diff -r 48c4eec2b7e6 -r 8c2e4d02f4ef wp/wp-includes/class-wp-script-modules.php
--- a/wp/wp-includes/class-wp-script-modules.php	Fri Sep 05 18:40:08 2025 +0200
+++ b/wp/wp-includes/class-wp-script-modules.php	Fri Sep 05 18:52:52 2025 +0200
@@ -31,6 +31,17 @@
 	private $enqueued_before_registered = array();
 
 	/**
+	 * Tracks whether the @wordpress/a11y script module is available.
+	 *
+	 * Some additional HTML is required on the page for the module to work. Track
+	 * whether it's available to print at the appropriate time.
+	 *
+	 * @since 6.7.0
+	 * @var bool
+	 */
+	private $a11y_available = false;
+
+	/**
 	 * Registers the script module if no script module with that script module
 	 * identifier has already been registered.
 	 *
@@ -182,6 +193,11 @@
 		add_action( 'admin_print_footer_scripts', array( $this, 'print_import_map' ) );
 		add_action( 'admin_print_footer_scripts', array( $this, 'print_enqueued_script_modules' ) );
 		add_action( 'admin_print_footer_scripts', array( $this, 'print_script_module_preloads' ) );
+
+		add_action( 'wp_footer', array( $this, 'print_script_module_data' ) );
+		add_action( 'admin_print_footer_scripts', array( $this, 'print_script_module_data' ) );
+		add_action( 'wp_footer', array( $this, 'print_a11y_script_module_html' ), 20 );
+		add_action( 'admin_print_footer_scripts', array( $this, 'print_a11y_script_module_html' ), 20 );
 	}
 
 	/**
@@ -227,26 +243,10 @@
 	 * Prints the import map using a script tag with a type="importmap" attribute.
 	 *
 	 * @since 6.5.0
-	 *
-	 * @global WP_Scripts $wp_scripts The WP_Scripts object for printing the polyfill.
 	 */
 	public function print_import_map() {
 		$import_map = $this->get_import_map();
 		if ( ! empty( $import_map['imports'] ) ) {
-			global $wp_scripts;
-			if ( isset( $wp_scripts ) ) {
-				wp_print_inline_script_tag(
-					wp_get_script_polyfill(
-						$wp_scripts,
-						array(
-							'HTMLScriptElement.supports && HTMLScriptElement.supports("importmap")' => 'wp-polyfill-importmap',
-						)
-					),
-					array(
-						'id' => 'wp-load-polyfill-importmap',
-					)
-				);
-			}
 			wp_print_inline_script_tag(
 				wp_json_encode( $import_map, JSON_HEX_TAG | JSON_HEX_AMP ),
 				array(
@@ -363,4 +363,144 @@
 
 		return $src;
 	}
+
+	/**
+	 * Print data associated with Script Modules.
+	 *
+	 * The data will be embedded in the page HTML and can be read by Script Modules on page load.
+	 *
+	 * @since 6.7.0
+	 *
+	 * Data can be associated with a Script Module via the
+	 * {@see "script_module_data_{$module_id}"} filter.
+	 *
+	 * The data for a Script Module will be serialized as JSON in a script tag with an ID of the
+	 * form `wp-script-module-data-{$module_id}`.
+	 */
+	public function print_script_module_data(): void {
+		$modules = array();
+		foreach ( array_keys( $this->get_marked_for_enqueue() ) as $id ) {
+			if ( '@wordpress/a11y' === $id ) {
+				$this->a11y_available = true;
+			}
+			$modules[ $id ] = true;
+		}
+		foreach ( array_keys( $this->get_import_map()['imports'] ) as $id ) {
+			if ( '@wordpress/a11y' === $id ) {
+				$this->a11y_available = true;
+			}
+			$modules[ $id ] = true;
+		}
+
+		foreach ( array_keys( $modules ) as $module_id ) {
+			/**
+			 * Filters data associated with a given Script Module.
+			 *
+			 * Script Modules may require data that is required for initialization or is essential
+			 * to have immediately available on page load. These are suitable use cases for
+			 * this data.
+			 *
+			 * The dynamic portion of the hook name, `$module_id`, refers to the Script Module ID
+			 * that the data is associated with.
+			 *
+			 * This is best suited to pass essential data that must be available to the module for
+			 * initialization or immediately on page load. It does not replace the REST API or
+			 * fetching data from the client.
+			 *
+			 * Example:
+			 *
+			 *     add_filter(
+			 *         'script_module_data_MyScriptModuleID',
+			 *         function ( array $data ): array {
+			 *             $data['dataForClient'] = 'ok';
+			 *             return $data;
+			 *         }
+			 *     );
+			 *
+			 * If the filter returns no data (an empty array), nothing will be embedded in the page.
+			 *
+			 * The data for a given Script Module, if provided, will be JSON serialized in a script
+			 * tag with an ID of the form `wp-script-module-data-{$module_id}`.
+			 *
+			 * The data can be read on the client with a pattern like this:
+			 *
+			 * Example:
+			 *
+			 *     const dataContainer = document.getElementById( 'wp-script-module-data-MyScriptModuleID' );
+			 *     let data = {};
+			 *     if ( dataContainer ) {
+			 *         try {
+			 *             data = JSON.parse( dataContainer.textContent );
+			 *         } catch {}
+			 *     }
+			 *     // data.dataForClient === 'ok';
+			 *     initMyScriptModuleWithData( data );
+			 *
+			 * @since 6.7.0
+			 *
+			 * @param array $data The data associated with the Script Module.
+			 */
+			$data = apply_filters( "script_module_data_{$module_id}", array() );
+
+			if ( is_array( $data ) && array() !== $data ) {
+				/*
+				 * This data will be printed as JSON inside a script tag like this:
+				 *   <script type="application/json"></script>
+				 *
+				 * A script tag must be closed by a sequence beginning with `</`. It's impossible to
+				 * close a script tag without using `<`. We ensure that `<` is escaped and `/` can
+				 * remain unescaped, so `</script>` will be printed as `\u003C/script\u00E3`.
+				 *
+				 *   - JSON_HEX_TAG: All < and > are converted to \u003C and \u003E.
+				 *   - JSON_UNESCAPED_SLASHES: Don't escape /.
+				 *
+				 * If the page will use UTF-8 encoding, it's safe to print unescaped unicode:
+				 *
+				 *   - JSON_UNESCAPED_UNICODE: Encode multibyte Unicode characters literally (instead of as `\uXXXX`).
+				 *   - JSON_UNESCAPED_LINE_TERMINATORS: The line terminators are kept unescaped when
+				 *     JSON_UNESCAPED_UNICODE is supplied. It uses the same behaviour as it was
+				 *     before PHP 7.1 without this constant. Available as of PHP 7.1.0.
+				 *
+				 * The JSON specification requires encoding in UTF-8, so if the generated HTML page
+				 * is not encoded in UTF-8 then it's not safe to include those literals. They must
+				 * be escaped to avoid encoding issues.
+				 *
+				 * @see https://www.rfc-editor.org/rfc/rfc8259.html for details on encoding requirements.
+				 * @see https://www.php.net/manual/en/json.constants.php for details on these constants.
+				 * @see https://html.spec.whatwg.org/#script-data-state for details on script tag parsing.
+				 */
+				$json_encode_flags = JSON_HEX_TAG | JSON_UNESCAPED_SLASHES | JSON_UNESCAPED_UNICODE | JSON_UNESCAPED_LINE_TERMINATORS;
+				if ( ! is_utf8_charset() ) {
+					$json_encode_flags = JSON_HEX_TAG | JSON_UNESCAPED_SLASHES;
+				}
+
+				wp_print_inline_script_tag(
+					wp_json_encode(
+						$data,
+						$json_encode_flags
+					),
+					array(
+						'type' => 'application/json',
+						'id'   => "wp-script-module-data-{$module_id}",
+					)
+				);
+			}
+		}
+	}
+
+	/**
+	 * @access private This is only intended to be called by the registered actions.
+	 *
+	 * @since 6.7.0
+	 */
+	public function print_a11y_script_module_html() {
+		if ( ! $this->a11y_available ) {
+			return;
+		}
+		echo '<div style="position:absolute;margin:-1px;padding:0;height:1px;width:1px;overflow:hidden;clip-path:inset(50%);border:0;word-wrap:normal !important;">'
+			. '<p id="a11y-speak-intro-text" class="a11y-speak-intro-text" hidden>' . esc_html__( 'Notifications' ) . '</p>'
+			. '<div id="a11y-speak-assertive" class="a11y-speak-region" aria-live="assertive" aria-relevant="additions text" aria-atomic="true"></div>'
+			. '<div id="a11y-speak-polite" class="a11y-speak-region" aria-live="polite" aria-relevant="additions text" aria-atomic="true"></div>'
+			. '</div>';
+	}
 }