.NET: [Feature]: Automatic translation of StateBag mutations and streaming tool-argument deltas to AG-UI state events #4177

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1. Andreas Adner (adner)

   added the

   Feature

   issue type on Feb 23, 2026
2. Mark Wallace (markwallace-microsoft)

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   triageUsage: [Issues], Target: All issues that still need to be triagedUsage: [Issues], Target: All issues that still need to be triaged

   on Feb 23, 2026
3. Mark Wallace (markwallace-microsoft)

   added this to Agent Frameworkon Feb 23, 2026
4. Mark Wallace (markwallace-microsoft)

   assigned

   Javier Calvarro Nelson (javiercn)

   and

   Evan Mattson (moonbox3)

   on Feb 23, 2026
5. Mark Wallace (markwallace-microsoft)

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   ag-ui

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   on Feb 23, 2026
6. Evan Mattson (moonbox3)

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   on Jun 1, 2026
7. Evan Mattson (moonbox3)

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   on Jun 1, 2026
8. github-actions

   changed the title [-][Feature]: Automatic translation of StateBag mutations and streaming tool-argument deltas to AG-UI state events[/-] [+].NET: [Feature]: Automatic translation of StateBag mutations and streaming tool-argument deltas to AG-UI state events[/+] on Jun 1, 2026
9. Evan Mattson (moonbox3)

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   ui integration

   ag-uiUsage: [Issues, PRs], Target: AG-UI protocol integrationUsage: [Issues, PRs], Target: AG-UI protocol integration

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   on Jun 17, 2026
10. danroth27 commented on Jul 25, 2026

    

    Daniel Roth (danroth27)

    on Jul 25, 2026

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    The AG-UI .NET SDK (AGUI.Server / AGUIStreamOptions) now lives in ag-ui-protocol/ag-ui, so the declarative stream-mapping portion of this request is tracked there: ag-ui-protocol/ag-ui#2245.

    Status of the pieces raised here:

    • ✅ Tool result → state now has declarative helpers on AGUIStreamOptions: MapResultAsStateSnapshot(toolName) and MapResultAsStateDelta(toolName). Custom SharedStateAgent.cs-style middleware is no longer required for that case.
    • ⏳ Predictive tool-argument streaming → state (the predict_state_config equivalent) is still manual via MapCall(...) — tracked in [.NET] Predictive state updates: stream a tool call's arguments to the UI as the model writes them ag-ui-protocol/ag-ui#2245.
    • ⏳ Auto-emitting state from AgentSession.StateBag mutations — still open here, since it touches AgentSession in agent-framework core.

    Framing note for anyone picking this up: state events now flow via RawRepresentation = StateSnapshotEvent / StateDeltaEvent and the MapResultAsState* / MapCall mappings rather than DataContent, and MapAGUI() is now MapAGUIServer(). The PredictiveStateUpdatesAgent.cs / SharedStateAgent.cs sample workarounds referenced above have been replaced by the declarative AGUIStreamOptions samples.

    👍React with 👍1Reacted by Andreas Adner
11. demidgost-sys commented on Aug 4, 2026

    

    Demid Valiullin (demidgost-sys)

    on Aug 4, 2026

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    Thanks — AgentSessionStateBag is documented as thread-safe, so individual SetValue operations should already be safe. What I was wondering about is the ordering guarantee in the proposed AG-UI bridge: if two mutations happen close together, should the generated RFC 6902 deltas be serialized or versioned so clients cannot apply them out of order? Would an integration test or a documented fallback to STATE_SNAPSHOT make sense for this case?
12. javiercn commented on Aug 18, 2026

    

    Javier Calvarro Nelson (javiercn)

    on Aug 18, 2026

    Contributor

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    The current framing conflates AgentSession.StateBag with AG-UI shared state.

    StateBag is arbitrary persisted session state used by Agent Framework and provider integrations. It can contain internal data such as:

    • chat-history provider state;
    • pending approval bookkeeping;
    • memory and compaction state;
    • queued/background work;
    • provider-specific continuation data.

    Automatically emitting its contents or mutations to an AG-UI client would expose implementation state that was never declared as part of the application's frontend state contract. StateBag also has no UI schema, mutation-observation contract, transaction boundary, version, or ordered RFC 6902 delta stream.

    AG-UI state should instead be application-defined and mapped explicitly through the public AG-UI SDK:

    var options = new AGUIStreamOptions()
        .MapResultAsStateSnapshot("create_plan")
        .MapResultAsStateDelta("update_plan_step");

    Applications can also use:

    • MapCall(...);
    • MapResult(...);
    • MapContent(...);
    • explicit StateSnapshotEvent / StateDeltaEvent values;
    • a delegating agent for application-specific state projection.

    Tool-argument streaming is similarly an explicit protocol-mapping concern. AGUI.Server exposes streaming argument extraction through MapStreamingToolCallArguments(...); deciding whether and how those fragments represent application state remains application-specific.

    The older DataContent conventions and sample middleware referenced in the issue have been superseded by public AGUI.Abstractions events and AGUIStreamOptions.

    We do not plan to automatically expose AgentSession.StateBag as AG-UI state. It remains session persistence infrastructure, not an implicit frontend state model. This issue can be closed as not planned.
13. Javier Calvarro Nelson (javiercn)

    closed this as not plannedon Aug 18, 2026
14. github-project-automation

    moved this to Done in Agent Frameworkon Aug 18, 2026