Function node_for_element 

pub fn node_for_element<H: UiHost>(
    app: &mut H,
    window: AppWindowId,
    element: GlobalElementId,
) -> Option<NodeId>

Returns the most recent retained NodeId mapping for element.

This is intentionally a last-known query surface for post-frame / component-policy code. Mechanism paths that already have access to UiTree or the declarative window frame should resolve a live attached node instead of treating this mapping as authoritative truth.