loadTransforms flag for LoadSession methods

LLama/ChatSession.cs

@@ -178,17 +178,17 @@ public class ChatSession
     /// Load a session from a session state.
     /// </summary>
     /// <param name="state"></param>
+    /// <param name="loadTransforms">If true loads transforms saved in the session state.</param>
     /// <returns></returns>
     /// <exception cref="ArgumentException"></exception>
-    public void LoadSession(SessionState state)
+    public void LoadSession(SessionState state, bool loadTransforms = true)
     {
         if (Executor is StatefulExecutorBase statefulExecutor)
         {
-            statefulExecutor.LoadState(state.ExecutorState);
-        }
-        else
-        {
-            throw new ArgumentException("Executor must be a StatefulExecutorBase to support loading of session state", nameof(state));
+            if (state.ExecutorState is not null)
+            {
+                statefulExecutor.LoadState(state.ExecutorState);
+            }
         }
         if (state.ContextState is null)
         {
@@ -199,18 +199,22 @@ public class ChatSession
             Executor.Context.LoadState(state.ContextState);
         }
         History = new ChatHistory(state.History);
-        InputTransformPipeline = state.InputTransformPipeline.Select(t => t.Clone()).ToList();
-        OutputTransform = state.OutputTransform.Clone();
-        HistoryTransform = state.HistoryTransform.Clone();
+        if (loadTransforms)
+        {
+            InputTransformPipeline = state.InputTransformPipeline.Select(t => t.Clone()).ToList();
+            OutputTransform = state.OutputTransform.Clone();
+            HistoryTransform = state.HistoryTransform.Clone();
+        }
     }
 
     /// <summary>
     /// Load a session from a directory.
     /// </summary>
     /// <param name="path"></param>
+    /// <param name="loadTransforms">If true loads transforms saved in the session state.</param>
     /// <returns></returns>
     /// <exception cref="ArgumentException"></exception>
-    public void LoadSession(string path)
+    public void LoadSession(string path, bool loadTransforms = true)
     {
         var state = SessionState.Load(path);
         // Handle non-polymorphic serialization of executor state
@@ -219,7 +223,7 @@ public class ChatSession
             var executorPath = Path.Combine(path, EXECUTOR_STATE_FILENAME);
             ((StatefulExecutorBase) Executor).LoadState(filename: executorPath); 
         }
-        LoadSession(state);
+        LoadSession(state, loadTransforms);
     }
 
     /// <summary>