Nuxtjs Guideline: Lifecycle — Use onPrehydrate for pre-hydration logic. Description: Run code before Nuxt hydrates the page. Do: onPrehydrate for client setup. Don't: onMounted for hydration-critical code. Good Example: onPrehydrate(() => { console.log(window) }). Bad Example: onMounted for pre-hydration needs. Severity: Low. Docs: https://nuxt.com/docs/api/composables/on-prehydrate.