agui-dotnet-human-in-the-loop

AG-UI .NET — human in the loop (approval & interrupts)

Goal: stop an agent run at a decision point, hand control to a person, and resume the same run with their decision — either approving a sensitive tool call or supplying input the agent asked for.

A paused run completes its turn with RUN_FINISHED { outcome: interrupt }. The client inspects the response, gets the human decision, then sends a follow-up turn that carries the answer; the SDK reconnects it to the paused tool call so the run continues.

Approval: gate a tool behind a human yes/no

This is the simple path and needs no custom endpoint code — ToChatRequestContext handles the resume.

Server: wrap the sensitive tool

Wrap the function in ApprovalRequiredAIFunction. When the model calls it, the function-invoking client raises a ToolApprovalRequestContent instead of executing:

using Microsoft.Extensions.AI;

var deleteFile = new ApprovalRequiredAIFunction(
    AIFunctionFactory.Create(DeleteFile, "delete_file", "Deletes a file."));

builder.Services.AddChatClient(/* provider IChatClient */)
    .ConfigureOptions(o => (o.Tools ??= []).Add(deleteFile))
    .UseFunctionInvocation();

Client: detect the request, decide, resume

The first turn returns a ToolApprovalRequestContent. Show it to the human, then resume by appending the request and the human's response and streaming again:

using Microsoft.Extensions.AI;

var messages = new List<ChatMessage> { new(ChatRole.User, "Delete report-draft.txt") };

var turn1 = new List<ChatResponseUpdate>();
await foreach (var u in client.GetStreamingResponseAsync(messages))
{
    turn1.Add(u);
}

var request = turn1.SelectMany(u => u.Contents)
                   .OfType<ToolApprovalRequestContent>()
                   .FirstOrDefault();

if (request is { ToolCall: FunctionCallContent call })
{
    bool approved = AskHuman($"Run {call.Name}?");   // your UI / prompt

    messages.Add(new ChatMessage(ChatRole.Assistant, [request]));
    messages.Add(new ChatMessage(ChatRole.User, [request.CreateResponse(approved)]));

    await foreach (var u in client.GetStreamingResponseAsync(messages))
    {
        Console.Write(u.Text);   // runs the tool if approved, skips it if not
    }
}