diff --git a/ABILITIES-API.md b/ABILITIES-API.md
new file mode 100644
index 000000000..0b7978bad
--- /dev/null
+++ b/ABILITIES-API.md
@@ -0,0 +1,163 @@
+# ActivityPub Abilities API
+
+WordPress Abilities API (WP 6.9+) integration for the ActivityPub plugin. Exposes ActivityPub functionality as discoverable, permissioned abilities for automation, workflows, and plugin interoperability.
+
+## Why?
+
+- **Plugin interoperability**: Other plugins can discover and call abilities in a consistent way
+- **Automation & workflows**: WP-Cron, WP-CLI, CI/CD, low-code tools can call abilities safely
+- **Self-documenting endpoints**: JSON Schema validation, easier tooling/testing
+- **REST exposure**: Standard `/wp-json/wp-abilities/v1/` endpoints
+
+## Categories
+
+| Slug | Label | Description |
+|------|-------|-------------|
+| `activitypub-discovery` | Discovery | Look up and discover remote actors in the Fediverse. |
+| `activitypub-social` | Social | Manage followers, following, and social connections. |
+
+## Implemented Abilities
+
+### Discovery (`activitypub-discovery`)
+
+| Ability | Description | Class |
+|---------|-------------|-------|
+| `activitypub/resolve-handle` | Look up WebFinger data for a handle. | `Ability\Webfinger` |
+| `activitypub/get-actor` | Fetch profile information for a remote actor. | `Ability\Actor` |
+
+### Social (`activitypub-social`)
+
+| Ability | Description | Class |
+|---------|-------------|-------|
+| `activitypub/get-followers` | List followers for a local actor. | `Ability\Followers` |
+| `activitypub/get-following` | List accounts being followed by a local actor. | `Ability\Following` |
+| `activitypub/follow` | Follow a remote actor. | `Ability\Following` |
+| `activitypub/unfollow` | Unfollow a remote actor. | `Ability\Following` |
+
+### Planned
+
+| Ability | Category | Description |
+|---------|----------|-------------|
+| `activitypub/publish-note` | publish | Publish a Note to the Fediverse. |
+| `activitypub/announce-post` | publish | Boost/announce an existing post. |
+| `activitypub/block-actor` | moderation | Block a specific actor. |
+| `activitypub/block-domain` | moderation | Block an entire domain. |
+| `activitypub/unblock` | moderation | Unblock actor or domain. |
+| `activitypub/get-inbox` | moderation | Get recent inbox activities. |
+| `activitypub/retry-delivery` | moderation | Retry failed activity delivery. |
+
+## Architecture
+
+### File Structure
+
+```
+activitypub.php                      # Hooks into wp_abilities_api_*_init
+includes/
+├── class-abilities.php              # Category registration + orchestration + extensibility hooks
+├── ability/
+│   ├── class-actor.php              # activitypub/get-actor
+│   ├── class-followers.php          # activitypub/get-followers
+│   ├── class-following.php          # activitypub/get-following, follow, unfollow
+│   └── class-webfinger.php          # activitypub/resolve-handle
+```
+
+### Registration Flow
+
+1. `activitypub.php` hooks `Abilities::register_categories` into `wp_abilities_api_categories_init`
+2. `activitypub.php` hooks `Abilities::register_abilities` into `wp_abilities_api_init`
+3. `Abilities::register_categories()` registers categories, then fires `activitypub_register_ability_categories`
+4. `Abilities::register_abilities()` calls each ability class's `register()`, then fires `activitypub_register_abilities`
+
+Ability classes are grouped by domain (e.g. `Webfinger`, `Actor`), not one-per-ability. A single class can register abilities across multiple categories.
+
+### Ability Class Template
+
+```php
+<?php
+namespace Activitypub\Ability;
+
+class Example {
+	public static function register() {
+		\wp_register_ability(
+			'activitypub/example',
+			array(
+				'label'               => \__( 'Example Ability', 'activitypub' ),
+				'description'         => \__( 'Does something useful.', 'activitypub' ),
+				'category'            => 'activitypub-discovery',
+				'execute_callback'    => array( self::class, 'execute' ),
+				'permission_callback' => array( self::class, 'permission_callback' ),
+				'input_schema'        => array(
+					'type'                 => 'object',
+					'properties'           => array(
+						'param' => array(
+							'type'        => 'string',
+							'description' => \__( 'A required parameter.', 'activitypub' ),
+						),
+					),
+					'required'             => array( 'param' ),
+					'additionalProperties' => false,
+				),
+				'output_schema'       => array(
+					'type' => 'object',
+				),
+				'meta'                => array(
+					'annotations'  => array(
+						'readonly'    => true,
+						'destructive' => false,
+						'idempotent'  => true,
+					),
+					'show_in_rest' => true,
+				),
+			)
+		);
+	}
+
+	public static function permission_callback( $input = null ) {
+		return \current_user_can( 'activitypub' );
+	}
+
+	public static function execute( $input ) {
+		// Implementation here.
+		return array( 'result' => 'value' );
+	}
+}
+```
+
+### Extensibility
+
+Third-party plugins can register additional categories and abilities:
+
+```php
+\add_action( 'activitypub_register_ability_categories', function () {
+	\wp_register_ability_category( 'my-plugin-category', array( ... ) );
+} );
+
+\add_action( 'activitypub_register_abilities', function () {
+	\wp_register_ability( 'my-plugin/my-ability', array( ... ) );
+} );
+```
+
+## Existing Services
+
+- `Webfinger::get_data()` — WebFinger lookups
+- `Collection\Remote_Actors::fetch_by_various()`, `::get_actor()` — Remote actor profiles
+- `Collection\Followers::query()` — Follower lists
+- `Collection\Following::query()` — Following lists
+- `Collection\Outbox::reschedule()` — Retry delivery
+- `Moderation` class — Block/unblock logic
+
+## Testing
+
+```bash
+# List categories
+curl -u admin:PASSWORD http://localhost:8888/wp-json/wp-abilities/v1/categories
+
+# List discovery abilities
+curl -u admin:PASSWORD 'http://localhost:8888/wp-json/wp-abilities/v1/abilities?category=activitypub-discovery'
+
+# Resolve a handle (GET — readonly abilities require GET)
+curl -u admin:PASSWORD 'http://localhost:8888/wp-json/wp-abilities/v1/abilities/activitypub/resolve-handle/run?input[handle]=user@example.com'
+
+# Get actor
+curl -u admin:PASSWORD 'http://localhost:8888/wp-json/wp-abilities/v1/abilities/activitypub/get-actor/run?input[actor]=user@example.com'
+```
diff --git a/activitypub.php b/activitypub.php
index 6bdfd0458..c8f9405fa 100644
--- a/activitypub.php
+++ b/activitypub.php
@@ -107,6 +107,10 @@ function plugin_init() {
 		\add_action( 'init', array( __NAMESPACE__ . '\Relay', 'init' ) );
 	}
 
+	// WordPress Abilities API (WP 6.9+). These hooks only fire when the API is available.
+	\add_action( 'wp_abilities_api_categories_init', array( __NAMESPACE__ . '\Abilities', 'register_categories' ) );
+	\add_action( 'wp_abilities_api_init', array( __NAMESPACE__ . '\Abilities', 'register_abilities' ) );
+
 	// Load development tools.
 	if ( 'local' === wp_get_environment_type() ) {
 		$loader_file = __DIR__ . '/local/load.php';
diff --git a/includes/ability/class-actor.php b/includes/ability/class-actor.php
new file mode 100644
index 000000000..7f5ef9624
--- /dev/null
+++ b/includes/ability/class-actor.php
@@ -0,0 +1,144 @@
+<?php
+/**
+ * Actor abilities.
+ *
+ * @package Activitypub
+ * @since unreleased
+ */
+
+namespace Activitypub\Ability;
+
+use Activitypub\Collection\Remote_Actors;
+
+/**
+ * Actor ability class.
+ *
+ * Provides abilities for looking up remote actor profiles.
+ *
+ * @since unreleased
+ */
+class Actor {
+
+	/**
+	 * Register Actor abilities.
+	 *
+	 * @since unreleased
+	 */
+	public static function register() {
+		\wp_register_ability(
+			'activitypub/get-actor',
+			array(
+				'label'               => \__( 'Get Actor', 'activitypub' ),
+				'description'         => \__( 'Fetch profile information for a remote ActivityPub actor.', 'activitypub' ),
+				'category'            => 'activitypub-discovery',
+				'execute_callback'    => array( self::class, 'get_actor_info' ),
+				'permission_callback' => array( self::class, 'permission_callback' ),
+				'input_schema'        => array(
+					'type'                 => 'object',
+					'properties'           => array(
+						'actor' => array(
+							'type'        => 'string',
+							'description' => \__( 'Actor URL or WebFinger handle', 'activitypub' ),
+						),
+					),
+					'required'             => array( 'actor' ),
+					'additionalProperties' => false,
+				),
+				'output_schema'       => array(
+					'type'       => 'object',
+					'properties' => array(
+						'id'                => array(
+							'type'   => 'string',
+							'format' => 'uri',
+						),
+						'type'              => array(
+							'type' => 'string',
+						),
+						'name'              => array(
+							'type' => 'string',
+						),
+						'preferredUsername' => array(
+							'type' => 'string',
+						),
+						'summary'           => array(
+							'type' => 'string',
+						),
+						'inbox'             => array(
+							'type'   => 'string',
+							'format' => 'uri',
+						),
+						'outbox'            => array(
+							'type'   => 'string',
+							'format' => 'uri',
+						),
+						'followers'         => array(
+							'type'   => 'string',
+							'format' => 'uri',
+						),
+						'following'         => array(
+							'type'   => 'string',
+							'format' => 'uri',
+						),
+						'icon'              => array(
+							'type' => 'object',
+						),
+					),
+				),
+				'meta'                => array(
+					'annotations'  => array(
+						'readonly'    => true,
+						'destructive' => false,
+						'idempotent'  => true,
+					),
+					'show_in_rest' => true,
+				),
+			)
+		);
+	}
+
+	/**
+	 * Permission callback.
+	 *
+	 * @since unreleased
+	 *
+	 * @return bool
+	 */
+	public static function permission_callback() {
+		return \current_user_can( 'activitypub' );
+	}
+
+	/**
+	 * Get actor information.
+	 *
+	 * @since unreleased
+	 *
+	 * @param array $input Input parameters.
+	 * @return array|\WP_Error
+	 */
+	public static function get_actor_info( $input ) {
+		$actor_input = \sanitize_text_field( $input['actor'] );
+
+		$post = Remote_Actors::fetch_by_various( $actor_input );
+		if ( \is_wp_error( $post ) ) {
+			return $post;
+		}
+
+		$actor = Remote_Actors::get_actor( $post );
+		if ( \is_wp_error( $actor ) ) {
+			return $actor;
+		}
+
+		return array(
+			'id'                => $actor->get_id(),
+			'type'              => $actor->get_type(),
+			'name'              => $actor->get_name(),
+			'preferredUsername' => $actor->get_preferred_username(),
+			'summary'           => $actor->get_summary(),
+			'inbox'             => $actor->get_inbox(),
+			'outbox'            => $actor->get_outbox(),
+			'followers'         => $actor->get_followers(),
+			'following'         => $actor->get_following(),
+			'icon'              => $actor->get_icon(),
+		);
+	}
+}
diff --git a/includes/ability/class-followers.php b/includes/ability/class-followers.php
new file mode 100644
index 000000000..663aa393a
--- /dev/null
+++ b/includes/ability/class-followers.php
@@ -0,0 +1,161 @@
+<?php
+/**
+ * Followers abilities.
+ *
+ * @package Activitypub
+ * @since unreleased
+ */
+
+namespace Activitypub\Ability;
+
+use Activitypub\Collection\Followers as Followers_Collection;
+use Activitypub\Collection\Remote_Actors;
+
+/**
+ * Followers ability class.
+ *
+ * Provides abilities for listing followers of a local actor.
+ *
+ * @since unreleased
+ */
+class Followers {
+
+	/**
+	 * Register Followers abilities.
+	 *
+	 * @since unreleased
+	 */
+	public static function register() {
+		\wp_register_ability(
+			'activitypub/get-followers',
+			array(
+				'label'               => \__( 'Get Followers', 'activitypub' ),
+				'description'         => \__( 'List followers for a local actor.', 'activitypub' ),
+				'category'            => 'activitypub-social',
+				'execute_callback'    => array( self::class, 'get_followers' ),
+				'permission_callback' => array( self::class, 'permission_callback' ),
+				'input_schema'        => array(
+					'type'                 => 'object',
+					'properties'           => array(
+						'user_id'  => array(
+							'type'        => 'integer',
+							'description' => \__( 'The local actor user ID.', 'activitypub' ),
+						),
+						'page'     => array(
+							'type'        => 'integer',
+							'description' => \__( 'Page number for pagination.', 'activitypub' ),
+						),
+						'per_page' => array(
+							'type'        => 'integer',
+							'description' => \__( 'Number of results per page.', 'activitypub' ),
+						),
+					),
+					'required'             => array( 'user_id' ),
+					'additionalProperties' => false,
+				),
+				'output_schema'       => array(
+					'type'       => 'object',
+					'properties' => array(
+						'followers' => array(
+							'type'  => 'array',
+							'items' => array(
+								'type'       => 'object',
+								'properties' => array(
+									'id'                => array(
+										'type'   => 'string',
+										'format' => 'uri',
+									),
+									'type'              => array(
+										'type' => 'string',
+									),
+									'name'              => array(
+										'type' => 'string',
+									),
+									'preferredUsername' => array(
+										'type' => 'string',
+									),
+									'followers'         => array(
+										'type'   => 'string',
+										'format' => 'uri',
+									),
+									'following'         => array(
+										'type'   => 'string',
+										'format' => 'uri',
+									),
+									'icon'              => array(
+										'type' => 'object',
+									),
+								),
+							),
+						),
+						'total'     => array(
+							'type' => 'integer',
+						),
+					),
+				),
+				'meta'                => array(
+					'annotations'  => array(
+						'readonly'    => true,
+						'destructive' => false,
+						'idempotent'  => true,
+					),
+					'show_in_rest' => true,
+				),
+			)
+		);
+	}
+
+	/**
+	 * Permission callback.
+	 *
+	 * @since unreleased
+	 *
+	 * @return bool
+	 */
+	public static function permission_callback() {
+		return \current_user_can( 'activitypub' );
+	}
+
+	/**
+	 * Get followers for a local actor.
+	 *
+	 * @since unreleased
+	 *
+	 * @param array $input Input parameters.
+	 * @return array|\WP_Error
+	 */
+	public static function get_followers( $input ) {
+		$user_id = \absint( $input['user_id'] );
+
+		if ( ! $user_id ) {
+			return new \WP_Error( 'activitypub_invalid_user_id', \__( 'Invalid user ID.', 'activitypub' ), array( 'status' => 400 ) );
+		}
+
+		$per_page = isset( $input['per_page'] ) ? \min( \absint( $input['per_page'] ), 100 ) : 20;
+		$page     = isset( $input['page'] ) ? \absint( $input['page'] ) : 1;
+
+		$data = Followers_Collection::query( $user_id, $per_page, $page );
+
+		$followers = array();
+		foreach ( $data['followers'] as $post ) {
+			$actor = Remote_Actors::get_actor( $post );
+			if ( \is_wp_error( $actor ) ) {
+				continue;
+			}
+			$followers[] = array(
+				'id'                => $actor->get_id(),
+				'type'              => $actor->get_type(),
+				'name'              => $actor->get_name(),
+				'preferredUsername' => $actor->get_preferred_username(),
+				'followers'         => $actor->get_followers(),
+				'following'         => $actor->get_following(),
+				'icon'              => $actor->get_icon(),
+			);
+		}
+
+		return array(
+			'followers' => $followers,
+			'total'     => $data['total'],
+		);
+	}
+}
diff --git a/includes/ability/class-following.php b/includes/ability/class-following.php
new file mode 100644
index 000000000..dca9cb11e
--- /dev/null
+++ b/includes/ability/class-following.php
@@ -0,0 +1,363 @@
+<?php
+/**
+ * Following abilities.
+ *
+ * @package Activitypub
+ * @since unreleased
+ */
+
+namespace Activitypub\Ability;
+
+use Activitypub\Collection\Following as Following_Collection;
+use Activitypub\Collection\Remote_Actors;
+
+use function Activitypub\follow;
+use function Activitypub\unfollow;
+
+/**
+ * Following ability class.
+ *
+ * Provides abilities for managing the following list of a local actor.
+ *
+ * @since unreleased
+ */
+class Following {
+
+	/**
+	 * Register Following abilities.
+	 *
+	 * @since unreleased
+	 */
+	public static function register() {
+		self::register_get_following();
+		self::register_follow();
+		self::register_unfollow();
+	}
+
+	/**
+	 * Register the get-following ability.
+	 *
+	 * @since unreleased
+	 */
+	private static function register_get_following() {
+		\wp_register_ability(
+			'activitypub/get-following',
+			array(
+				'label'               => \__( 'Get Following', 'activitypub' ),
+				'description'         => \__( 'List accounts being followed by a local actor.', 'activitypub' ),
+				'category'            => 'activitypub-social',
+				'execute_callback'    => array( self::class, 'get_following' ),
+				'permission_callback' => array( self::class, 'permission_callback' ),
+				'input_schema'        => array(
+					'type'                 => 'object',
+					'properties'           => array(
+						'user_id'  => array(
+							'type'        => 'integer',
+							'description' => \__( 'The local actor user ID.', 'activitypub' ),
+						),
+						'page'     => array(
+							'type'        => 'integer',
+							'description' => \__( 'Page number for pagination.', 'activitypub' ),
+						),
+						'per_page' => array(
+							'type'        => 'integer',
+							'description' => \__( 'Number of results per page.', 'activitypub' ),
+						),
+					),
+					'required'             => array( 'user_id' ),
+					'additionalProperties' => false,
+				),
+				'output_schema'       => array(
+					'type'       => 'object',
+					'properties' => array(
+						'following' => array(
+							'type'  => 'array',
+							'items' => array(
+								'type'       => 'object',
+								'properties' => array(
+									'id'                => array(
+										'type'   => 'string',
+										'format' => 'uri',
+									),
+									'type'              => array(
+										'type' => 'string',
+									),
+									'name'              => array(
+										'type' => 'string',
+									),
+									'preferredUsername' => array(
+										'type' => 'string',
+									),
+									'followers'         => array(
+										'type'   => 'string',
+										'format' => 'uri',
+									),
+									'following'         => array(
+										'type'   => 'string',
+										'format' => 'uri',
+									),
+									'icon'              => array(
+										'type' => 'object',
+									),
+								),
+							),
+						),
+						'total'     => array(
+							'type' => 'integer',
+						),
+					),
+				),
+				'meta'                => array(
+					'annotations'  => array(
+						'readonly'    => true,
+						'destructive' => false,
+						'idempotent'  => true,
+					),
+					'show_in_rest' => true,
+				),
+			)
+		);
+	}
+
+	/**
+	 * Register the follow ability.
+	 *
+	 * @since unreleased
+	 */
+	private static function register_follow() {
+		\wp_register_ability(
+			'activitypub/follow',
+			array(
+				'label'               => \__( 'Follow', 'activitypub' ),
+				'description'         => \__( 'Follow a remote actor.', 'activitypub' ),
+				'category'            => 'activitypub-social',
+				'execute_callback'    => array( self::class, 'follow' ),
+				'permission_callback' => array( self::class, 'permission_callback' ),
+				'input_schema'        => array(
+					'type'                 => 'object',
+					'properties'           => array(
+						'actor'   => array(
+							'type'        => 'string',
+							'description' => \__( 'Actor URL or WebFinger handle to follow.', 'activitypub' ),
+						),
+						'user_id' => array(
+							'type'        => 'integer',
+							'description' => \__( 'The local actor user ID. Defaults to the current user.', 'activitypub' ),
+						),
+					),
+					'required'             => array( 'actor' ),
+					'additionalProperties' => false,
+				),
+				'output_schema'       => array(
+					'type'       => 'object',
+					'properties' => array(
+						'outbox_item_id' => array(
+							'type' => 'integer',
+						),
+						'status'         => array(
+							'type' => 'string',
+						),
+					),
+				),
+				'meta'                => array(
+					'annotations'  => array(
+						'readonly'    => false,
+						'destructive' => false,
+						'idempotent'  => false,
+					),
+					'show_in_rest' => true,
+				),
+			)
+		);
+	}
+
+	/**
+	 * Register the unfollow ability.
+	 *
+	 * @since unreleased
+	 */
+	private static function register_unfollow() {
+		\wp_register_ability(
+			'activitypub/unfollow',
+			array(
+				'label'               => \__( 'Unfollow', 'activitypub' ),
+				'description'         => \__( 'Unfollow a remote actor.', 'activitypub' ),
+				'category'            => 'activitypub-social',
+				'execute_callback'    => array( self::class, 'unfollow' ),
+				'permission_callback' => array( self::class, 'permission_callback' ),
+				'input_schema'        => array(
+					'type'                 => 'object',
+					'properties'           => array(
+						'actor'   => array(
+							'type'        => 'string',
+							'description' => \__( 'Actor URL or WebFinger handle to unfollow.', 'activitypub' ),
+						),
+						'user_id' => array(
+							'type'        => 'integer',
+							'description' => \__( 'The local actor user ID. Defaults to the current user.', 'activitypub' ),
+						),
+					),
+					'required'             => array( 'actor' ),
+					'additionalProperties' => false,
+				),
+				'output_schema'       => array(
+					'type'       => 'object',
+					'properties' => array(
+						'success' => array(
+							'type' => 'boolean',
+						),
+					),
+				),
+				'meta'                => array(
+					'annotations'  => array(
+						'readonly'    => false,
+						'destructive' => false,
+						'idempotent'  => false,
+					),
+					'show_in_rest' => true,
+				),
+			)
+		);
+	}
+
+	/**
+	 * Permission callback.
+	 *
+	 * @since unreleased
+	 *
+	 * @return bool
+	 */
+	public static function permission_callback() {
+		return \current_user_can( 'activitypub' );
+	}
+
+	/**
+	 * Get following for a local actor.
+	 *
+	 * @since unreleased
+	 *
+	 * @param array $input Input parameters.
+	 * @return array|\WP_Error
+	 */
+	public static function get_following( $input ) {
+		$user_id = \absint( $input['user_id'] );
+
+		if ( ! $user_id ) {
+			return new \WP_Error( 'activitypub_invalid_user_id', \__( 'Invalid user ID.', 'activitypub' ), array( 'status' => 400 ) );
+		}
+
+		if ( \get_current_user_id() !== $user_id && ! \current_user_can( 'manage_options' ) ) {
+			return new \WP_Error(
+				'activitypub_forbidden',
+				\__( 'You are not allowed to view another user\'s following list.', 'activitypub' ),
+				array( 'status' => 403 )
+			);
+		}
+
+		$per_page = isset( $input['per_page'] ) ? \min( \absint( $input['per_page'] ), 100 ) : 20;
+		$page     = isset( $input['page'] ) ? \absint( $input['page'] ) : 1;
+
+		$data = Following_Collection::query( $user_id, $per_page, $page );
+
+		$following = array();
+		foreach ( $data['following'] as $post ) {
+			$actor = Remote_Actors::get_actor( $post );
+			if ( \is_wp_error( $actor ) ) {
+				continue;
+			}
+			$following[] = array(
+				'id'                => $actor->get_id(),
+				'type'              => $actor->get_type(),
+				'name'              => $actor->get_name(),
+				'preferredUsername' => $actor->get_preferred_username(),
+				'followers'         => $actor->get_followers(),
+				'following'         => $actor->get_following(),
+				'icon'              => $actor->get_icon(),
+			);
+		}
+
+		return array(
+			'following' => $following,
+			'total'     => $data['total'],
+		);
+	}
+
+	/**
+	 * Follow a remote actor.
+	 *
+	 * @since unreleased
+	 *
+	 * @param array $input Input parameters.
+	 * @return array|\WP_Error
+	 */
+	public static function follow( $input ) {
+		if ( '1' !== \get_option( 'activitypub_following_ui', '0' ) ) {
+			return new \WP_Error(
+				'activitypub_following_disabled',
+				\__( 'Following feature is disabled.', 'activitypub' ),
+				array( 'status' => 403 )
+			);
+		}
+
+		$actor   = \sanitize_text_field( $input['actor'] );
+		$user_id = isset( $input['user_id'] ) ? \absint( $input['user_id'] ) : \get_current_user_id();
+
+		if ( \get_current_user_id() !== $user_id && ! \current_user_can( 'manage_options' ) ) {
+			return new \WP_Error(
+				'activitypub_forbidden',
+				\__( 'You are not allowed to act on behalf of another user.', 'activitypub' ),
+				array( 'status' => 403 )
+			);
+		}
+
+		$result = follow( $actor, $user_id );
+
+		if ( \is_wp_error( $result ) ) {
+			return $result;
+		}
+
+		return array(
+			'outbox_item_id' => $result,
+			'status'         => 'pending',
+		);
+	}
+
+	/**
+	 * Unfollow a remote actor.
+	 *
+	 * @since unreleased
+	 *
+	 * @param array $input Input parameters.
+	 * @return array|\WP_Error
+	 */
+	public static function unfollow( $input ) {
+		if ( '1' !== \get_option( 'activitypub_following_ui', '0' ) ) {
+			return new \WP_Error(
+				'activitypub_following_disabled',
+				\__( 'Following feature is disabled.', 'activitypub' ),
+				array( 'status' => 403 )
+			);
+		}
+
+		$actor   = \sanitize_text_field( $input['actor'] );
+		$user_id = isset( $input['user_id'] ) ? \absint( $input['user_id'] ) : \get_current_user_id();
+
+		if ( \get_current_user_id() !== $user_id && ! \current_user_can( 'manage_options' ) ) {
+			return new \WP_Error(
+				'activitypub_forbidden',
+				\__( 'You are not allowed to act on behalf of another user.', 'activitypub' ),
+				array( 'status' => 403 )
+			);
+		}
+
+		$result = unfollow( $actor, $user_id );
+
+		if ( \is_wp_error( $result ) ) {
+			return $result;
+		}
+
+		return array(
+			'success' => true,
+		);
+	}
+}
diff --git a/includes/ability/class-webfinger.php b/includes/ability/class-webfinger.php
new file mode 100644
index 000000000..f6e2ae60c
--- /dev/null
+++ b/includes/ability/class-webfinger.php
@@ -0,0 +1,86 @@
+<?php
+/**
+ * WebFinger abilities.
+ *
+ * @package Activitypub
+ * @since unreleased
+ */
+
+namespace Activitypub\Ability;
+
+use Activitypub\Webfinger as Webfinger_Util;
+
+/**
+ * WebFinger ability class.
+ *
+ * Provides abilities for resolving WebFinger handles.
+ *
+ * @since unreleased
+ */
+class Webfinger {
+
+	/**
+	 * Register WebFinger abilities.
+	 *
+	 * @since unreleased
+	 */
+	public static function register() {
+		\wp_register_ability(
+			'activitypub/resolve-handle',
+			array(
+				'label'               => \__( 'Resolve WebFinger Handle', 'activitypub' ),
+				'description'         => \__( 'Resolve a WebFinger handle to an ActivityPub actor URL.', 'activitypub' ),
+				'category'            => 'activitypub-discovery',
+				'execute_callback'    => array( self::class, 'resolve_handle' ),
+				'permission_callback' => array( self::class, 'permission_callback' ),
+				'input_schema'        => array(
+					'type'                 => 'object',
+					'properties'           => array(
+						'handle' => array(
+							'type'        => 'string',
+							'description' => \__( 'WebFinger handle (e.g., user@example.com)', 'activitypub' ),
+						),
+					),
+					'required'             => array( 'handle' ),
+					'additionalProperties' => false,
+				),
+				'output_schema'       => array(
+					'type' => 'object',
+				),
+				'meta'                => array(
+					'annotations'  => array(
+						'readonly'    => true,
+						'destructive' => false,
+						'idempotent'  => true,
+					),
+					'show_in_rest' => true,
+				),
+			)
+		);
+	}
+
+	/**
+	 * Permission callback.
+	 *
+	 * @since unreleased
+	 *
+	 * @return bool
+	 */
+	public static function permission_callback() {
+		return \current_user_can( 'activitypub' );
+	}
+
+	/**
+	 * Resolve a WebFinger handle to an actor URL.
+	 *
+	 * @since unreleased
+	 *
+	 * @param array $input Input parameters.
+	 * @return array|\WP_Error
+	 */
+	public static function resolve_handle( $input ) {
+		$handle = \sanitize_text_field( $input['handle'] );
+
+		return Webfinger_Util::get_data( $handle );
+	}
+}
diff --git a/includes/class-abilities.php b/includes/class-abilities.php
new file mode 100644
index 000000000..3246f38d2
--- /dev/null
+++ b/includes/class-abilities.php
@@ -0,0 +1,82 @@
+<?php
+/**
+ * Abilities API integration.
+ *
+ * @package Activitypub
+ * @since unreleased
+ */
+
+namespace Activitypub;
+
+use Activitypub\Ability\Actor;
+use Activitypub\Ability\Followers;
+use Activitypub\Ability\Following;
+use Activitypub\Ability\Webfinger;
+
+/**
+ * Abilities class.
+ *
+ * Handles registration of ActivityPub ability categories and abilities
+ * for the WordPress Abilities API (WP 6.9+).
+ *
+ * @since unreleased
+ */
+class Abilities {
+
+	/**
+	 * Register ActivityPub ability categories.
+	 *
+	 * Hooked into `wp_abilities_api_categories_init`.
+	 *
+	 * @since unreleased
+	 */
+	public static function register_categories() {
+		\wp_register_ability_category(
+			'activitypub-discovery',
+			array(
+				'label'       => \__( 'Discovery', 'activitypub' ),
+				'description' => \__( 'Look up and discover remote actors in the Fediverse.', 'activitypub' ),
+			)
+		);
+
+		\wp_register_ability_category(
+			'activitypub-social',
+			array(
+				'label'       => \__( 'Social', 'activitypub' ),
+				'description' => \__( 'Manage followers, following, and social connections.', 'activitypub' ),
+			)
+		);
+
+		/**
+		 * Fires after built-in ability categories are registered.
+		 *
+		 * Use this hook to register additional ability categories.
+		 *
+		 * @since unreleased
+		 */
+		\do_action( 'activitypub_register_ability_categories' );
+	}
+
+	/**
+	 * Register all ActivityPub abilities.
+	 *
+	 * Hooked into `wp_abilities_api_init`.
+	 *
+	 * @since unreleased
+	 */
+	public static function register_abilities() {
+		Actor::register();
+		Followers::register();
+		Following::register();
+		Webfinger::register();
+
+		/**
+		 * Fires after built-in abilities are registered.
+		 *
+		 * Use this hook to register additional abilities.
+		 *
+		 * @since unreleased
+		 */
+		\do_action( 'activitypub_register_abilities' );
+	}
+}