.NET: Foundry-hosted workflows accept incomplete reply batches #9530

// Copyright (c) Microsoft. All rights reserved.

using System.Runtime.CompilerServices;
using System.Text.Json;
using Microsoft.Agents.AI;
using Microsoft.Agents.AI.Foundry.Hosting;
using Microsoft.Agents.AI.Workflows;
using Microsoft.Extensions.AI;

var innerAgent = new TwoFunctionCallsAgent();
var workflow = new WorkflowBuilder(innerAgent.BindAsExecutor(
    new AIAgentHostOptions { InterceptUnterminatedFunctionCalls = false, EmitAgentUpdateEvents = false })).Build();
var agent = workflow.AsAIAgent(name: "hosted-partial-repro", includeExceptionDetails: true);
var builder = WebApplication.CreateBuilder(args);
builder.Services.AddFoundryResponses(agent, new InMemoryAgentSessionStore());
var app = builder.Build();
app.MapFoundryResponses();
app.Run();

internal sealed class TwoFunctionCallsAgent : AIAgent
{
    protected override string IdCore => "lookup-agent";

    protected override async IAsyncEnumerable<AgentResponseUpdate> RunCoreStreamingAsync(
        IEnumerable<ChatMessage> messages, AgentSession? session, AgentRunOptions? options,
        [EnumeratorCancellation] CancellationToken cancellationToken = default)
    {
        var results = messages.SelectMany(message => message.Contents).OfType<FunctionResultContent>().ToList();
        if (results.Count == 0)
        {
            yield return new AgentResponseUpdate(ChatRole.Assistant,
                [new FunctionCallContent("call-A", "lookup"), new FunctionCallContent("call-B", "lookup")]);
        }
        else
        {
            var ids = string.Join(", ", results.Select(result => result.CallId));
            Console.WriteLine($"REPRO: inner agent received {ids}");
            yield return new AgentResponseUpdate(ChatRole.Assistant, $"Received: {ids}");
        }

        await Task.CompletedTask.ConfigureAwait(false);
    }

    protected override Task<AgentResponse> RunCoreAsync(
        IEnumerable<ChatMessage> messages, AgentSession? session, AgentRunOptions? options,
        CancellationToken cancellationToken = default) =>
        this.RunStreamingAsync(messages, session, options, cancellationToken).ToAgentResponseAsync(cancellationToken);

    protected override ValueTask<AgentSession> CreateSessionCoreAsync(CancellationToken cancellationToken = default) =>
        new(new Session());

    protected override ValueTask<JsonElement> SerializeSessionCoreAsync(
        AgentSession session, JsonSerializerOptions? jsonSerializerOptions, CancellationToken cancellationToken = default) =>
        new(JsonSerializer.SerializeToElement(new { }));

    protected override ValueTask<AgentSession> DeserializeSessionCoreAsync(
        JsonElement serializedState, JsonSerializerOptions? jsonSerializerOptions, CancellationToken cancellationToken = default) =>
        new(new Session());

    private sealed class Session : AgentSession;
}