Function render_channel 

pub fn render_channel<S, W>() -> (RenderSender<S, W>, RenderReceiver<S, W>)

Create the UI→render channel: a depth-1 latest-wins scene slot fused with a FIFO lifecycle-command queue behind one condvar.

S is the scene payload type (frust_scene::Scene in a real shell), W the surface-handle type a RenderCommand::SurfaceCreated carries — both generic so this crate stays render-free (see the module docs’ Layering choice).