rendering: document managed srp v1 boundaries

managed/XCEngine.ScriptCore/Rendering/Core/DirectionalShadowExecutionContext.cs

@@ -1,5 +1,8 @@
 namespace XCEngine.Rendering
 {
+    // SRP v1 shadow hook only configures whether the native main directional
+    // shadow execution should run. It does not expose a custom managed shadow
+    // graph or scene backend.
     public sealed class DirectionalShadowExecutionContext
     {
         private readonly ulong m_nativeHandle;

managed/XCEngine.ScriptCore/Rendering/Core/RenderSceneSetupContext.cs

@@ -1,5 +1,7 @@
 namespace XCEngine.Rendering
 {
+    // Managed hook for scene-setup policy only. Scene extraction, culling, and
+    // the actual scene draws still execute through the native backend.
     public sealed class RenderSceneSetupContext
     {
         private readonly ulong m_nativeHandle;

managed/XCEngine.ScriptCore/Rendering/Core/ScriptableRenderContext.cs

@@ -2,6 +2,9 @@ using XCEngine;
 
 namespace XCEngine.Rendering
 {
+    // SRP v1 managed recording surface. Scene recording still delegates to the
+    // native SceneDrawBackend, and raster-pass recording is limited to the
+    // fullscreen PostProcess / FinalOutput stages.
     public sealed class ScriptableRenderContext
     {
         private readonly ulong m_nativeHandle;
@@ -38,6 +41,9 @@ namespace XCEngine.Rendering
                     .Rendering_ScriptableRenderContext_GetDepthTargetHandle(
                         m_nativeHandle));
 
+        // Records the default native scene sequence for MainScene or explicit
+        // scene-pass-request stages. This does not replace the native scene
+        // extraction / culling / draw backend.
         public bool RecordScene()
         {
             return RecordBeforeOpaqueInjection() &&
@@ -241,6 +247,9 @@ namespace XCEngine.Rendering
                         name));
         }
 
+        // SRP v1 wrapper over managed fullscreen raster requests. Commit only
+        // succeeds on fullscreen sequence stages and the execution kinds remain
+        // limited to the built-in fullscreen pass family.
         public RenderGraphRasterPassBuilder AddRasterPass(
             string passName)
         {

managed/XCEngine.ScriptCore/Rendering/Core/ScriptableRenderPipelinePlanningContext.cs

@@ -2,6 +2,9 @@ using XCEngine;
 
 namespace XCEngine.Rendering
 {
+    // SRP v1 planning surface. Managed planning can request fullscreen stages
+    // plus depth / shadow side stages, but main-scene backend ownership stays
+    // on the native pipeline and scene draw backend.
     public sealed class ScriptableRenderPipelinePlanningContext
     {
         private readonly ulong m_nativeHandle;
@@ -49,6 +52,8 @@ namespace XCEngine.Rendering
             CameraFrameColorSource source,
             bool usesGraphManagedOutputColor = false)
         {
+            // Only PostProcess / FinalOutput are valid fullscreen sequence
+            // stages here. Other stages return false and remain unchanged.
             return InternalCalls
                 .Rendering_ScriptableRenderPipelinePlanningContext_RequestFullscreenStage(
                     m_nativeHandle,

managed/XCEngine.ScriptCore/Rendering/Graph/RenderGraphRasterPassBuilder.cs

@@ -12,6 +12,9 @@ namespace XCEngine.Rendering
         FinalColorFullscreen = 3
     }
 
+    // Managed SRP v1 raster recording is intentionally narrow: this builder
+    // only describes fullscreen raster passes that map onto the built-in
+    // ColorScale / ShaderVector / FinalColor executions.
     public sealed class RenderGraphRasterPassBuilder
     {
         private struct TextureBindingRequest
@@ -184,6 +187,8 @@ namespace XCEngine.Rendering
 
         public bool Commit()
         {
+            // Native bridge rejects raster pass recording outside the
+            // fullscreen sequence stages.
             if (m_finalized ||
                 !HasExecutionConfigured() ||
                 !HasAnyColorAttachment())