One-line: the primary app navigation — a 256px rail on the tinted --sidebar surface, one level of nesting maximum.

```jsx
<Sidebar>
  <SidebarHeader>…</SidebarHeader>
  <SidebarContent>
    <SidebarGroup>
      <SidebarGroupLabel>Workspace</SidebarGroupLabel>
      <SidebarMenu>
        <SidebarMenuItem><SidebarMenuButton isActive><CalendarIcon /><span>Bookings</span></SidebarMenuButton><SidebarMenuBadge>12</SidebarMenuBadge></SidebarMenuItem>
      </SidebarMenu>
    </SidebarGroup>
  </SidebarContent>
  <SidebarFooter>…</SidebarFooter>
</Sidebar>
```

The active row is a 4% wash plus medium weight — never a coloured pill or a left accent bar.
