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.NET: Thread persistence does not work by default in MapAGUI #2517

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.NET: Thread persistence does not work by default in MapAGUI#2517
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javiercn
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.NETUsage: [Issues, PRs], Target: .Netag-uiUsage: [Issues, PRs], Target: AG-UI protocol integrationhostingUsage: [Issues, PRs], Target: all hosting related solutions

Description

@DavidParks8
David Parks (DavidParks8)
opened on Nov 28, 2025

Summary

MapAGUI in Microsoft.Agents.AI.Hosting.AGUI.AspNetCore passes thread: null to AIAgent.RunStreamingAsync(), which means the agent's ChatMessageStoreFactory configuration is not properly utilized for thread persistence across requests.

Current Behavior

Looking at AGUIEndpointRouteBuilderExtensions.cs:

var events = aiAgent.RunStreamingAsync(
    messages,
    options: runOptions,    // <-- No thread parameter passed (defaults to null)
    cancellationToken: cancellationToken)

When thread is null, ChatClientAgent calls GetNewThread() which creates a new ChatClientAgentThread with a new ChatMessageStore instance for every single request.

The AG-UI thread ID is passed via ChatOptions.AdditionalProperties[\"ag_ui_thread_id\"], but since no AgentThread is passed, each request:

  1. Creates a brand new thread
  2. Creates a brand new ChatMessageStore via ChatMessageStoreFactory
  3. The ChatMessageStore has no way to correlate with the AG-UI thread ID until AddMessagesAsync is called (after the factory)

Expected Behavior

MapAGUI should support server-side thread persistence so that:

  1. If an agent has a ChatMessageStoreFactory configured, it should be used to restore/persist conversation history per AG-UI thread ID
  2. The ChatMessageStore should be created with knowledge of the AG-UI thread ID upfront
  3. On subsequent requests with the same ag_ui_thread_id, the same logical thread/store should be used

Workaround

Currently, developers must use ambient context (AsyncLocal) to pass the AG-UI thread ID from middleware to the ChatMessageStore, and manually manage thread storage outside of the Agent Framework's normal patterns:

// In middleware before agent runs:
CurrentThreadContext.ThreadId = ExtractThreadIdFromOptions(options);

// In ChatMessageStoreFactory:
ChatMessageStoreFactory = ctx => new CustomChatMessageStore(
    threadStore,
    CurrentThreadContext.ThreadId, // Read from ambient context
    ctx.SerializedState
)

This is fragile and requires duplicating message storage logic outside of the normal Agent Framework patterns.

Related Issues

Environment

  • Package: Microsoft.Agents.AI.Hosting.AGUI.AspNetCore

Activity

  1. Mark Wallace (markwallace-microsoft)
    added
    .NETUsage: [Issues, PRs], Target: .Net
    pythonUsage: [Issues, PRs], Target: Python
    triageUsage: [Issues], Target: All issues that still need to be triaged
    on Nov 28, 2025
  2. github-actions
    changed the title [-]Thread persistence does not work by default in MapAGUI[/-] [+].NET: Thread persistence does not work by default in MapAGUI[/+] on Nov 28, 2025
  3. github-actions
    changed the title [-].NET: Thread persistence does not work by default in MapAGUI[/-] [+]Python: Thread persistence does not work by default in MapAGUI[/+] on Nov 28, 2025
  4. Mark Wallace (markwallace-microsoft)
    assigned
    Javier Calvarro Nelson (javiercn)
    on Nov 28, 2025
  5. Mark Wallace (markwallace-microsoft)
    added
    agent hosting
    ag-ui
    and removed
    triageUsage: [Issues], Target: All issues that still need to be triaged
    on Nov 28, 2025
  6. Mark Wallace (markwallace-microsoft)
    added this to Agent Frameworkon Nov 28, 2025
  7. Mark Wallace (markwallace-microsoft)
    added the
    Bug
    issue type on Nov 28, 2025

  8. javiercn commented on Nov 28, 2025

    @javiercn
    Javier Calvarro Nelson (javiercn)
    on Nov 28, 2025
    Contributor

    David Parks (@DavidParks8) thanks for contacting us.

    This is a current limitation. We will be working on more comprehensive support for this in the future.

  9. DavidParks8 commented on Nov 28, 2025

    @DavidParks8
    David Parks (DavidParks8)
    on Nov 28, 2025
    MemberAuthor

    Javier Calvarro Nelson (@javiercn) How soon would that be? I'm trying to decide if I should rely on MapAGUI for a live product or if I should just roll my own.

  10. vecode commented on Dec 14, 2025

    @vecode
    Marvin Danker (vecode)
    on Dec 14, 2025

    David Parks (@DavidParks8) Could you provide more details on how/where you are extracting the thread ID?

  11. arjendeblok commented on Dec 14, 2025

    @arjendeblok
    Arjen de Blok (arjendeblok)
    on Dec 14, 2025

    I also see that in AGUIChatClient the property agui_thread_id is used and in AGUIEndpointRouteBuilderExtensions the property ag_ui_thread_id is used with an additional underscore. I also would like to store my thread in the agent server side.

  12. Evan Mattson (moonbox3)
    changed the title [-]Python: Thread persistence does not work by default in MapAGUI[/-] [+].NET: Thread persistence does not work by default in MapAGUI[/+] on Feb 3, 2026

  13. tigertop commented on Mar 15, 2026

    @tigertop
    Tigran Topchyan (tigertop)
    on Mar 15, 2026

    Any news on this one? Any known workarounds possible at the moment?

  14. Eduard van Valkenburg (eavanvalkenburg)
    removed
    pythonUsage: [Issues, PRs], Target: Python
    on Jun 2, 2026
  15. Evan Mattson (moonbox3)
    added
    hostingUsage: [Issues, PRs], Target: all hosting related solutions
    ui integration
    ag-uiUsage: [Issues, PRs], Target: AG-UI protocol integration
    and removed
    ag-ui
    agent hosting
    ui integration
    on Jun 17, 2026

  16. javiercn commented on Aug 18, 2026

    @javiercn
    Javier Calvarro Nelson (javiercn)
    on Aug 18, 2026
    Contributor

    This is resolved by the current MapAGUIServer hosting implementation.

    AG-UI threadId is now used to load or create an AgentSession, which is passed to the agent and saved after streaming:

    builder.Services.AddAGUIServer();

builder.AddAIAgent("assistant", (_, _) => agent)
    .WithInMemorySessionStore();

var app = builder.Build();
app.MapAGUIServer("assistant", "/ag-ui");

    Requests using the same AG-UI thread resume the stored session; a replacement thread starts a new session.

    Persistence must be configured explicitly. Without an AgentSessionStore, sessions are intentionally ephemeral. WithInMemorySessionStore is appropriate for single-process development; distributed applications should register a durable store.

    Multi-user hosts must additionally scope session lookup by an authenticated user or tenant rather than treating threadId as authorization.

    The former AgentThread/ChatMessageStoreFactory model has been replaced by AgentSession/AgentSessionStore. Since hosted AG-UI sessions now persist through the supported mechanism, this issue can be closed as resolved.

  17. Javier Calvarro Nelson (javiercn)
    closed this as completedon Aug 18, 2026
  18. github-project-automation
    moved this to Done in Agent Frameworkon Aug 18, 2026
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