Nuxtjs Guideline: Routing — Use validate for route params. Description: Validate dynamic route parameters before rendering. Do: validate function in definePageMeta. Don't: Manual validation in setup. Good Example: definePageMeta({ validate: (route) => /^\d+$/.test(route.params.id) }). Bad Example: if (!valid) navigateTo('/404'). Severity: Medium. Docs: https://nuxt.com/docs/api/utils/define-page-meta.