Shared shell
The shared application shell has a collapsible left sidebar page menu, bottom-left user menu, common user configuration dialog and login screen; mobile adapts the same shell to an accessible drawer. Page-local navigation components do not select a different shell layout. The shell owns account controls, settings entry and page framing. Compose destinations from declared pages; do not duplicate route lists in a second registry. navbar, menu, megamenu, dock, link and breadcrumbs present those destinations. The breadcrumb ancestry is derived from the declared route.
A missing or newly forbidden destination disappears from discovery, and direct requests are checked again. Membership, team selection and policy changes invalidate earlier eligibility. See roles and operation permissions, read policies, and layout components.
Composition
Use a page for a routable screen and reusable views for repeated presentation. Collection detail, forms and canonical actions should stay attached to their owning page or record context. The shell supplies the frame; generated renderers return page content rather than a competing shell.