storybook/docs/snippets/common/test-runner-auth.ts.mdx

```ts
// .storybook/test-runner.ts

import type { TestRunnerConfig } from '@storybook/test-runner';

const config: TestRunnerConfig = {
  getHttpHeaders: async (url) => {
    const token = url.includes('prod') ? 'prod-token' : 'dev-token';
    return {
      Authorization: `Bearer ${token}`,
    };
  },
};

export default config;
```