Program.cs

#:package HotChocolate.AspNetCore@16.1.3
#:package HotChocolate.Types.Analyzers@16.1.3

using HotChocolate;
using HotChocolate.Execution;
using HotChocolate.Types;
using HotChocolateBatchResolverBug;
using Microsoft.Extensions.DependencyInjection;

[assembly: Module("BugTypes")]

var executor = await new ServiceCollection()
    .AddGraphQL()
    .AddQueryType<Query>()
    .AddBugTypes()
    .BuildRequestExecutorAsync();

Console.WriteLine("Test 1: Sync parent");
await executor.ExecuteAsync("{ syncParents { children { computed } } }");
Console.WriteLine("  OK\n");

Console.WriteLine("Test 2: Async parent (1 item)");
await executor.ExecuteAsync("{ asyncParent { children { computed } } }");
Console.WriteLine("  OK\n");

Console.WriteLine("Test 3: Async parent (2 items) - will hang");
await executor.ExecuteAsync("{ asyncParents { children { computed } } }");
Console.WriteLine("  OK"); // Never reached

namespace HotChocolateBatchResolverBug
{
    public class Query
    {
        public List<SyncParent> SyncParents => [new(), new()];
        public AsyncParent AsyncParent => new();
        public List<AsyncParent> AsyncParents => [new(), new()];
    }

    public record SyncParent
    {
        public List<Child> Children => [new()];
    }

    public record AsyncParent
    {
        public Task<List<Child>> Children => Task.FromResult<List<Child>>([new()]);
    }

    public record Child;

    [ObjectType<Child>]
    public static partial class ChildNode
    {
        [BatchResolver]
        public static List<string> GetComputed([Parent] List<Child> c) => [.. c.Select(_ => "x")];
    }
}