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

[DavidParks8]

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

• .NET: Sync AG-UI conversation history from backend #2510 - .NET: Sync AG-UI conversation history from backend (related but focused on MESSAGE_SNAPSHOT events)
• Python: sync AG-UI conversation history from backend #2458 - Python: sync AG-UI conversation history from backend

Environment

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

[javiercn]

@DavidParks8 thanks for contacting us.

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

[DavidParks8]

@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.

[vecode]

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

[arjendeblok]

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.