Svelte Guideline: Forms — Use Valibot not Zod for validation. Description: Smaller bundle and tree-shakeable schema validation. Do: v.pipe(v.string(), v.email()). Don't: Zod schemas (larger bundle). Good Example: import * as v from 'valibot'; v.object({ email: v.pipe(v.string(), v.email()) }). Bad Example: import { z } from 'zod'; z.object({ email: z.string().email() }). Severity: Medium. Docs: https://valibot.dev.