Function compute_widget_layout 

pub unsafe fn compute_widget_layout(
    taffy: &mut TaffyTree,
    root: NodeId,
    available: Size<AvailableSpace>,
    nodes: &HashMap<NodeId, *mut dyn Widget>,
    bindings: &BoundNodeMap,
    text: &mut TextRenderer,
) -> Result<(), WidgetLayoutError>

Measure the host tree and settle allocation-dependent styles before calling Widget::apply_layout. App and the headless runner use this same solver. Manual hosts may use it with the maps from their current build_layout. Raw Taffy layout still works for ordinary Grid tracks, but cannot resolve CardGrid’s below-minimum single-column fallback without this adjustment.

This changes styles only: widget state and node identities are retained. Paint-only and scroll-translation frames do not need to call it.

Errors

Returns a Taffy error or DidNotSettle; callers must skip applying/painting an unsettled layout.

Safety

nodes and bindings must describe this exact live tree. The caller must exclusively own every referenced widget throughout the call, without moving, rebuilding or destroying widgets or allowing pointers to escape.