Add HEAD method support for performance optimization

includes/rest-api/endpoints/class-wp-rest-abilities-list-controller.php

@@ -94,10 +94,6 @@ public function register_routes(): void {
 	 * @return \WP_REST_Response Response object on success.
 	 */
 	public function get_items( $request ) {
-		// TODO: Add HEAD method support for performance optimization.
-		// Should return early with empty body but include X-WP-Total and X-WP-TotalPages headers.
-		// See: https://github.com/WordPress/wordpress-develop/blob/trunk/src/wp-includes/rest-api/endpoints/class-wp-rest-comments-controller.php#L316-L318
-
 		$abilities = wp_get_abilities();
 
 		// Handle pagination with explicit defaults.
@@ -109,15 +105,19 @@ public function get_items( $request ) {
 		$total_abilities = count( $abilities );
 		$max_pages       = ceil( $total_abilities / $per_page );
 
-		$abilities = array_slice( $abilities, $offset, $per_page );
+		if ( $request->is_method( 'HEAD' ) ) {
+			$response = new \WP_REST_Response( array() );
+		} else {
+			$abilities = array_slice( $abilities, $offset, $per_page );
 
-		$data = array();
-		foreach ( $abilities as $ability ) {
-			$item   = $this->prepare_item_for_response( $ability, $request );
-			$data[] = $this->prepare_response_for_collection( $item );
-		}
+			$data = array();
+			foreach ( $abilities as $ability ) {
+				$item   = $this->prepare_item_for_response( $ability, $request );
+				$data[] = $this->prepare_response_for_collection( $item );
+			}
 
-		$response = rest_ensure_response( $data );
+			$response = rest_ensure_response( $data );
+		}
 
 		$response->header( 'X-WP-Total', (string) $total_abilities );
 		$response->header( 'X-WP-TotalPages', (string) $max_pages );

tests/unit/rest-api/wpRestAbilitiesListController.php

@@ -273,6 +273,23 @@ public function test_pagination_headers(): void {
 		$this->assertEquals( ceil( $total_abilities / 10 ), (int) $headers['X-WP-TotalPages'] );
 	}
 
+	/**
+	 * Test HEAD method returns empty body with proper headers.
+	 */
+	public function test_head_request(): void {
+		$request  = new WP_REST_Request( 'HEAD', '/wp/v2/abilities' );
+		$response = $this->server->dispatch( $request );
+
+		// Verify empty response body
+		$data = $response->get_data();
+		$this->assertEmpty( $data );
+
+		// Verify pagination headers are present
+		$headers = $response->get_headers();
+		$this->assertArrayHasKey( 'X-WP-Total', $headers );
+		$this->assertArrayHasKey( 'X-WP-TotalPages', $headers );
+	}
+
 	/**
 	 * Test pagination links.
 	 */