Svelte 5 Runes: Reactive Form with Real-Time Validation

This prompt targets Svelte 5's new Runes API and asks an AI coding assistant to build a fully interactive form component that showcases three core primitives: $state for reactive variable declarations, $derived for computed values that update automatically, and $effect for side-effect handling. The result is a practical reference implementation where validation messages, error highlights, and submit-button states all respond instantly as the user types — without any manual event wiring or store boilerplate.

This kind of prompt is ideal for developers migrating from Svelte 4 or learning the Runes paradigm from scratch, since it grounds abstract concepts in a concrete, familiar UI pattern. It also works well as a starting template for login screens, registration flows, or any data-entry interface where instant feedback improves usability. To adapt it further, try requesting additional field types such as dropdowns or file inputs, ask for Zod-based schema validation, or specify a particular design system like Tailwind or shadcn-svelte to shape the visual output.