Agent Skills: Format Storybook

Format Storybook

Based on "A Storybook format that scales with you" by Cassondra Roberts.

This skill provides patterns and conventions for building maintainable Storybook implementations that scale with your component library.

Core Principles

1. Compose, don't duplicate - Import child component templates instead of copying markup
2. Consistency over perfection - Pick patterns and stick with them across your library
3. Progressive disclosure - Provide sensible defaults with optional controls for edge cases
4. Self-documenting structure - Organize files so the architecture is immediately clear

File Structure

Keep Storybook assets close to component source files:

component/
├── component.js
├── component.css
└── stories/
    ├── component.stories.js    # Story definitions, controls, config
    ├── template.js              # Reusable render functions
    ├── component.docs.mdx       # [Optional] Documentation
    └── component.test.js        # [Optional] Visual regression grids

Story File Structure

Default Export

Every story file needs a default export with metadata:

export default {
  title: "Components/Button",           // Sidebar hierarchy
  component: "Button",                  // Component name
  argTypes: { /* control definitions */ },
  args: { /* default values */ },
  parameters: { /* additional config */ },
  tags: [ /* organizational tags */ ]
};

Organizing Controls

Group controls into logical categories for easy navigation:

• State - Interactive states (focused, open, disabled)
• Variant - Design variations (size, appearance)
• Content - Text, images, nested components
• Advanced - Edge cases and specialized configs

argTypes: {
  size: {
    control: "select",
    options: ["sm", "md", "lg"],
    description: "The size of the button",
    table: { category: "Variant" }
  },
  isDisabled: {
    control: "boolean",
    description: "Whether the button is disabled",
    table: { category: "State" }
  }
}

Tip: Create shared control files in .storybook/controls/ to reuse across components.

Default Values

Always provide sensible defaults so the primary story renders in a useful state:

args: {
  size: "md",
  isDisabled: false,
  label: "Click me"
}

Avoid meaningless "default" or "normal" options - use undefined instead.

Creating Individual Stories

Use .bind({}) to create stories that inherit from defaults:

export const Default = Template.bind({});
Default.args = {};

export const Disabled = Template.bind({});
Disabled.args = {
  isDisabled: true
};

export const WithIcon = Template.bind({});
WithIcon.args = {
  icon: "settings",
  label: "Settings"
};

Story Naming Conventions

Use concise, descriptive names:

• ✅ Default - Primary interactive example
• ✅ With Icon - Optional features
• ✅ Loading State - Specific states
• ✅ Error Variant - Edge cases
• ❌ Button Default - Don't repeat component name

Useful Tags

• !dev - Hide stories from sidebar (documentation-only stories)
• !autodocs - Exclude from auto-generated docs
• Combine both for visual regression testing grids

Template Files

The template.js file contains your rendering logic.

Template Structure

Export a primary Template(args, context) function:

import { html } from "lit";
import { classMap } from "lit/directives/class-map.js";
import { ifDefined } from "lit/directives/if-defined.js";

export const Template = (args, context) => {
  const {
    rootClass = "button",
    id,
    testId,
    customClasses = [],
    customStyles = {},
    size = "md",
    isDisabled = false,
    label = "Button"
  } = args;

  return html`
    <button
      class=${classMap({
        [rootClass]: true,
        [`${rootClass}--${size}`]: size,
        [`${rootClass}--disabled`]: isDisabled,
        ...customClasses.reduce((acc, c) => ({ ...acc, [c]: true }), {})
      })}
      style=${styleMap(customStyles)}
      id=${ifDefined(id)}
      data-testid=${ifDefined(testId)}
      ?disabled=${isDisabled}
    >
      ${label}
    </button>
  `;
};

Standard Arguments

Accept these common arguments for flexibility:

• rootClass - Base CSS class
• id and testId - Identification and testing
• customClasses - Array of additional classes
• customStyles - Object of custom CSS properties

Composition Pattern

Import and render nested component templates:

import { Template as Popover } from "@design-system/popover/stories/template.js";
import { Template as Button } from "@design-system/button/stories/template.js";

export const Template = (args, context) => Popover({
  ...args,
  isOpen: true,
  trigger: (passthroughs, ctx) => Button({
    label: "Open Menu",
    ...passthroughs
  }, ctx),
  content: [/* child content */]
}, context);

Lit Directives for Dynamic Behavior

• classMap - Conditional classes
• styleMap - Inline style objects
• ifDefined - Optional attributes (only render when defined)
• when - Conditional template regions

For interactive examples, use context.updateArgs to toggle state:

onclick=${() => context.updateArgs({ isOpen: !args.isOpen })}

Visual Regression Testing

For tools like Chromatic, create test grids in component.test.js:

import { Template } from "./template.js";

export const TestGrid = {
  render: Template,
  parameters: {
    chromatic: { disableSnapshot: false }
  }
};

export const Default = TestGrid.bind({});
Default.tags = ["!autodocs", "!dev"];
Default.args = {
  // Test-specific args
};

Strategy: Group many states and variants into a single snapshot grid to optimize test runs.

Accessibility

Always provide ARIA attributes through arguments:

argTypes: {
  ariaHasPopup: {
    control: "select",
    options: ["true", "false", "menu", "dialog"],
    table: { category: "Advanced" }
  },
  ariaExpanded: {
    control: "boolean",
    table: { category: "State" }
  }
}

Use ifDefined so they only render when needed:

aria-haspopup=${ifDefined(args.ariaHasPopup)}
aria-expanded=${ifDefined(args.ariaExpanded)}

Documentation and Metadata

Design Links

Connect stories to design files:

parameters: {
  design: {
    type: "figma",
    url: "https://www.figma.com/..."
  }
}

Package Information

Include metadata for documentation:

import packageJson from "../package.json";

export default {
  parameters: {
    packageJson,
    status: { type: "stable" } // or "experimental", "deprecated"
  }
};

Component Status

Use tags to communicate lifecycle:

tags: ["stable", "migrated"]

Setup Recommendations

Path Aliasing

Configure package aliases in Storybook to avoid relative imports:

// .storybook/main.js
export default {
  viteFinal: (config) => {
    config.resolve.alias = {
      ...config.resolve.alias,
      "@design-system": path.resolve(__dirname, "../packages")
    };
    return config;
  }
};

Use in imports:

// ✅ Good
import { Template } from "@design-system/button/stories/template.js";

// ❌ Avoid
import { Template } from "../../../button/stories/template.js";

Rendering Library (Vanilla Projects)

For projects without a framework, use lit for templates:

npm install lit

Benefits:

• Lightweight and performant
• Conditional classes and styles
• Optional attributes
• Dynamic rendering utilities

Auto-Generated Titles

Map folder structure to sidebar hierarchy:

// .storybook/main.js
export default {
  stories: [
    {
      directory: '../packages/components',
      files: '*.stories.*',
      titlePrefix: 'Components',
    },
  ],
};

Dos and Don'ts

Do

• ✅ Import child component templates instead of duplicating markup
• ✅ Keep template.js focused on the component itself
• ✅ Categorize controls and set sensible defaults
• ✅ Hide VRT-only stories from sidebar using tags
• ✅ Reuse shared controls from a common location
• ✅ Include proper ARIA attributes
• ✅ Link to design files in parameters

Don't

• ❌ Hardcode IDs - use a helper function to generate random IDs
• ❌ Duplicate markup from nested components
• ❌ Skip accessibility attributes
• ❌ Create stories for every possible variant (let users explore via controls)
• ❌ Use relative imports when aliases are available
• ❌ Add meaningless "default" or "normal" variant options

Quick Reference

Minimal Story File

import { Template } from "./template.js";

export default {
  title: "Components/Button",
  component: "Button",
  argTypes: {
    size: {
      control: "select",
      options: ["sm", "md", "lg"],
      table: { category: "Variant" }
    }
  },
  args: {
    size: "md",
    label: "Click me"
  }
};

export const Default = Template.bind({});

Minimal Template File

import { html } from "lit";
import { classMap } from "lit/directives/class-map.js";

export const Template = (args) => {
  const { rootClass = "button", size = "md", label = "Button" } = args;
  
  return html`
    <button class=${classMap({
      [rootClass]: true,
      [`${rootClass}--${size}`]: size
    })}>
      ${label}
    </button>
  `;
};

References

Read these when you need more detail than the guidelines above:

• storybook-docs.md - Read when you need to look up specific Storybook APIs, addon configuration, or testing integrations (Chromatic, test runner)
• lit-templates.md - Read when you need details on Lit directives (classMap, styleMap, ifDefined, when) or template rendering patterns
• article.md - Read when you want the philosophy and reasoning behind these patterns, or need comprehensive end-to-end examples