chore: import upstream snapshot with attribution

dotnet/samples/GettingStartedWithProcesses/Step04/KernelExtensions.cs

@@ -0,0 +1,37 @@
+// Copyright (c) Microsoft. All rights reserved.
+
+using Microsoft.Extensions.DependencyInjection;
+using Microsoft.SemanticKernel;
+using Microsoft.SemanticKernel.Agents;
+using Microsoft.SemanticKernel.ChatCompletion;
+
+namespace Step04;
+
+/// <summary>
+/// Convenience extensions for agent based process patterns.
+/// </summary>
+internal static class KernelExtensions
+{
+    /// <summary>
+    /// Return chat history from a singleton <see cref="IChatHistoryProvider"/>.
+    /// </summary>
+    public static IChatHistoryProvider GetHistory(this Kernel kernel) =>
+        kernel.Services.GetRequiredService<IChatHistoryProvider>();
+
+    /// <summary>
+    /// Access an agent as a keyed service.
+    /// </summary>
+    public static TAgent GetAgent<TAgent>(this Kernel kernel, string key) where TAgent : Agent =>
+        kernel.Services.GetRequiredKeyedService<TAgent>(key);
+
+    /// <summary>
+    /// Summarize chat history using reducer accessed as a keyed service.
+    /// </summary>
+    public static async Task<string> SummarizeHistoryAsync(this Kernel kernel, string key, IReadOnlyList<ChatMessageContent> history)
+    {
+        ChatHistorySummarizationReducer reducer = kernel.Services.GetRequiredKeyedService<ChatHistorySummarizationReducer>(key);
+        IEnumerable<ChatMessageContent>? reducedResponse = await reducer.ReduceAsync(history);
+        ChatMessageContent summary = reducedResponse?.First() ?? throw new InvalidDataException("No summary available");
+        return summary.ToString();
+    }
+}