Add a sample showcasing how to render to console

src/SampleApp/Sample/ConsoleRenderExtensions.cs

@@ -0,0 +1,61 @@
+using System.Runtime.CompilerServices;
+using System.Text.Json;
+using Microsoft.Extensions.DependencyInjection;
+
+namespace Devlooped.WhatsApp;
+
+static class ConsoleRenderExtensions
+{
+    /// <summary>
+    /// Renders text message and responses to the console as JSON for 
+    /// troubleshooting.
+    /// </summary>
+    public static WhatsAppHandlerBuilder UseConsoleRender(this WhatsAppHandlerBuilder builder)
+        => builder.Use((inner, services)
+            => new ConsoleRenderHandler(inner, services.GetRequiredService<IWhatsAppClient>()));
+
+    /// <summary>
+    /// Checks whether the given service number ID is a CLI local endpoint.
+    /// </summary>
+    static bool IsCLI(this string serviceId)
+        => serviceId.StartsWith("http://localhost", StringComparison.OrdinalIgnoreCase);
+
+    class ConsoleRenderHandler(IWhatsAppHandler inner, IWhatsAppClient client) : DelegatingWhatsAppHandler(inner)
+    {
+        public override async IAsyncEnumerable<Response> HandleAsync(IEnumerable<IMessage> messages, [EnumeratorCancellation] CancellationToken cancellation = default)
+        {
+            var user = messages.OfType<UserMessage>().LastOrDefault();
+            if (user != null && user.Service.Id.IsCLI())
+            {
+                await client.SendAsync(user,
+                    $"""
+                    ```
+                    {JsonSerializer.Serialize(
+                        messages.Where(x => x is UserMessage || x is TextResponse),
+                        JsonContext.DefaultOptions)}
+                    ```
+                    """);
+            }
+
+            var responses = new List<Response>();
+
+            await foreach (var response in base.HandleAsync(messages, cancellation))
+            {
+                if (response is TextResponse)
+                    responses.Add(response);
+
+                yield return response;
+            }
+
+            if (user != null && user.Service.Id.IsCLI())
+            {
+                await client.SendAsync(user,
+                    $"""
+                    ```
+                    {JsonSerializer.Serialize(responses, JsonContext.DefaultOptions)}
+                    ```
+                    """);
+            }
+        }
+    }
+}

src/SampleApp/Sample/Program.cs

@@ -60,6 +60,8 @@
     .Use(EchoAndHandle)
     .UseConversation(conversationWindowSeconds: 300 /* default */)
     .UseConsole();
+// Uncomment next line to render a JSON of text message/responses 
+//.UseConsoleRender();
 
 // If event grid is set up, switch to processing messages using that
 if (builder.Configuration["EventGrid:Topic"] is { Length: > 0 } topic &&