Storybook Addon Flow Direction

Validate components across writing modes and text directions directly in Storybook. Detect physical CSS usage and get logical-property suggestions before shipping.

Install

pnpm add -D storybook-addon-flow-direction

npm install -D storybook-addon-flow-direction

yarn add -D storybook-addon-flow-direction

Register the addon

Add it to .storybook/main.ts:

import type { StorybookConfig } from '@storybook/react-vite';

const config: StorybookConfig = {
  framework: '@storybook/react-vite',
  addons: ['storybook-addon-flow-direction'],
};

export default config;

Toolbar

The Flow Direction toolbar includes:

• writing mode (horizontal-tb, vertical-rl, vertical-lr)
• direction (ltr, rtl)
• matrix mode toggle
• reset action

Use the toolbar to switch context, then run a scan from the panel.

Scanner

The scanner checks rendered DOM and authored styles for physical CSS that can break in RTL or vertical layouts.

It reports matches from:

• stylesheet declarations that are readable via CSSOM
• inline style attributes

Examples:

• padding-left -> padding-inline-start
• margin-right -> margin-inline-end
• left -> inset-inline-start
• text-align: left -> text-align: start
• scroll-snap-type: x mandatory -> scroll-snap-type: inline mandatory

Cross-origin stylesheets that block cssRules access are skipped.

Panel workflow

1. Open a story.
2. Click Re-scan in the Flow Direction panel.
3. Review grouped findings.
4. Click Focus offender to jump to the element in preview.

Selector hints used by Focus offender are derived in this order: data-testid, data-flow-direction-label, id, then the first class token. Class tokens keep semantic hyphenated names intact (for example physical-toast), while CSS-module style underscore hash suffixes are normalized for readability.

Configuration

Supported parameters:

• flowDirection.matrix (boolean, story-level) - render the story in a six-cell matrix
• flowDirection.supportedWritingModes (FlowWritingMode[], project-level) - writing modes shown in toolbar and matrix
• flowDirection.supportedDirections (FlowDirection[], project-level) - directions shown in toolbar and matrix
• flowDirection.scanScope ({ include?: (string | RegExp)[]; exclude?: (string | RegExp)[] }) - restrict scanner to matching stylesheet sources

Set project-wide defaults in .storybook/preview.ts:

import type { Preview } from '@storybook/react-vite';

const preview: Preview = {
  parameters: {
    flowDirection: {
      supportedWritingModes: ['horizontal-tb', 'vertical-rl', 'vertical-lr'],
      supportedDirections: ['ltr', 'rtl'],
      // Optional:
      // scanScope: { include: [/my-app/], exclude: ['vendor.css'] },
      scanScope: {
        // Match local story stylesheets in root-level `stories/` setups.
        // Include build-time asset URLs so hashed CSS chunks are scanned too.
        include: ['/src/stories/', '\\src\\stories\\', '.stories.', '.module.css', '/stories/', '\\stories\\', '/assets/', '\\assets\\'],
      },
    },
  },
};

export default preview;

If your story CSS still does not appear in scan results, add project-specific identifiers from generated stylesheet sources (for example chunk names) and keep the include list focused so you do not scan unrelated Storybook UI/vendor styles.

Compatibility

• Storybook 10.x
• Node.js >=20.19

License

MIT