Svelte Guideline: Patterns — Use svelte-sonner for toasts. Description: Toast notifications with auto-dismiss and stacking. Do: toast.success('Saved'); toast.error('Failed'). Don't: Custom toast implementation. Good Example: import { toast } from 'svelte-sonner'; toast.success('Done'). Bad Example: showNotification({ type: 'success', message: 'Done' }). Severity: Medium. Docs: https://svelte-sonner.vercel.app.