chore: import upstream snapshot with attribution

dotnet/samples/02-agents/Agents/Agent_Step06_DependencyInjection/Program.cs

@@ -0,0 +1,80 @@
+// Copyright (c) Microsoft. All rights reserved.
+
+#pragma warning disable CA1812
+
+// Dependency Injection — Register and resolve agents via DI
+//
+// This sample shows how to use dependency injection to register an
+// AIAgent and consume it from a hosted service with a chat loop.
+
+using Azure.AI.Projects;
+using Azure.Identity;
+using Microsoft.Agents.AI;
+using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.Hosting;
+
+var endpoint = Environment.GetEnvironmentVariable("FOUNDRY_PROJECT_ENDPOINT") ?? throw new InvalidOperationException("FOUNDRY_PROJECT_ENDPOINT is not set.");
+var deploymentName = Environment.GetEnvironmentVariable("FOUNDRY_MODEL") ?? "gpt-5.4-mini";
+
+// Create a host builder that we will register services with and then run.
+HostApplicationBuilder builder = Host.CreateApplicationBuilder(args);
+
+// Create the AI agent from the Azure AI Foundry project client.
+// WARNING: DefaultAzureCredential is convenient for development but requires careful consideration in production.
+// In production, consider using a specific credential (e.g., ManagedIdentityCredential) to avoid
+// latency issues, unintended credential probing, and potential security risks from fallback mechanisms.
+AIProjectClient aiProjectClient = new(new Uri(endpoint), new DefaultAzureCredential());
+AIAgent agent = aiProjectClient.AsAIAgent(model: deploymentName, name: "Joker", instructions: "You are good at telling jokes.");
+builder.Services.AddSingleton(agent);
+
+// Add a sample service that will use the agent to respond to user input.
+builder.Services.AddHostedService<SampleService>();
+
+// Build and run the host.
+using IHost host = builder.Build();
+await host.RunAsync().ConfigureAwait(false);
+
+/// <summary>
+/// A sample service that uses an AI agent to respond to user input.
+/// </summary>
+internal sealed class SampleService(AIAgent agent, IHostApplicationLifetime appLifetime) : IHostedService
+{
+    private AgentSession? _session;
+
+    public async Task StartAsync(CancellationToken cancellationToken)
+    {
+        // Create a session that will be used for the entirety of the service lifetime so that the user can ask follow up questions.
+        this._session = await agent.CreateSessionAsync(cancellationToken);
+        _ = this.RunAsync(appLifetime.ApplicationStopping);
+    }
+
+    public async Task RunAsync(CancellationToken cancellationToken)
+    {
+        // Delay a little to allow the service to finish starting.
+        await Task.Delay(100, cancellationToken);
+
+        while (!cancellationToken.IsCancellationRequested)
+        {
+            Console.WriteLine("\nAgent: Ask me to tell you a joke about a specific topic. To exit just press Ctrl+C or enter without any input.\n");
+            Console.Write("> ");
+            var input = Console.ReadLine();
+
+            // If the user enters no input, signal the application to shut down.
+            if (string.IsNullOrWhiteSpace(input))
+            {
+                appLifetime.StopApplication();
+                break;
+            }
+
+            // Stream the output to the console as it is generated.
+            await foreach (var update in agent.RunStreamingAsync(input, this._session, cancellationToken: cancellationToken))
+            {
+                Console.Write(update);
+            }
+
+            Console.WriteLine();
+        }
+    }
+
+    public Task StopAsync(CancellationToken cancellationToken) => Task.CompletedTask;
+}