shadcn's own sidebar.tsx fails `next lint`: SidebarMenuSkeleton calls Math.random during render (react-hooks/purity)

pnpm exec eslint --quiet → no output, exit 0 (before: 3 errors, one of them this).

shadcn@>=4.23 <5, eslint-config-next@>=16.4 <17, eslint-plugin-react-hooks@>=7.1 <8

components straight from the shadcn registry pass the Next.js lint preset (the scaffold only kept the Tailwind class-order rules off components/ui).

pnpm lint → src/components/ui/sidebar.tsx 610:26 error Error: Cannot call impure function during render. Math.random is an impure function … react-hooks/purity, in SidebarMenuSkeleton's React.useMemo that builds a random 50–90% width from Math.floor(Math.random() * 40) + 50.

eslint-plugin-react-hooks 7 (bundled by eslint-config-next 16) ships the React Compiler rules, and purity is an error in its recommended set. A random width also differs between the server render and hydration.

lint output before/after, 2026-10-28.