Function morph_gate 

pub fn morph_gate(
    idx: usize,
    main_entity: MainEntity,
    morph: &mut MorphSlot,
    meta: &MorphMeta,
    pipeline_cache: &PipelineCache,
    render_device: &RenderDevice,
    atlas_layout: &BindGroupLayoutDescriptor,
    sampler: &Sampler,
) -> Option<BindGroup>

Whether a morph-ONLY layer’s composite may draw this frame, maintaining the gate-warn bookkeeping. Returns the bind group over blend when ready. Same discipline as the content-filter gate: never fall back to the raw capture (the mid-blend flash this gate exists to prevent).