Add: WordPress Core get settings ability

[jorgefilipecosta]

Part of: WordPress/ai#40
Inspired by the work on https://github.com/galatanovidiu/mcp-adapter-implementation-example/tree/experiment/layerd-mcp-tools/includes/Abilities by @galatanovidiu.

Summary

This PR adds a core/get-settings ability to the WordPress Abilities API. This ability dynamically discovers and exposes all WordPress settings. For now all abilities that are register show_in_rest = true are exposed. We should probably have a setting related to the ability exposition but can be a follow.

Organization

Following the pattern established in #10665, this PR adds a new class WP_Settings_Abilities in src/wp-includes/abilities/class-wp-settings-abilities.php. The class is organized into:

• Initialization: init() method that collects available groups and builds the output schema
• Schema Building: build_output_schema() creates a rich JSON Schema from registered settings metadata
• Ability Registration: register_get_settings() registers the ability with dynamic schemas
• Execution: execute_get_settings() retrieves and returns settings grouped by their registration group
• Utilities: Helper methods for permission checking and value type casting

Test plan

• Open http://localhost:6888/site-wp-dev-1/wp-admin/post-new.php
• Open the browser console and run the following examples:

// Get all settings
await wp.apiFetch({
  path: '/wp-abilities/v1/abilities/core/get-settings/run',
  method: 'POST',
  data: { input: {} }
});

• Verify all settings are returned grouped by their registration group (general, reading, writing, discussion)

// Get only general settings
await wp.apiFetch({
  path: '/wp-abilities/v1/abilities/core/get-settings/run',
  method: 'POST',
  data: { input: { group: 'general' } }
});

• Verify only general settings are returned when filtering by group

// Check the ability schema
await wp.apiFetch({
  path: '/wp-abilities/v1/abilities/core/get-settings',
  method: 'GET'
});

• Verify the input schema includes a dynamic enum of available groups

• Verify the output schema documents each group and its settings with types, descriptions, and defaults

• Test permission check: Verify non-admin users cannot access the ability (requires manage_options capability)

[github-actions]

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Props jorgefilipecosta, mukesh27, justlevine, jason_the_adams.

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[github-actions]

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[jorgefilipecosta]

Hi @justlevine, @mukeshpanchal27, thank you both for the reviews, I tried to address or answerer them all. I think it is ready for another pass.

[JasonTheAdams]

@jorgefilipecosta Out of curiosity, why are we coupling this to the REST API? Why would this Ability limit itself to settings that are configured to work with REST? Or am I misunderstanding something?

[JasonTheAdams]

I think I'm inclined away from using a preexisting configuration in an unexpected way.

[JasonTheAdams]

I guess I'm also not understanding the purpose of this Ability. Why would someone use this over the get_option() function? What's this for?