storybook/docs/_snippets/sveltekit-add-framework.md

export default {
  // ...
  framework: '@storybook/sveltekit', // 👈 Add this
  // svelteOptions: { ... }, 👈 Remove this
};

import { StorybookConfig } from '@storybook/nextjs';

const config: StorybookConfig = {
  // ...
  framework: '@storybook/sveltekit', // 👈 Add this
  // svelteOptions: { ... }, 👈 Remove this
};

export default config;