.NET: [Bug]: DevUI always sends new session

[hintdesk]

Description

Hi everyone,

I'm trying to save conversation messages to a database using ChatHistoryProvider. However, InvokeContext.Session.StateBag seems to reset with every new message, creating a fresh session context each time. As a result, I can't track or associate incoming messages with their parent conversation.

Is DevUI designed to spawn a new session per message, or is there a specific way I should be passing/maintaining the conversation ID across requests?

Thanks for any insights!

The conversationId is red in image below because it has been recreated

Code Sample

using Microsoft.Agents.AI;
using Microsoft.Agents.AI.DevUI;
using Microsoft.Agents.AI.Hosting;
using Microsoft.Extensions.AI;
using OpenAI;
using OpenAI.Chat;
using System.ClientModel;
using TestChatHistoryProvider;

var builder = WebApplication.CreateBuilder(args);

// Add services to the container.

builder.Services.AddControllers();
// Learn more about configuring OpenAPI at https://aka.ms/aspnet/openapi
builder.Services.AddOpenApi();

var apiKey = builder.Configuration["ApiKey"]
    ?? throw new InvalidOperationException("Configuration value 'ApiKey' is missing.");


var openAIClient = new ChatClient(
    model: "gpt-5-mini",
    credential: new ApiKeyCredential(apiKey),
    options: new OpenAIClientOptions()
    {
        Endpoint = new Uri("myendpoind")
    }
).AsIChatClient();

var agentBuilder = builder.AddAIAgent("Alex", (sp, key) =>
{
    return openAIClient.AsAIAgent(new ChatClientAgentOptions()
    {
        Name = "Alex",
        ChatOptions = new ChatOptions()
        {

            Instructions = "You are a helpful assistant.",
     
        },
        
        ChatHistoryProvider = new CosmosChatHistoryProvider()


    })
    .AsBuilder()
    .UseToolApproval(new ToolApprovalAgentOptions
    {
        AutoApprovalRules = [AgentSkillsProvider.AllToolsAutoApprovalRule],
    })
    .Build()
    ;
});

builder.Services.AddOpenAIResponses();
builder.Services.AddOpenAIConversations();
builder.AddDevUI();

var app = builder.Build();

// Configure the HTTP request pipeline.
if (app.Environment.IsDevelopment())
{
    app.MapOpenApi();
}

app.MapOpenAIResponses();
app.MapOpenAIConversations();
app.MapDevUI();


app.UseHttpsRedirection();

app.UseAuthorization();

app.MapControllers();

app.Run();




using Microsoft.Agents.AI;
using Microsoft.Extensions.AI;

namespace TestChatHistoryProvider
{
    public class DummyChatHistoryProvider : ChatHistoryProvider, IAsyncDisposable
    {
        private readonly ProviderSessionState<State> _sessionState;
        public DummyChatHistoryProvider()
        {
            _sessionState = new ProviderSessionState<State>((_ => new State(Guid.NewGuid().ToString("N"))), this.GetType().Name);

        }

        protected override ValueTask<IEnumerable<ChatMessage>> ProvideChatHistoryAsync(InvokingContext context, CancellationToken cancellationToken = default)
        {
//context.Session.StateBag here is recreated with new incoming messages
            var state = _sessionState.GetOrInitializeState(context.Session);
            return base.ProvideChatHistoryAsync(context, cancellationToken);
        }
        public ValueTask DisposeAsync()
        {
            return ValueTask.CompletedTask;
        }

        public sealed class State
        {
            public State(string conversationId)
            {
                this.ConversationId = conversationId ?? throw new ArgumentNullException(nameof(conversationId));
            }
            public string ConversationId { get; set; }
        }
    }
}

Error Messages / Stack Traces

Package Versions

<PackageReference Include="Microsoft.Agents.AI" Version="1.15.0" />     <PackageReference Include="Microsoft.Agents.AI.DevUI" Version="1.15.0-preview.260722.1" />     <PackageReference Include="Microsoft.Agents.AI.Hosting.OpenAI" Version="1.15.0-alpha.260722.1" />     <PackageReference Include="Microsoft.Agents.AI.OpenAI" Version="1.15.0" />     <PackageReference Include="Microsoft.AspNetCore.OpenApi" Version="10.0.10" />

.NET Version

.NET 10

Additional Context

No response

[github-actions]

👋 Hi @hintdesk — thanks for the report!

Your usage of ChatHistoryProvider and ProviderSessionState appears correct. The screenshot showing the conversationId being recreated in red, combined with the observation that context.Session.StateBag resets on every message, strongly suggests DevUI's session management is not preserving session identity across messages within a conversation. This appears to be a legitimate gap in DevUI's implementation rather than a configuration issue on your side. We were unable to inspect the current source to confirm whether this has been addressed in a newer build.

If this still reproduces after trying the above, please reopen and we'll take another look. 🙏