diff --git a/src/Microsoft.OpenApi.Hidi/Microsoft.OpenApi.Hidi.csproj b/src/Microsoft.OpenApi.Hidi/Microsoft.OpenApi.Hidi.csproj
index 9cec2ceab..921c39e70 100644
--- a/src/Microsoft.OpenApi.Hidi/Microsoft.OpenApi.Hidi.csproj
+++ b/src/Microsoft.OpenApi.Hidi/Microsoft.OpenApi.Hidi.csproj
@@ -16,6 +16,7 @@
     <NoWarn>$(NoWarn);NU5048;NU5104;CA1848;</NoWarn>
     <PackageReadmeFile>readme.md</PackageReadmeFile>
     <AnalysisMode>All</AnalysisMode>
+    <AssemblyOriginatorKeyFile>..\Microsoft.OpenApi.snk</AssemblyOriginatorKeyFile>
   </PropertyGroup>
 
   <ItemGroup>
@@ -51,7 +52,10 @@
   <!-- Make internals available for Unit Testing -->
   <ItemGroup>
     <AssemblyAttribute Include="System.Runtime.CompilerServices.InternalsVisibleTo">
-      <_Parameter1>Microsoft.OpenApi.Hidi.Tests</_Parameter1>
+      <_Parameter1>Microsoft.OpenApi.Hidi.Tests, PublicKey=0024000004800000940000000602000000240000525341310004000001000100957cb48387b2a5f54f5ce39255f18f26d32a39990db27cf48737afc6bc62759ba996b8a2bfb675d4e39f3d06ecb55a178b1b4031dcb2a767e29977d88cce864a0d16bfc1b3bebb0edf9fe285f10fffc0a85f93d664fa05af07faa3aad2e545182dbf787e3fd32b56aca95df1a3c4e75dec164a3f1a4c653d971b01ffc39eb3c4</_Parameter1>
+    </AssemblyAttribute>
+    <AssemblyAttribute Include="System.Runtime.CompilerServices.InternalsVisibleTo">
+      <_Parameter1>DynamicProxyGenAssembly2, PublicKey=0024000004800000940000000602000000240000525341310004000001000100c547cac37abd99c8db225ef2f6c8a3602f3b3606cc9891605d02baa56104f4cfc0734aa39b93bf7852f7d9266654753cc297e7d2edfe0bac1cdcf9f717241550e0a7b191195b7667bb4f64bcb8e2121380fd1d9d46ad2d92d2d15605093924cceaf74c4861eff62abf69b9291ed0a340e113be11e6a7d3113e92484cf7045cc7</_Parameter1>
     </AssemblyAttribute>
   </ItemGroup>
     <!-- End Unit test Internals -->
diff --git a/src/Microsoft.OpenApi.Hidi/Properties/AssemblyInfo.cs b/src/Microsoft.OpenApi.Hidi/Properties/AssemblyInfo.cs
deleted file mode 100644
index e5a59206e..000000000
--- a/src/Microsoft.OpenApi.Hidi/Properties/AssemblyInfo.cs
+++ /dev/null
@@ -1,4 +0,0 @@
-
-using System.Runtime.CompilerServices;
-
-[assembly: InternalsVisibleTo("DynamicProxyGenAssembly2, PublicKey=0024000004800000940000000602000000240000525341310004000001000100c547cac37abd99c8db225ef2f6c8a3602f3b3606cc9891605d02baa56104f4cfc0734aa39b93bf7852f7d9266654753cc297e7d2edfe0bac1cdcf9f717241550e0a7b191195b7667bb4f64bcb8e2121380fd1d9d46ad2d92d2d15605093924cceaf74c4861eff62abf69b9291ed0a340e113be11e6a7d3113e92484cf7045cc7")]
diff --git a/src/Microsoft.OpenApi/Properties/AssemblyInfo.cs b/src/Microsoft.OpenApi/Properties/AssemblyInfo.cs
index 559c86738..272a83e1e 100644
--- a/src/Microsoft.OpenApi/Properties/AssemblyInfo.cs
+++ b/src/Microsoft.OpenApi/Properties/AssemblyInfo.cs
@@ -3,6 +3,9 @@
 
 using System.Runtime.CompilerServices;
 
+[assembly:
+    InternalsVisibleTo(
+        "Microsoft.OpenApi.Hidi, PublicKey=0024000004800000940000000602000000240000525341310004000001000100957cb48387b2a5f54f5ce39255f18f26d32a39990db27cf48737afc6bc62759ba996b8a2bfb675d4e39f3d06ecb55a178b1b4031dcb2a767e29977d88cce864a0d16bfc1b3bebb0edf9fe285f10fffc0a85f93d664fa05af07faa3aad2e545182dbf787e3fd32b56aca95df1a3c4e75dec164a3f1a4c653d971b01ffc39eb3c4")]
 [assembly:
     InternalsVisibleTo(
         "Microsoft.OpenApi.Tests, PublicKey=0024000004800000940000000602000000240000525341310004000001000100957cb48387b2a5f54f5ce39255f18f26d32a39990db27cf48737afc6bc62759ba996b8a2bfb675d4e39f3d06ecb55a178b1b4031dcb2a767e29977d88cce864a0d16bfc1b3bebb0edf9fe285f10fffc0a85f93d664fa05af07faa3aad2e545182dbf787e3fd32b56aca95df1a3c4e75dec164a3f1a4c653d971b01ffc39eb3c4")]
diff --git a/src/Microsoft.OpenApi/Services/OpenApiUrlTreeNode.cs b/src/Microsoft.OpenApi/Services/OpenApiUrlTreeNode.cs
index fd031d8aa..4885f4fe8 100644
--- a/src/Microsoft.OpenApi/Services/OpenApiUrlTreeNode.cs
+++ b/src/Microsoft.OpenApi/Services/OpenApiUrlTreeNode.cs
@@ -251,7 +251,7 @@ public void WriteMermaid(TextWriter writer)
         /// <summary>
         /// Dictionary that maps a set of HTTP methods to HTML color.  Keys are sorted, upper-cased, concatenated HTTP methods.
         /// </summary>
-        public readonly static IReadOnlyDictionary<string, MermaidNodeStyle> MermaidNodeStyles = new Dictionary<string, MermaidNodeStyle>(StringComparer.OrdinalIgnoreCase)
+        internal static readonly IReadOnlyDictionary<string, MermaidNodeStyle> MermaidNodeStyles = new Dictionary<string, MermaidNodeStyle>(StringComparer.OrdinalIgnoreCase)
         {
             { "GET", new MermaidNodeStyle("lightSteelBlue", MermaidNodeShape.SquareCornerRectangle) },
             { "POST", new MermaidNodeStyle("Lightcoral", MermaidNodeShape.OddShape) },
@@ -334,7 +334,7 @@ private static string SanitizeMermaidNode(string token)
     /// <summary>
     /// Defines the color and shape of a node in a Mermaid graph diagram
     /// </summary>
-    public class MermaidNodeStyle
+    internal class MermaidNodeStyle
     {
         /// <summary>
         /// Create a style that defines the color and shape of a diagram element
@@ -361,7 +361,7 @@ internal MermaidNodeStyle(string color, MermaidNodeShape shape)
     /// <summary>
     /// Shapes supported by Mermaid diagrams
     /// </summary>
-    public enum MermaidNodeShape
+    internal enum MermaidNodeShape
     {
         /// <summary>
         /// Rectangle with square corners
diff --git a/test/Microsoft.OpenApi.Hidi.Tests/Microsoft.OpenApi.Hidi.Tests.csproj b/test/Microsoft.OpenApi.Hidi.Tests/Microsoft.OpenApi.Hidi.Tests.csproj
index b06645c39..f9b2b41bf 100644
--- a/test/Microsoft.OpenApi.Hidi.Tests/Microsoft.OpenApi.Hidi.Tests.csproj
+++ b/test/Microsoft.OpenApi.Hidi.Tests/Microsoft.OpenApi.Hidi.Tests.csproj
@@ -8,6 +8,8 @@
     <IsPackable>false</IsPackable>
     <AnalysisMode>All</AnalysisMode>
     <NoWarn>CA2007</NoWarn>
+    <SignAssembly>true</SignAssembly>
+    <AssemblyOriginatorKeyFile>..\..\src\Microsoft.OpenApi.snk</AssemblyOriginatorKeyFile>
   </PropertyGroup>
 
   <ItemGroup>
diff --git a/test/Microsoft.OpenApi.Tests/PublicApi/PublicApi.approved.txt b/test/Microsoft.OpenApi.Tests/PublicApi/PublicApi.approved.txt
index a12c2ee9d..7913206f1 100644
--- a/test/Microsoft.OpenApi.Tests/PublicApi/PublicApi.approved.txt
+++ b/test/Microsoft.OpenApi.Tests/PublicApi/PublicApi.approved.txt
@@ -1,5 +1,6 @@
 [assembly: System.Reflection.AssemblyMetadata("IsTrimmable", "True")]
 [assembly: System.Reflection.AssemblyMetadata("RepositoryUrl", "https://github.com/Microsoft/OpenAPI.NET")]
+[assembly: System.Runtime.CompilerServices.InternalsVisibleTo(@"Microsoft.OpenApi.Hidi, PublicKey=0024000004800000940000000602000000240000525341310004000001000100957cb48387b2a5f54f5ce39255f18f26d32a39990db27cf48737afc6bc62759ba996b8a2bfb675d4e39f3d06ecb55a178b1b4031dcb2a767e29977d88cce864a0d16bfc1b3bebb0edf9fe285f10fffc0a85f93d664fa05af07faa3aad2e545182dbf787e3fd32b56aca95df1a3c4e75dec164a3f1a4c653d971b01ffc39eb3c4")]
 [assembly: System.Runtime.CompilerServices.InternalsVisibleTo(@"Microsoft.OpenApi.Readers.Tests, PublicKey=0024000004800000940000000602000000240000525341310004000001000100957cb48387b2a5f54f5ce39255f18f26d32a39990db27cf48737afc6bc62759ba996b8a2bfb675d4e39f3d06ecb55a178b1b4031dcb2a767e29977d88cce864a0d16bfc1b3bebb0edf9fe285f10fffc0a85f93d664fa05af07faa3aad2e545182dbf787e3fd32b56aca95df1a3c4e75dec164a3f1a4c653d971b01ffc39eb3c4")]
 [assembly: System.Runtime.CompilerServices.InternalsVisibleTo(@"Microsoft.OpenApi.Tests, PublicKey=0024000004800000940000000602000000240000525341310004000001000100957cb48387b2a5f54f5ce39255f18f26d32a39990db27cf48737afc6bc62759ba996b8a2bfb675d4e39f3d06ecb55a178b1b4031dcb2a767e29977d88cce864a0d16bfc1b3bebb0edf9fe285f10fffc0a85f93d664fa05af07faa3aad2e545182dbf787e3fd32b56aca95df1a3c4e75dec164a3f1a4c653d971b01ffc39eb3c4")]
 [assembly: System.Runtime.Versioning.TargetFramework(".NETCoreApp,Version=v8.0", FrameworkDisplayName=".NET 8.0")]
@@ -356,19 +357,6 @@ namespace Microsoft.OpenApi
         Object = 32,
         Array = 64,
     }
-    public enum MermaidNodeShape
-    {
-        SquareCornerRectangle = 0,
-        RoundedCornerRectangle = 1,
-        Circle = 2,
-        Rhombus = 3,
-        OddShape = 4,
-    }
-    public class MermaidNodeStyle
-    {
-        public string Color { get; }
-        public Microsoft.OpenApi.MermaidNodeShape Shape { get; }
-    }
     public sealed class MethodExpression : Microsoft.OpenApi.RuntimeExpression
     {
         public const string Method = "$method";
@@ -1413,7 +1401,6 @@ namespace Microsoft.OpenApi
     }
     public class OpenApiUrlTreeNode
     {
-        public static readonly System.Collections.Generic.IReadOnlyDictionary<string, Microsoft.OpenApi.MermaidNodeStyle> MermaidNodeStyles;
         public System.Collections.Generic.IDictionary<string, System.Collections.Generic.List<string>> AdditionalData { get; set; }
         public System.Collections.Generic.IDictionary<string, Microsoft.OpenApi.OpenApiUrlTreeNode> Children { get; }
         public bool IsParameter { get; }