Systems and traversal

Write systems with EcsSystem and Each, and opt traversals into partitioning.

[EcsSystem]

[EcsSystem] marks a synchronous static void method. Supported parameters are scoped named queries and the capabilities listed in Resources and local state, Commands, and Messages.

Private methods are callable through generated invokers inside their partial owner. Overloads, generic methods, async methods, iterators, and ref returns are rejected (diagnostic AV005).

[Each]

public static partial class MotionKernel
{
    [Each(Partitioned = true), Without<Frozen>]
    public static void Move(scoped ref Position position, scoped in Velocity velocity)
    {
        position = position with { X = position.X + velocity.X };
    }
}

[Each] calls the method once per matching entity.

• Use scoped ref T for writes and scoped in T for reads.
• An optional Entity parameter supplies identity.
• Membership and change-filter attributes apply to the method.
• Components passed by value are rejected.

Partitioning

[Each] executes one traversal by default. [Each(Partitioned = true)] opts into splitting matched chunks across the world’s execution budget, which matters once parallel execution is enabled.

Partitioned methods accept component refs, Entity, and readonly unmanaged resources, including optional resources without owner-thread affinity. Locals, commands, messages, managed resources, mutable resources, and named queries are excluded. An unsafe partition request is reported as AV010.

Descriptors

The generator exposes each method as Owner.MethodName_Descriptor. Runtime composition accepts these descriptors through BoundSchedule.Bind. See Schedules.