.NET: [BREAKING] Implement Polymorphic Routing (#3792)

* feat: Implement Polymorphic Routing

* feat: Add support for Send/Yield annotations with basic Executor

* Adds annotations to Declarative workflow executors

* fix: Address PR Comments

* Implicit filter in collection loops
* Remove debug / usused / superfluous code
* Fix ProtocolBuilder implicit output registrations
* Fix logic error in ExecuteRouteGeneratorTests.ClassWithManualConfigureProtocol_DoesNotGenerate

* fix: Solidify type checks and send/yield type registrations

* fix: Suppress generation of TurnTokens out of AggregateTurnMessagesExecutor

* Fixes an issue where ConcurrentEndExecutor is not expecting TurnTokens.

* fix: Add ProtocolBuilder support for chained-delegation

* Updates Declarative pacakge to rely on chained-delegation Send/Yield registration
* Renames DeclarativeActionExectuor's new ExecuteAsync to ExecuteActionAsync to avoid colliding with Executor.ExecutoeAsync

* fix: Address PR Comments

* Fixes type mapping in FanInEdgeRunner
* Fixes and expalins send/yield type registration in FunctionExecutor

* fixup: build-break

* fix: Add missing SendsMesage declaration to InvokeAzureAgentExecutor

dotnet/samples/GettingStarted/Workflows/Agents/CustomAgentExecutors/CustomAgentExecutors.csproj

@@ -16,6 +16,9 @@
 
   <ItemGroup>
     <ProjectReference Include="..\..\..\..\..\src\Microsoft.Agents.AI.Workflows\Microsoft.Agents.AI.Workflows.csproj" />
+    <ProjectReference Include="..\..\..\..\..\src\Microsoft.Agents.AI.Workflows.Generators\Microsoft.Agents.AI.Workflows.Generators.csproj"
+                      OutputItemType="Analyzer"
+                      ReferenceOutputAssembly="false" />
     <ProjectReference Include="..\..\..\..\..\src\Microsoft.Agents.AI\Microsoft.Agents.AI.csproj" />
   </ItemGroup>
 

dotnet/samples/GettingStarted/Workflows/Agents/CustomAgentExecutors/Program.cs

@@ -109,7 +109,7 @@ internal sealed class SloganGeneratedEvent(SloganResult sloganResult) : Workflow
 /// 1. HandleAsync(string message): Handles the initial task to create a slogan.
 /// 2. HandleAsync(Feedback message): Handles feedback to improve the slogan.
 /// </summary>
-internal sealed class SloganWriterExecutor : Executor
+internal sealed partial class SloganWriterExecutor : Executor
 {
     private readonly AIAgent _agent;
     private AgentSession? _session;
@@ -133,10 +133,7 @@ internal sealed class SloganWriterExecutor : Executor
         this._agent = new ChatClientAgent(chatClient, agentOptions);
     }
 
-    protected override RouteBuilder ConfigureRoutes(RouteBuilder routeBuilder) =>
-        routeBuilder.AddHandler<string, SloganResult>(this.HandleAsync)
-                    .AddHandler<FeedbackResult, SloganResult>(this.HandleAsync);
-
+    [MessageHandler]
     public async ValueTask<SloganResult> HandleAsync(string message, IWorkflowContext context, CancellationToken cancellationToken = default)
     {
         this._session ??= await this._agent.CreateSessionAsync(cancellationToken);
@@ -149,6 +146,7 @@ internal sealed class SloganWriterExecutor : Executor
         return sloganResult;
     }
 
+    [MessageHandler]
     public async ValueTask<SloganResult> HandleAsync(FeedbackResult message, IWorkflowContext context, CancellationToken cancellationToken = default)
     {
         var feedbackMessage = $"""

dotnet/samples/GettingStarted/Workflows/Observability/WorkflowAsAnAgent/WorkflowAsAnAgentObservability.csproj

@@ -23,6 +23,9 @@
 
   <ItemGroup>
     <ProjectReference Include="..\..\..\..\..\src\Microsoft.Agents.AI.Workflows\Microsoft.Agents.AI.Workflows.csproj" />
+    <ProjectReference Include="..\..\..\..\..\src\Microsoft.Agents.AI.Workflows.Generators\Microsoft.Agents.AI.Workflows.Generators.csproj"
+                      OutputItemType="Analyzer"
+                      ReferenceOutputAssembly="false" />
     <ProjectReference Include="..\..\..\..\..\src\Microsoft.Agents.AI\Microsoft.Agents.AI.csproj" />
   </ItemGroup>
 

dotnet/samples/GettingStarted/Workflows/Observability/WorkflowAsAnAgent/WorkflowHelper.cs

@@ -6,7 +6,7 @@ using Microsoft.Extensions.AI;
 
 namespace WorkflowAsAnAgentObservabilitySample;
 
-internal static class WorkflowHelper
+internal static partial class WorkflowHelper
 {
     /// <summary>
     /// Creates a workflow that uses two language agents to process input concurrently.
@@ -50,21 +50,16 @@ internal static class WorkflowHelper
     /// <summary>
     /// Executor that starts the concurrent processing by sending messages to the agents.
     /// </summary>
-    private sealed class ConcurrentStartExecutor() : Executor("ConcurrentStartExecutor")
+    private sealed partial class ConcurrentStartExecutor() : Executor("ConcurrentStartExecutor")
     {
-        protected override RouteBuilder ConfigureRoutes(RouteBuilder routeBuilder)
-        {
-            return routeBuilder
-                .AddHandler<List<ChatMessage>>(this.RouteMessages)
-                .AddHandler<TurnToken>(this.RouteTurnTokenAsync);
-        }
-
-        private ValueTask RouteMessages(List<ChatMessage> messages, IWorkflowContext context, CancellationToken cancellationToken)
+        [MessageHandler]
+        internal ValueTask RouteMessages(List<ChatMessage> messages, IWorkflowContext context, CancellationToken cancellationToken)
         {
             return context.SendMessageAsync(messages, cancellationToken: cancellationToken);
         }
 
-        private ValueTask RouteTurnTokenAsync(TurnToken token, IWorkflowContext context, CancellationToken cancellationToken)
+        [MessageHandler]
+        internal ValueTask RouteTurnTokenAsync(TurnToken token, IWorkflowContext context, CancellationToken cancellationToken)
         {
             return context.SendMessageAsync(token, cancellationToken: cancellationToken);
         }
@@ -73,7 +68,8 @@ internal static class WorkflowHelper
     /// <summary>
     /// Executor that aggregates the results from the concurrent agents.
     /// </summary>
-    private sealed class ConcurrentAggregationExecutor() : Executor<List<ChatMessage>>("ConcurrentAggregationExecutor")
+    [YieldsOutput(typeof(List<ChatMessage>))]
+    private sealed partial class ConcurrentAggregationExecutor() : Executor<List<ChatMessage>>("ConcurrentAggregationExecutor")
     {
         private readonly List<ChatMessage> _messages = [];
 

dotnet/samples/GettingStarted/Workflows/_Foundational/08_WriterCriticWorkflow/08_WriterCriticWorkflow.csproj

@@ -1,4 +1,4 @@
-<Project Sdk="Microsoft.NET.Sdk">
+<Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
     <OutputType>Exe</OutputType>
@@ -11,6 +11,10 @@
 
   <ItemGroup>
     <ProjectReference Include="..\..\..\..\..\src\Microsoft.Agents.AI.Workflows\Microsoft.Agents.AI.Workflows.csproj" />
+    <ProjectReference Include="..\..\..\..\..\src\Microsoft.Agents.AI.Workflows.Generators\Microsoft.Agents.AI.Workflows.Generators.csproj" 
+                      OutputItemType="Analyzer" 
+                      ReferenceOutputAssembly="false" />
+    
     <ProjectReference Include="..\..\..\..\..\src\Microsoft.Agents.AI\Microsoft.Agents.AI.csproj" />
   </ItemGroup>
 

dotnet/samples/GettingStarted/Workflows/_Foundational/08_WriterCriticWorkflow/Program.cs

@@ -196,7 +196,7 @@ internal sealed class CriticDecision
 /// Executor that creates or revises content based on user requests or critic feedback.
 /// This executor demonstrates multiple message handlers for different input types.
 /// </summary>
-internal sealed class WriterExecutor : Executor
+internal sealed partial class WriterExecutor : Executor
 {
     private readonly AIAgent _agent;
 
@@ -213,15 +213,11 @@ internal sealed class WriterExecutor : Executor
         );
     }
 
-    protected override RouteBuilder ConfigureRoutes(RouteBuilder routeBuilder) =>
-        routeBuilder
-            .AddHandler<string, ChatMessage>(this.HandleInitialRequestAsync)
-            .AddHandler<CriticDecision, ChatMessage>(this.HandleRevisionRequestAsync);
-
     /// <summary>
     /// Handles the initial writing request from the user.
     /// </summary>
-    private async ValueTask<ChatMessage> HandleInitialRequestAsync(
+    [MessageHandler]
+    public async ValueTask<ChatMessage> HandleInitialRequestAsync(
         string message,
         IWorkflowContext context,
         CancellationToken cancellationToken = default)
@@ -232,7 +228,8 @@ internal sealed class WriterExecutor : Executor
     /// <summary>
     /// Handles revision requests from the critic with feedback.
     /// </summary>
-    private async ValueTask<ChatMessage> HandleRevisionRequestAsync(
+    [MessageHandler]
+    public async ValueTask<ChatMessage> HandleRevisionRequestAsync(
         CriticDecision decision,
         IWorkflowContext context,
         CancellationToken cancellationToken = default)