Canvas Component Metadata

---
name: canvas-component-metadata
description:
  Define valid component.yml metadata for Canvas components, including props,
  slots, and enums. Use when (1) Creating a new component, (2) Adding or
  modifying props, (3) Troubleshooting "not a valid choice" or prop type errors,
  (4) Mapping enums to CVA variants.
---

## File structure

Every `component.yml` must include these top-level keys:

```yaml
name: Component Name # Human-readable display name
machineName: component-name # Machine name in kebab-case
status: true # Whether the component is enabled
required: [] # Array of required prop names
props:
  properties:
    # ... prop definitions
slots: [] # Use [] only when there are no slots; otherwise use an object map
```

## Props

### Requirements

Every prop definition must include a `title` for the UI label. The `examples`
array is required for required props and recommended for all others. Only the
first example value is used by Drupal Canvas.

```yaml
props:
  properties:
    heading:
      title: Heading
      type: string
      examples:
        - Enter a heading...
```

**Prop IDs must be camelCase versions of their titles.**

The prop ID (the key under `properties`) must be the camelCase conversion of the
`title` value.

Only include user-facing, Canvas-editable props in `component.yml`.
Implementation-only React props must stay in JSX and must not be added to
metadata.

**Never include `className` in `component.yml`.** Treat it as a composition prop
for developers, not a Canvas editor control.

```yaml
# Correct
props:
  properties:
    buttonText:           # camelCase of "Button Text"
      title: Button Text
      type: string
    backgroundColor:      # camelCase of "Background Color"
      title: Background Color
      type: string
    isVisible:            # camelCase of "Is Visible"
      title: Is Visible
      type: boolean

# Wrong
props:
  properties:
    btn_text:             # should be "buttonText" for title "Button Text"
      title: Button Text
    bgColor:              # should be "backgroundColor" for title "Background Color"
      title: Background Color
```

### Prop types

#### Text

Basic text input. Stored as a string value.

```yaml
type: string
examples:
  - Hello, world!
```

#### Formatted text

Rich text content with HTML formatting support, displayed in a block context.

```yaml
type: string
contentMediaType: text/html
x-formatting-context: block
examples:
  - <p>This is <strong>formatted</strong> text with HTML.</p>
```

#### Link

URL or URI reference for links to internal or external resources.

```yaml
type: string
format: uri-reference
examples:
  - /about/contact
```

**Note:** The format can be either `uri` (accepts only absolute URLs) or
`uri-reference` (accepts both absolute and relative URLs).

**IMPORTANT: Use proper path examples for URL props.** Do not use `#` as an
example value for `uri-reference` props—it can cause validation failures during
upload. Always use realistic path-like examples:

```yaml
# Correct
examples:
  - /resources
  - /about/team
  - https://example.com/page

# Wrong
examples:
  - "#"
  - ""
```

#### Image

Reference to an image object with metadata like alt text, dimensions, and file
URL. Only the file URL is required to exist, all other metadata is always
optional.

```yaml
type: object
$ref: json-schema-definitions://canvas.module/image
examples:
  - src: >-
      https://images.unsplash.com/photo-1484959014842-cd1d967a39cf?ixlib=rb-1.2.1&ixid=MnwxMjA3fDB8MHxwaG90by1wYWdlfHx8fGVufDB8fHx8&auto=format&fit=crop&w=1770&q=80
    alt: Woman playing the violin
    width: 1770
    height: 1180
```

#### Video

Reference to a video object with metadata like dimensions and file URL. Only the
file URL is required to exist, all other metadata is always optional.

```yaml
type: object
$ref: json-schema-definitions://canvas.module/video
examples:
  - src: https://media.istockphoto.com/id/1340051874/video/aerial-top-down-view-of-a-container-cargo-ship.mp4?s=mp4-640x640-is&k=20&c=5qPpYI7TOJiOYzKq9V2myBvUno6Fq2XM3ITPGFE8Cd8=
    poster: https://example.com/600x400.png
```

#### Boolean

True or false value.

```yaml
type: boolean
examples:
  - false
```

#### Integer

Whole number value without decimal places.

```yaml
type: integer
examples:
  - 42
```

#### Number

Numeric value that can include decimal places.

```yaml
type: number
examples:
  - 3.14
```

#### List: text

A predefined list of text options that the user can select from.

```yaml
type: string
enum:
  - option1
  - option2
  - option3
meta:enum:
  option1: Option 1
  option2: Option 2
  option3: Option 3
examples:
  - option1
```

#### List: integer

A predefined list of integer options that the user can select from.

```yaml
type: integer
enum:
  - 1
  - 2
  - 3
meta:enum:
  1: Option 1
  2: Option 2
  3: Option 3
examples:
  - 1
```

## Enums

Enum values must use lowercase, machine-friendly identifiers. Use `meta:enum` to
provide human-readable display labels for the UI.

**Note:** Enum values cannot contain dots.

```yaml
# Correct
enum:
  - left_aligned
  - center_aligned
meta:enum:
  left_aligned: Left aligned
  center_aligned: Center aligned
examples:
  - left_aligned

# Wrong
enum:
  - Left aligned
  - Center aligned
```

The `examples` value must be the enum value, not the display label.

### Enum values must match JSX component variants

When using class-variance-authority (CVA) or similar libraries in the JSX
component, the variant keys must exactly match the enum values defined in
`component.yml`.

```jsx
// component.yml defines: enum: [left_aligned, center_aligned]
// CVA variants must match:
const variants = cva("base-classes", {
  variants: {
    layout: {
      left_aligned: "text-left", // matches enum value
      center_aligned: "text-center", // matches enum value
    },
  },
});
```

## Slots

Slots allow other components to be embedded within a component. In React, each
slot is received as a named prop that matches the slot key.

This section is the slot schema source of truth. Other skills should reference
these rules instead of redefining slot schema details.

Before creating slots, confirm with the user unless the use case is clearly
compositional (for example, rich nested content, or repeatable embedded
components). For simple text-like values, prefer a prop.

**Important:** Do not map Canvas slots to the `children` prop by default. If the
slot key is `content`, consume it as `content` in JSX.

Using a slot key named `children` is technically possible, but it is not
recommended because slot naming often flows into user-facing Canvas labels.
Prefer explicit slot keys such as `content`, `media`, or `actions`.

`slots` must be either:

1. An object map keyed by slot name (`content`, `sidebar`, etc.)
2. `[]` when the component has no slots

```yaml
slots:
  content:
    title: Content
  buttons:
    title: Buttons
```

In the JSX component, slots are destructured as named props and rendered
directly:

```jsx
const Section = ({ width, content }) => {
  return <div className={sectionVariants({ width })}>{content}</div>;
};
```

```jsx
// Wrong when the slot key is `content`: this does not consume the named slot.
const Section = ({ children }) => {
  return <div>{children}</div>;
};
```

Use `slots: []` only when the component has no slots:

```yaml
slots: []
```

Do not use arrays of slot objects:

```yaml
# Wrong
slots:
  - name: content
    title: Content
```