.NET: Replace internal AG-UI implementation with external ag-ui packages

Remove the in-tree Microsoft.Agents.AI.AGUI sources and consume the external
AG-UI .NET SDK packages (AGUI.Abstractions, AGUI.Formatting, AGUI.Protobuf,
AGUI.Client, AGUI.Server) at 0.1.0-preview instead.

- Microsoft.Agents.AI.Hosting.AGUI.AspNetCore keeps its own ASP.NET glue
  (MapAGUI / AddAGUI / SSE result) layered over the framework-agnostic
  AGUI.Server primitives (ToChatRequestContext / AsAGUIEventStreamAsync).
- Migrate call sites to the options-based AGUIChatClient constructor and recover
  the originating AG-UI input via ChatOptions.TryGetRunAgentInput.
- Multi-turn continuation flows through parentRunId + threadId on
  RawRepresentationFactory; shared state flows through RunAgentInput.State and is
  surfaced as StateSnapshotEvent raw representations.
- Update samples, hosting/unit/integration tests, and central package versions.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: javiercn

dotnet/Directory.Packages.props

@@ -1,4 +1,4 @@
-<Project>
+<Project>
   <PropertyGroup>
     <!-- Enable central package management -->
     <!-- https://learn.microsoft.com/en-us/nuget/consume-packages/Central-Package-Management -->
@@ -52,7 +52,13 @@
     <PackageVersion Include="System.Diagnostics.DiagnosticSource" Version="10.0.8" />
     <PackageVersion Include="System.Linq.AsyncEnumerable" Version="10.0.5" />
     <PackageVersion Include="System.Net.Http.Json" Version="10.0.0" />
-    <PackageVersion Include="System.Net.ServerSentEvents" Version="10.0.5" />
+    <PackageVersion Include="System.Net.ServerSentEvents" Version="10.0.8" />
+    <!-- AG-UI .NET SDK packages (published by the AG-UI team). -->
+    <PackageVersion Include="AGUI.Abstractions" Version="0.1.0-preview" />
+    <PackageVersion Include="AGUI.Formatting" Version="0.1.0-preview" />
+    <PackageVersion Include="AGUI.Protobuf" Version="0.1.0-preview" />
+    <PackageVersion Include="AGUI.Client" Version="0.1.0-preview" />
+    <PackageVersion Include="AGUI.Server" Version="0.1.0-preview" />
     <PackageVersion Include="System.Text.Json" Version="10.0.8" />
     <PackageVersion Include="System.Threading.Channels" Version="10.0.8" />
     <PackageVersion Include="System.Threading.Tasks.Extensions" Version="4.6.3" />
@@ -88,7 +94,7 @@
     <PackageVersion Include="Microsoft.Extensions.Configuration.UserSecrets" Version="10.0.1" />
     <PackageVersion Include="Microsoft.Extensions.DependencyInjection" Version="10.0.1" />
     <PackageVersion Include="Microsoft.Extensions.DependencyInjection.Abstractions" Version="10.0.8" />
-    <PackageVersion Include="Microsoft.Extensions.FileSystemGlobbing" Version="10.0.6" />
+    <PackageVersion Include="Microsoft.Extensions.FileSystemGlobbing" Version="10.0.8" />
     <PackageVersion Include="Microsoft.Extensions.Hosting" Version="10.0.1" />
     <PackageVersion Include="Microsoft.Extensions.Http.Resilience" Version="10.0.0" />
     <PackageVersion Include="Microsoft.Extensions.Logging" Version="10.0.1" />

dotnet/agent-framework-dotnet.slnx

@@ -600,7 +600,6 @@
     <Project Path="src/Aspire.Hosting.AgentFramework.DevUI/Aspire.Hosting.AgentFramework.DevUI.csproj" />
     <Project Path="src/Microsoft.Agents.AI.A2A/Microsoft.Agents.AI.A2A.csproj" />
     <Project Path="src/Microsoft.Agents.AI.Abstractions/Microsoft.Agents.AI.Abstractions.csproj" />
-    <Project Path="src/Microsoft.Agents.AI.AGUI/Microsoft.Agents.AI.AGUI.csproj" />
     <Project Path="src/Microsoft.Agents.AI.Anthropic/Microsoft.Agents.AI.Anthropic.csproj" />
     <Project Path="src/Microsoft.Agents.AI.AzureAI.Persistent/Microsoft.Agents.AI.AzureAI.Persistent.csproj" />
     <Project Path="src/Microsoft.Agents.AI.CopilotStudio/Microsoft.Agents.AI.CopilotStudio.csproj" />
@@ -659,7 +658,6 @@
     <Project Path="tests/Aspire.Hosting.AgentFramework.DevUI.UnitTests/Aspire.Hosting.AgentFramework.DevUI.UnitTests.csproj" />
     <Project Path="tests/Microsoft.Agents.AI.A2A.UnitTests/Microsoft.Agents.AI.A2A.UnitTests.csproj" />
     <Project Path="tests/Microsoft.Agents.AI.Abstractions.UnitTests/Microsoft.Agents.AI.Abstractions.UnitTests.csproj" />
-    <Project Path="tests/Microsoft.Agents.AI.AGUI.UnitTests/Microsoft.Agents.AI.AGUI.UnitTests.csproj" />
     <Project Path="tests/Microsoft.Agents.AI.Anthropic.UnitTests/Microsoft.Agents.AI.Anthropic.UnitTests.csproj" />
     <Project Path="tests/Microsoft.Agents.AI.AzureAI.Persistent.UnitTests/Microsoft.Agents.AI.AzureAI.Persistent.UnitTests.csproj" />
     <Project Path="tests/Microsoft.Agents.AI.CosmosNoSql.UnitTests/Microsoft.Agents.AI.CosmosNoSql.UnitTests.csproj" />

dotnet/agent-framework-release.slnf

@@ -4,7 +4,6 @@
     "projects": [
       "src\\Microsoft.Agents.AI.A2A\\Microsoft.Agents.AI.A2A.csproj",
       "src\\Microsoft.Agents.AI.Abstractions\\Microsoft.Agents.AI.Abstractions.csproj",
-      "src\\Microsoft.Agents.AI.AGUI\\Microsoft.Agents.AI.AGUI.csproj",
       "src\\Microsoft.Agents.AI.Anthropic\\Microsoft.Agents.AI.Anthropic.csproj",
       "src\\Microsoft.Agents.AI.GitHub.Copilot\\Microsoft.Agents.AI.GitHub.Copilot.csproj",
       "src\\Microsoft.Agents.AI.Harness\\Microsoft.Agents.AI.Harness.csproj",

dotnet/samples/02-agents/AGUI/README.md

@@ -35,7 +35,7 @@ A basic AG-UI server and client that demonstrate the foundational concepts.
 A basic AG-UI server that hosts an AI agent accessible via HTTP. Demonstrates:
 
 - Creating an ASP.NET Core web application
-- Setting up an AG-UI server endpoint with `MapAGUI`
+- Setting up an AG-UI server endpoint with `MapAGUIServer`
 - Creating an AI agent from an Azure OpenAI chat client
 - Streaming responses via Server-Sent Events (SSE)
 
@@ -204,7 +204,7 @@ dotnet run
 ### Server-Side
 
 1. Client sends HTTP POST request with messages
-2. ASP.NET Core endpoint receives the request via `MapAGUI`
+2. ASP.NET Core endpoint receives the request via `MapAGUIServer`
 3. Agent processes messages using Agent Framework
 4. Responses are streamed back as Server-Sent Events (SSE)
 
@@ -214,14 +214,14 @@ dotnet run
 2. Server responds with SSE stream
 3. Client parses events into `AgentResponseUpdate` objects
 4. Updates are displayed based on content type
-5. `ConversationId` maintains conversation context
+5. The client sends the full message history each turn (the stateless AG-UI client does not rely on a server-assigned `ConversationId`)
 
 ### Protocol Features
 
 - **HTTP POST** for requests
 - **Server-Sent Events (SSE)** for streaming responses
 - **JSON** for event serialization
-- **Thread IDs** (as `ConversationId`) for conversation context
+- **Thread IDs** (read from the `RUN_STARTED` event's raw representation) for conversation context. `AGUIChatClient` is stateless and intentionally does not surface a `ConversationId`.
 - **Run IDs** (as `ResponseId`) for tracking individual executions
 
 ## Troubleshooting

dotnet/samples/02-agents/AGUI/Step01_GettingStarted/Client/Client.csproj

@@ -1,4 +1,4 @@
-<Project Sdk="Microsoft.NET.Sdk">
+<Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
     <OutputType>Exe</OutputType>
@@ -9,7 +9,7 @@
 
   <ItemGroup>
     <ProjectReference Include="..\..\..\..\..\src\Microsoft.Agents.AI\Microsoft.Agents.AI.csproj" />
-    <ProjectReference Include="..\..\..\..\..\src\Microsoft.Agents.AI.AGUI\Microsoft.Agents.AI.AGUI.csproj" />
+    <PackageReference Include="AGUI.Client" />
   </ItemGroup>
 
 </Project>

dotnet/samples/02-agents/AGUI/Step01_GettingStarted/Client/Program.cs

@@ -1,7 +1,8 @@
 // Copyright (c) Microsoft. All rights reserved.
 
+using AGUI.Abstractions;
+using AGUI.Client;
 using Microsoft.Agents.AI;
-using Microsoft.Agents.AI.AGUI;
 using Microsoft.Extensions.AI;
 
 string serverUrl = Environment.GetEnvironmentVariable("AGUI_SERVER_URL") ?? "http://localhost:8888";
@@ -14,7 +15,7 @@
     Timeout = TimeSpan.FromSeconds(60)
 };
 
-AGUIChatClient chatClient = new(httpClient, serverUrl);
+AGUIChatClient chatClient = new(new(httpClient, serverUrl));
 
 AIAgent agent = chatClient.AsAIAgent(
     name: "agui-client",
@@ -49,7 +50,7 @@
 
         // Stream the response
         bool isFirstUpdate = true;
-        string? sessionId = null;
+        string? threadId = null;
 
         await foreach (AgentResponseUpdate update in agent.RunStreamingAsync(messages, session))
         {
@@ -58,9 +59,11 @@
             // First update indicates run started
             if (isFirstUpdate)
             {
-                sessionId = chatUpdate.ConversationId;
+                // AGUIChatClient is stateless and never surfaces a ConversationId; the thread
+                // id is carried on the AG-UI RUN_STARTED event's raw representation.
+                threadId = (chatUpdate.RawRepresentation as RunStartedEvent)?.ThreadId;
                 Console.ForegroundColor = ConsoleColor.Yellow;
-                Console.WriteLine($"\n[Run Started - Session: {chatUpdate.ConversationId}, Run: {chatUpdate.ResponseId}]");
+                Console.WriteLine($"\n[Run Started - Thread: {threadId}, Run: {chatUpdate.ResponseId}]");
                 Console.ResetColor();
                 isFirstUpdate = false;
             }
@@ -84,7 +87,7 @@
         }
 
         Console.ForegroundColor = ConsoleColor.Green;
-        Console.WriteLine($"\n[Run Finished - Session: {sessionId}]");
+        Console.WriteLine($"\n[Run Finished - Thread: {threadId}]");
         Console.ResetColor();
     }
 }

dotnet/samples/02-agents/AGUI/Step01_GettingStarted/Server/Program.cs

@@ -1,4 +1,4 @@
-// Copyright (c) Microsoft. All rights reserved.
+// Copyright (c) Microsoft. All rights reserved.
 
 using Azure.AI.OpenAI;
 using Azure.Identity;
@@ -8,7 +8,7 @@
 
 WebApplicationBuilder builder = WebApplication.CreateBuilder(args);
 builder.Services.AddHttpClient().AddLogging();
-builder.Services.AddAGUI();
+builder.Services.AddAGUIServer();
 
 // WARNING: When adding session persistence (e.g., WithInMemorySessionStore), or running in production,
 // make sure to also register a SessionIsolationKeyProvider to scope sessions by principal in multi-user
@@ -36,6 +36,6 @@
     instructions: "You are a helpful assistant.");
 
 // Map the AG-UI agent endpoint
-app.MapAGUI("/", agent);
+app.MapAGUIServer("/", agent);
 
 await app.RunAsync();

dotnet/samples/02-agents/AGUI/Step02_BackendTools/Client/Client.csproj

@@ -1,4 +1,4 @@
-<Project Sdk="Microsoft.NET.Sdk">
+<Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
     <OutputType>Exe</OutputType>
@@ -9,7 +9,7 @@
 
   <ItemGroup>
     <ProjectReference Include="..\..\..\..\..\src\Microsoft.Agents.AI\Microsoft.Agents.AI.csproj" />
-    <ProjectReference Include="..\..\..\..\..\src\Microsoft.Agents.AI.AGUI\Microsoft.Agents.AI.AGUI.csproj" />
+    <PackageReference Include="AGUI.Client" />
   </ItemGroup>
 
 </Project>

dotnet/samples/02-agents/AGUI/Step02_BackendTools/Client/Program.cs

@@ -1,7 +1,8 @@
 // Copyright (c) Microsoft. All rights reserved.
 
+using AGUI.Abstractions;
+using AGUI.Client;
 using Microsoft.Agents.AI;
-using Microsoft.Agents.AI.AGUI;
 using Microsoft.Extensions.AI;
 
 string serverUrl = Environment.GetEnvironmentVariable("AGUI_SERVER_URL") ?? "http://localhost:8888";
@@ -14,7 +15,7 @@
     Timeout = TimeSpan.FromSeconds(60)
 };
 
-AGUIChatClient chatClient = new(httpClient, serverUrl);
+AGUIChatClient chatClient = new(new(httpClient, serverUrl));
 
 AIAgent agent = chatClient.AsAIAgent(
     name: "agui-client",
@@ -49,7 +50,7 @@
 
         // Stream the response
         bool isFirstUpdate = true;
-        string? sessionId = null;
+        string? threadId = null;
 
         await foreach (AgentResponseUpdate update in agent.RunStreamingAsync(messages, session))
         {
@@ -58,9 +59,11 @@
             // First update indicates run started
             if (isFirstUpdate)
             {
-                sessionId = chatUpdate.ConversationId;
+                // AGUIChatClient is stateless and never surfaces a ConversationId; the thread
+                // id is carried on the AG-UI RUN_STARTED event's raw representation.
+                threadId = (chatUpdate.RawRepresentation as RunStartedEvent)?.ThreadId;
                 Console.ForegroundColor = ConsoleColor.Yellow;
-                Console.WriteLine($"\n[Run Started - Session: {chatUpdate.ConversationId}, Run: {chatUpdate.ResponseId}]");
+                Console.WriteLine($"\n[Run Started - Thread: {threadId}, Run: {chatUpdate.ResponseId}]");
                 Console.ResetColor();
                 isFirstUpdate = false;
             }
@@ -116,7 +119,7 @@
         }
 
         Console.ForegroundColor = ConsoleColor.Green;
-        Console.WriteLine($"\n[Run Finished - Session: {sessionId}]");
+        Console.WriteLine($"\n[Run Finished - Thread: {threadId}]");
         Console.ResetColor();
     }
 }

dotnet/samples/02-agents/AGUI/Step02_BackendTools/Server/Program.cs

@@ -1,4 +1,4 @@
-// Copyright (c) Microsoft. All rights reserved.
+// Copyright (c) Microsoft. All rights reserved.
 
 using System.ComponentModel;
 using System.Text.Json.Serialization;
@@ -14,7 +14,7 @@
 builder.Services.AddHttpClient().AddLogging();
 builder.Services.ConfigureHttpJsonOptions(options =>
     options.SerializerOptions.TypeInfoResolverChain.Add(SampleJsonSerializerContext.Default));
-builder.Services.AddAGUI();
+builder.Services.AddAGUIServer();
 
 // WARNING: When adding session persistence (e.g., WithInMemorySessionStore), or running in production,
 // make sure to also register a SessionIsolationKeyProvider to scope sessions by principal in multi-user
@@ -93,7 +93,7 @@ static RestaurantSearchResponse SearchRestaurants(
     tools: tools);
 
 // Map the AG-UI agent endpoint
-app.MapAGUI("/", agent);
+app.MapAGUIServer("/", agent);
 
 await app.RunAsync();