Program.cs

// Copyright (c) Microsoft. All rights reserved.

// This sample shows how to use dependency injection to register a AIAgent and use it from a hosted service.

using Azure.AI.Projects;
using Azure.Identity;
using Microsoft.Agents.AI;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using SampleApp;

string endpoint = Environment.GetEnvironmentVariable("FOUNDRY_PROJECT_ENDPOINT") ?? throw new InvalidOperationException("FOUNDRY_PROJECT_ENDPOINT is not set.");
string deploymentName = Environment.GetEnvironmentVariable("FOUNDRY_MODEL") ?? "gpt-5.4-mini";

// 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(deploymentName,
    instructions: "You are good at telling jokes.",
    name: "JokerAgent");

// Create a host builder that we will register services with and then run.
HostApplicationBuilder builder = Host.CreateApplicationBuilder(args);

// Add the AI agent to the service collection.
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);

namespace SampleApp
{
    /// <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)
        {
            this._session = await agent.CreateSessionAsync(cancellationToken);
            _ = this.RunAsync(appLifetime.ApplicationStopping);
        }

        public async Task RunAsync(CancellationToken cancellationToken)
        {
            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("> ");
                string? input = Console.ReadLine();

                if (string.IsNullOrWhiteSpace(input))
                {
                    appLifetime.StopApplication();
                    break;
                }

                await foreach (AgentResponseUpdate update in agent.RunStreamingAsync(input, this._session, cancellationToken: cancellationToken))
                {
                    Console.Write(update);
                }

                Console.WriteLine();
            }
        }

        public Task StopAsync(CancellationToken cancellationToken)
        {
            Console.WriteLine("\nShutting down...");
            return Task.CompletedTask;
        }
    }
}