.NET: Support dynamic agent resolution in AG-UI endpoints

dotnet/samples/GettingStarted/AGUI/README.md

@@ -199,6 +199,41 @@ cd Step05_StateManagement/Client
 dotnet run
 ```
 
+### Step06_DynamicAgentResolution
+
+Demonstrates dynamic agent resolution based on route parameters. This enables multi-tenant applications, agent selection by ID, and runtime agent configuration.
+
+#### Server (`Step06_DynamicAgentResolution/Server`)
+
+An AG-UI server that dynamically selects agents based on route parameters. Demonstrates:
+
+- Using `MapAGUI` with a factory delegate for dynamic agent resolution
+- Extracting route parameters with `HttpContext.GetRouteValue`
+- Returning `null` from the factory for 404 responses
+- Supporting multiple agent configurations on a single route pattern
+
+**Run the server:**
+
+```bash
+cd Step06_DynamicAgentResolution/Server
+dotnet run --urls http://localhost:8888
+```
+
+Available agents: `general`, `code`, `writer`
+
+#### Client (`Step06_DynamicAgentResolution/Client`)
+
+A client that demonstrates connecting to different dynamically-resolved agents.
+
+**Run the client:**
+
+```bash
+cd Step06_DynamicAgentResolution/Client
+dotnet run
+```
+
+The client allows you to switch between different agent types at runtime. Type `:back` to switch agents or `:q` to quit.
+
 ## How AG-UI Works
 
 ### Server-Side
@@ -284,6 +319,7 @@ The samples above demonstrate the AG-UI features currently available in C#:
 - ✅ **Streaming Responses**: Real-time Server-Sent Events
 - ✅ **State Management**: State schemas with predictive updates
 - ✅ **Human-in-the-Loop**: Approval workflows for sensitive operations
+- ✅ **Dynamic Agent Resolution**: Route-based agent selection for multi-tenant scenarios
 
 ### Coming Soon to C#
 

dotnet/samples/GettingStarted/AGUI/Step06_DynamicAgentResolution/Client/Client.csproj

@@ -0,0 +1,15 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFrameworks>net10.0</TargetFrameworks>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="..\..\..\..\..\src\Microsoft.Agents.AI\Microsoft.Agents.AI.csproj" />
+    <ProjectReference Include="..\..\..\..\..\src\Microsoft.Agents.AI.AGUI\Microsoft.Agents.AI.AGUI.csproj" />
+  </ItemGroup>
+
+</Project>

dotnet/samples/GettingStarted/AGUI/Step06_DynamicAgentResolution/Client/Program.cs

@@ -0,0 +1,93 @@
+// Copyright (c) Microsoft. All rights reserved.
+
+using Microsoft.Agents.AI;
+using Microsoft.Agents.AI.AGUI;
+using Microsoft.Extensions.AI;
+
+string serverUrl = Environment.GetEnvironmentVariable("AGUI_SERVER_URL") ?? "http://localhost:8888";
+
+Console.WriteLine("AG-UI Dynamic Agent Resolution Demo");
+Console.WriteLine("====================================\n");
+Console.WriteLine("Available agents: general, code, writer");
+Console.WriteLine($"Server URL: {serverUrl}\n");
+
+using HttpClient httpClient = new()
+{
+    Timeout = TimeSpan.FromSeconds(60)
+};
+
+while (true)
+{
+    // Get agent selection
+    Console.Write("Select agent (general/code/writer) or 'quit': ");
+    string? agentId = Console.ReadLine()?.Trim();
+
+    if (string.IsNullOrWhiteSpace(agentId) || agentId.Equals("quit", StringComparison.OrdinalIgnoreCase) || agentId == ":q")
+    {
+        break;
+    }
+
+    // Create client for specific agent
+    string agentUrl = $"{serverUrl.TrimEnd('/')}/agents/{agentId}";
+    AGUIChatClient chatClient = new(httpClient, agentUrl);
+
+    AIAgent agent = chatClient.CreateAIAgent(
+        name: $"agui-client-{agentId}",
+        description: $"AG-UI Client for {agentId} agent");
+
+    AgentThread thread = agent.GetNewThread();
+    List<ChatMessage> messages = [];
+
+    Console.WriteLine($"\nConnected to '{agentId}' agent. Type ':back' to switch agents.\n");
+
+    // Conversation loop for this agent
+    while (true)
+    {
+        Console.Write($"[{agentId}] User: ");
+        string? message = Console.ReadLine();
+
+        if (string.IsNullOrWhiteSpace(message))
+        {
+            continue;
+        }
+
+        if (message == ":back")
+        {
+            Console.WriteLine();
+            break;
+        }
+
+        if (message == ":q" || message == "quit")
+        {
+            return;
+        }
+
+        messages.Add(new ChatMessage(ChatRole.User, message));
+
+        // Stream the response
+        Console.Write($"[{agentId}] Assistant: ");
+
+        try
+        {
+            await foreach (AgentRunResponseUpdate update in agent.RunStreamingAsync(messages, thread))
+            {
+                foreach (AIContent content in update.Contents)
+                {
+                    if (content is TextContent textContent)
+                    {
+                        Console.Write(textContent.Text);
+                    }
+                }
+            }
+
+            Console.WriteLine("\n");
+        }
+        catch (HttpRequestException ex) when (ex.StatusCode == System.Net.HttpStatusCode.NotFound)
+        {
+            Console.ForegroundColor = ConsoleColor.Red;
+            Console.WriteLine($"\nAgent '{agentId}' not found. Please try a different agent.\n");
+            Console.ResetColor();
+            break;
+        }
+    }
+}

dotnet/samples/GettingStarted/AGUI/Step06_DynamicAgentResolution/Server/Program.cs

@@ -0,0 +1,66 @@
+// Copyright (c) Microsoft. All rights reserved.
+
+using Azure.AI.OpenAI;
+using Azure.Identity;
+using Microsoft.Agents.AI;
+using Microsoft.Agents.AI.Hosting.AGUI.AspNetCore;
+using Microsoft.Extensions.AI;
+using OpenAI.Chat;
+
+WebApplicationBuilder builder = WebApplication.CreateBuilder(args);
+builder.Services.AddHttpClient().AddLogging();
+builder.Services.AddAGUI();
+
+WebApplication app = builder.Build();
+
+string endpoint = builder.Configuration["AZURE_OPENAI_ENDPOINT"]
+    ?? throw new InvalidOperationException("AZURE_OPENAI_ENDPOINT is not set.");
+string deploymentName = builder.Configuration["AZURE_OPENAI_DEPLOYMENT_NAME"]
+    ?? throw new InvalidOperationException("AZURE_OPENAI_DEPLOYMENT_NAME is not set.");
+
+// Create chat client (shared across agents)
+ChatClient chatClient = new AzureOpenAIClient(
+        new Uri(endpoint),
+        new DefaultAzureCredential())
+    .GetChatClient(deploymentName);
+
+// Define available agent configurations
+Dictionary<string, (string Name, string Instructions)> agentConfigs = new(StringComparer.OrdinalIgnoreCase)
+{
+    ["general"] = ("GeneralAssistant", "You are a helpful general assistant."),
+    ["code"] = ("CodeAssistant", "You are an expert programmer. Help users write, debug, and optimize code."),
+    ["writer"] = ("WriterAssistant", "You are a professional writer. Help users with writing, editing, and creative content.")
+};
+
+// Map AG-UI endpoint with dynamic agent resolution
+app.MapAGUI("/agents/{agentId}", async (HttpContext context, CancellationToken cancellationToken) =>
+{
+    // Extract agent ID from route
+    string? agentId = context.GetRouteValue("agentId")?.ToString();
+
+    if (string.IsNullOrEmpty(agentId))
+    {
+        return null;
+    }
+
+    // Look up agent configuration
+    if (!agentConfigs.TryGetValue(agentId, out (string Name, string Instructions) config))
+    {
+        return null; // Returns 404
+    }
+
+    // Create and return agent (could also cache this)
+    IChatClient client = chatClient.AsIChatClient();
+    return client.CreateAIAgent(
+        name: config.Name,
+        instructions: config.Instructions);
+});
+
+// Also map a root endpoint for discovery
+app.MapGet("/", () => Results.Json(new
+{
+    availableAgents = agentConfigs.Keys.ToArray(),
+    usage = "POST to /agents/{agentId} with AG-UI protocol"
+}));
+
+await app.RunAsync();

dotnet/samples/GettingStarted/AGUI/Step06_DynamicAgentResolution/Server/Properties/launchSettings.json

@@ -0,0 +1,23 @@
+{
+  "$schema": "https://json.schemastore.org/launchsettings.json",
+  "profiles": {
+    "http": {
+      "commandName": "Project",
+      "dotnetRunMessages": true,
+      "launchBrowser": true,
+      "applicationUrl": "http://localhost:8888",
+      "environmentVariables": {
+        "ASPNETCORE_ENVIRONMENT": "Development"
+      }
+    },
+    "https": {
+      "commandName": "Project",
+      "dotnetRunMessages": true,
+      "launchBrowser": true,
+      "applicationUrl": "https://localhost:7047;http://localhost:8888",
+      "environmentVariables": {
+        "ASPNETCORE_ENVIRONMENT": "Development"
+      }
+    }
+  }
+}

dotnet/samples/GettingStarted/AGUI/Step06_DynamicAgentResolution/Server/Server.csproj

@@ -0,0 +1,21 @@
+<Project Sdk="Microsoft.NET.Sdk.Web">
+
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFrameworks>net10.0</TargetFrameworks>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <PackageReference Include="Azure.AI.OpenAI" />
+    <PackageReference Include="Azure.Identity" />
+    <PackageReference Include="Microsoft.Extensions.AI.OpenAI" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="..\..\..\..\..\src\Microsoft.Agents.AI.Hosting.AGUI.AspNetCore\Microsoft.Agents.AI.Hosting.AGUI.AspNetCore.csproj" />
+    <ProjectReference Include="..\..\..\..\..\src\Microsoft.Agents.AI.OpenAI\Microsoft.Agents.AI.OpenAI.csproj" />
+  </ItemGroup>
+
+</Project>

dotnet/samples/GettingStarted/AGUI/Step06_DynamicAgentResolution/Server/appsettings.Development.json

@@ -0,0 +1,8 @@
+{
+  "Logging": {
+    "LogLevel": {
+      "Default": "Information",
+      "Microsoft.AspNetCore": "Warning"
+    }
+  }
+}

dotnet/samples/GettingStarted/AGUI/Step06_DynamicAgentResolution/Server/appsettings.json

@@ -0,0 +1,9 @@
+{
+  "Logging": {
+    "LogLevel": {
+      "Default": "Information",
+      "Microsoft.AspNetCore": "Warning"
+    }
+  },
+  "AllowedHosts": "*"
+}