diff -r 48c4eec2b7e6 -r 8c2e4d02f4ef wp/wp-includes/html-api/class-wp-html-processor-state.php
--- a/wp/wp-includes/html-api/class-wp-html-processor-state.php	Fri Sep 05 18:40:08 2025 +0200
+++ b/wp/wp-includes/html-api/class-wp-html-processor-state.php	Fri Sep 05 18:52:52 2025 +0200
@@ -48,6 +48,66 @@
 	const INSERTION_MODE_INITIAL = 'insertion-mode-initial';
 
 	/**
+	 * Before HTML insertion mode for full HTML parser.
+	 *
+	 * @since 6.7.0
+	 *
+	 * @see https://html.spec.whatwg.org/#the-before-html-insertion-mode
+	 * @see WP_HTML_Processor_State::$insertion_mode
+	 *
+	 * @var string
+	 */
+	const INSERTION_MODE_BEFORE_HTML = 'insertion-mode-before-html';
+
+	/**
+	 * Before head insertion mode for full HTML parser.
+	 *
+	 * @since 6.7.0
+	 *
+	 * @see https://html.spec.whatwg.org/#parsing-main-beforehead
+	 * @see WP_HTML_Processor_State::$insertion_mode
+	 *
+	 * @var string
+	 */
+	const INSERTION_MODE_BEFORE_HEAD = 'insertion-mode-before-head';
+
+	/**
+	 * In head insertion mode for full HTML parser.
+	 *
+	 * @since 6.7.0
+	 *
+	 * @see https://html.spec.whatwg.org/#parsing-main-inhead
+	 * @see WP_HTML_Processor_State::$insertion_mode
+	 *
+	 * @var string
+	 */
+	const INSERTION_MODE_IN_HEAD = 'insertion-mode-in-head';
+
+	/**
+	 * In head noscript insertion mode for full HTML parser.
+	 *
+	 * @since 6.7.0
+	 *
+	 * @see https://html.spec.whatwg.org/#parsing-main-inheadnoscript
+	 * @see WP_HTML_Processor_State::$insertion_mode
+	 *
+	 * @var string
+	 */
+	const INSERTION_MODE_IN_HEAD_NOSCRIPT = 'insertion-mode-in-head-noscript';
+
+	/**
+	 * After head insertion mode for full HTML parser.
+	 *
+	 * @since 6.7.0
+	 *
+	 * @see https://html.spec.whatwg.org/#parsing-main-afterhead
+	 * @see WP_HTML_Processor_State::$insertion_mode
+	 *
+	 * @var string
+	 */
+	const INSERTION_MODE_AFTER_HEAD = 'insertion-mode-after-head';
+
+	/**
 	 * In body insertion mode for full HTML parser.
 	 *
 	 * @since 6.4.0
@@ -60,6 +120,197 @@
 	const INSERTION_MODE_IN_BODY = 'insertion-mode-in-body';
 
 	/**
+	 * In table insertion mode for full HTML parser.
+	 *
+	 * @since 6.7.0
+	 *
+	 * @see https://html.spec.whatwg.org/#parsing-main-intable
+	 * @see WP_HTML_Processor_State::$insertion_mode
+	 *
+	 * @var string
+	 */
+	const INSERTION_MODE_IN_TABLE = 'insertion-mode-in-table';
+
+	/**
+	 * In table text insertion mode for full HTML parser.
+	 *
+	 * @since 6.7.0
+	 *
+	 * @see https://html.spec.whatwg.org/#parsing-main-intabletext
+	 * @see WP_HTML_Processor_State::$insertion_mode
+	 *
+	 * @var string
+	 */
+	const INSERTION_MODE_IN_TABLE_TEXT = 'insertion-mode-in-table-text';
+
+	/**
+	 * In caption insertion mode for full HTML parser.
+	 *
+	 * @since 6.7.0
+	 *
+	 * @see https://html.spec.whatwg.org/#parsing-main-incaption
+	 * @see WP_HTML_Processor_State::$insertion_mode
+	 *
+	 * @var string
+	 */
+	const INSERTION_MODE_IN_CAPTION = 'insertion-mode-in-caption';
+
+	/**
+	 * In column group insertion mode for full HTML parser.
+	 *
+	 * @since 6.7.0
+	 *
+	 * @see https://html.spec.whatwg.org/#parsing-main-incolumngroup
+	 * @see WP_HTML_Processor_State::$insertion_mode
+	 *
+	 * @var string
+	 */
+	const INSERTION_MODE_IN_COLUMN_GROUP = 'insertion-mode-in-column-group';
+
+	/**
+	 * In table body insertion mode for full HTML parser.
+	 *
+	 * @since 6.7.0
+	 *
+	 * @see https://html.spec.whatwg.org/#parsing-main-intablebody
+	 * @see WP_HTML_Processor_State::$insertion_mode
+	 *
+	 * @var string
+	 */
+	const INSERTION_MODE_IN_TABLE_BODY = 'insertion-mode-in-table-body';
+
+	/**
+	 * In row insertion mode for full HTML parser.
+	 *
+	 * @since 6.7.0
+	 *
+	 * @see https://html.spec.whatwg.org/#parsing-main-inrow
+	 * @see WP_HTML_Processor_State::$insertion_mode
+	 *
+	 * @var string
+	 */
+	const INSERTION_MODE_IN_ROW = 'insertion-mode-in-row';
+
+	/**
+	 * In cell insertion mode for full HTML parser.
+	 *
+	 * @since 6.7.0
+	 *
+	 * @see https://html.spec.whatwg.org/#parsing-main-incell
+	 * @see WP_HTML_Processor_State::$insertion_mode
+	 *
+	 * @var string
+	 */
+	const INSERTION_MODE_IN_CELL = 'insertion-mode-in-cell';
+
+	/**
+	 * In select insertion mode for full HTML parser.
+	 *
+	 * @since 6.7.0
+	 *
+	 * @see https://html.spec.whatwg.org/#parsing-main-inselect
+	 * @see WP_HTML_Processor_State::$insertion_mode
+	 *
+	 * @var string
+	 */
+	const INSERTION_MODE_IN_SELECT = 'insertion-mode-in-select';
+
+	/**
+	 * In select in table insertion mode for full HTML parser.
+	 *
+	 * @since 6.7.0
+	 *
+	 * @see https://html.spec.whatwg.org/#parsing-main-inselectintable
+	 * @see WP_HTML_Processor_State::$insertion_mode
+	 *
+	 * @var string
+	 */
+	const INSERTION_MODE_IN_SELECT_IN_TABLE = 'insertion-mode-in-select-in-table';
+
+	/**
+	 * In template insertion mode for full HTML parser.
+	 *
+	 * @since 6.7.0
+	 *
+	 * @see https://html.spec.whatwg.org/#parsing-main-intemplate
+	 * @see WP_HTML_Processor_State::$insertion_mode
+	 *
+	 * @var string
+	 */
+	const INSERTION_MODE_IN_TEMPLATE = 'insertion-mode-in-template';
+
+	/**
+	 * After body insertion mode for full HTML parser.
+	 *
+	 * @since 6.7.0
+	 *
+	 * @see https://html.spec.whatwg.org/#parsing-main-afterbody
+	 * @see WP_HTML_Processor_State::$insertion_mode
+	 *
+	 * @var string
+	 */
+	const INSERTION_MODE_AFTER_BODY = 'insertion-mode-after-body';
+
+	/**
+	 * In frameset insertion mode for full HTML parser.
+	 *
+	 * @since 6.7.0
+	 *
+	 * @see https://html.spec.whatwg.org/#parsing-main-inframeset
+	 * @see WP_HTML_Processor_State::$insertion_mode
+	 *
+	 * @var string
+	 */
+	const INSERTION_MODE_IN_FRAMESET = 'insertion-mode-in-frameset';
+
+	/**
+	 * After frameset insertion mode for full HTML parser.
+	 *
+	 * @since 6.7.0
+	 *
+	 * @see https://html.spec.whatwg.org/#parsing-main-afterframeset
+	 * @see WP_HTML_Processor_State::$insertion_mode
+	 *
+	 * @var string
+	 */
+	const INSERTION_MODE_AFTER_FRAMESET = 'insertion-mode-after-frameset';
+
+	/**
+	 * After after body insertion mode for full HTML parser.
+	 *
+	 * @since 6.7.0
+	 *
+	 * @see https://html.spec.whatwg.org/#the-after-after-body-insertion-mode
+	 * @see WP_HTML_Processor_State::$insertion_mode
+	 *
+	 * @var string
+	 */
+	const INSERTION_MODE_AFTER_AFTER_BODY = 'insertion-mode-after-after-body';
+
+	/**
+	 * After after frameset insertion mode for full HTML parser.
+	 *
+	 * @since 6.7.0
+	 *
+	 * @see https://html.spec.whatwg.org/#the-after-after-frameset-insertion-mode
+	 * @see WP_HTML_Processor_State::$insertion_mode
+	 *
+	 * @var string
+	 */
+	const INSERTION_MODE_AFTER_AFTER_FRAMESET = 'insertion-mode-after-after-frameset';
+
+	/**
+	 * The stack of template insertion modes.
+	 *
+	 * @since 6.7.0
+	 *
+	 * @see https://html.spec.whatwg.org/#the-insertion-mode:stack-of-template-insertion-modes
+	 *
+	 * @var array<string>
+	 */
+	public $stack_of_template_insertion_modes = array();
+
+	/**
 	 * Tracks open elements while scanning HTML.
 	 *
 	 * This property is initialized in the constructor and never null.
@@ -70,7 +321,7 @@
 	 *
 	 * @var WP_HTML_Open_Elements
 	 */
-	public $stack_of_open_elements = null;
+	public $stack_of_open_elements;
 
 	/**
 	 * Tracks open formatting elements, used to handle mis-nested formatting element tags.
@@ -83,7 +334,7 @@
 	 *
 	 * @var WP_HTML_Active_Formatting_Elements
 	 */
-	public $active_formatting_elements = null;
+	public $active_formatting_elements;
 
 	/**
 	 * Refers to the currently-matched tag, if any.
@@ -109,14 +360,74 @@
 	 * Context node initializing fragment parser, if created as a fragment parser.
 	 *
 	 * @since 6.4.0
+	 * @deprecated 6.8.0 WP_HTML_Processor tracks the context_node internally.
 	 *
-	 * @see https://html.spec.whatwg.org/#concept-frag-parse-context
-	 *
-	 * @var [string, array]|null
+	 * @var null
 	 */
 	public $context_node = null;
 
 	/**
+	 * The recognized encoding of the input byte stream.
+	 *
+	 * > The stream of code points that comprises the input to the tokenization
+	 * > stage will be initially seen by the user agent as a stream of bytes
+	 * > (typically coming over the network or from the local file system).
+	 * > The bytes encode the actual characters according to a particular character
+	 * > encoding, which the user agent uses to decode the bytes into characters.
+	 *
+	 * @since 6.7.0
+	 *
+	 * @var string|null
+	 */
+	public $encoding = null;
+
+	/**
+	 * The parser's confidence in the input encoding.
+	 *
+	 * > When the HTML parser is decoding an input byte stream, it uses a character
+	 * > encoding and a confidence. The confidence is either tentative, certain, or
+	 * > irrelevant. The encoding used, and whether the confidence in that encoding
+	 * > is tentative or certain, is used during the parsing to determine whether to
+	 * > change the encoding. If no encoding is necessary, e.g. because the parser is
+	 * > operating on a Unicode stream and doesn't have to use a character encoding
+	 * > at all, then the confidence is irrelevant.
+	 *
+	 * @since 6.7.0
+	 *
+	 * @var string
+	 */
+	public $encoding_confidence = 'tentative';
+
+	/**
+	 * HEAD element pointer.
+	 *
+	 * @since 6.7.0
+	 *
+	 * @see https://html.spec.whatwg.org/multipage/parsing.html#head-element-pointer
+	 *
+	 * @var WP_HTML_Token|null
+	 */
+	public $head_element = null;
+
+	/**
+	 * FORM element pointer.
+	 *
+	 * > points to the last form element that was opened and whose end tag has
+	 * > not yet been seen. It is used to make form controls associate with
+	 * > forms in the face of dramatically bad markup, for historical reasons.
+	 * > It is ignored inside template elements.
+	 *
+	 * @todo This may be invalidated by a seek operation.
+	 *
+	 * @see https://html.spec.whatwg.org/#form-element-pointer
+	 *
+	 * @since 6.7.0
+	 *
+	 * @var WP_HTML_Token|null
+	 */
+	public $form_element = null;
+
+	/**
 	 * The frameset-ok flag indicates if a `FRAMESET` element is allowed in the current state.
 	 *
 	 * > The frameset-ok flag is set to "ok" when the parser is created. It is set to "not ok" after certain tokens are seen.