next-app-template/.storybook/main.ts

import type { StorybookConfig } from '@storybook/nextjs';
const config: StorybookConfig = {
  stories: ['../components/**/*.(stories|story).@(js|jsx|ts|tsx)'],
  addons: ['@storybook/addon-essentials', 'storybook-dark-mode', '@storybook/addon-styling'],
  framework: {
    name: '@storybook/nextjs',
    options: {},
  },
};
export default config;