What?

Part of #71792, related to #73845

Adds automatic DataForm inspector controls for PHP auto-registered blocks.

Why?

PHP-only blocks currently have no way to edit their attributes in the editor. This PR enables the automatic generation of inspector controls from the block's attribute definitions, making PHP-only blocks more useful and dynamic.

How?

1. On the PHP side, gutenberg_mark_auto_inspector_control_attributes marks user-defined attributes with __experimentalAutoInspectorControl during block registration. This runs before block supports add their attributes, so only user-defined attributes are marked (why this is important: the first version of this implementation incorrectly generated inspector controls for block supports, too).

2. On the client, generateFieldsFromAttributes in the block-editor package converts marked attributes to DataForm field definitions based on their types. This is necessary to keep this API close to block.json, as they slightly diverge with the Field API.

   • string → text field
   • number → number field
   • integer → integer field
   • boolean → boolean field
   • string with enum → select field

This will be obsolete once #74105 lands

3. Exclusions: Attributes are excluded from auto-generation if they:
   • Have a source (attributes edited inline)
   • Have role: 'local' (internal state like media uploads)
   • Were added by block supports

Testing Instructions

1. Register a PHP-only block with attributes:

register_block_type(
    'my-plugin/example',
    array(
        'title'           => 'My Example Block',
        'attributes'      => array(
            'title'   => array(
                'type'    => 'string',
                'default' => 'Hello World',
            ),
            'count'   => array(
                'type'    => 'integer',
                'default' => 5,
            ),
            'enabled' => array(
                'type'    => 'boolean',
                'default' => true,
            ),
            'size'    => array(
                'type'    => 'string',
                'enum'    => array( 'small', 'medium', 'large' ),
                'default' => 'medium',
            ),
        ),
        'render_callback' => function ( $attributes ) {
            return sprintf(
                '<div>%s: %d items (%s)</div>',
                esc_html( $attributes['title'] ),
                $attributes['count'],
                $attributes['size']
            );
        },
        'supports'        => array(
            'auto_register' => true,
        ),
    )
);

2. Insert the block in the editor
3. Verify inspector controls appear for each attribute type

Screencast

Follow-ups

• Custom descriptions, and placeholders
• Validation rules
• Conditional visibility
• More field types
• Number formatting
• Handle attributes with source: 'html' by generating a RichText control? I'm not sure this is a good UX