Program.cs

using Archevolt;
using System.Numerics;

namespace Archevolt.Particles;

[Component] public readonly record struct Position(Vector3 Value);
[Component] public readonly record struct Velocity(Vector3 Value);
[Component] public readonly struct Frozen;
[Resource] public readonly record struct FrameTime(float DeltaSeconds);
[Bundle] public readonly partial record struct Particle(Position Position, Velocity Velocity);

[Query, Write<Position>, Read<Velocity>, Without<Frozen>]
public readonly ref partial struct Moving;

public static partial class Motion
{
    [EcsSystem]
    public static void Integrate(scoped Moving moving, scoped Res<FrameTime> time)
    {
        foreach (var row in moving)
        {
            ref var position = ref row.Position;
            position = position with { Value = position.Value + row.Velocity.Value * time.Value.DeltaSeconds };
        }
    }
}

public static partial class MotionKernel
{
    [Each(Partitioned = true), Without<Frozen>]
    public static void Integrate(scoped ref Position position, scoped in Velocity velocity, scoped Res<FrameTime> time) =>
        position = position with { Value = position.Value + velocity.Value * time.Value.DeltaSeconds };
}

[EcsModule, IncludeSystems(typeof(Motion)), IncludeSystems(typeof(MotionKernel)), IncludeBundle<Particle>, IncludeResource<FrameTime>]
public static partial class GameEcs;
[Schedule, Run(typeof(Motion), nameof(Motion.Integrate), Order = 0)] public sealed partial class Simulation;
[Schedule, Run(typeof(MotionKernel), nameof(MotionKernel.Integrate), Order = 0)] public sealed partial class KernelSimulation;

public static class Program
{
    public static void Main()
    {
        Run(1);
        Run(4);
        Console.WriteLine("ecs=ok");
    }

    static void Run(int concurrency)
    {
        using var world = new WorldBuilder().UseParallelExecution(concurrency).AddModule(GameEcs.Module).Build();
        world.InsertResource(new FrameTime(1));
        var entities = new Entity[100_000];
        for (int index = 0; index < entities.Length; index++)
            entities[index] = world.Spawn(new Particle(new Position(Vector3.Zero), new Velocity(Vector3.UnitX)));
        using var kernel = KernelSimulation.Create(world);
        kernel.Run();
        foreach (var entity in entities)
            if (world.Get<Position>(entity).Value != Vector3.UnitX) throw new InvalidOperationException("Each failed to update an entity.");
        world.Insert(entities[0], new Frozen());
        kernel.Run();
        if (world.Get<Position>(entities[0]).Value.X != 1 || world.Get<Position>(entities[^1]).Value.X != 2)
            throw new InvalidOperationException("Adding a tag did not update query membership.");
        world.Remove<Frozen>(entities[0]);
        using var simulation = Simulation.Create(world);
        simulation.Run();
        if (world.Get<Position>(entities[0]).Value.X != 2 || world.Get<Position>(entities[^1]).Value.X != 3)
            throw new InvalidOperationException("Named queries did not observe the updated archetypes.");
    }
}