType == TEXT("TextureCube")) { Out = EShaderLabPropertyType::TextureCube; return true; }
+		if (HlslType == TEXT("Texture2DArray")) { Out = EShaderLabPropertyType::Texture2DArray; return true; }
+		if (HlslType == TEXT("Texture3D")) { Out = EShaderLabPropertyType::Texture3D; return true; }
+		if (HlslType == TEXT("TextureCubeArray")) { Out = EShaderLabPropertyType::TextureCubeArray; return true; }
 		return false;
 	}
 
@@ -514,6 +538,96 @@ namespace
 		return true;
 	}
 
+	/** True if `Body` references `Ident` as a whole identifier token (not as a substring of a longer word). */
+	bool BodyReferencesIdentifier(const FString& Body, const TCHAR* Ident)
+	{
+		const FString Needle(Ident);
+		const int32 NeedleLen = Needle.Len();
+		auto IsIdentChar = [](TCHAR C) { return FChar::IsAlnum(C) || C == TEXT('_'); };
+		int32 From = 0;
+		for (;;)
+		{
+			const int32 At = Body.Find(Needle, ESearchCase::CaseSensitive, ESearchDir::FromStart, From);
+			if (At == INDEX_NONE)
+			{
+				return false;
+			}
+			const bool bLeftOk = (At == 0) || !IsIdentChar(Body[At - 1]);
+			const int32 EndIdx = At + NeedleLen;
+			const bool bRightOk = (EndIdx >= Body.Len()) || !IsIdentChar(Body[EndIdx]);
+			if (bLeftOk && bRightOk)
+			{
+				return true;
+			}
+			From = At + 1;
+		}
+	}
+
+	/**
+	 * Validate the optional material `Parameters` context parameter on a body-bearing construct, and check
+	 * the body's use of it. Contract:
+	 *   - When bRequireStruct, the output-struct parameter (its type starts with "FShaderLab") must be the
+	 *     LAST parameter, so the graph builder's `Last()` selects it as the output struct.
+	 *   - Any non-struct parameter must be a single `Parameters` of type `ParamsType` (the frequency-correct
+	 *     FMaterial{Pixel,Vertex}Parameters), named literally `Parameters` — matching the ambient variable UE
+	 *     injects into the generated Custom node (its declared signature is dropped at real compile).
+	 *   - If the body references the `Parameters` identifier it MUST be declared, so the IDE (which sees the
+	 *     declaration) and the real compile (which uses the ambient `Parameters`) agree.
+	 * Reports the first violation at (ErrLine, ErrCol) and returns false.
+	 */
+	bool ValidateBodyParameters(FScanner& S, const TArray<FShaderLabEntryParam>& Params, const FString& Body,
+		const TCHAR* ParamsType, bool bRequireStruct, const TCHAR* What, int32 ErrLine, int32 ErrCol)
+	{
+		bool bHasParameters = false;
+		for (int32 i = 0; i < Params.Num(); ++i)
+		{
+			const FShaderLabEntryParam& P = Params[i];
+			const bool bIsStruct = P.Type.StartsWith(TEXT("FShaderLab"));
+			if (bIsStruct)
+			{
+				if (!bRequireStruct)
+				{
+					S.Error(FString::Printf(TEXT("%s takes no output-struct parameter"), What), ErrLine, ErrCol);
+					return false;
+				}
+				if (i != Params.Num() - 1)
+				{
+					S.Error(FString::Printf(TEXT("%s: the output-struct parameter must be the last parameter (put `Parameters` before it)"), What), ErrLine, ErrCol);
+					return false;
+				}
+				continue;
+			}
+			// A non-struct parameter is only allowed as the optional material context.
+			if (P.Name != TEXT("Parameters"))
+			{
+				S.Error(FString::Printf(TEXT("%s: unexpected parameter '%s' (only an optional `Parameters` context parameter is allowed)"), What, *P.Name), ErrLine, ErrCol);
+				return false;
+			}
+			if (P.Type != ParamsType)
+			{
+				S.Error(FString::Printf(TEXT("%s: `Parameters` must be of type %s here"), What, ParamsType), ErrLine, ErrCol);
+				return false;
+			}
+			if (bHasParameters)
+			{
+				S.Error(FString::Printf(TEXT("%s: duplicate `Parameters` parameter"), What), ErrLine, ErrCol);
+				return false;
+			}
+			bHasParameters = true;
+		}
+		if (bRequireStruct && (Params.Num() == 0 || !Params.Last().Type.StartsWith(TEXT("FShaderLab"))))
+		{
+			S.Error(FString::Printf(TEXT("%s must take an (inout FShaderLab...) output parameter as its last parameter"), What), ErrLine, ErrCol);
+			return false;
+		}
+		if (!bHasParameters && BodyReferencesIdentifier(Body, TEXT("Parameters")))
+		{
+			S.Error(FString::Printf(TEXT("%s uses `Parameters` but does not declare it; add a `%s Parameters` parameter to the signature"), What, ParamsType), ErrLine, ErrCol);
+			return false;
+		}
+		return true;
+	}
+
 	void ParseSettings(FScanner& S, FShaderLabModel& Model)
 	{
 		FShaderLabSettings& Out = Model.Settings;
@@ -589,11 +703,7 @@ namespace
 		Key = Key.TrimStartAndEnd();
 		Value = Value.TrimStartAndEnd();
 
-		if (Key == TEXT("DisplayName"))
-		{
-			Prop.DisplayName = Value.TrimQuotes();
-		}
-		else if (Key == TEXT("Category"))
+		if (Key == TEXT("Category"))
 		{
 			Prop.Group = Value.TrimQuotes();
 		}
@@ -605,24 +715,28 @@ namespace
 		{
 			Prop.TextureDefault = Value.TrimQuotes();
 		}
-		else if (Key == TEXT("Range"))
+		else if (Key == TEXT("ClampMin"))
 		{
-			// Trim exactly the one wrapping (...) then split — preserves paren-awareness of the interior.
-			if (!Value.StartsWith(TEXT("(")) || !Value.EndsWith(TEXT(")")))
+			// UE UPROPERTY-style slider lower bound (maps to ScalarParameter SliderMin).
+			Prop.bHasClampMin = true;
+			Prop.ClampMin = FCString::Atof(*Value);
+		}
+		else if (Key == TEXT("ClampMax"))
+		{
+			// UE UPROPERTY-style slider upper bound (maps to ScalarParameter SliderMax).
+			Prop.bHasClampMax = true;
+			Prop.ClampMax = FCString::Atof(*Value);
+		}
+		else if (Key == TEXT("CustomPrimitiveData"))
+		{
+			// Value is the mandatory, author-specified float slot index (no auto-assignment).
+			if (!IsNonNegativeInteger(Value))
 			{
-				S.Error(FString::Printf(TEXT("Property '%s' Range expects (min,max)"), *Prop.Name.ToString()), ErrLine, ErrCol);
+				S.Error(FString::Printf(TEXT("Property '%s' CustomPrimitiveData expects a non-negative integer index"), *Prop.Name.ToString()), ErrLine, ErrCol);
 				return;
 			}
-			const FString Inner = Value.Mid(1, Value.Len() - 2);
-			const TArray<FString> Comps = SplitTopLevel(Inner, TEXT(','));
-			if (Comps.Num() != 2)
-			{
-				S.Error(FString::Printf(TEXT("Property '%s' Range expects (min,max)"), *Prop.Name.ToString()), ErrLine, ErrCol);
-				return;
-			}
-			Prop.bHasRange = true;
-			Prop.RangeMin = FCString::Atof(*Comps[0]);
-			Prop.RangeMax = FCString::Atof(*Comps[1]);
+			Prop.bUseCustomPrimitiveData = true;
+			Prop.PrimitiveDataIndex = FCString::Atoi(*Value);
 		}
 		else
 		{
@@ -697,7 +811,7 @@ namespace
 			}
 			if (!InferPropertyType(TypeTok, Prop.Type))
 			{
-				S.Error(FString::Printf(TEXT("Unsupported property type '%s' (use float/float3/float4/Texture2D/TextureCube or `#define` for StaticBool)"), *TypeTok));
+				S.Error(FString::Printf(TEXT("Unsupported property type '%s' (use float/float3/float4/Texture2D/TextureCube/Texture2DArray/Texture3D/TextureCubeArray or `#define` for StaticBool)"), *TypeTok));
 				return;
 			}
 			FString Name;
@@ -710,7 +824,7 @@ namespace
 			NameCol = S.Column;
 			Prop.Name = FName(*Name);
 
-			const bool bIsTexture = (Prop.Type == EShaderLabPropertyType::Texture2D || Prop.Type == EShaderLabPropertyType::TextureCube);
+			const bool bIsTexture = ShaderLabIsTextureType(Prop.Type);
 			if (bIsTexture)
 			{
 				// `Texture2D Name;` (no initializer) optionally followed by `SamplerState NameSampler;`.
@@ -774,9 +888,20 @@ namespace
 				return;
 			}
 		}
-		if (Prop.DisplayName.IsEmpty())
+		// CustomPrimitiveData contract: only Scalar/Vector support it in UE, and it is mutually exclusive
+		// with the slider clamps (the MIC editor disables the slider under bUseCustomPrimitiveData).
+		if (Prop.bUseCustomPrimitiveData)
 		{
-			Prop.DisplayName = Prop.Name.ToString();
+			if (Prop.Type != EShaderLabPropertyType::Scalar && Prop.Type != EShaderLabPropertyType::Vector)
+			{
+				S.Error(FString::Printf(TEXT("Property '%s': CustomPrimitiveData is only valid on Scalar (float) or Vector (float4) properties"), *Prop.Name.ToString()), NameLine, NameCol);
+				return;
+			}
+			if (Prop.bHasClampMin || Prop.bHasClampMax)
+			{
+				S.Error(FString::Printf(TEXT("Property '%s': ClampMin/ClampMax cannot be combined with CustomPrimitiveData"), *Prop.Name.ToString()), NameLine, NameCol);
+				return;
+			}
 		}
 		if (Model.FindProperty(Prop.Name) != nullptr)
 		{
@@ -912,14 +1037,139 @@ namespace
 		Model.Functions.Add(MoveTemp(Fn));
 	}
 
-	void ParseEntry(FScanner& S, FShaderLabModel& Model, const FString& Marker)
+	/**
+	 * Parse BSDF node modifiers from an SL_SURFACE/SL_SLAB(...) specifier list. Empty list is fine. Each modifier
+	 * is validated for applicability to BsdfType (contract-style: a modifier the target BSDF can't consume is a
+	 * hard error, not a silent no-op): SubsurfaceProfile -> Slab/Eye; SpecularProfile/SubSurfaceType -> Slab;
+	 * ToonProfile -> Toon.
+	 */
+	bool ParseBsdfModifiers(FScanner& S, const FString& Inner, EShaderLabBsdfType BsdfType, FShaderLabBsdfModifiers& Out, const TCHAR* What)
 	{
-		// Marker macro takes no args: SL_SURFACE()/SL_POSTPROCESS()/SL_UI()/SL_VERTEX().
-		FString Ignored;
-		if (!S.ReadBalanced(TEXT('('), TEXT(')'), Ignored))
+		const bool bIsSlab = (BsdfType == EShaderLabBsdfType::Slab);
+		const bool bIsEye = (BsdfType == EShaderLabBsdfType::Eye);
+		const bool bIsToon = (BsdfType == EShaderLabBsdfType::Toon);
+		for (const FString& StmtRaw : SplitTopLevel(Inner, TEXT(',')))
+		{
+			const FString Stmt = StmtRaw.TrimStartAndEnd();
+			if (Stmt.IsEmpty()) { continue; }
+			FString Key, Value;
+			if (!Stmt.Split(TEXT("="), &Key, &Value))
+			{
+				S.Error(FString::Printf(TEXT("%s has malformed specifier '%s' (expected Key = Value)"), What, *Stmt));
+				return false;
+			}
+			Key = Key.TrimStartAndEnd();
+			Value = Value.TrimStartAndEnd().TrimQuotes();
+			if (Key == TEXT("SubsurfaceProfile"))
+			{
+				if (!bIsSlab && !bIsEye) { S.Error(FString::Printf(TEXT("%s: SubsurfaceProfile only applies to SL_SURFACE/SL_SLAB or SL_EYE"), What)); return false; }
+				Out.SubsurfaceProfilePath = Value;
+			}
+			else if (Key == TEXT("SpecularProfile"))
+			{
+				if (!bIsSlab) { S.Error(FString::Printf(TEXT("%s: SpecularProfile only applies to SL_SURFACE/SL_SLAB"), What)); return false; }
+				Out.SpecularProfilePath = Value;
+			}
+			else if (Key == TEXT("SubSurfaceType"))
+			{
+				if (!bIsSlab) { S.Error(FString::Printf(TEXT("%s: SubSurfaceType only applies to SL_SURFACE/SL_SLAB"), What)); return false; }
+				Out.SubSurfaceType = Value;
+			}
+			else if (Key == TEXT("ToonProfile"))
+			{
+				if (!bIsToon) { S.Error(FString::Printf(TEXT("%s: ToonProfile only applies to SL_TOON"), What)); return false; }
+				Out.ToonProfilePath = Value;
+			}
+			else { S.Error(FString::Printf(TEXT("%s has unknown specifier '%s' (use SubsurfaceProfile/SpecularProfile/ToonProfile/SubSurfaceType)"), What, *Key)); return false; }
+		}
+		return true;
+	}
+
+	/** SL_COLLECTION(Path="...", [Parameter="..."]) floatN <Name>; — a Material Parameter Collection read. */
+	void ParseCollection(FScanner& S, FShaderLabModel& Model)
+	{
+		FString Inner;
+		if (!S.ReadBalanced(TEXT('('), TEXT(')'), Inner))
 		{
 			return;
 		}
+		FShaderLabCollectionParam C;
+		for (const FString& StmtRaw : SplitTopLevel(Inner, TEXT(',')))
+		{
+			const FString Stmt = StmtRaw.TrimStartAndEnd();
+			if (Stmt.IsEmpty()) { continue; }
+			FString Key, Value;
+			if (!Stmt.Split(TEXT("="), &Key, &Value))
+			{
+				S.Error(FString::Printf(TEXT("Malformed SL_COLLECTION specifier '%s' (expected Key = Value)"), *Stmt));
+				return;
+			}
+			Key = Key.TrimStartAndEnd();
+			Value = Value.TrimStartAndEnd().TrimQuotes();
+			if (Key == TEXT("Path")) { C.CollectionPath = Value; }
+			else if (Key == TEXT("Parameter")) { C.ParameterName = FName(*Value); }
+			else { S.Error(FString::Printf(TEXT("SL_COLLECTION has unknown specifier '%s' (use Path / Parameter)"), *Key)); return; }
+		}
+		S.SkipTrivia();
+		const int32 DeclLine = S.Line, DeclCol = S.Column;
+		FString TypeTok;
+		if (!S.ReadIdentifier(TypeTok))
+		{
+			S.Error(TEXT("SL_COLLECTION must be followed by a `float/float3/float4 <Name>;` declaration"), DeclLine, DeclCol);
+			return;
+		}
+		if (!InferPropertyType(TypeTok, C.Type)
+			|| !(C.Type == EShaderLabPropertyType::Scalar || C.Type == EShaderLabPropertyType::Color || C.Type == EShaderLabPropertyType::Vector))
+		{
+			S.Error(FString::Printf(TEXT("SL_COLLECTION type must be float/float3/float4, got '%s'"), *TypeTok), DeclLine, DeclCol);
+			return;
+		}
+		FString Name;
+		if (!S.ReadIdentifier(Name))
+		{
+			S.Error(TEXT("SL_COLLECTION declaration is missing a name"), DeclLine, DeclCol);
+			return;
+		}
+		if (!S.Expect(TEXT(';'), TEXT("after an SL_COLLECTION declaration")))
+		{
+			return;
+		}
+		if (C.CollectionPath.IsEmpty())
+		{
+			S.Error(FString::Printf(TEXT("SL_COLLECTION '%s' requires Path = \"/Game/...\""), *Name), DeclLine, DeclCol);
+			return;
+		}
+		C.Name = FName(*Name);
+		C.Line = DeclLine;
+		if (C.ParameterName.IsNone()) { C.ParameterName = C.Name; }
+		if (Model.Collections.ContainsByPredicate([&C](const FShaderLabCollectionParam& E) { return E.Name == C.Name; }))
+		{
+			S.Error(FString::Printf(TEXT("Duplicate SL_COLLECTION name '%s'"), *Name), DeclLine, DeclCol);
+			return;
+		}
+		Model.Collections.Add(MoveTemp(C));
+	}
+
+	void ParseEntry(FScanner& S, FShaderLabModel& Model, const FString& Marker)
+	{
+		// SL_SURFACE(...) accepts BSDF modifier specifiers; the other entries take no args.
+		FString SpecInner;
+		if (!S.ReadBalanced(TEXT('('), TEXT(')'), SpecInner))
+		{
+			return;
+		}
+		if (Marker != TEXT("SL_SURFACE") && !SpecInner.TrimStartAndEnd().IsEmpty())
+		{
+			S.Error(FString::Printf(TEXT("%s takes no specifiers (only SL_SURFACE/SL_SLAB accept BSDF modifiers)"), *Marker));
+			return;
+		}
+		FShaderLabBsdfModifiers EntryMods;
+		if (Marker == TEXT("SL_SURFACE") && !ParseBsdfModifiers(S, SpecInner, EShaderLabBsdfType::Slab, EntryMods, *Marker))
+		{
+			return;
+		}
+		S.SkipTrivia();
+		const int32 DeclLine = S.Line, DeclCol = S.Column;
 		FString Name, SigInner, Body;
 		int32 BodyLine = 0;
 		if (!ParseAnnotatedFunction(S, Name, SigInner, Body, BodyLine))
@@ -933,6 +1183,15 @@ namespace
 			return;
 		}
 
+		// Vertex/Interpolator run at vertex frequency; Surface/PostProcess/UI at pixel frequency. An optional
+		// explicit `Parameters` context parameter must match that frequency (see ValidateBodyParameters).
+		const bool bVertexEntry = (Marker == TEXT("SL_VERTEX"));
+		const TCHAR* ParamsType = bVertexEntry ? TEXT("FMaterialVertexParameters") : TEXT("FMaterialPixelParameters");
+		if (!ValidateBodyParameters(S, Params, Body, ParamsType, /*bRequireStruct*/ true, *Marker, DeclLine, DeclCol))
+		{
+			return;
+		}
+
 		if (Marker == TEXT("SL_VERTEX"))
 		{
 			Model.VertexParams = MoveTemp(Params);
@@ -954,12 +1213,26 @@ namespace
 		Model.SurfaceEntry = (Marker == TEXT("SL_POSTPROCESS")) ? EShaderLabEntry::PostProcess
 			: (Marker == TEXT("SL_UI")) ? EShaderLabEntry::UI
 			: EShaderLabEntry::Surface;
+		if (Model.SurfaceEntry == EShaderLabEntry::Surface)
+		{
+			Model.SurfaceModifiers = MoveTemp(EntryMods);
+		}
 	}
 
-	void ParseSlab(FScanner& S, FShaderLabModel& Model)
+	/**
+	 * Parse a named BSDF block: `SL_SLAB()`/`SL_HAIR()`/... `void <Name>(inout F<Bsdf> X){...}`. BsdfType comes
+	 * from the marker; ExpectedStruct is the required output-struct type name (e.g. "FShaderLabHair"). Blocks go
+	 * into Model.Slabs; a single dedicated (non-Slab) block with no SL_FRONTMATERIAL is auto-rooted at end-of-parse.
+	 */
+	void ParseBsdfBlock(FScanner& S, FShaderLabModel& Model, EShaderLabBsdfType BsdfType, const TCHAR* Marker, const TCHAR* ExpectedStruct)
 	{
-		FString Ignored;
-		if (!S.ReadBalanced(TEXT('('), TEXT(')'), Ignored)) // SL_SLAB()
+		FString SpecInner;
+		if (!S.ReadBalanced(TEXT('('), TEXT(')'), SpecInner)) // marker(...)
+		{
+			return;
+		}
+		FShaderLabBsdfModifiers BlockMods;
+		if (!ParseBsdfModifiers(S, SpecInner, BsdfType, BlockMods, Marker))
 		{
 			return;
 		}
@@ -974,7 +1247,17 @@ namespace
 		TArray<FShaderLabEntryParam> Params;
 		if (!ParseEntryParams(SigInner, Params) || Params.Num() < 1)
 		{
-			S.Error(FString::Printf(TEXT("Slab '%s' must take an (inout FShaderLabSurface) parameter"), *Name), DeclLine, DeclCol);
+			S.Error(FString::Printf(TEXT("%s '%s' must take an (inout %s) parameter"), Marker, *Name, ExpectedStruct), DeclLine, DeclCol);
+			return;
+		}
+		if (!ValidateBodyParameters(S, Params, Body, TEXT("FMaterialPixelParameters"), /*bRequireStruct*/ true,
+			*FString::Printf(TEXT("%s '%s'"), Marker, *Name), DeclLine, DeclCol))
+		{
+			return;
+		}
+		if (Params.Last().Type != ExpectedStruct)
+		{
+			S.Error(FString::Printf(TEXT("%s '%s' must take an (inout %s), got '%s'"), Marker, *Name, ExpectedStruct, *Params.Last().Type), DeclLine, DeclCol);
 			return;
 		}
 		const FName SlabName(*Name);
@@ -985,9 +1268,11 @@ namespace
 		}
 		FShaderLabSlab Slab;
 		Slab.Name = SlabName;
+		Slab.BsdfType = BsdfType;
 		Slab.OutParamName = Params.Last().Name;
 		Slab.Body = MoveTemp(Body);
 		Slab.BodyLine = BodyLine;
+		Slab.Modifiers = MoveTemp(BlockMods);
 		Model.Slabs.Add(MoveTemp(Slab));
 	}
 
@@ -1006,6 +1291,17 @@ namespace
 		{
 			return;
 		}
+		TArray<FShaderLabEntryParam> Params;
+		if (!ParseEntryParams(SigInner, Params))
+		{
+			S.Error(FString::Printf(TEXT("Value '%s' has a malformed parameter signature"), *Name), DeclLine, DeclCol);
+			return;
+		}
+		if (!ValidateBodyParameters(S, Params, Body, TEXT("FMaterialPixelParameters"), /*bRequireStruct*/ false,
+			*FString::Printf(TEXT("Value '%s'"), *Name), DeclLine, DeclCol))
+		{
+			return;
+		}
 		const FName ValueName(*Name);
 		if (Model.Values.ContainsByPredicate([&ValueName](const FShaderLabValue& E) { return E.Name == ValueName; }))
 		{
@@ -1066,6 +1362,17 @@ namespace
 		{
 			return;
 		}
+		TArray<FShaderLabEntryParam> Params;
+		if (!ParseEntryParams(SigInner, Params))
+		{
+			S.Error(FString::Printf(TEXT("Interpolator '%s' has a malformed parameter signature"), *Name), DeclLine, DeclCol);
+			return;
+		}
+		if (!ValidateBodyParameters(S, Params, Body, TEXT("FMaterialVertexParameters"), /*bRequireStruct*/ false,
+			*FString::Printf(TEXT("Interpolator '%s'"), *Name), DeclLine, DeclCol))
+		{
+			return;
+		}
 		const FName IName(*Name);
 		if (Model.Interpolators.ContainsByPredicate([&IName](const FShaderLabInterpolator& E) { return E.Name == IName; }))
 		{
@@ -1221,6 +1528,8 @@ namespace
 	/** Recursively parse a FrontMaterial topology expression; returns the node index (INDEX_NONE on error). */
 	int32 ParseTopoExpr(FScanner& S, FShaderLabModel& Model)
 	{
+		S.SkipTrivia();
+		const int32 NodeLine = S.Line; // source line of this operator/leaf token, for composition-error mapping
 		FString Name;
 		if (!S.ReadIdentifier(Name))
 		{
@@ -1234,6 +1543,7 @@ namespace
 			FShaderLabTopoNode Leaf;
 			Leaf.Op = EShaderLabOp::SlabRef;
 			Leaf.SlabRef = FName(*Name);
+			Leaf.SourceLine = NodeLine;
 			return Model.Topology.Add(Leaf);
 		}
 
@@ -1257,6 +1567,7 @@ namespace
 		}
 		FShaderLabTopoNode Node;
 		Node.Op = Op;
+		Node.SourceLine = NodeLine;
 		Node.ChildA = ParseTopoExpr(S, Model);
 		if (S.bFailed) { return INDEX_NONE; }
 		if (NumExprChildren >= 2)
@@ -1433,6 +1744,11 @@ bool FShaderLabParser::Parse(
 		{
 			ParseProperty(S, OutModel);
 		}
+		else if (Token == TEXT("SL_COLLECTION"))
+		{
+			if (RejectInLibrary(TEXT("SL_COLLECTION"))) { return false; }
+			ParseCollection(S, OutModel);
+		}
 		else if (Token == TEXT("SL_SURFACE") || Token == TEXT("SL_POSTPROCESS") || Token == TEXT("SL_UI") || Token == TEXT("SL_VERTEX"))
 		{
 			if (RejectInLibrary(TEXT("A pixel/vertex entry"))) { return false; }
@@ -1441,7 +1757,47 @@ bool FShaderLabParser::Parse(
 		else if (Token == TEXT("SL_SLAB"))
 		{
 			if (RejectInLibrary(TEXT("SL_SLAB"))) { return false; }
-			ParseSlab(S, OutModel);
+			ParseBsdfBlock(S, OutModel, EShaderLabBsdfType::Slab, TEXT("SL_SLAB"), TEXT("FShaderLabSurface"));
+		}
+		else if (Token == TEXT("SL_UNLIT"))
+		{
+			if (RejectInLibrary(TEXT("SL_UNLIT"))) { return false; }
+			ParseBsdfBlock(S, OutModel, EShaderLabBsdfType::Unlit, TEXT("SL_UNLIT"), TEXT("FShaderLabUnlit"));
+		}
+		else if (Token == TEXT("SL_HAIR"))
+		{
+			if (RejectInLibrary(TEXT("SL_HAIR"))) { return false; }
+			ParseBsdfBlock(S, OutModel, EShaderLabBsdfType::Hair, TEXT("SL_HAIR"), TEXT("FShaderLabHair"));
+		}
+		else if (Token == TEXT("SL_EYE"))
+		{
+			if (RejectInLibrary(TEXT("SL_EYE"))) { return false; }
+			ParseBsdfBlock(S, OutModel, EShaderLabBsdfType::Eye, TEXT("SL_EYE"), TEXT("FShaderLabEye"));
+		}
+		else if (Token == TEXT("SL_WATER"))
+		{
+			if (RejectInLibrary(TEXT("SL_WATER"))) { return false; }
+			ParseBsdfBlock(S, OutModel, EShaderLabBsdfType::Water, TEXT("SL_WATER"), TEXT("FShaderLabWater"));
+		}
+		else if (Token == TEXT("SL_CLEARCOAT"))
+		{
+			if (RejectInLibrary(TEXT("SL_CLEARCOAT"))) { return false; }
+			ParseBsdfBlock(S, OutModel, EShaderLabBsdfType::ClearCoat, TEXT("SL_CLEARCOAT"), TEXT("FShaderLabClearCoat"));
+		}
+		else if (Token == TEXT("SL_TOON"))
+		{
+			if (RejectInLibrary(TEXT("SL_TOON"))) { return false; }
+			ParseBsdfBlock(S, OutModel, EShaderLabBsdfType::Toon, TEXT("SL_TOON"), TEXT("FShaderLabToon"));
+		}
+		else if (Token == TEXT("SL_VOLUME"))
+		{
+			if (RejectInLibrary(TEXT("SL_VOLUME"))) { return false; }
+			ParseBsdfBlock(S, OutModel, EShaderLabBsdfType::Volume, TEXT("SL_VOLUME"), TEXT("FShaderLabVolume"));
+		}
+		else if (Token == TEXT("SL_LIGHTFUNCTION"))
+		{
+			if (RejectInLibrary(TEXT("SL_LIGHTFUNCTION"))) { return false; }
+			ParseBsdfBlock(S, OutModel, EShaderLabBsdfType::LightFunction, TEXT("SL_LIGHTFUNCTION"), TEXT("FShaderLabLightFunction"));
 		}
 		else if (Token == TEXT("SL_VALUE"))
 		{
@@ -1468,6 +1824,16 @@ bool FShaderLabParser::Parse(
 			if (RejectInLibrary(TEXT("SL_OPACITY_MASK"))) { return false; }
 			ParseMaterialOutput(S, OutModel.OpacityMaskValueName, TEXT("SL_OPACITY_MASK"));
 		}
+		else if (Token == TEXT("SL_REFRACTION"))
+		{
+			if (RejectInLibrary(TEXT("SL_REFRACTION"))) { return false; }
+			ParseMaterialOutput(S, OutModel.RefractionValueName, TEXT("SL_REFRACTION"));
+		}
+		else if (Token == TEXT("SL_PIXEL_DEPTH_OFFSET"))
+		{
+			if (RejectInLibrary(TEXT("SL_PIXEL_DEPTH_OFFSET"))) { return false; }
+			ParseMaterialOutput(S, OutModel.PixelDepthOffsetValueName, TEXT("SL_PIXEL_DEPTH_OFFSET"));
+		}
 		else
 		{
 			// Not a ShaderLab macro: a free top-level HLSL declaration (helper function / struct /
@@ -1499,6 +1865,17 @@ bool FShaderLabParser::Parse(
 		return true;
 	}
 
+	// Names must be unique across SL_PROPERTY and SL_COLLECTION — both resolve to the same in-body identifier
+	// and are wired through the same PropertyNodes map, so a collision would overwrite one and double-wire.
+	for (const FShaderLabCollectionParam& C : OutModel.Collections)
+	{
+		if (OutModel.FindProperty(C.Name))
+		{
+			S.Error(FString::Printf(TEXT("'%s' is declared as both an SL_PROPERTY and an SL_COLLECTION"), *C.Name.ToString()));
+			return false;
+		}
+	}
+
 	// Pixel stage: exactly one of { single Surface } or { named Slabs + FrontMaterial }.
 	const bool bHasMultiSlab = OutModel.Slabs.Num() > 0 || OutModel.TopologyRoot != INDEX_NONE;
 	if (OutModel.bHasSurface && bHasMultiSlab)
@@ -1511,17 +1888,41 @@ bool FShaderLabParser::Parse(
 		S.Error(TEXT("Shader must declare a SL_SURFACE(...) entry point, or SL_SLAB blocks with a SL_FRONTMATERIAL expression"));
 		return false;
 	}
+
+	// Material-level output markers only apply to the multi-Slab path (they name a Value block). In a single
+	// pixel entry they would be silently dropped — reject with guidance to use the S.* fields instead.
+	if (OutModel.bHasSurface
+		&& (!OutModel.OpacityValueName.IsNone() || !OutModel.OpacityMaskValueName.IsNone()
+			|| !OutModel.RefractionValueName.IsNone() || !OutModel.PixelDepthOffsetValueName.IsNone()))
+	{
+		S.Error(TEXT("SL_OPACITY / SL_OPACITY_MASK / SL_REFRACTION / SL_PIXEL_DEPTH_OFFSET are for multi-Slab shaders (with SL_FRONTMATERIAL). In a single SL_SURFACE, set S.Opacity / S.OpacityMask / S.Refraction / S.PixelDepthOffset instead."));
+		return false;
+	}
 	if (bHasMultiSlab)
 	{
 		if (OutModel.Slabs.Num() == 0)
 		{
-			S.Error(TEXT("SL_FRONTMATERIAL requires at least one SL_SLAB block"));
+			S.Error(TEXT("SL_FRONTMATERIAL requires at least one BSDF block"));
 			return false;
 		}
 		if (OutModel.TopologyRoot == INDEX_NONE)
 		{
-			S.Error(TEXT("SL_SLAB blocks require a SL_FRONTMATERIAL(...) topology expression"));
-			return false;
+			// A single dedicated BSDF block (SL_UNLIT/HAIR/EYE/WATER/CLEARCOAT/TOON/VOLUME/LIGHTFUNCTION) is
+			// the whole material: auto-root it. A lone SL_SLAB (BsdfType == Slab) still requires SL_FRONTMATERIAL,
+			// as do multiple blocks (which need a topology expression to combine them).
+			if (OutModel.Slabs.Num() == 1 && OutModel.Slabs[0].BsdfType != EShaderLabBsdfType::Slab)
+			{
+				FShaderLabTopoNode Leaf;
+				Leaf.Op = EShaderLabOp::SlabRef;
+				Leaf.SlabRef = OutModel.Slabs[0].Name;
+				Leaf.SourceLine = OutModel.Slabs[0].BodyLine;
+				OutModel.TopologyRoot = OutModel.Topology.Add(Leaf);
+			}
+			else
+			{
+				S.Error(TEXT("SL_SLAB blocks require a SL_FRONTMATERIAL(...) topology expression"));
+				return false;
+			}
 		}
 	}
 
@@ -1545,5 +1946,21 @@ bool FShaderLabParser::Parse(
 		return false;
 	}
 
+	// Volume / LightFunction domains use their dedicated BSDF entry as the (sole) root block.
+	auto HasSoleBsdf = [&OutModel](EShaderLabBsdfType Type) -> bool
+	{
+		return !OutModel.bHasSurface && OutModel.Slabs.Num() == 1 && OutModel.Slabs[0].BsdfType == Type;
+	};
+	if (Domain == EShaderLabDomain::Volume && !HasSoleBsdf(EShaderLabBsdfType::Volume))
+	{
+		S.Error(TEXT("Domain = Volume requires a single SL_VOLUME(inout FShaderLabVolume) entry"));
+		return false;
+	}
+	if (Domain == EShaderLabDomain::LightFunction && !HasSoleBsdf(EShaderLabBsdfType::LightFunction))
+	{
+		S.Error(TEXT("Domain = LightFunction requires a single SL_LIGHTFUNCTION(inout FShaderLabLightFunction) entry"));
+		return false;
+	}
+
 	return true;
 }
diff --git a/Source/UShaderLab/Private/ShaderLabRuntimeBuilder.cpp b/Source/UShaderLab/Private/ShaderLabRuntimeBuilder.cpp
index 25af586..07e53a7 100644
--- a/Source/UShaderLab/Private/ShaderLabRuntimeBuilder.cpp
+++ b/Source/UShaderLab/Private/ShaderLabRuntimeBuilder.cpp
@@ -17,6 +17,8 @@ void FShaderLabRuntimeBuilder::ApplySettings(UMaterial& Material, const FShaderL
 	case EShaderLabDomain::PostProcess: Material.MaterialDomain = MD_PostProcess; break;
 	case EShaderLabDomain::UI: Material.MaterialDomain = MD_UI; break;
 	case EShaderLabDomain::Decal: Material.MaterialDomain = MD_DeferredDecal; break;
+	case EShaderLabDomain::Volume: Material.MaterialDomain = MD_Volume; break;
+	case EShaderLabDomain::LightFunction: Material.MaterialDomain = MD_LightFunction; break;
 	case EShaderLabDomain::Surface:
 	default: Material.MaterialDomain = MD_Surface; break;
 	}
@@ -27,6 +29,8 @@ void FShaderLabRuntimeBuilder::ApplySettings(UMaterial& Material, const FShaderL
 	case EShaderLabBlendMode::Translucent: Material.BlendMode = BLEND_Translucent; break;
 	case EShaderLabBlendMode::Additive: Material.BlendMode = BLEND_Additive; break;
 	case EShaderLabBlendMode::Modulate: Material.BlendMode = BLEND_Modulate; break;
+	case EShaderLabBlendMode::AlphaComposite: Material.BlendMode = BLEND_AlphaComposite; break;
+	case EShaderLabBlendMode::AlphaHoldout: Material.BlendMode = BLEND_AlphaHoldout; break;
 	case EShaderLabBlendMode::Opaque:
 	default: Material.BlendMode = BLEND_Opaque; break;
 	}
diff --git a/Source/UShaderLab/Private/ShaderLabSettingsApplier.cpp b/Source/UShaderLab/Private/ShaderLabSettingsApplier.cpp
index fe38313..8b0b892 100644
--- a/Source/UShaderLab/Private/ShaderLabSettingsApplier.cpp
+++ b/Source/UShaderLab/Private/ShaderLabSettingsApplier.cpp
@@ -25,6 +25,7 @@ namespace ShaderLabSettings_Private
 			FName(TEXT("bContactShadows")),
 			FName(TEXT("bIsThinSurface")),
 			FName(TEXT("DitheredLODTransition")),
+			FName(TEXT("RefractionMethod")),
 		};
 		return Names;
 	}
diff --git a/Source/UShaderLab/Public/ShaderLabModel.h b/Source/UShaderLab/Public/ShaderLabModel.h
index 69a8c0b..ec7f2ae 100644
--- a/Source/UShaderLab/Public/ShaderLabModel.h
+++ b/Source/UShaderLab/Public/ShaderLabModel.h
@@ -21,15 +21,28 @@ enum class EShaderLabPropertyType : uint8
 	Vector,
 	Texture2D,
 	TextureCube,
+	Texture2DArray,
+	Texture3D,        // volume texture
+	TextureCubeArray,
 	StaticBool,
 };
 
+/** True for any texture-object property type (2D/Cube/2DArray/3D/CubeArray). */
+inline bool ShaderLabIsTextureType(EShaderLabPropertyType T)
+{
+	return T == EShaderLabPropertyType::Texture2D || T == EShaderLabPropertyType::TextureCube
+		|| T == EShaderLabPropertyType::Texture2DArray || T == EShaderLabPropertyType::Texture3D
+		|| T == EShaderLabPropertyType::TextureCubeArray;
+}
+
 enum class EShaderLabDomain : uint8
 {
 	Surface,
 	PostProcess,
 	UI,
 	Decal,
+	Volume,        // MD_Volume — volumetric fog/cloud materials; requires an SL_VOLUME entry
+	LightFunction, // MD_LightFunction — light gobo/pattern; requires an SL_LIGHTFUNCTION entry
 };
 
 /** Which single pixel-entry a shader declared (when bHasSurface). Selects the output struct + wiring. */
@@ -40,6 +53,26 @@ enum class EShaderLabEntry : uint8
 	UI,           // FShaderLabUI -> EmissiveColor/Opacity
 };
 
+/**
+ * Which Substrate BSDF a named block (`FShaderLabSlab`) or single-entry sugar builds. Slab is the classic
+ * composable path (SL_SURFACE / SL_SLAB); the others are dedicated BSDFs (SL_UNLIT/HAIR/EYE/WATER/CLEARCOAT/
+ * TOON/VOLUME/LIGHTFUNCTION). Each maps to a concrete UMaterialExpressionSubstrate*BSDF node + output struct.
+ * The graph builder keys a per-BSDF descriptor table on this. Composition legality (which types may feed which
+ * topology operator) is validated by FShaderLabModel::ValidateTopology mirroring the engine allow-lists.
+ */
+enum class EShaderLabBsdfType : uint8
+{
+	Slab,          // FShaderLabSurface       -> UMaterialExpressionSubstrateSlabBSDF
+	Unlit,         // FShaderLabUnlit         -> UMaterialExpressionSubstrateUnlitBSDF
+	Hair,          // FShaderLabHair          -> UMaterialExpressionSubstrateHairBSDF
+	Eye,           // FShaderLabEye           -> UMaterialExpressionSubstrateEyeBSDF
+	Water,         // FShaderLabWater         -> UMaterialExpressionSubstrateSingleLayerWaterBSDF
+	Volume,        // FShaderLabVolume        -> UMaterialExpressionSubstrateVolumetricFogCloudBSDF
+	ClearCoat,     // FShaderLabClearCoat     -> UMaterialExpressionSubstrateSimpleClearCoatBSDF
+	Toon,          // FShaderLabToon          -> UMaterialExpressionSubstrateToonBSDF
+	LightFunction, // FShaderLabLightFunction -> UMaterialExpressionSubstrateLightFunction
+};
+
 enum class EShaderLabBlendMode : uint8
 {
 	Opaque,
@@ -47,6 +80,8 @@ enum class EShaderLabBlendMode : uint8
 	Translucent,
 	Additive,
 	Modulate,
+	AlphaComposite, // BLEND_AlphaComposite — premultiplied alpha
+	AlphaHoldout,   // BLEND_AlphaHoldout
 };
 
 /** A single declared shader property -> becomes a standard UE material parameter. */
@@ -55,14 +90,23 @@ struct USHADERLAB_API FShaderLabProperty
 	FName Name;
 	EShaderLabPropertyType Type = EShaderLabPropertyType::Scalar;
 
-	FString DisplayName;
 	FString Group;
 	int32 SortPriority = 0;
 
-	/** Range(min,max) meta — only meaningful for Scalar. */
-	bool bHasRange = false;
-	float RangeMin = 0.0f;
-	float RangeMax = 1.0f;
+	/** ClampMin/ClampMax slider bounds (UE UPROPERTY style) — only meaningful for Scalar. Each is
+	 *  independent; a set field maps to the ScalarParameter's SliderMin/SliderMax respectively. */
+	bool bHasClampMin = false;
+	float ClampMin = 0.0f;
+	bool bHasClampMax = false;
+	float ClampMax = 1.0f;
+
+	/**
+	 * bUseCustomPrimitiveData: read this parameter from the component's Custom Primitive Data instead of a
+	 * material uniform (per-instance data without a Material Instance). Only Scalar/Vector support it in UE.
+	 * PrimitiveDataIndex is the mandatory, author-specified float slot (Scalar uses 1 float, Vector uses 4).
+	 */
+	bool bUseCustomPrimitiveData = false;
+	int32 PrimitiveDataIndex = INDEX_NONE;
 
 	// Defaults (only the field matching Type is meaningful).
 	float ScalarDefault = 0.0f;
@@ -72,6 +116,20 @@ struct USHADERLAB_API FShaderLabProperty
 	bool bStaticBoolDefault = false;
 };
 
+/**
+ * A `SL_COLLECTION(Path="...", [Parameter="..."]) floatN <Name>;` declaration: a read of a Material Parameter
+ * Collection (MPC) value. Unlike SL_PROPERTY it is NOT a per-instance knob — it reads a global collection
+ * value (UMaterialExpressionCollectionParameter). Type (Scalar/Color/Vector) is inferred from the HLSL type.
+ */
+struct USHADERLAB_API FShaderLabCollectionParam
+{
+	FName Name;                 // in-HLSL identifier the body references
+	FString CollectionPath;     // asset path of the UMaterialParameterCollection
+	FName ParameterName;        // parameter name within the collection (defaults to Name)
+	EShaderLabPropertyType Type = EShaderLabPropertyType::Scalar; // Scalar / Color / Vector
+	int32 Line = 0;
+};
+
 /** A parameter in a `Surface(...)`/`Vertex(...)` entry-point signature. */
 struct USHADERLAB_API FShaderLabEntryParam
 {
@@ -80,14 +138,34 @@ struct USHADERLAB_API FShaderLabEntryParam
 	bool bInout = false;
 };
 
-/** A named `Slab <Name>(inout FShaderLabSurface S){...}` block in a multi-slab shader. */
+/**
+ * Non-pin BSDF node modifiers set via marker specifiers (SL_SURFACE/SL_SLAB(...), etc.): asset references and
+ * enum selectors that are node properties, not connectable float pins. Empty/None means "leave the node default".
+ * SubsurfaceProfile/SpecularProfile apply to Slab (SubsurfaceProfile also to Eye); ToonProfile applies to Toon;
+ * SubSurfaceType (Slab) is one of None/Wrap/TwoSidedWrap/Diffusion/SimpleVolume.
+ */
+struct USHADERLAB_API FShaderLabBsdfModifiers
+{
+	FString SubsurfaceProfilePath;
+	FString SpecularProfilePath;
+	FString ToonProfilePath;
+	FString SubSurfaceType; // enum token; empty = leave default
+};
+
+/**
+ * A named BSDF block in a multi-slab / multi-BSDF shader, e.g. `SL_SLAB() void <Name>(inout FShaderLabSurface S){...}`
+ * or `SL_HAIR() void <Name>(inout FShaderLabHair H){...}`. BsdfType (set by the marker) selects the engine node
+ * and output struct; the graph builder keys its per-BSDF descriptor table on it.
+ */
 struct USHADERLAB_API FShaderLabSlab
 {
 	FName Name;
+	EShaderLabBsdfType BsdfType = EShaderLabBsdfType::Slab;
 	/** Name of the inout output-struct parameter (e.g. "S"). */
 	FString OutParamName;
 	FString Body;
 	int32 BodyLine = 0;
+	FShaderLabBsdfModifiers Modifiers;
 };
 
 /** A named `Value <Name>(){ return <float HLSL>; }` block, used as a topology mix factor. */
@@ -190,6 +268,8 @@ struct USHADERLAB_API FShaderLabTopoNode
 	int32 ChildB = INDEX_NONE;     // second material input (binary ops)
 	bool bHasFactor = false;
 	FShaderLabFactor Factor;       // for VerticalLayer/HorizontalMix/Weight/Select
+	/** 1-based source line of this operator/leaf token inside SL_FRONTMATERIAL, for composition-error mapping. */
+	int32 SourceLine = 0;
 };
 
 struct USHADERLAB_API FShaderLabSettings
@@ -227,6 +307,8 @@ struct USHADERLAB_API FShaderLabModel
 	TArray<TPair<FString, FString>> RawSettings;
 
 	TArray<FShaderLabProperty> Properties;
+	/** Material Parameter Collection reads (SL_COLLECTION). Global values, not per-instance knobs. */
+	TArray<FShaderLabCollectionParam> Collections;
 	TArray<FString> Includes;
 
 	/**
@@ -258,15 +340,19 @@ struct USHADERLAB_API FShaderLabModel
 	bool bHasSurface = false;
 	/** Which single pixel-entry was declared (valid when bHasSurface). */
 	EShaderLabEntry SurfaceEntry = EShaderLabEntry::Surface;
+	/** BSDF node modifiers from SL_SURFACE(...) specifiers (only meaningful for the Surface entry). */
+	FShaderLabBsdfModifiers SurfaceModifiers;
 
 	// Multi-slab topology (used when !bHasSurface).
 	TArray<FShaderLabSlab> Slabs;
 	TArray<FShaderLabValue> Values;
 	TArray<FShaderLabTopoNode> Topology;
 	int32 TopologyRoot = INDEX_NONE;
-	/** Optional material-level outputs (multi-slab): names of Value blocks feeding Opacity/OpacityMask. */
+	/** Optional material-level outputs (multi-slab): names of Value blocks feeding Opacity/OpacityMask/Refraction/PDO. */
 	FName OpacityValueName;
 	FName OpacityMaskValueName;
+	FName RefractionValueName;
+	FName PixelDepthOffsetValueName;
 
 	// Vertex stage (optional).
 	bool bHasVertex = false;
@@ -291,4 +377,12 @@ struct USHADERLAB_API FShaderLabModel
 
 	/** True if any property is a StaticBool (drives shader-map permutation count). */
 	bool HasStaticSwitches() const;
+
+	/**
+	 * Validate the FrontMaterial topology against the Substrate operator BSDF-type allow-lists (mirrors the
+	 * engine's SubstrateTranslatorCommon allow-lists): VerticalLayer/HorizontalMix/Add accept only Slab; Weight
+	 * accepts Unlit/Slab/Toon; Select accepts Slab/Hair/Eye/Toon. On an illegal combination, appends an error
+	 * mapped to the offending operator's .usl line. Returns true when the topology is legal (or empty).
+	 */
+	bool ValidateTopology(TArray<FString>& OutErrors) const;
 };
diff --git a/Source/UShaderLabEditor/Private/ShaderLabGraphBuilder.cpp b/Source/UShaderLabEditor/Private/ShaderLabGraphBuilder.cpp
index 81afe2b..edc6c7f 100644
--- a/Source/UShaderLabEditor/Private/ShaderLabGraphBuilder.cpp
+++ b/Source/UShaderLabEditor/Private/ShaderLabGraphBuilder.cpp
@@ -11,11 +11,23 @@
 #include "Engine/Texture2D.h"
 #include "Materials/Material.h"
 #include "Materials/MaterialExpressionConstant.h"
+#include "Materials/MaterialExpressionCollectionParameter.h"
 #include "Materials/MaterialExpressionCustom.h"
+#include "Materials/MaterialParameterCollection.h"
 #include "Materials/MaterialExpressionScalarParameter.h"
 #include "Materials/MaterialExpressionStaticBoolParameter.h"
 #include "Materials/MaterialExpressionStaticSwitch.h"
+#include "Materials/MaterialExpressionQualitySwitch.h"
+#include "Materials/MaterialExpressionFeatureLevelSwitch.h"
+#include "Materials/MaterialExpressionShadingPathSwitch.h"
+#include "SceneTypes.h"
+#include "RHIDefinitions.h"
 #include "Materials/MaterialExpressionSubstrate.h"
+#include "Materials/MaterialExpressionSingleLayerWaterMaterialOutput.h"
+#include "Materials/MaterialExpressionSceneTexture.h"
+#include "Engine/SubsurfaceProfile.h"
+#include "Engine/SpecularProfile.h"
+#include "Engine/ToonProfile.h"
 #include "Materials/MaterialExpressionTextureObjectParameter.h"
 #include "Materials/MaterialExpressionVectorParameter.h"
 #include "Materials/MaterialExpressionVertexInterpolator.h"
@@ -30,6 +42,7 @@
 #include "Interfaces/IPluginManager.h"
 #include "Misc/FileHelper.h"
 #include "ShaderCore.h"
+#include "SceneTypes.h"
 
 #define SHADERLAB_COMMON_INCLUDE TEXT("/Plugin/ShaderLab/Private/ShaderLabCommon.ush")
 #define SHADERLAB_FUNCTIONS_INCLUDE TEXT("/Plugin/ShaderLab/Private/ShaderLabUEFunctions.ush")
@@ -206,6 +219,8 @@ namespace ShaderLabGraph
 		case EShaderLabDomain::PostProcess: return MD_PostProcess;
 		case EShaderLabDomain::UI: return MD_UI;
 		case EShaderLabDomain::Decal: return MD_DeferredDecal;
+		case EShaderLabDomain::Volume: return MD_Volume;
+		case EShaderLabDomain::LightFunction: return MD_LightFunction;
 		case EShaderLabDomain::Surface:
 		default: return MD_Surface;
 		}
@@ -219,6 +234,8 @@ namespace ShaderLabGraph
 		case EShaderLabBlendMode::Translucent: return BLEND_Translucent;
 		case EShaderLabBlendMode::Additive: return BLEND_Additive;
 		case EShaderLabBlendMode::Modulate: return BLEND_Modulate;
+		case EShaderLabBlendMode::AlphaComposite: return BLEND_AlphaComposite;
+		case EShaderLabBlendMode::AlphaHoldout: return BLEND_AlphaHoldout;
 		case EShaderLabBlendMode::Opaque:
 		default: return BLEND_Opaque;
 		}
@@ -235,6 +252,225 @@ namespace ShaderLabGraph
 		return Expr;
 	}
 
+	/** A trivial Custom node that emits `#define <Name> <Value>` (used for the before-attributes define leak). */
+	static UMaterialExpressionCustom* MakeDefineNode(UMaterial& Material, int32& IoY, const TCHAR* Name, const TCHAR* Value)
+	{
+		UMaterialExpressionCustom* D = NewExpr<UMaterialExpressionCustom>(Material, IoY, -1300);
+		D->Description = TEXT("ShaderLab Define");
+		D->OutputType = CMOT_Float1;
+		D->Code = TEXT("return 0;");
+		FCustomDefine DD;
+		DD.DefineName = Name;
+		DD.DefineValue = Value;
+		D->AdditionalDefines.Add(DD);
+		return D;
+	}
+
+	// --- Per-BSDF descriptor -----------------------------------------------------------------------
+	// Each Substrate BSDF is described by {output struct, default fn, field->pin table, node factory,
+	// pin resolver}. The generic BuildBsdf() works off this so all BSDFs share one code path. The engine
+	// BSDF node classes are distinct C++ types with no common named-pin base, so each descriptor supplies
+	// its own MakeNode (news the concrete node) and GetPin (casts + returns the FExpressionInput*).
+	struct FBsdfDesc
+	{
+		EShaderLabBsdfType Type;
+		const TCHAR* CustomDesc;    // Custom-node Description (kept "ShaderLab Surface" for Slab: tests key on it)
+		const TCHAR* StructName;    // e.g. "FShaderLabSurface"
+		const TCHAR* DefaultFn;     // e.g. "ShaderLabDefaultSurface"
+		const FSlabFieldDef* Fields;
+		int32 NumFields;
+		UMaterialExpression* (*MakeNode)(UMaterial&, int32& IoY);
+		FExpressionInput* (*GetPin)(UMaterialExpression*, const FString& Field);
+	};
+
+	static UMaterialExpression* MakeSlabNode(UMaterial& M, int32& IoY)
+	{
+		return NewExpr<UMaterialExpressionSubstrateSlabBSDF>(M, IoY, 0);
+	}
+	static FExpressionInput* GetSlabPinGeneric(UMaterialExpression* Node, const FString& Field)
+	{
+		UMaterialExpressionSubstrateSlabBSDF* Slab = Cast<UMaterialExpressionSubstrateSlabBSDF>(Node);
+		return Slab ? GetSlabPin(Slab, Field) : nullptr;
+	}
+
+	// --- Unlit ---
+	static const FSlabFieldDef GUnlitFields[] = {
+		{ TEXT("EmissiveColor"), CMOT_Float3 }, { TEXT("TransmittanceColor"), CMOT_Float3 }, { TEXT("Normal"), CMOT_Float3 },
+	};
+	static UMaterialExpression* MakeUnlitNode(UMaterial& M, int32& IoY) { return NewExpr<UMaterialExpressionSubstrateUnlitBSDF>(M, IoY, 0); }
+	static FExpressionInput* GetUnlitPin(UMaterialExpression* N, const FString& F)
+	{
+		UMaterialExpressionSubstrateUnlitBSDF* B = Cast<UMaterialExpressionSubstrateUnlitBSDF>(N); if (!B) return nullptr;
+		if (F == TEXT("EmissiveColor")) return &B->EmissiveColor;
+		if (F == TEXT("TransmittanceColor")) return &B->TransmittanceColor;
+		if (F == TEXT("Normal")) return &B->Normal;
+		return nullptr;
+	}
+
+	// --- Hair ---
+	static const FSlabFieldDef GHairFields[] = {
+		{ TEXT("BaseColor"), CMOT_Float3 }, { TEXT("Scatter"), CMOT_Float1 }, { TEXT("Specular"), CMOT_Float1 },
+		{ TEXT("Roughness"), CMOT_Float1 }, { TEXT("Backlit"), CMOT_Float3 }, { TEXT("Tangent"), CMOT_Float3 },
+		{ TEXT("EmissiveColor"), CMOT_Float3 },
+	};
+	static UMaterialExpression* MakeHairNode(UMaterial& M, int32& IoY) { return NewExpr<UMaterialExpressionSubstrateHairBSDF>(M, IoY, 0); }
+	static FExpressionInput* GetHairPin(UMaterialExpression* N, const FString& F)
+	{
+		UMaterialExpressionSubstrateHairBSDF* B = Cast<UMaterialExpressionSubstrateHairBSDF>(N); if (!B) return nullptr;
+		if (F == TEXT("BaseColor")) return &B->BaseColor;
+		if (F == TEXT("Scatter")) return &B->Scatter;
+		if (F == TEXT("Specular")) return &B->Specular;
+		if (F == TEXT("Roughness")) return &B->Roughness;
+		if (F == TEXT("Backlit")) return &B->Backlit;
+		if (F == TEXT("Tangent")) return &B->Tangent;
+		if (F == TEXT("EmissiveColor")) return &B->EmissiveColor;
+		return nullptr;
+	}
+
+	// --- Eye ---
+	static const FSlabFieldDef GEyeFields[] = {
+		{ TEXT("DiffuseColor"), CMOT_Float3 }, { TEXT("Roughness"), CMOT_Float1 }, { TEXT("CorneaNormal"), CMOT_Float3 },
+		{ TEXT("IrisNormal"), CMOT_Float3 }, { TEXT("IrisPlaneNormal"), CMOT_Float3 }, { TEXT("IrisMask"), CMOT_Float1 },
+		{ TEXT("IrisDistance"), CMOT_Float1 }, { TEXT("EmissiveColor"), CMOT_Float3 },
+	};
+	static UMaterialExpression* MakeEyeNode(UMaterial& M, int32& IoY) { return NewExpr<UMaterialExpressionSubstrateEyeBSDF>(M, IoY, 0); }
+	static FExpressionInput* GetEyePin(UMaterialExpression* N, const FString& F)
+	{
+		UMaterialExpressionSubstrateEyeBSDF* B = Cast<UMaterialExpressionSubstrateEyeBSDF>(N); if (!B) return nullptr;
+		if (F == TEXT("DiffuseColor")) return &B->DiffuseColor;
+		if (F == TEXT("Roughness")) return &B->Roughness;
+		if (F == TEXT("CorneaNormal")) return &B->CorneaNormal;
+		if (F == TEXT("IrisNormal")) return &B->IrisNormal;
+		if (F == TEXT("IrisPlaneNormal")) return &B->IrisPlaneNormal;
+		if (F == TEXT("IrisMask")) return &B->IrisMask;
+		if (F == TEXT("IrisDistance")) return &B->IrisDistance;
+		if (F == TEXT("EmissiveColor")) return &B->EmissiveColor;
+		return nullptr;
+	}
+
+	// --- Single Layer Water ---
+	static const FSlabFieldDef GWaterFields[] = {
+		{ TEXT("BaseColor"), CMOT_Float3 }, { TEXT("Metallic"), CMOT_Float1 }, { TEXT("Specular"), CMOT_Float1 },
+		{ TEXT("Roughness"), CMOT_Float1 }, { TEXT("Normal"), CMOT_Float3 }, { TEXT("EmissiveColor"), CMOT_Float3 },
+		{ TEXT("TopMaterialOpacity"), CMOT_Float3 }, { TEXT("WaterAlbedo"), CMOT_Float3 }, { TEXT("WaterExtinction"), CMOT_Float3 },
+		{ TEXT("WaterPhaseG"), CMOT_Float1 }, { TEXT("ColorScaleBehindWater"), CMOT_Float3 },
+	};
+	static UMaterialExpression* MakeWaterNode(UMaterial& M, int32& IoY) { return NewExpr<UMaterialExpressionSubstrateSingleLayerWaterBSDF>(M, IoY, 0); }
+	static FExpressionInput* GetWaterPin(UMaterialExpression* N, const FString& F)
+	{
+		UMaterialExpressionSubstrateSingleLayerWaterBSDF* B = Cast<UMaterialExpressionSubstrateSingleLayerWaterBSDF>(N); if (!B) return nullptr;
+		if (F == TEXT("BaseColor")) return &B->BaseColor;
+		if (F == TEXT("Metallic")) return &B->Metallic;
+		if (F == TEXT("Specular")) return &B->Specular;
+		if (F == TEXT("Roughness")) return &B->Roughness;
+		if (F == TEXT("Normal")) return &B->Normal;
+		if (F == TEXT("EmissiveColor")) return &B->EmissiveColor;
+		if (F == TEXT("TopMaterialOpacity")) return &B->TopMaterialOpacity;
+		if (F == TEXT("WaterAlbedo")) return &B->WaterAlbedo;
+		if (F == TEXT("WaterExtinction")) return &B->WaterExtinction;
+		if (F == TEXT("WaterPhaseG")) return &B->WaterPhaseG;
+		if (F == TEXT("ColorScaleBehindWater")) return &B->ColorScaleBehindWater;
+		return nullptr;
+	}
+
+	// --- Volumetric-Fog-Cloud ---
+	static const FSlabFieldDef GVolumeFields[] = {
+		{ TEXT("Albedo"), CMOT_Float3 }, { TEXT("Extinction"), CMOT_Float3 }, { TEXT("EmissiveColor"), CMOT_Float3 },
+		{ TEXT("AmbientOcclusion"), CMOT_Float1 },
+	};
+	static UMaterialExpression* MakeVolumeNode(UMaterial& M, int32& IoY) { return NewExpr<UMaterialExpressionSubstrateVolumetricFogCloudBSDF>(M, IoY, 0); }
+	static FExpressionInput* GetVolumePin(UMaterialExpression* N, const FString& F)
+	{
+		UMaterialExpressionSubstrateVolumetricFogCloudBSDF* B = Cast<UMaterialExpressionSubstrateVolumetricFogCloudBSDF>(N); if (!B) return nullptr;
+		if (F == TEXT("Albedo")) return &B->Albedo;
+		if (F == TEXT("Extinction")) return &B->Extinction;
+		if (F == TEXT("EmissiveColor")) return &B->EmissiveColor;
+		if (F == TEXT("AmbientOcclusion")) return &B->AmbientOcclusion;
+		return nullptr;
+	}
+
+	// --- Simple Clear Coat ---
+	static const FSlabFieldDef GClearCoatFields[] = {
+		{ TEXT("DiffuseAlbedo"), CMOT_Float3 }, { TEXT("F0"), CMOT_Float3 }, { TEXT("Roughness"), CMOT_Float1 },
+		{ TEXT("ClearCoatCoverage"), CMOT_Float1 }, { TEXT("ClearCoatRoughness"), CMOT_Float1 }, { TEXT("Normal"), CMOT_Float3 },
+		{ TEXT("EmissiveColor"), CMOT_Float3 }, { TEXT("BottomNormal"), CMOT_Float3 },
+	};
+	static UMaterialExpression* MakeClearCoatNode(UMaterial& M, int32& IoY) { return NewExpr<UMaterialExpressionSubstrateSimpleClearCoatBSDF>(M, IoY, 0); }
+	static FExpressionInput* GetClearCoatPin(UMaterialExpression* N, const FString& F)
+	{
+		UMaterialExpressionSubstrateSimpleClearCoatBSDF* B = Cast<UMaterialExpressionSubstrateSimpleClearCoatBSDF>(N); if (!B) return nullptr;
+		if (F == TEXT("DiffuseAlbedo")) return &B->DiffuseAlbedo;
+		if (F == TEXT("F0")) return &B->F0;
+		if (F == TEXT("Roughness")) return &B->Roughness;
+		if (F == TEXT("ClearCoatCoverage")) return &B->ClearCoatCoverage;
+		if (F == TEXT("ClearCoatRoughness")) return &B->ClearCoatRoughness;
+		if (F == TEXT("Normal")) return &B->Normal;
+		if (F == TEXT("EmissiveColor")) return &B->EmissiveColor;
+		if (F == TEXT("BottomNormal")) return &B->BottomNormal;
+		return nullptr;
+	}
+
+	// --- Toon (experimental) ---
+	static const FSlabFieldDef GToonFields[] = {
+		{ TEXT("BaseColor"), CMOT_Float3 }, { TEXT("Metallic"), CMOT_Float1 }, { TEXT("Specular"), CMOT_Float1 },
+		{ TEXT("Roughness"), CMOT_Float1 }, { TEXT("Normal"), CMOT_Float3 }, { TEXT("EmissiveColor"), CMOT_Float3 },
+		{ TEXT("PatternUVs"), CMOT_Float2 }, { TEXT("Anisotropy"), CMOT_Float1 }, { TEXT("Tangent"), CMOT_Float3 },
+	};
+	static UMaterialExpression* MakeToonNode(UMaterial& M, int32& IoY) { return NewExpr<UMaterialExpressionSubstrateToonBSDF>(M, IoY, 0); }
+	static FExpressionInput* GetToonPin(UMaterialExpression* N, const FString& F)
+	{
+		UMaterialExpressionSubstrateToonBSDF* B = Cast<UMaterialExpressionSubstrateToonBSDF>(N); if (!B) return nullptr;
+		if (F == TEXT("BaseColor")) return &B->BaseColor;
+		if (F == TEXT("Metallic")) return &B->Metallic;
+		if (F == TEXT("Specular")) return &B->Specular;
+		if (F == TEXT("Roughness")) return &B->Roughness;
+		if (F == TEXT("Normal")) return &B->Normal;
+		if (F == TEXT("EmissiveColor")) return &B->EmissiveColor;
+		if (F == TEXT("PatternUVs")) return &B->PatternUVs;
+		if (F == TEXT("Anisotropy")) return &B->Anisotropy;
+		if (F == TEXT("Tangent")) return &B->Tangent;
+		return nullptr;
+	}
+
+	// --- Light Function ---
+	static const FSlabFieldDef GLightFunctionFields[] = {
+		{ TEXT("Color"), CMOT_Float3 },
+	};
+	static UMaterialExpression* MakeLightFunctionNode(UMaterial& M, int32& IoY) { return NewExpr<UMaterialExpressionSubstrateLightFunction>(M, IoY, 0); }
+	static FExpressionInput* GetLightFunctionPin(UMaterialExpression* N, const FString& F)
+	{
+		UMaterialExpressionSubstrateLightFunction* B = Cast<UMaterialExpressionSubstrateLightFunction>(N); if (!B) return nullptr;
+		if (F == TEXT("Color")) return &B->Color;
+		return nullptr;
+	}
+
+	static const FBsdfDesc GBsdfDescs[] = {
+		{ EShaderLabBsdfType::Slab,          TEXT("ShaderLab Surface"),       TEXT("FShaderLabSurface"),       TEXT("ShaderLabDefaultSurface"),
+		  GSlabFields,          UE_ARRAY_COUNT(GSlabFields),          &MakeSlabNode,          &GetSlabPinGeneric },
+		{ EShaderLabBsdfType::Unlit,         TEXT("ShaderLab Unlit"),         TEXT("FShaderLabUnlit"),         TEXT("ShaderLabDefaultUnlit"),
+		  GUnlitFields,         UE_ARRAY_COUNT(GUnlitFields),         &MakeUnlitNode,         &GetUnlitPin },
+		{ EShaderLabBsdfType::Hair,          TEXT("ShaderLab Hair"),          TEXT("FShaderLabHair"),          TEXT("ShaderLabDefaultHair"),
+		  GHairFields,          UE_ARRAY_COUNT(GHairFields),          &MakeHairNode,          &GetHairPin },
+		{ EShaderLabBsdfType::Eye,           TEXT("ShaderLab Eye"),           TEXT("FShaderLabEye"),           TEXT("ShaderLabDefaultEye"),
+		  GEyeFields,           UE_ARRAY_COUNT(GEyeFields),           &MakeEyeNode,           &GetEyePin },
+		{ EShaderLabBsdfType::Water,         TEXT("ShaderLab Water"),         TEXT("FShaderLabWater"),         TEXT("ShaderLabDefaultWater"),
+		  GWaterFields,         UE_ARRAY_COUNT(GWaterFields),         &MakeWaterNode,         &GetWaterPin },
+		{ EShaderLabBsdfType::Volume,        TEXT("ShaderLab Volume"),        TEXT("FShaderLabVolume"),        TEXT("ShaderLabDefaultVolume"),
+		  GVolumeFields,        UE_ARRAY_COUNT(GVolumeFields),        &MakeVolumeNode,        &GetVolumePin },
+		{ EShaderLabBsdfType::ClearCoat,     TEXT("ShaderLab ClearCoat"),     TEXT("FShaderLabClearCoat"),     TEXT("ShaderLabDefaultClearCoat"),
+		  GClearCoatFields,     UE_ARRAY_COUNT(GClearCoatFields),     &MakeClearCoatNode,     &GetClearCoatPin },
+		{ EShaderLabBsdfType::Toon,          TEXT("ShaderLab Toon"),          TEXT("FShaderLabToon"),          TEXT("ShaderLabDefaultToon"),
+		  GToonFields,          UE_ARRAY_COUNT(GToonFields),          &MakeToonNode,          &GetToonPin },
+		{ EShaderLabBsdfType::LightFunction, TEXT("ShaderLab LightFunction"), TEXT("FShaderLabLightFunction"), TEXT("ShaderLabDefaultLightFunction"),
+		  GLightFunctionFields, UE_ARRAY_COUNT(GLightFunctionFields), &MakeLightFunctionNode, &GetLightFunctionPin },
+	};
+
+	static const FBsdfDesc* FindBsdfDesc(EShaderLabBsdfType Type)
+	{
+		for (const FBsdfDesc& D : GBsdfDescs) { if (D.Type == Type) { return &D; } }
+		return nullptr;
+	}
+
 	/** One intrinsic call resolved to a Custom-node input wired from an engine expression node. */
 	struct FIntrinsicWire
 	{
@@ -631,6 +867,18 @@ namespace ShaderLabGraph
 			OutParams.Add(FString::Printf(TEXT("TextureCube %s"), *Name));
 			OutParams.Add(FString::Printf(TEXT("SamplerState %sSampler"), *Name));
 			break;
+		case EShaderLabPropertyType::Texture2DArray:
+			OutParams.Add(FString::Printf(TEXT("Texture2DArray %s"), *Name));
+			OutParams.Add(FString::Printf(TEXT("SamplerState %sSampler"), *Name));
+			break;
+		case EShaderLabPropertyType::Texture3D:
+			OutParams.Add(FString::Printf(TEXT("Texture3D %s"), *Name));
+			OutParams.Add(FString::Printf(TEXT("SamplerState %sSampler"), *Name));
+			break;
+		case EShaderLabPropertyType::TextureCubeArray:
+			OutParams.Add(FString::Printf(TEXT("TextureCubeArray %s"), *Name));
+			OutParams.Add(FString::Printf(TEXT("SamplerState %sSampler"), *Name));
+			break;
 		default: break; // StaticBool never becomes a parameter (reaches bodies via the global #define).
 		}
 	}
@@ -640,7 +888,7 @@ namespace ShaderLabGraph
 	{
 		const FString Name = Prop.Name.ToString();
 		OutArgs.Add(Name);
-		if (Prop.Type == EShaderLabPropertyType::Texture2D || Prop.Type == EShaderLabPropertyType::TextureCube)
+		if (ShaderLabIsTextureType(Prop.Type))
 		{
 			OutArgs.Add(Name + TEXT("Sampler"));
 		}
@@ -1079,7 +1327,8 @@ namespace ShaderLabGraph
 	 * Iterating the (deduped) promoted property set once means a property that is both never doubles up.
 	 */
 	static void WirePropInputs(UMaterialExpressionCustom& Custom, const FShaderLabResolvedProgram& Program,
-		const TMap<FName, FParamNode>& PropertyNodes, const FString& InBody, const TSet<FName>& ReqProps)
+		const TMap<FName, FParamNode>& PropertyNodes, const FString& InBody, const TSet<FName>& ReqProps,
+		const TArray<FShaderLabCollectionParam>& Collections)
 	{
 		for (const FShaderLabProperty& Prop : Program.Properties)
 		{
@@ -1100,6 +1349,22 @@ namespace ShaderLabGraph
 				Custom.Inputs.Add(In);
 			}
 		}
+		// Material Parameter Collection reads: same wiring as a property (deterministic declaration order).
+		for (const FShaderLabCollectionParam& C : Collections)
+		{
+			if (!ReferencesToken(InBody, C.Name.ToString()))
+			{
+				continue;
+			}
+			const FParamNode* Node = PropertyNodes.Find(C.Name);
+			if (Node && Node->Expr)
+			{
+				FCustomInput In;
+				In.InputName = C.Name;
+				In.Input.Connect(0, Node->Expr);
+				Custom.Inputs.Add(In);
+			}
+		}
 	}
 
 	/** Map an SL_INTERPOLATOR return type to a Custom-node output type (parser guarantees float1..4). */
@@ -1319,12 +1584,68 @@ namespace ShaderLabGraph
 		}
 	}
 
+	/** Map a SubSurfaceType token to the engine enum. */
+	static bool ParseSubSurfaceType(const FString& Token, EMaterialSubSurfaceType& Out)
+	{
+		if (Token == TEXT("None")) { Out = MSS_None; return true; }
+		if (Token == TEXT("Wrap")) { Out = MSS_Wrap; return true; }
+		if (Token == TEXT("TwoSidedWrap")) { Out = MSS_TwoSidedWrap; return true; }
+		if (Token == TEXT("Diffusion")) { Out = MSS_Diffusion; return true; }
+		if (Token == TEXT("SimpleVolume")) { Out = MSS_SimpleVolume; return true; }
+		return false;
+	}
+
 	/**
-	 * Emit the Custom node for a pixel-stage body that writes FShaderLabSurface fields and wire it into
-	 * a fresh Substrate Slab BSDF. Returns the slab (nullptr only on error). When bAllowMaterialOutputs,
-	 * S.Opacity / S.OpacityMask are wired to the material-level pins (single-Surface sugar path only).
+	 * Apply non-pin BSDF modifiers (asset profiles + SubSurfaceType) onto the concrete node. Only modifiers
+	 * applicable to the node type are consumed; others are ignored. Returns false (with an error) on a bad
+	 * asset path or enum token.
 	 */
-	static UMaterialExpressionSubstrateSlabBSDF* BuildSlab(
+	template <typename TProfile>
+	static bool LoadProfileAsset(const FString& Path, const TCHAR* What, TObjectPtr<TProfile>& OutPtr, TArray<FString>& OutErrors)
+	{
+		if (Path.IsEmpty()) { return true; }
+		TProfile* P = LoadObject<TProfile>(nullptr, *Path);
+		if (!P) { OutErrors.Add(FString::Printf(TEXT("%s: cannot load '%s'"), What, *Path)); return false; }
+		OutPtr = P;
+		return true;
+	}
+
+	static bool ApplyBsdfModifiers(UMaterialExpression* Bsdf, const FShaderLabBsdfModifiers& M, TArray<FString>& OutErrors)
+	{
+		if (UMaterialExpressionSubstrateSlabBSDF* Slab = Cast<UMaterialExpressionSubstrateSlabBSDF>(Bsdf))
+		{
+			if (!LoadProfileAsset(M.SubsurfaceProfilePath, TEXT("SubsurfaceProfile"), Slab->SubsurfaceProfile, OutErrors)) { return false; }
+			if (!LoadProfileAsset(M.SpecularProfilePath, TEXT("SpecularProfile"), Slab->SpecularProfile, OutErrors)) { return false; }
+			if (!M.SubSurfaceType.IsEmpty())
+			{
+				EMaterialSubSurfaceType T;
+				if (!ParseSubSurfaceType(M.SubSurfaceType, T))
+				{
+					OutErrors.Add(FString::Printf(TEXT("Unknown SubSurfaceType '%s' (use None/Wrap/TwoSidedWrap/Diffusion/SimpleVolume)"), *M.SubSurfaceType));
+					return false;
+				}
+				Slab->SubSurfaceType = T;
+			}
+		}
+		else if (UMaterialExpressionSubstrateEyeBSDF* Eye = Cast<UMaterialExpressionSubstrateEyeBSDF>(Bsdf))
+		{
+			if (!LoadProfileAsset(M.SubsurfaceProfilePath, TEXT("SubsurfaceProfile"), Eye->SubsurfaceProfile, OutErrors)) { return false; }
+		}
+		else if (UMaterialExpressionSubstrateToonBSDF* Toon = Cast<UMaterialExpressionSubstrateToonBSDF>(Bsdf))
+		{
+			if (!LoadProfileAsset(M.ToonProfilePath, TEXT("ToonProfile"), Toon->ToonProfile, OutErrors)) { return false; }
+		}
+		return true;
+	}
+
+	/**
+	 * Emit the Custom node for a pixel-stage body that writes the given BSDF's output-struct fields and wire
+	 * it into a fresh Substrate BSDF node (chosen by Desc). Returns the BSDF node (nullptr only on error).
+	 * When bAllowMaterialOutputs, S.Opacity / S.OpacityMask are wired to the material-level pins (single-entry
+	 * sugar path only). Generic across all Substrate BSDFs via the FBsdfDesc field->pin table.
+	 */
+	static UMaterialExpression* BuildBsdf(
+		const FBsdfDesc& Desc, const FShaderLabBsdfModifiers& Modifiers,
 		UMaterial& Material, UMaterialEditorOnlyData& EditorOnly, const FString& OutParamName,
 		const FString& InBody, int32 BodyLine, const FShaderLabModel& Model,
 		const FShaderLabResolvedProgram& Program, const FLibraryEmit& Emit,
@@ -1332,11 +1653,25 @@ namespace ShaderLabGraph
 		const TMap<FName, UMaterialExpression*>& InterpByName, TSet<FName>& UsedInterps,
 		bool bAllowMaterialOutputs, int32& IoY, TArray<FString>& OutErrors)
 	{
-		UMaterialExpressionSubstrateSlabBSDF* Slab = NewExpr<UMaterialExpressionSubstrateSlabBSDF>(Material, IoY, 0);
+		UMaterialExpression* Bsdf = Desc.MakeNode(Material, IoY);
+		if (!ApplyBsdfModifiers(Bsdf, Modifiers, OutErrors))
+		{
+			return nullptr;
+		}
+
+		// Single Layer Water additionally requires a companion SingleLayerWaterMaterialOutput node — the
+		// lighting / ray-tracing shaders call GetSingleLayerWaterMaterialOutputN, which only exists when that
+		// node is in the graph. Add it up-front (so even an empty water body compiles); wire it below.
+		UMaterialExpressionSingleLayerWaterMaterialOutput* WaterOut = nullptr;
+		if (Desc.Type == EShaderLabBsdfType::Water)
+		{
+			WaterOut = NewExpr<UMaterialExpressionSingleLayerWaterMaterialOutput>(Material, IoY, -600);
+		}
 
 		TArray<const FSlabFieldDef*> UsedSlab;
-		for (const FSlabFieldDef& F : GSlabFields)
+		for (int32 i = 0; i < Desc.NumFields; ++i)
 		{
+			const FSlabFieldDef& F = Desc.Fields[i];
 			if (ReferencesToken(InBody, OutParamName + TEXT(".") + F.Field))
 			{
 				UsedSlab.Add(&F);
@@ -1344,14 +1679,16 @@ namespace ShaderLabGraph
 		}
 		const bool bUsesOpacity = bAllowMaterialOutputs && ReferencesToken(InBody, OutParamName + TEXT(".Opacity"));
 		const bool bUsesOpacityMask = bAllowMaterialOutputs && ReferencesToken(InBody, OutParamName + TEXT(".OpacityMask"));
+		const bool bUsesRefraction = bAllowMaterialOutputs && ReferencesToken(InBody, OutParamName + TEXT(".Refraction"));
+		const bool bUsesPDO = bAllowMaterialOutputs && ReferencesToken(InBody, OutParamName + TEXT(".PixelDepthOffset"));
 
-		if (UsedSlab.Num() == 0 && !bUsesOpacity && !bUsesOpacityMask)
+		if (UsedSlab.Num() == 0 && !bUsesOpacity && !bUsesOpacityMask && !bUsesRefraction && !bUsesPDO)
 		{
-			return Slab; // Empty body: a default Substrate slab.
+			return Bsdf; // Empty body: a default Substrate BSDF.
 		}
 
 		UMaterialExpressionCustom* Custom = NewExpr<UMaterialExpressionCustom>(Material, IoY, -300);
-		Custom->Description = TEXT("ShaderLab Surface");
+		Custom->Description = Desc.CustomDesc;
 		Custom->OutputType = CMOT_Float1;
 		AddIncludes(*Custom, Model);
 
@@ -1369,11 +1706,11 @@ namespace ShaderLabGraph
 			In.Input.Connect(Wire.OutputIndex, Wire.Expr);
 			Custom->Inputs.Add(In);
 		}
-		WirePropInputs(*Custom, Program, PropertyNodes, InBody, ReqProps);
+		WirePropInputs(*Custom, Program, PropertyNodes, InBody, ReqProps, Model.Collections);
 
 		const FString SrcPath = MakeLineDirectivePath(Model.SourceFilePath);
-		FString Code = FString::Printf(TEXT("FShaderLabSurface %s = ShaderLabDefaultSurface();\n{\n%s}\n"),
-			*OutParamName, *WrapBodyWithLineMapping(Body, BodyLine, SrcPath));
+		FString Code = FString::Printf(TEXT("%s %s = %s();\n{\n%s}\n"),
+			Desc.StructName, *OutParamName, Desc.DefaultFn, *WrapBodyWithLineMapping(Body, BodyLine, SrcPath));
 
 		int32 OutputIndex = 1; // index 0 is the (unused) main return
 		TArray<TPair<const FSlabFieldDef*, int32>> SlabOutputs;
@@ -1403,20 +1740,54 @@ namespace ShaderLabGraph
 			Code += FString::Printf(TEXT("SLO_OpacityMask = %s.OpacityMask;\n"), *OutParamName);
 			OpacityMaskOutIdx = OutputIndex++;
 		}
+		int32 RefractionOutIdx = INDEX_NONE;
+		int32 PDOOutIdx = INDEX_NONE;
+		if (bUsesRefraction)
+		{
+			FCustomOutput Out; Out.OutputName = TEXT("SLO_Refraction"); Out.OutputType = CMOT_Float1;
+			Custom->AdditionalOutputs.Add(Out);
+			Code += FString::Printf(TEXT("SLO_Refraction = %s.Refraction;\n"), *OutParamName);
+			RefractionOutIdx = OutputIndex++;
+		}
+		if (bUsesPDO)
+		{
+			FCustomOutput Out; Out.OutputName = TEXT("SLO_PixelDepthOffset"); Out.OutputType = CMOT_Float1;
+			Custom->AdditionalOutputs.Add(Out);
+			Code += FString::Printf(TEXT("SLO_PixelDepthOffset = %s.PixelDepthOffset;\n"), *OutParamName);
+			PDOOutIdx = OutputIndex++;
+		}
 		Code += TEXT("return 0.0f;\n");
 		Custom->Code = Code;
 		Custom->RebuildOutputs();
 
 		for (const TPair<const FSlabFieldDef*, int32>& Pair : SlabOutputs)
 		{
-			if (FExpressionInput* Pin = GetSlabPin(Slab, Pair.Key->Field))
+			if (FExpressionInput* Pin = Desc.GetPin(Bsdf, Pair.Key->Field))
 			{
 				Pin->Connect(Pair.Value, Custom);
 			}
 		}
 		if (OpacityOutIdx != INDEX_NONE) { EditorOnly.Opacity.Connect(OpacityOutIdx, Custom); }
 		if (OpacityMaskOutIdx != INDEX_NONE) { EditorOnly.OpacityMask.Connect(OpacityMaskOutIdx, Custom); }
-		return Slab;
+		if (RefractionOutIdx != INDEX_NONE) { EditorOnly.Refraction.Connect(RefractionOutIdx, Custom); }
+		if (PDOOutIdx != INDEX_NONE) { EditorOnly.PixelDepthOffset.Connect(PDOOutIdx, Custom); }
+
+		// Wire the water volume fields into the companion output node (by matching Custom output field name).
+		if (WaterOut)
+		{
+			auto ConnectWaterOut = [&](FExpressionInput& Pin, const TCHAR* FieldName)
+			{
+				for (const TPair<const FSlabFieldDef*, int32>& P : SlabOutputs)
+				{
+					if (FCString::Strcmp(P.Key->Field, FieldName) == 0) { Pin.Connect(P.Value, Custom); return; }
+				}
+			};
+			ConnectWaterOut(WaterOut->ScatteringCoefficients, TEXT("WaterAlbedo"));
+			ConnectWaterOut(WaterOut->AbsorptionCoefficients, TEXT("WaterExtinction"));
+			ConnectWaterOut(WaterOut->PhaseG, TEXT("WaterPhaseG"));
+			ConnectWaterOut(WaterOut->ColorScaleBehindWater, TEXT("ColorScaleBehindWater"));
+		}
+		return Bsdf;
 	}
 
 	/**
@@ -1450,7 +1821,7 @@ namespace ShaderLabGraph
 			In.Input.Connect(Wire.OutputIndex, Wire.Expr);
 			Custom->Inputs.Add(In);
 		}
-		WirePropInputs(*Custom, Program, PropertyNodes, InBody, ReqProps);
+		WirePropInputs(*Custom, Program, PropertyNodes, InBody, ReqProps, Model.Collections);
 
 		const bool bUsesColor = ReferencesToken(InBody, OutParamName + TEXT(".Color"));
 		const bool bUsesOpacity = ReferencesToken(InBody, OutParamName + TEXT(".Opacity"));
@@ -1512,7 +1883,7 @@ namespace ShaderLabGraph
 			In.Input.Connect(Wire.OutputIndex, Wire.Expr);
 			Custom->Inputs.Add(In);
 		}
-		WirePropInputs(*Custom, Program, PropertyNodes, Value.Body, ReqProps);
+		WirePropInputs(*Custom, Program, PropertyNodes, Value.Body, ReqProps, Model.Collections);
 
 		// The body itself contains `return <scalar>;`, so it is the Custom function's body directly.
 		const FString SrcPath = MakeLineDirectivePath(Model.SourceFilePath);
@@ -1553,7 +1924,7 @@ namespace ShaderLabGraph
 			In.Input.Connect(Wire.OutputIndex, Wire.Expr);
 			Custom->Inputs.Add(In);
 		}
-		WirePropInputs(*Custom, Program, PropertyNodes, Interp.Body, ReqProps);
+		WirePropInputs(*Custom, Program, PropertyNodes, Interp.Body, ReqProps, Model.Collections);
 
 		// The body contains `return <expr>;`, so it is the Custom function's body directly.
 		Custom->Code = WrapBodyWithLineMapping(Body, Interp.BodyLine, MakeLineDirectivePath(Model.SourceFilePath));
@@ -1613,7 +1984,7 @@ namespace ShaderLabGraph
 	/** Recursively build the Substrate expression for topology node `Index`. Returns nullptr on error. */
 	static UMaterialExpression* BuildTopologyNode(
 		UMaterial& Material, int32 Index, const FShaderLabModel& Model,
-		const TMap<FName, UMaterialExpressionSubstrateSlabBSDF*>& SlabByName,
+		const TMap<FName, UMaterialExpression*>& SlabByName,
 		const TMap<FName, UMaterialExpressionCustom*>& ValueByName,
 		const TMap<FName, FParamNode>& PropertyNodes,
 		const TMap<FName, UMaterialExpression*>& InterpByName, TSet<FName>& UsedInterps,
@@ -1628,7 +1999,7 @@ namespace ShaderLabGraph
 
 		if (Node.Op == EShaderLabOp::SlabRef)
 		{
-			if (UMaterialExpressionSubstrateSlabBSDF* const* Found = SlabByName.Find(Node.SlabRef))
+			if (UMaterialExpression* const* Found = SlabByName.Find(Node.SlabRef))
 			{
 				return *Found;
 			}
@@ -1862,6 +2233,50 @@ bool FShaderLabGraphBuilder::BuildInto(UMaterial& Material, const FShaderLabMode
 	TMap<FName, UMaterialExpression*> InterpByName;
 	TSet<FName> UsedInterps;
 
+	// CustomPrimitiveData contract: author-specified slot indices must fit the fixed float budget and must
+	// not overlap. Scalar occupies 1 float, Vector 4 (starting at PrimitiveDataIndex). Validated across all
+	// declared CPD properties (parser already guarantees Scalar/Vector-only + a non-negative index).
+	{
+		constexpr int32 NumFloats = FCustomPrimitiveData::NumCustomPrimitiveDataFloats;
+		int32 SlotOwner[NumFloats];
+		for (int32 i = 0; i < NumFloats; ++i) { SlotOwner[i] = INDEX_NONE; }
+		bool bCpdError = false;
+		for (int32 PropIdx = 0; PropIdx < Program.Properties.Num(); ++PropIdx)
+		{
+			const FShaderLabProperty& Prop = Program.Properties[PropIdx];
+			if (!Prop.bUseCustomPrimitiveData)
+			{
+				continue;
+			}
+			const int32 Size = (Prop.Type == EShaderLabPropertyType::Scalar) ? 1 : 4;
+			const int32 Start = Prop.PrimitiveDataIndex;
+			if (Start + Size > NumFloats)
+			{
+				OutErrors.Add(FString::Printf(
+					TEXT("Property '%s': CustomPrimitiveData index %d + %d float(s) exceeds the %d-float budget"),
+					*Prop.Name.ToString(), Start, Size, NumFloats));
+				bCpdError = true;
+				continue;
+			}
+			for (int32 s = Start; s < Start + Size; ++s)
+			{
+				if (SlotOwner[s] != INDEX_NONE)
+				{
+					OutErrors.Add(FString::Printf(
+						TEXT("Property '%s': CustomPrimitiveData slot %d overlaps property '%s'"),
+						*Prop.Name.ToString(), s, *Program.Properties[SlotOwner[s]].Name.ToString()));
+					bCpdError = true;
+					break;
+				}
+				SlotOwner[s] = PropIdx;
+			}
+		}
+		if (bCpdError)
+		{
+			return false; // Contract-style hard failure (surfaced through the standard error path).
+		}
+	}
+
 	for (const FShaderLabProperty& Prop : Program.Properties)
 	{
 		const FString NameStr = Prop.Name.ToString();
@@ -1918,10 +2333,18 @@ bool FShaderLabGraphBuilder::BuildInto(UMaterial& Material, const FShaderLabMode
 			E->DefaultValue = Prop.ScalarDefault;
 			E->Group = FName(*Prop.Group);
 			E->SortPriority = Prop.SortPriority;
-			if (Prop.bHasRange)
+			if (Prop.bHasClampMin)
 			{
-				E->SliderMin = Prop.RangeMin;
-				E->SliderMax = Prop.RangeMax;
+				E->SliderMin = Prop.ClampMin;
+			}
+			if (Prop.bHasClampMax)
+			{
+				E->SliderMax = Prop.ClampMax;
+			}
+			if (Prop.bUseCustomPrimitiveData)
+			{
+				E->bUseCustomPrimitiveData = true;
+				E->PrimitiveDataIndex = static_cast<uint8>(Prop.PrimitiveDataIndex);
 			}
 			Node.Expr = E;
 			break;
@@ -1934,6 +2357,11 @@ bool FShaderLabGraphBuilder::BuildInto(UMaterial& Material, const FShaderLabMode
 			E->DefaultValue = Prop.VectorDefault;
 			E->Group = FName(*Prop.Group);
 			E->SortPriority = Prop.SortPriority;
+			if (Prop.bUseCustomPrimitiveData)
+			{
+				E->bUseCustomPrimitiveData = true;
+				E->PrimitiveDataIndex = static_cast<uint8>(Prop.PrimitiveDataIndex);
+			}
 			Node.Expr = E;
 			break;
 		}
@@ -1951,6 +2379,22 @@ bool FShaderLabGraphBuilder::BuildInto(UMaterial& Material, const FShaderLabMode
 			Node.bIsTexture = true;
 			break;
 		}
+		case EShaderLabPropertyType::Texture2DArray:
+		case EShaderLabPropertyType::Texture3D:
+		case EShaderLabPropertyType::TextureCubeArray:
+		{
+			// Array / volume texture object parameter. The engine assigns a matching-dimension default when
+			// Texture is left null; the artist binds a real asset on the Material Instance. (Built-in white/
+			// black/grey/normal default tokens only exist for Texture2D, so they are not applied here.)
+			UMaterialExpressionTextureObjectParameter* E = NewExpr<UMaterialExpressionTextureObjectParameter>(Material, ParamY, -1000);
+			E->ParameterName = Prop.Name;
+			E->Group = FName(*Prop.Group);
+			E->SortPriority = Prop.SortPriority;
+			E->SamplerType = SAMPLERTYPE_Color;
+			Node.Expr = E;
+			Node.bIsTexture = true;
+			break;
+		}
 		default:
 			break;
 		}
@@ -1960,6 +2404,41 @@ bool FShaderLabGraphBuilder::BuildInto(UMaterial& Material, const FShaderLabMode
 		}
 	}
 
+	// 1a2) Material Parameter Collection reads (SL_COLLECTION): a CollectionParameter node per referenced
+	// declaration, registered in PropertyNodes so WirePropInputs wires it into bodies exactly like a property.
+	for (const FShaderLabCollectionParam& C : Model.Collections)
+	{
+		const FString NameStr = C.Name.ToString();
+		bool bRef = Model.bHasSurface && ReferencesToken(Model.SurfaceBody, NameStr);
+		for (const FShaderLabSlab& Slab : Model.Slabs) { bRef |= ReferencesToken(Slab.Body, NameStr); }
+		for (const FShaderLabValue& Value : Model.Values) { bRef |= ReferencesToken(Value.Body, NameStr); }
+		for (const FShaderLabInterpolator& Interp : Model.Interpolators) { bRef |= ReferencesToken(Interp.Body, NameStr); }
+		if (Model.bHasVertex) { bRef |= ReferencesToken(Model.VertexBody, NameStr); }
+		if (!bRef)
+		{
+			continue; // Declared but unreferenced: skip (keeps the graph minimal/deterministic).
+		}
+		UMaterialParameterCollection* Coll = LoadObject<UMaterialParameterCollection>(nullptr, *C.CollectionPath);
+		if (!Coll)
+		{
+			OutErrors.Add(FString::Printf(TEXT("SL_COLLECTION '%s': cannot load Material Parameter Collection '%s'"), *NameStr, *C.CollectionPath));
+			return false;
+		}
+		const FGuid ParamId = Coll->GetParameterId(C.ParameterName);
+		if (!ParamId.IsValid())
+		{
+			OutErrors.Add(FString::Printf(TEXT("SL_COLLECTION '%s': parameter '%s' not found in '%s'"), *NameStr, *C.ParameterName.ToString(), *C.CollectionPath));
+			return false;
+		}
+		UMaterialExpressionCollectionParameter* E = NewExpr<UMaterialExpressionCollectionParameter>(Material, ParamY, -1000);
+		E->Collection = Coll;
+		E->ParameterName = C.ParameterName;
+		E->ParameterId = ParamId;
+		FParamNode Node;
+		Node.Expr = E;
+		PropertyNodes.Add(C.Name, Node);
+	}
+
 	// 1b) Build a Vertex Interpolator node per declared interpolator (Custom @ vertex freq -> VertexInterpolator).
 	for (const FShaderLabInterpolator& Interp : Model.Interpolators)
 	{
@@ -1998,7 +2477,8 @@ bool FShaderLabGraphBuilder::BuildInto(UMaterial& Material, const FShaderLabMode
 	{
 		// Single-Surface sugar: one slab straight to FrontMaterial, with S.Opacity/S.OpacityMask
 		// allowed as material-level outputs.
-		UMaterialExpressionSubstrateSlabBSDF* Slab = BuildSlab(
+		UMaterialExpression* Slab = BuildBsdf(
+			*FindBsdfDesc(EShaderLabBsdfType::Slab), Model.SurfaceModifiers,
 			Material, *EditorOnly, SurfaceOutParam->Name, Model.SurfaceBody, Model.SurfaceBodyLine,
 			Model, Program, Emit, PropertyNodes, InterpByName, UsedInterps, /*bAllowMaterialOutputs*/ true, ParamY, OutErrors);
 		if (!Slab)
@@ -2009,9 +2489,10 @@ bool FShaderLabGraphBuilder::BuildInto(UMaterial& Material, const FShaderLabMode
 	}
 	else
 	{
-		// Multi-slab: each named Slab -> its own slab node; Value blocks -> scalar Custom nodes; the
-		// FrontMaterial topology tree mixes them; Opacity/OpacityMask come from named Value blocks.
-		TMap<FName, UMaterialExpressionSubstrateSlabBSDF*> SlabByName;
+		// Multi-BSDF: each named block -> its own Substrate BSDF node (type from FShaderLabSlab.BsdfType);
+		// Value blocks -> scalar Custom nodes; the FrontMaterial topology tree mixes them; Opacity/OpacityMask
+		// come from named Value blocks.
+		TMap<FName, UMaterialExpression*> SlabByName;
 		for (const FShaderLabSlab& SlabDecl : Model.Slabs)
 		{
 			if (SlabByName.Contains(SlabDecl.Name))
@@ -2019,7 +2500,14 @@ bool FShaderLabGraphBuilder::BuildInto(UMaterial& Material, const FShaderLabMode
 				OutErrors.Add(FString::Printf(TEXT("Duplicate Slab name '%s'"), *SlabDecl.Name.ToString()));
 				return false;
 			}
-			UMaterialExpressionSubstrateSlabBSDF* Slab = BuildSlab(
+			const FBsdfDesc* Desc = FindBsdfDesc(SlabDecl.BsdfType);
+			if (!Desc)
+			{
+				OutErrors.Add(FString::Printf(TEXT("Slab '%s' has an unsupported BSDF type"), *SlabDecl.Name.ToString()));
+				return false;
+			}
+			UMaterialExpression* Slab = BuildBsdf(
+				*Desc, SlabDecl.Modifiers,
 				Material, *EditorOnly, SlabDecl.OutParamName, SlabDecl.Body, SlabDecl.BodyLine,
 				Model, Program, Emit, PropertyNodes, InterpByName, UsedInterps, /*bAllowMaterialOutputs*/ false, ParamY, OutErrors);
 			if (!Slab)
@@ -2046,6 +2534,13 @@ bool FShaderLabGraphBuilder::BuildInto(UMaterial& Material, const FShaderLabMode
 			ValueByName.Add(ValueDecl.Name, ValueNode);
 		}
 
+		// Composition legality: validate operator/BSDF-type combinations up-front (mirrors the engine's Substrate
+		// allow-lists) so an illegal combo errors with a .usl line instead of a generic engine node-name error.
+		if (!Model.ValidateTopology(OutErrors))
+		{
+			return false;
+		}
+
 		// Every declared Slab must be reachable from FrontMaterial (contract: no dead slabs).
 		TSet<FName> ReferencedSlabs;
 		for (const FShaderLabTopoNode& Node : Model.Topology)
@@ -2084,6 +2579,8 @@ bool FShaderLabGraphBuilder::BuildInto(UMaterial& Material, const FShaderLabMode
 		};
 		if (!ConnectMaterialOutput(EditorOnly->Opacity, Model.OpacityValueName, TEXT("Opacity"))) { return false; }
 		if (!ConnectMaterialOutput(EditorOnly->OpacityMask, Model.OpacityMaskValueName, TEXT("OpacityMask"))) { return false; }
+		if (!ConnectMaterialOutput(EditorOnly->Refraction, Model.RefractionValueName, TEXT("Refraction"))) { return false; }
+		if (!ConnectMaterialOutput(EditorOnly->PixelDepthOffset, Model.PixelDepthOffsetValueName, TEXT("PixelDepthOffset"))) { return false; }
 	}
 
 	// 3) Optional Vertex stage. Per-pixel/vertex context is read via UE_* intrinsics, so the entry
@@ -2128,7 +2625,7 @@ bool FShaderLabGraphBuilder::BuildInto(UMaterial& Material, const FShaderLabMode
 				In.Input.Connect(Wire.OutputIndex, Wire.Expr);
 				VCustom->Inputs.Add(In);
 			}
-			WirePropInputs(*VCustom, Program, PropertyNodes, Model.VertexBody, VtxReqProps);
+			WirePropInputs(*VCustom, Program, PropertyNodes, Model.VertexBody, VtxReqProps, Model.Collections);
 
 			const FString VSrcPath = MakeLineDirectivePath(Model.SourceFilePath);
 			Code += FString::Printf(TEXT("FShaderLabVertex %s = ShaderLabDefaultVertex();\n{\n%s}\n"),
@@ -2186,6 +2683,88 @@ bool FShaderLabGraphBuilder::BuildInto(UMaterial& Material, const FShaderLabMode
 		}
 	}
 
+	// Read-only permutation macros (SHADERLAB_QUALITY / _FEATURELEVEL / _SHADINGPATH). When a body references
+	// one, wire the matching engine switch (Quality/FeatureLevel/ShadingPath) with per-branch `#define` Custom
+	// nodes into the ParameterAnchor. The switch compiles ONLY the branch for the current permutation (verified
+	// for the real, non-validating compile), so exactly one ordered value leaks ahead of every body `#if`.
+	{
+		auto AnyBodyUses = [&](const TCHAR* Token) -> bool
+		{
+			if (Model.bHasSurface && ReferencesToken(Model.SurfaceBody, Token)) { return true; }
+			for (const FShaderLabSlab& Slab : Model.Slabs) { if (ReferencesToken(Slab.Body, Token)) { return true; } }
+			for (const FShaderLabValue& Value : Model.Values) { if (ReferencesToken(Value.Body, Token)) { return true; } }
+			for (const FShaderLabInterpolator& Interp : Model.Interpolators) { if (ReferencesToken(Interp.Body, Token)) { return true; } }
+			if (Model.bHasVertex && ReferencesToken(Model.VertexBody, Token)) { return true; }
+			return false;
+		};
+
+		if (AnyBodyUses(TEXT("SHADERLAB_QUALITY")))
+		{
+			UMaterialExpressionQualitySwitch* Sw = NewExpr<UMaterialExpressionQualitySwitch>(Material, ParamY, -1150);
+			// Ordered values: Low<Medium<High<Epic. Engine enum order is Low,High,Medium,Epic.
+			Sw->Default.Connect(0, MakeDefineNode(Material, ParamY, TEXT("SHADERLAB_QUALITY"), TEXT("2")));
+			Sw->Inputs[EMaterialQualityLevel::Low].Connect(0, MakeDefineNode(Material, ParamY, TEXT("SHADERLAB_QUALITY"), TEXT("0")));
+			Sw->Inputs[EMaterialQualityLevel::Medium].Connect(0, MakeDefineNode(Material, ParamY, TEXT("SHADERLAB_QUALITY"), TEXT("1")));
+			Sw->Inputs[EMaterialQualityLevel::High].Connect(0, MakeDefineNode(Material, ParamY, TEXT("SHADERLAB_QUALITY"), TEXT("2")));
+			Sw->Inputs[EMaterialQualityLevel::Epic].Connect(0, MakeDefineNode(Material, ParamY, TEXT("SHADERLAB_QUALITY"), TEXT("3")));
+			AnchorInputs.Add(Sw);
+		}
+		if (AnyBodyUses(TEXT("SHADERLAB_FEATURELEVEL")))
+		{
+			UMaterialExpressionFeatureLevelSwitch* Sw = NewExpr<UMaterialExpressionFeatureLevelSwitch>(Material, ParamY, -1150);
+			Sw->Default.Connect(0, MakeDefineNode(Material, ParamY, TEXT("SHADERLAB_FEATURELEVEL"), TEXT("1")));
+			Sw->Inputs[ERHIFeatureLevel::ES3_1].Connect(0, MakeDefineNode(Material, ParamY, TEXT("SHADERLAB_FEATURELEVEL"), TEXT("0")));
+			Sw->Inputs[ERHIFeatureLevel::SM5].Connect(0, MakeDefineNode(Material, ParamY, TEXT("SHADERLAB_FEATURELEVEL"), TEXT("1")));
+			Sw->Inputs[ERHIFeatureLevel::SM6].Connect(0, MakeDefineNode(Material, ParamY, TEXT("SHADERLAB_FEATURELEVEL"), TEXT("2")));
+			AnchorInputs.Add(Sw);
+		}
+		if (AnyBodyUses(TEXT("SHADERLAB_SHADINGPATH")))
+		{
+			UMaterialExpressionShadingPathSwitch* Sw = NewExpr<UMaterialExpressionShadingPathSwitch>(Material, ParamY, -1150);
+			Sw->Default.Connect(0, MakeDefineNode(Material, ParamY, TEXT("SHADERLAB_SHADINGPATH"), TEXT("0")));
+			Sw->Inputs[ERHIShadingPath::Deferred].Connect(0, MakeDefineNode(Material, ParamY, TEXT("SHADERLAB_SHADINGPATH"), TEXT("0")));
+			Sw->Inputs[ERHIShadingPath::Forward].Connect(0, MakeDefineNode(Material, ParamY, TEXT("SHADERLAB_SHADINGPATH"), TEXT("1")));
+			Sw->Inputs[ERHIShadingPath::Mobile].Connect(0, MakeDefineNode(Material, ParamY, TEXT("SHADERLAB_SHADINGPATH"), TEXT("2")));
+			AnchorInputs.Add(Sw);
+		}
+	}
+
+	// Scene-texture reads: the UE_SceneColor/SceneDepth/CustomDepth/CustomStencil/SceneTexture helpers call the
+	// engine's SceneTextureLookup in HLSL. That only works when the material sets bNeedsSceneTextures, which the
+	// engine derives from a UMaterialExpressionSceneTexture node being present + compiled. We add one hidden node
+	// wired into the ParameterAnchor (compiled before attributes, so its Compile always runs and flips the flag).
+	{
+		auto BodyUsesScene = [](const FString& Body) -> bool
+		{
+			return ReferencesToken(Body, TEXT("UE_SceneColor")) || ReferencesToken(Body, TEXT("UE_SceneDepth"))
+				|| ReferencesToken(Body, TEXT("UE_CustomDepth")) || ReferencesToken(Body, TEXT("UE_CustomStencil"))
+				|| ReferencesToken(Body, TEXT("UE_SceneTexture"));
+		};
+		bool bUsesScene = Model.bHasSurface && BodyUsesScene(Model.SurfaceBody);
+		for (const FShaderLabSlab& Slab : Model.Slabs) { bUsesScene |= BodyUsesScene(Slab.Body); }
+		for (const FShaderLabValue& Value : Model.Values) { bUsesScene |= BodyUsesScene(Value.Body); }
+
+		if (bUsesScene)
+		{
+			const EShaderLabDomain Dom = Model.Settings.Domain;
+			const bool bNonOpaqueSurface = (Dom == EShaderLabDomain::Surface)
+				&& Model.Settings.BlendMode != EShaderLabBlendMode::Opaque
+				&& Model.Settings.BlendMode != EShaderLabBlendMode::Masked;
+			const bool bDomainOk = (Dom == EShaderLabDomain::PostProcess) || (Dom == EShaderLabDomain::Decal) || bNonOpaqueSurface;
+			if (!bDomainOk)
+			{
+				OutErrors.Add(TEXT("Scene-texture reads (UE_SceneColor/UE_SceneDepth/UE_SceneTexture/...) require a PostProcess or Decal material, or a translucent (non-opaque) Surface material."));
+				return false;
+			}
+			// The hidden node flips bNeedsSceneTextures. In PostProcess use PostProcessInput0; elsewhere use
+			// SceneDepth — the only scene-texture family the engine permits outside PostProcess/Decal (scene
+			// color via SceneTexture is disallowed there, so we don't request it).
+			UMaterialExpressionSceneTexture* Hidden = NewExpr<UMaterialExpressionSceneTexture>(Material, ParamY, -1300);
+			Hidden->SceneTextureId = (Dom == EShaderLabDomain::PostProcess) ? PPI_PostProcessInput0 : PPI_SceneDepth;
+			AnchorInputs.Add(Hidden);
+		}
+	}
+
 	// Funnel every static-switch selector into the ParameterAnchor. The anchor is a CustomOutput compiled
 	// BEFORE the material attributes (ShouldCompileBeforeAttributes), so compiling it compiles each
 	// selector — emitting the selected `#define <Name> 0/1` for the current permutation ahead of every