--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/wp/wp-includes/style-engine/class-wp-style-engine-css-rules-store.php	Fri Sep 05 18:40:08 2025 +0200
@@ -0,0 +1,166 @@
+<?php
+/**
+ * Style Engine: WP_Style_Engine_CSS_Rules_Store class
+ *
+ * @package WordPress
+ * @subpackage StyleEngine
+ * @since 6.1.0
+ */
+
+/**
+ * Core class used as a store for WP_Style_Engine_CSS_Rule objects.
+ *
+ * Holds, sanitizes, processes, and prints CSS declarations for the style engine.
+ *
+ * @since 6.1.0
+ */
+#[AllowDynamicProperties]
+class WP_Style_Engine_CSS_Rules_Store {
+
+	/**
+	 * An array of named WP_Style_Engine_CSS_Rules_Store objects.
+	 *
+	 * @static
+	 *
+	 * @since 6.1.0
+	 * @var WP_Style_Engine_CSS_Rules_Store[]
+	 */
+	protected static $stores = array();
+
+	/**
+	 * The store name.
+	 *
+	 * @since 6.1.0
+	 * @var string
+	 */
+	protected $name = '';
+
+	/**
+	 * An array of CSS Rules objects assigned to the store.
+	 *
+	 * @since 6.1.0
+	 * @var WP_Style_Engine_CSS_Rule[]
+	 */
+	protected $rules = array();
+
+	/**
+	 * Gets an instance of the store.
+	 *
+	 * @since 6.1.0
+	 *
+	 * @param string $store_name The name of the store.
+	 * @return WP_Style_Engine_CSS_Rules_Store|void
+	 */
+	public static function get_store( $store_name = 'default' ) {
+		if ( ! is_string( $store_name ) || empty( $store_name ) ) {
+			return;
+		}
+		if ( ! isset( static::$stores[ $store_name ] ) ) {
+			static::$stores[ $store_name ] = new static();
+			// Set the store name.
+			static::$stores[ $store_name ]->set_name( $store_name );
+		}
+		return static::$stores[ $store_name ];
+	}
+
+	/**
+	 * Gets an array of all available stores.
+	 *
+	 * @since 6.1.0
+	 *
+	 * @return WP_Style_Engine_CSS_Rules_Store[]
+	 */
+	public static function get_stores() {
+		return static::$stores;
+	}
+
+	/**
+	 * Clears all stores from static::$stores.
+	 *
+	 * @since 6.1.0
+	 */
+	public static function remove_all_stores() {
+		static::$stores = array();
+	}
+
+	/**
+	 * Sets the store name.
+	 *
+	 * @since 6.1.0
+	 *
+	 * @param string $name The store name.
+	 */
+	public function set_name( $name ) {
+		$this->name = $name;
+	}
+
+	/**
+	 * Gets the store name.
+	 *
+	 * @since 6.1.0
+	 *
+	 * @return string
+	 */
+	public function get_name() {
+		return $this->name;
+	}
+
+	/**
+	 * Gets an array of all rules.
+	 *
+	 * @since 6.1.0
+	 *
+	 * @return WP_Style_Engine_CSS_Rule[]
+	 */
+	public function get_all_rules() {
+		return $this->rules;
+	}
+
+	/**
+	 * Gets a WP_Style_Engine_CSS_Rule object by its selector.
+	 * If the rule does not exist, it will be created.
+	 *
+	 * @since 6.1.0
+	 * @since 6.6.0 Added the $rules_group parameter.
+	 *
+	 * @param string $selector The CSS selector.
+	 * @param string $rules_group A parent CSS selector in the case of nested CSS, or a CSS nested @rule,
+	 *                            such as `@media (min-width: 80rem)` or `@layer module`.
+	 * @return WP_Style_Engine_CSS_Rule|void Returns a WP_Style_Engine_CSS_Rule object,
+	 *                                       or void if the selector is empty.
+	 */
+	public function add_rule( $selector, $rules_group = '' ) {
+		$selector    = $selector ? trim( $selector ) : '';
+		$rules_group = $rules_group ? trim( $rules_group ) : '';
+
+		// Bail early if there is no selector.
+		if ( empty( $selector ) ) {
+			return;
+		}
+
+		if ( ! empty( $rules_group ) ) {
+			if ( empty( $this->rules[ "$rules_group $selector" ] ) ) {
+				$this->rules[ "$rules_group $selector" ] = new WP_Style_Engine_CSS_Rule( $selector, array(), $rules_group );
+			}
+			return $this->rules[ "$rules_group $selector" ];
+		}
+
+		// Create the rule if it doesn't exist.
+		if ( empty( $this->rules[ $selector ] ) ) {
+			$this->rules[ $selector ] = new WP_Style_Engine_CSS_Rule( $selector );
+		}
+
+		return $this->rules[ $selector ];
+	}
+
+	/**
+	 * Removes a selector from the store.
+	 *
+	 * @since 6.1.0
+	 *
+	 * @param string $selector The CSS selector.
+	 */
+	public function remove_rule( $selector ) {
+		unset( $this->rules[ $selector ] );
+	}
+}