public class CoreService
{
    private int _connectionCount = 42;
    private void ResetInternalState() { /* reset */ }
}

// UnsafeAccessor generates direct IL access with 0 reflection overhead!
public static class Accessors
{
    [UnsafeAccessor(UnsafeAccessorKind.Field, Name = "_connectionCount")]
    public extern static ref int GetConnectionCount(CoreService service);

    [UnsafeAccessor(UnsafeAccessorKind.Method, Name = "ResetInternalState")]
    public extern static void ResetState(CoreService service);
}