3 files changed, 46 insertions, 4 deletions

diff --git a/src/api/wix/WixToolset.Extensibility/BaseLibrarianExtension.cs b/src/api/wix/WixToolset.Extensibility/BaseLibrarianExtension.cs
index cbc9e4ba..ff5edae3 100644
--- a/src/api/wix/WixToolset.Extensibility/BaseLibrarianExtension.cs
+++ b/src/api/wix/WixToolset.Extensibility/BaseLibrarianExtension.cs
@@ -48,8 +48,8 @@ namespace WixToolset.Extensibility
         /// <summary>
         /// Called at the end of combining.
         /// </summary>
-        /// <param name="library">Combined library intermediate.</param>
-        public virtual void PostCombine(Intermediate library)
+        /// <param name="result">Combined library result.</param>
+        public virtual void PostCombine(ILibraryResult result)
         {
         }
 
diff --git a/src/api/wix/WixToolset.Extensibility/Data/ILibraryResult.cs b/src/api/wix/WixToolset.Extensibility/Data/ILibraryResult.cs
new file mode 100644
index 00000000..6974e265
--- /dev/null
+++ b/src/api/wix/WixToolset.Extensibility/Data/ILibraryResult.cs
@@ -0,0 +1,25 @@
+// Copyright (c) .NET Foundation and contributors. All rights reserved. Licensed under the Microsoft Reciprocal License. See LICENSE.TXT file in the project root for full license information.
+
+namespace WixToolset.Extensibility.Data
+{
+    using System;
+    using System.Collections.Generic;
+    using System.Threading;
+    using WixToolset.Data;
+
+    /// <summary>
+    /// Result of a library combine operation.
+    /// </summary>
+    public interface ILibraryResult
+    {
+        /// <summary>
+        /// Collection of files tracked when binding files into the library.
+        /// </summary>
+        IReadOnlyCollection<ITrackedFile> TrackedFiles { get; set; }
+
+        /// <summary>
+        /// Output of librarian.
+        /// </summary>
+        Intermediate Library { get; set; }
+    }
+}
diff --git a/src/api/wix/WixToolset.Extensibility/ILibrarianExtension.cs b/src/api/wix/WixToolset.Extensibility/ILibrarianExtension.cs
index d9b04cd2..d25da5e4 100644
--- a/src/api/wix/WixToolset.Extensibility/ILibrarianExtension.cs
+++ b/src/api/wix/WixToolset.Extensibility/ILibrarianExtension.cs
@@ -5,13 +5,30 @@ namespace WixToolset.Extensibility
     using WixToolset.Data;
     using WixToolset.Extensibility.Data;
 
-#pragma warning disable 1591 // TODO: add documentation
+    /// <summary>
+    /// Interface all librarian extensions implement.
+    /// </summary>
     public interface ILibrarianExtension
     {
+        /// <summary>
+        /// Called at the beginning of combining.
+        /// </summary>
+        /// <param name="context">Librarian context.</param>
         void PreCombine(ILibraryContext context);
 
+        /// <summary>
+        /// Resolves a path to a file path on disk.
+        /// </summary>
+        /// <param name="sourceLineNumber">Source line number for the path to resolve.</param>
+        /// <param name="symbolDefinition">Symbol related to the path to resolve.</param>
+        /// <param name="path">Path to resolve.</param>
+        /// <returns>Optional resolved file result.</returns>
         IResolveFileResult ResolveFile(SourceLineNumber sourceLineNumber, IntermediateSymbolDefinition symbolDefinition, string path);
 
-        void PostCombine(Intermediate library);
+        /// <summary>
+        /// Called at the end of combining.
+        /// </summary>
+        /// <param name="result">Combined library result.</param>
+        void PostCombine(ILibraryResult result);
     }
 }