create-component

Creating new components

Creating a component is an act of design. Before scaffolding files, understand what the component needs to represent — its content areas, layout structure, and the CMS data it will render. The template you start from is a starting point, not a constraint.

Step 0: Deep Understanding Before Scaffolding

Before creating any component:

1. Inspect the source section's DOM structure. What HTML elements, CSS layout, and content areas does this section use? How many columns? What's dynamic vs. static?
2. Draft the component interface first. List every prop (with type), every slot, and every variant the component needs. Write this down before touching code.
3. Choose a template based on interface needs, not just visual similarity. If you need a multi-column footer with menus and social links, don't start from a component that only has a {text} prop — even if it's called "footer."
4. Don't let the template constrain you. A copied component is scaffolding. Replace its props, slots, and JSX entirely if the target section demands a different structure.

After creation, verify: can this component represent the full structure of its target section? Every content area in the source should map to a prop or slot. If it can't, the component is incomplete.

Scaffolding Steps

When asked to create a new component:

1. Browse canvas/src/components/ to find a similar component that can serve as a starting point (e.g., use blockquote as a base for an "alert" component, or button for any interactive element)
2. Copy the component folder to canvas/src/components/<new_name>/
3. Copy the corresponding story from canvas/src/stories/
4. Modify the copied files to implement the new component

CRITICAL: Every component MUST have its own individual story file. When copying from existing components, always copy both the component folder AND its corresponding story file. The story file naming convention is <component-name>.stories.jsx (using kebab-case with hyphens).

This approach ensures consistent patterns for component.yml structure, JSX conventions, and Storybook story format across all components.

Example: To create a new "Alert" component based on the Blockquote example:

cp -r canvas/src/components/blockquote canvas/src/components/alert
cp canvas/src/stories/components/blockquote.stories.tsx canvas/src/stories/components/alert.stories.tsx

Then modify the copied files to implement the Alert component.

Components use the @/components import alias, which points to canvas/src/components. When you copy and modify exisiting components, the imports will work automatically.

Dependency Resolution When Copying Components

When copying a component as a template, you must also copy its dependencies:

1. Read the component's index.jsx
2. Find all @/components/<name> imports
3. For each imported component, check if it already exists in canvas/src/components/
4. If missing: recursively copy it from the source (existing components or examples)
5. Recurse: each copied dependency may have its own @/components/<name> imports

Example: Copying hero which imports heading and button:

• Check canvas/src/components/heading/ — exists? Skip. Missing? Copy.
• Check canvas/src/components/button/ — exists? Skip. Missing? Copy.
• Check heading's imports — imports @/components/text? Copy if missing.

Never overwrite existing components during dependency copying. Only copy what's missing.

Component naming conventions

Use simple, generic names. Never prefix component names with the project or site name. Components should be reusable and their names should describe their purpose, not their origin.

# Correct - simple, descriptive names
footer
hero
navigation
contact_form

# Wrong - prefixed with project/site name
nebula_footer
acme_hero
mysite_navigation
projectx_contact_form

This ensures components remain portable and their names clearly communicate their function rather than their project context.

Reuse existing components

Always check canvas/src/components/ before creating new UI elements. When building a component that needs common UI elements (buttons, headings, images, etc.), import and use existing components rather than duplicating their functionality.

// ✅ GOOD: Import and use the existing button component
import Button from '@/components/button';

const NewsletterSignup = ({ onSubmit }) => (
  <form onSubmit={onSubmit}>
    <input type="email" placeholder="Enter your email" />
    <Button variant="primary">Subscribe</Button>
  </form>
);

// ❌ BAD: Duplicating button styles instead of reusing the component
const NewsletterSignup = ({ onSubmit }) => (
  <form onSubmit={onSubmit}>
    <input type="email" placeholder="Enter your email" />
    <button className="rounded bg-primary-600 px-4 py-2 text-white">
      Subscribe
    </button>
  </form>
);

This ensures visual consistency, reduces duplication, and makes updates easier since changes to a shared component automatically apply everywhere it's used.

Design components for composability. By default, avoid building layout constraints (like max-width or centering) into individual components. Layout components such as section handle width constraints when composing pages, so most components should remain flexible and adapt to their container.

Include built-in layout constraints when the component doesn't make sense in any other layout context (such as header or footer), or when the design specifically requires it.

// ✅ GOOD: Component adapts to its container width
const Card = ({ title, children }) => (
  <div className="rounded-lg border p-4">
    <h3>{title}</h3>
    {children}
  </div>
);

// ❌ BAD: Component has built-in width constraints (limits composability)
const Card = ({ title, children }) => (
  <div className="mx-auto max-w-md rounded-lg border p-4">
    <h3>{title}</h3>
    {children}
  </div>
);

Required component contract

Every component must satisfy the 4-part contract:

1. index.jsx — React component implementation (default export)
2. component.yml — Canvas metadata defining props, slots, and enums
3. Folder name matching machineName — lowercase snake_case (preferred) or kebab-case
4. A Storybook story file — in canvas/src/stories/components/

If any part is missing, the component is incomplete and will fail upload or editor rendering.

Recommended build order

1. Metadata first — define component.yml with props, slots, enums
2. Composability — decide what should be slots vs props
3. Styling — define design tokens in global.css, create CVA variants
4. Utilities — use FormattedText for HTML props, Image for image props
5. Data fetching — add SWR/JsonApiClient if the component fetches data
6. Story — create Storybook story with realistic content
7. Validate — run cd canvas && npm run code:fix (Prettier + ESLint + Canvas requirements), then cd canvas && npm run canvas:validate, then cd canvas && npm run canvas:ssr-test
8. Upload — run cd canvas && npm run canvas:upload -- -- -c <name> only after validation passes

Required component folder structure

CRITICAL: Every component folder in canvas/src/components/ MUST contain two files:

canvas/src/components/<component_name>/
├── index.jsx      # React component source code (REQUIRED)
└── component.yml  # Component metadata and props (REQUIRED)

Never create a component folder without both files. The index.jsx contains the actual React component implementation. The component.yml defines the component's metadata, props, and slots for Drupal Canvas.

The directory name must match machineName. The component folder name must exactly match the machineName value defined in component.yml. Use snake_case as the preferred format, though kebab-case is also supported.

After creating components, verify the folder structure:

# List all component folders and their contents
ls -la canvas/src/components/*/

# Verify each new component has both required files
ls canvas/src/components/<component_name>/index.jsx
ls canvas/src/components/<component_name>/component.yml

If a component folder is missing either file, the component is incomplete and will not work. Both index.jsx and component.yml are required.

Internal components

For internal re-use that should not be exposed to content editors via the library of components, ensure you set status: false in the component.yml file.

Common utilities

Utility/helper function can be placed in a utils_<name> component with an React component as a default export. These should always be internal components, so status: false MUST be set in the component.yml file.

Stories

Every non-internal component should have a corresponding story file in canvas/src/stories/components/. Where appropriate, internal components should also have a story file.

Use the stories skill when creating or modifying stories.

Drupal CMS Documentation

When creating components for Drupal CMS, consult the official platform documentation to ensure your component follows platform conventions and avoids known pitfalls. Use the canvas-docs-explorer skill:

/canvas-docs-explorer creating custom components

Important: never remove components via the Component Library UI (known bug that can break the site). Use the Code component panel instead.

Canvas-Starter Reference

For the canonical component contract and naming conventions, see .claude/reference/canvas-starter/canvas-component-definition/SKILL.md.