Add ActivityCompleted notification for workflow activity completion (#6675)

* Initial plan for issue

* Add ActivityCompleted notification and send it when activity completes

Co-authored-by: sfmskywalker <938393+sfmskywalker@users.noreply.github.com>

* Prepare implementation plan for ActivityCompleted notification

Co-authored-by: sfmskywalker <938393+sfmskywalker@users.noreply.github.com>

* Move ActivityCompleted notification to NotificationPublishingMiddleware

Co-authored-by: sfmskywalker <938393+sfmskywalker@users.noreply.github.com>

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: sfmskywalker <938393+sfmskywalker@users.noreply.github.com>

src/modules/Elsa.Workflows.Core/Middleware/Activities/NotificationPublishingMiddleware.cs

@@ -5,7 +5,12 @@ using Elsa.Workflows.Pipelines.ActivityExecution;
 namespace Elsa.Workflows.Middleware.Activities;
 
 /// <summary>
-/// An activity execution middleware component that publishes <see cref="ActivityExecuting"/> and <see cref="ActivityExecuted"/> events as an activity executes.
+/// An activity execution middleware component that publishes activity notifications:
+/// <list type="bullet">
+/// <item><see cref="ActivityExecuting"/> when an activity starts executing</item>
+/// <item><see cref="ActivityExecuted"/> when an activity has executed</item>
+/// <item><see cref="Notifications.ActivityCompleted"/> when an activity transitions from Running to Completed status</item>
+/// </list>
 /// </summary>
 public class NotificationPublishingMiddleware : IActivityExecutionMiddleware
 {
@@ -24,19 +29,31 @@ public class NotificationPublishingMiddleware : IActivityExecutionMiddleware
     /// <inheritdoc />
     public async ValueTask InvokeAsync(ActivityExecutionContext context)
     {
+        // Store the status before execution
+        var statusBeforeExecution = context.Status;
+        
+        // Send notification that activity is executing
         await _notificationSender.SendAsync(new ActivityExecuting(context));
+        
+        // Execute the activity
         await _next(context);
+        
+        // Send notification that activity has executed
         await _notificationSender.SendAsync(new ActivityExecuted(context));
+        
+        // Send notification that activity has completed if status transitioned from Running to Completed
+        if (statusBeforeExecution == ActivityStatus.Running && context.Status == ActivityStatus.Completed)
+            await _notificationSender.SendAsync(new Notifications.ActivityCompleted(context));
     }
 }
 
 /// <summary>
-/// Extends <see cref="IActivityExecutionPipelineBuilder"/> to install the <see cref="LoggingMiddleware"/> component.
+/// Extends <see cref="IActivityExecutionPipelineBuilder"/> to install the <see cref="NotificationPublishingMiddleware"/> component.
 /// </summary>
 public static class NotificationPublishingMiddlewareExtensions
 {
     /// <summary>
-    /// Installs the <see cref="LoggingMiddleware"/> component.
+    /// Installs the <see cref="NotificationPublishingMiddleware"/> component.
     /// </summary>
     public static IActivityExecutionPipelineBuilder UseNotifications(this IActivityExecutionPipelineBuilder pipelineBuilder) => pipelineBuilder.UseMiddleware<NotificationPublishingMiddleware>();
 }

src/modules/Elsa.Workflows.Core/Notifications/ActivityCompleted.cs

@@ -0,0 +1,9 @@
+using Elsa.Mediator.Contracts;
+
+namespace Elsa.Workflows.Notifications;
+
+/// <summary>
+/// A notification that is sent when an activity has completed.
+/// </summary>
+/// <param name="ActivityExecutionContext">The activity execution context.</param>
+public record ActivityCompleted(ActivityExecutionContext ActivityExecutionContext) : INotification;

tempvalidator/Program.cs

@@ -0,0 +1,2 @@
+// See https://aka.ms/new-console-template for more information
+Console.WriteLine("Hello, World!");

tempvalidator/tempvalidator.csproj

@@ -0,0 +1,10 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFramework>net8.0</TargetFramework>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+  </PropertyGroup>
+
+</Project>