From 1ed6db3ca27d427664455d86a4a10015d3a88740 Mon Sep 17 00:00:00 2001
From: Gutenberg Repository Automation <gutenberg@wordpress.org>
Date: Wed, 27 Sep 2023 11:49:20 +0000
Subject: [PATCH 1/8] Bump plugin version to 16.7.0

---
 gutenberg.php     | 2 +-
 package-lock.json | 4 ++--
 package.json      | 2 +-
 3 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/gutenberg.php b/gutenberg.php
index 632f52eb5aa75..ea22c8c7ad82d 100644
--- a/gutenberg.php
+++ b/gutenberg.php
@@ -5,7 +5,7 @@
  * Description: Printing since 1440. This is the development plugin for the block editor, site editor, and other future WordPress core functionality.
  * Requires at least: 6.2
  * Requires PHP: 7.0
- * Version: 16.7.0-rc.2
+ * Version: 16.7.0
  * Author: Gutenberg Team
  * Text Domain: gutenberg
  *
diff --git a/package-lock.json b/package-lock.json
index 8f7616dd1e556..5895a051a0741 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -1,12 +1,12 @@
 {
 	"name": "gutenberg",
-	"version": "16.7.0-rc.2",
+	"version": "16.7.0",
 	"lockfileVersion": 2,
 	"requires": true,
 	"packages": {
 		"": {
 			"name": "gutenberg",
-			"version": "16.7.0-rc.2",
+			"version": "16.7.0",
 			"hasInstallScript": true,
 			"license": "GPL-2.0-or-later",
 			"dependencies": {
diff --git a/package.json b/package.json
index 4dd57cd0d9b7b..02fe8c3843ba4 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
 	"name": "gutenberg",
-	"version": "16.7.0-rc.2",
+	"version": "16.7.0",
 	"private": true,
 	"description": "A new WordPress editor experience.",
 	"author": "The WordPress Contributors",

From aa7cc4d0404e0a830144c57e5211335b48f9ba2d Mon Sep 17 00:00:00 2001
From: Andrew Hayward <andrew.hayward@automattic.com>
Date: Wed, 27 Sep 2023 12:55:14 +0100
Subject: [PATCH 2/8] Deprecating `isPressed` in `Button` component (#54740)

* Deprecating `isPressed` in `Button` component

* Updating CHANGELOG.md

* Undoing deprecation/other changes, to reduce overall impact

* Updating README.md

* Updating `aria-pressed` doc metadata

* Refactoring `is-pressed` logic

* Adding extra tests for `aria-pressed` values
---
 packages/components/CHANGELOG.md              |  1 +
 packages/components/src/button/README.md      |  2 +
 packages/components/src/button/index.tsx      | 37 ++++++++--
 .../src/button/stories/index.story.tsx        | 11 +++
 packages/components/src/button/style.scss     |  3 +-
 packages/components/src/button/test/index.tsx | 73 +++++++++++++++++--
 6 files changed, 113 insertions(+), 14 deletions(-)

diff --git a/packages/components/CHANGELOG.md b/packages/components/CHANGELOG.md
index 5aac419d20932..36ba45825e54f 100644
--- a/packages/components/CHANGELOG.md
+++ b/packages/components/CHANGELOG.md
@@ -5,6 +5,7 @@
 ### Enhancements
 
 -   `SearchControl`: polish metrics for `compact` size variant ([#54663](https://github.com/WordPress/gutenberg/pull/54663)).
+-   `Button`: deprecating `isPressed` prop in favour of `aria-pressed` ([#54740](https://github.com/WordPress/gutenberg/pull/54740)).
 
 ### Bug Fix
 
diff --git a/packages/components/src/button/README.md b/packages/components/src/button/README.md
index fdd46b0255ccf..3af46280b1bc9 100644
--- a/packages/components/src/button/README.md
+++ b/packages/components/src/button/README.md
@@ -186,6 +186,8 @@ Renders a red text-based button style to indicate destructive behavior.
 
 Renders a pressed button style.
 
+If the native `aria-pressed` attribute is also set, it will take precedence.
+
 -   Required: No
 
 #### `isSmall`: `boolean`
diff --git a/packages/components/src/button/index.tsx b/packages/components/src/button/index.tsx
index a199c1bb350cd..b14e85fa52f7f 100644
--- a/packages/components/src/button/index.tsx
+++ b/packages/components/src/button/index.tsx
@@ -34,6 +34,7 @@ function useDeprecatedProps( {
 	isSecondary,
 	isTertiary,
 	isLink,
+	isPressed,
 	isSmall,
 	size,
 	variant,
@@ -42,6 +43,11 @@ function useDeprecatedProps( {
 	let computedSize = size;
 	let computedVariant = variant;
 
+	const newProps: { 'aria-pressed'?: boolean } = {
+		// @TODO Mark `isPressed` as deprecated
+		'aria-pressed': isPressed,
+	};
+
 	if ( isSmall ) {
 		computedSize ??= 'small';
 	}
@@ -73,6 +79,7 @@ function useDeprecatedProps( {
 	}
 
 	return {
+		...newProps,
 		...otherProps,
 		size: computedSize,
 		variant: computedVariant,
@@ -85,7 +92,6 @@ export function UnforwardedButton(
 ) {
 	const {
 		__next40pxDefaultSize,
-		isPressed,
 		isBusy,
 		isDestructive,
 		className,
@@ -106,10 +112,16 @@ export function UnforwardedButton(
 		...buttonOrAnchorProps
 	} = useDeprecatedProps( props );
 
-	const { href, target, ...additionalProps } =
-		'href' in buttonOrAnchorProps
-			? buttonOrAnchorProps
-			: { href: undefined, target: undefined, ...buttonOrAnchorProps };
+	const {
+		href,
+		target,
+		'aria-checked': ariaChecked,
+		'aria-pressed': ariaPressed,
+		'aria-selected': ariaSelected,
+		...additionalProps
+	} = 'href' in buttonOrAnchorProps
+		? buttonOrAnchorProps
+		: { href: undefined, target: undefined, ...buttonOrAnchorProps };
 
 	const instanceId = useInstanceId(
 		Button,
@@ -124,6 +136,12 @@ export function UnforwardedButton(
 			// Tooltip should not considered as a child
 			children?.[ 0 ]?.props?.className !== 'components-tooltip' );
 
+	const truthyAriaPressedValues: ( typeof ariaPressed )[] = [
+		true,
+		'true',
+		'mixed',
+	];
+
 	const classes = classnames( 'components-button', className, {
 		'is-next-40px-default-size': __next40pxDefaultSize,
 		'is-secondary': variant === 'secondary',
@@ -131,7 +149,10 @@ export function UnforwardedButton(
 		'is-small': size === 'small',
 		'is-compact': size === 'compact',
 		'is-tertiary': variant === 'tertiary',
-		'is-pressed': isPressed,
+
+		'is-pressed': truthyAriaPressedValues.includes( ariaPressed ),
+		'is-pressed-mixed': ariaPressed === 'mixed',
+
 		'is-busy': isBusy,
 		'is-link': variant === 'link',
 		'is-destructive': isDestructive,
@@ -146,7 +167,9 @@ export function UnforwardedButton(
 			? {
 					type: 'button',
 					disabled: trulyDisabled,
-					'aria-pressed': isPressed,
+					'aria-checked': ariaChecked,
+					'aria-pressed': ariaPressed,
+					'aria-selected': ariaSelected,
 			  }
 			: {};
 	const anchorProps: ComponentPropsWithoutRef< 'a' > =
diff --git a/packages/components/src/button/stories/index.story.tsx b/packages/components/src/button/stories/index.story.tsx
index a1dadab081d8a..2981319cfb323 100644
--- a/packages/components/src/button/stories/index.story.tsx
+++ b/packages/components/src/button/stories/index.story.tsx
@@ -26,6 +26,17 @@ const meta: Meta< typeof Button > = {
 	component: Button,
 	argTypes: {
 		// Overrides a limitation of the docgen interpreting our TS types for this as required.
+		'aria-pressed': {
+			control: { type: 'select' },
+			description:
+				'Indicates the current "pressed" state, implying it is a toggle button. Implicitly set by `isPressed`, but takes precedence if both are provided.',
+			options: [ undefined, 'true', 'false', 'mixed' ],
+			table: {
+				type: {
+					summary: 'boolean | "true" | "false" | "mixed"',
+				},
+			},
+		},
 		href: { type: { name: 'string', required: false } },
 		icon: {
 			control: { type: 'select' },
diff --git a/packages/components/src/button/style.scss b/packages/components/src/button/style.scss
index b572e96e4335f..0487d19db99df 100644
--- a/packages/components/src/button/style.scss
+++ b/packages/components/src/button/style.scss
@@ -308,7 +308,8 @@
 	}
 
 	// Toggled style.
-	&.is-pressed {
+	&[aria-pressed="true"],
+	&[aria-pressed="mixed"] {
 		color: $components-color-foreground-inverted;
 		background: $components-color-foreground;
 
diff --git a/packages/components/src/button/test/index.tsx b/packages/components/src/button/test/index.tsx
index d70b8b075aa1e..fb6c6a72b9adc 100644
--- a/packages/components/src/button/test/index.tsx
+++ b/packages/components/src/button/test/index.tsx
@@ -72,12 +72,6 @@ describe( 'Button', () => {
 			expect( button ).toHaveClass( 'is-link' );
 		} );
 
-		it( 'should render a button element with is-pressed without button class', () => {
-			render( <Button isPressed /> );
-
-			expect( screen.getByRole( 'button' ) ).toHaveClass( 'is-pressed' );
-		} );
-
 		it( 'should render a button element with has-text when children are passed', async () => {
 			const user = userEvent.setup();
 
@@ -347,6 +341,56 @@ describe( 'Button', () => {
 
 			await cleanupTooltip( user );
 		} );
+
+		describe( 'using `aria-pressed` prop', () => {
+			it( 'should render a button element with is-pressed when `true`', () => {
+				render( <Button aria-pressed /> );
+
+				expect( screen.getByRole( 'button' ) ).toHaveClass(
+					'is-pressed'
+				);
+			} );
+
+			it( 'should render a button element with is-pressed when `"true"`', () => {
+				render( <Button aria-pressed="true" /> );
+
+				expect( screen.getByRole( 'button' ) ).toHaveClass(
+					'is-pressed'
+				);
+			} );
+
+			it( 'should render a button element with is-pressed/is-pressed-mixed when `"mixed"`', () => {
+				render( <Button aria-pressed="mixed" /> );
+
+				expect( screen.getByRole( 'button' ) ).toHaveClass(
+					'is-pressed is-pressed-mixed'
+				);
+			} );
+
+			it( 'should render a button element without is-pressed when `undefined`', () => {
+				render( <Button aria-pressed={ undefined } /> );
+
+				expect( screen.getByRole( 'button' ) ).not.toHaveClass(
+					'is-pressed'
+				);
+			} );
+
+			it( 'should render a button element without is-pressed when `false`', () => {
+				render( <Button aria-pressed={ false } /> );
+
+				expect( screen.getByRole( 'button' ) ).not.toHaveClass(
+					'is-pressed'
+				);
+			} );
+
+			it( 'should render a button element without is-pressed when `"false"`', () => {
+				render( <Button aria-pressed="false" /> );
+
+				expect( screen.getByRole( 'button' ) ).not.toHaveClass(
+					'is-pressed'
+				);
+			} );
+		} );
 	} );
 
 	describe( 'with href property', () => {
@@ -434,6 +478,23 @@ describe( 'Button', () => {
 			);
 			expect( screen.getByRole( 'button' ) ).toHaveClass( 'is-compact' );
 		} );
+
+		it( 'should not break when the legacy isPressed prop is passed', () => {
+			render( <Button isPressed /> );
+
+			expect( screen.getByRole( 'button' ) ).toHaveAttribute(
+				'aria-pressed',
+				'true'
+			);
+		} );
+
+		it( 'should prioritize the `aria-pressed` prop over `isPressed`', () => {
+			render( <Button isPressed aria-pressed="mixed" /> );
+			expect( screen.getByRole( 'button' ) ).toHaveAttribute(
+				'aria-pressed',
+				'mixed'
+			);
+		} );
 	} );
 
 	describe( 'static typing', () => {

From 7cec843673d607c06ea6a93c81e5bfb38bf25112 Mon Sep 17 00:00:00 2001
From: Gutenberg Repository Automation <gutenberg@wordpress.org>
Date: Wed, 27 Sep 2023 12:31:03 +0000
Subject: [PATCH 3/8] Update Changelog for 16.7.0

---
 changelog.txt | 198 +++++++++++++++++++-------------------------------
 1 file changed, 73 insertions(+), 125 deletions(-)

diff --git a/changelog.txt b/changelog.txt
index 447476fea96de..67f16cbcb9026 100644
--- a/changelog.txt
+++ b/changelog.txt
@@ -1,137 +1,20 @@
 == Changelog ==
 
-= 16.7.0-rc.2 =
+= 16.7.0 =
 
 ## Changelog
 
 ### Features
 
-#### Typography
-- Font Library: Font Collections frontend. ([54566](https://github.com/WordPress/gutenberg/pull/54566))
-
-
-### Enhancements
-
-#### Interactivity API
-- Query block: Start prefetching on first click to next/previous. ([54781](https://github.com/WordPress/gutenberg/pull/54781))
-
-#### Collaborative Editing
-- Try bundling sync package. ([54738](https://github.com/WordPress/gutenberg/pull/54738))
-
-#### Patterns
-- Memoize `useSelect` for `usePatterns`. ([54588](https://github.com/WordPress/gutenberg/pull/54588))
-
-#### Design Tools
-- Improve background image control. ([54439](https://github.com/WordPress/gutenberg/pull/54439))
-
-#### List View
-- Try directing focus to the list view toggle button when closing the list view. ([54175](https://github.com/WordPress/gutenberg/pull/54175))
-
-#### Typography
-- Font Library: Load collection JSON data from a URL in the collection configuration. ([54067](https://github.com/WordPress/gutenberg/pull/54067))
-
-
-### Bug Fixes
-
-- Block Editor: Fix 'isBlockSubtreeDisabled' private selector. ([54618](https://github.com/WordPress/gutenberg/pull/54618))
-- Make sure sync code only runs when experiment is enabled. ([54710](https://github.com/WordPress/gutenberg/pull/54710))
-
-#### Patterns
-- Add My patterns back to post editor inserter categories. ([54767](https://github.com/WordPress/gutenberg/pull/54767))
-- De-emphasise pattern filters in inserter. ([54681](https://github.com/WordPress/gutenberg/pull/54681))
-- Fix All Patterns category default display. ([54721](https://github.com/WordPress/gutenberg/pull/54721))
-- Fix bug with new categories not showing. ([54768](https://github.com/WordPress/gutenberg/pull/54768))
-- Fix bug with pattern categories not saving sometimes. ([54676](https://github.com/WordPress/gutenberg/pull/54676))
-- Fix category type for back link. ([54753](https://github.com/WordPress/gutenberg/pull/54753))
-- Fix duplication of uncategorized patterns. ([54755](https://github.com/WordPress/gutenberg/pull/54755))
-- Inject the theme name into the block attributes. ([54595](https://github.com/WordPress/gutenberg/pull/54595))
-- Reinstate my patterns category in site editor. ([54726](https://github.com/WordPress/gutenberg/pull/54726))
-- Require a title in the creation modal. ([54717](https://github.com/WordPress/gutenberg/pull/54717))
-- Use slug as fallback for empty title. ([54731](https://github.com/WordPress/gutenberg/pull/54731))
-
-#### Typography
-- Font Face: Get name from "fontFamily" setting, not "name". ([54615](https://github.com/WordPress/gutenberg/pull/54615))
-- Font Library: Fix modal width on mobile viewport. ([54518](https://github.com/WordPress/gutenberg/pull/54518))
-
-#### Block Editor
-- Reset page after changing pattern filters or search value. ([54774](https://github.com/WordPress/gutenberg/pull/54774))
-
-#### Interactivity API
-- Query Loop: Select first anchor inside Post Template with "enhanced pagination" enabled. ([54730](https://github.com/WordPress/gutenberg/pull/54730))
-
-#### Plugin
-- Update cherry-pick script to correctly verify GitHub CLI setup. ([54720](https://github.com/WordPress/gutenberg/pull/54720))
-
-#### Block API
-- Block Hooks: Avoid processing empty content for loaded templates. ([54719](https://github.com/WordPress/gutenberg/pull/54719))
-
-#### Site Editor
-- CreateTemplatePartModal: Disable the 'Create' button while saving. ([54716](https://github.com/WordPress/gutenberg/pull/54716))
-
-#### Design Tools
-- Background Image control: Use consistent button, ensure descriptive text accounts for no image selected. ([54711](https://github.com/WordPress/gutenberg/pull/54711))
-
 #### Block Library
-- Replace the `gutenberg_` prefix with `wp_` in image block. ([54678](https://github.com/WordPress/gutenberg/pull/54678))
-
-#### Components
-- DateTimePicker: Fix onChange callback check so that it also works inside iframes. ([54669](https://github.com/WordPress/gutenberg/pull/54669))
-
-#### Fonts API
-- Font Library: Fix space above theme fonts in font library modal. ([54598](https://github.com/WordPress/gutenberg/pull/54598))
-
-
-### Accessibility
-
-#### Components
-- Allow Modal to place focus on first element within contents via new API. ([54590](https://github.com/WordPress/gutenberg/pull/54590))
-- Improve the placeholder instructions accessibility. ([45801](https://github.com/WordPress/gutenberg/pull/45801))
-
-
-### Documentation
-
-- Add missing global declaration in DocBlock of interactivity files. ([54683](https://github.com/WordPress/gutenberg/pull/54683))
-
-
-### Code Quality
-
-#### Site Editor
-- Prune store constants. ([54585](https://github.com/WordPress/gutenberg/pull/54585))
-- Use constants rather than hard coded template strings. ([54586](https://github.com/WordPress/gutenberg/pull/54586))
-
-#### Patterns
-- Fix sidebar nav screen fallback category. ([54754](https://github.com/WordPress/gutenberg/pull/54754))
+- Social Links: Add X. ([54092](https://github.com/WordPress/gutenberg/pull/54092))
 
 #### Typography
-- Font Library: Refactor logic to disable font library in the frontend. ([54748](https://github.com/WordPress/gutenberg/pull/54748))
-
-#### Plugin
-- Ensure that Block Hooks work correctly after landing in WP core. ([54651](https://github.com/WordPress/gutenberg/pull/54651))
-- Update uuid package to 9.0.1. ([54725](https://github.com/WordPress/gutenberg/pull/54725))
-
-### Tools
-
-#### Testing
-- Font Library: Use resolvable domain in test. ([54763](https://github.com/WordPress/gutenberg/pull/54763))
-
-
-## Contributors
-
-The following contributors merged PRs in this release:
-
-@aaronrobertshaw @afercia @andrewserong @ciampo @DAreRodz @getdave @glendaviesnz @gziolo @hellofromtonya @kevin940726 @luisherranz @madhusudhand @Mamaduka @matiasbenedetto @mikachan @ramonjd @richtabor @SaxonF @scruffian @t-hamano @tellthemachines
-
-
-= 16.7.0-rc.1 =
-
-## Changelog
-
-### Features
-
-#### Typography
-- Font Library: Add mime type validation for font uploads. ([53986](https://github.com/WordPress/gutenberg/pull/53986))
-- Font Library: Font Collection backend. ([54098](https://github.com/WordPress/gutenberg/pull/54098))
-- Font Library: Frontend [Stage 1]. ([53884](https://github.com/WordPress/gutenberg/pull/53884))
+Font Library:
+- Add mime type validation for font uploads. ([53986](https://github.com/WordPress/gutenberg/pull/53986))
+- Font Collection backend. ([54098](https://github.com/WordPress/gutenberg/pull/54098))
+- Frontend [Stage 1]. ([53884](https://github.com/WordPress/gutenberg/pull/53884))
+- Font Collections frontend. ([54566](https://github.com/WordPress/gutenberg/pull/54566))
 
 #### Patterns
 - Allow import/export patterns as JSON files. ([54337](https://github.com/WordPress/gutenberg/pull/54337))
@@ -196,6 +79,7 @@ The following contributors merged PRs in this release:
 - Override unfinished `navigate` calls. ([54201](https://github.com/WordPress/gutenberg/pull/54201))
 - Query Loop: Add design enhancements for the "enhanced pagination" setting. ([54455](https://github.com/WordPress/gutenberg/pull/54455))
 - Query Loop: Allow "enhanced pagination" only with core blocks. ([54347](https://github.com/WordPress/gutenberg/pull/54347))
+- Query block: Start prefetching on first click to next/previous. ([54781](https://github.com/WordPress/gutenberg/pull/54781))
 
 #### Patterns
 - Add categories to user patterns, and allow filtering by these in site and post editor. ([53835](https://github.com/WordPress/gutenberg/pull/53835))
@@ -205,6 +89,8 @@ The following contributors merged PRs in this release:
 - Apply white background to the preview as a fallback. ([54534](https://github.com/WordPress/gutenberg/pull/54534))
 - Merge unsynced into inserter patterns tab and add paging and filtering. ([54007](https://github.com/WordPress/gutenberg/pull/54007))
 - Update empty template part label. ([53842](https://github.com/WordPress/gutenberg/pull/53842))
+- Memoize `useSelect` for `usePatterns`. ([54588](https://github.com/WordPress/gutenberg/pull/54588))
+- Site Editor: Prevent unintended actions on the classic theme. ([54422](https://github.com/WordPress/gutenberg/pull/54422))
 
 #### Design Tools
 - Add back tooltip to styles UI. ([54574](https://github.com/WordPress/gutenberg/pull/54574))
@@ -214,6 +100,7 @@ The following contributors merged PRs in this release:
 - Block Supports: Add background image support to Group block. ([53934](https://github.com/WordPress/gutenberg/pull/53934))
 - Columns: Adopt button and heading element colors. ([54104](https://github.com/WordPress/gutenberg/pull/54104))
 - Update block styles UI. ([54446](https://github.com/WordPress/gutenberg/pull/54446))
+- Improve background image control. ([54439](https://github.com/WordPress/gutenberg/pull/54439))
 
 #### Site Editor
 - Copy: End the Templates page description in the Site Editor with a period. ([54221](https://github.com/WordPress/gutenberg/pull/54221))
@@ -230,10 +117,13 @@ The following contributors merged PRs in this release:
 - Use gray color on link control advanced toggle. ([54545](https://github.com/WordPress/gutenberg/pull/54545))
 - Verse: Exit on triple Enter. ([53332](https://github.com/WordPress/gutenberg/pull/53332))
 - Block editor: hooks: Fix rules of hooks violations (2). ([48943](https://github.com/WordPress/gutenberg/pull/48943))
+- Always show the total number of patterns even with only one page. ([54813](https://github.com/WordPress/gutenberg/pull/54813))
 
 #### Typography
 - Font Face: Backport from Core changeset 56500. ([54218](https://github.com/WordPress/gutenberg/pull/54218))
 - Font Library: Changing the upload directory to wp-content/fonts. ([54122](https://github.com/WordPress/gutenberg/pull/54122))
+- Font Library: Load collection JSON data from a URL in the collection configuration. ([54067](https://github.com/WordPress/gutenberg/pull/54067))
+- Font Library: Use wporg cdn to host the google fonts json data. ([54795](https://github.com/WordPress/gutenberg/pull/54795))
 
 #### Themes
 - Theme Previews: Make the back button customizable. ([54242](https://github.com/WordPress/gutenberg/pull/54242))
@@ -246,6 +136,7 @@ The following contributors merged PRs in this release:
 
 #### List View
 - Allow Escape key to deselect blocks if blocks are selected. ([48708](https://github.com/WordPress/gutenberg/pull/48708))
+- Try directing focus to the list view toggle button when closing the list view. ([54175](https://github.com/WordPress/gutenberg/pull/54175))
 
 #### Block API
 - Deprecated `get_file_path_from_theme` method. ([45831](https://github.com/WordPress/gutenberg/pull/45831))
@@ -256,6 +147,9 @@ The following contributors merged PRs in this release:
 #### Blob
 - refactor(blob): Type URL parameter as optional. ([49201](https://github.com/WordPress/gutenberg/pull/49201))
 
+#### Collaborative Editing
+- Try bundling sync package. ([54738](https://github.com/WordPress/gutenberg/pull/54738))
+
 
 ### New APIs
 
@@ -288,6 +182,7 @@ The following contributors merged PRs in this release:
 - Storybook: Update doc param values for ConfirmDialog. ([54130](https://github.com/WordPress/gutenberg/pull/54130))
 - Update borderFocus to ADMIN.theme. ([54425](https://github.com/WordPress/gutenberg/pull/54425))
 - Use standard focus style on BorderControl. ([54429](https://github.com/WordPress/gutenberg/pull/54429))
+- DateTimePicker: Fix onChange callback check so that it also works inside iframes. ([54669](https://github.com/WordPress/gutenberg/pull/54669))
 
 #### Post Editor
 - Adds animation state for DFM off to post editor header. ([54244](https://github.com/WordPress/gutenberg/pull/54244))
@@ -310,6 +205,8 @@ The following contributors merged PRs in this release:
 - PreviewOptions: Fix critical error when children not passed. ([54284](https://github.com/WordPress/gutenberg/pull/54284))
 - Remove `role` attribute when set to `null` in `data-wp-bind`. ([54608](https://github.com/WordPress/gutenberg/pull/54608))
 - [Commands]: Add group/ungroup commands only when eligible. ([53988](https://github.com/WordPress/gutenberg/pull/53988))
+- Replace the `gutenberg_` prefix with `wp_` in image block. ([54678](https://github.com/WordPress/gutenberg/pull/54678))
+- Navigation block: Fix padding on mobile overlay when global padding is 0. ([53725](https://github.com/WordPress/gutenberg/pull/53725))
 
 #### Patterns
 - Command Palette: Fix duplicate Patterns command. ([54133](https://github.com/WordPress/gutenberg/pull/54133))
@@ -317,6 +214,22 @@ The following contributors merged PRs in this release:
 - Fix user pattern categories in site editor inserter. ([54641](https://github.com/WordPress/gutenberg/pull/54641))
 - Remove pattern category as a variation for post terms block. ([54532](https://github.com/WordPress/gutenberg/pull/54532))
 - StartPageOptions: Improve conditions to show modal only on a brand new page. ([54245](https://github.com/WordPress/gutenberg/pull/54245))
+- Add My patterns back to post editor inserter categories. ([54767](https://github.com/WordPress/gutenberg/pull/54767))
+- De-emphasise pattern filters in inserter. ([54681](https://github.com/WordPress/gutenberg/pull/54681))
+- Fix All Patterns category default display. ([54721](https://github.com/WordPress/gutenberg/pull/54721))
+- Fix bug with new categories not showing. ([54768](https://github.com/WordPress/gutenberg/pull/54768))
+- Fix bug with pattern categories not saving sometimes. ([54676](https://github.com/WordPress/gutenberg/pull/54676))
+- Fix category type for back link. ([54753](https://github.com/WordPress/gutenberg/pull/54753))
+- Fix duplication of uncategorized patterns. ([54755](https://github.com/WordPress/gutenberg/pull/54755))
+- Inject the theme name into the block attributes. ([54595](https://github.com/WordPress/gutenberg/pull/54595))
+- Reinstate my patterns category in site editor. ([54726](https://github.com/WordPress/gutenberg/pull/54726))
+- Require a title in the creation modal. ([54717](https://github.com/WordPress/gutenberg/pull/54717))
+- Use slug as fallback for empty title. ([54731](https://github.com/WordPress/gutenberg/pull/54731))
+- Allow non-user patterns under Standard sync filter. ([54756](https://github.com/WordPress/gutenberg/pull/54756))
+- Check that pattern is synced before replacing blocks with synced pattern on creation. ([54804](https://github.com/WordPress/gutenberg/pull/54804))
+- Fix back navigation after pattern creation. ([54852](https://github.com/WordPress/gutenberg/pull/54852))
+- Fix category control width in site editor. ([54853](https://github.com/WordPress/gutenberg/pull/54853))
+- Improve sentence case consistency of labels and notices. ([54807](https://github.com/WordPress/gutenberg/pull/54807))
 
 #### Block Editor
 - Add keyboardReturn submit button back to LinkControl. ([52620](https://github.com/WordPress/gutenberg/pull/52620))
@@ -324,23 +237,34 @@ The following contributors merged PRs in this release:
 - List: Merge consecutive lists. ([52995](https://github.com/WordPress/gutenberg/pull/52995))
 - Rich text: Fix useAnchor (remove nextElementSibling). ([54013](https://github.com/WordPress/gutenberg/pull/54013))
 - Iframe: Adjust keydown event bubbling. ([54565](https://github.com/WordPress/gutenberg/pull/54565))
+- Reset page after changing pattern filters or search value. ([54774](https://github.com/WordPress/gutenberg/pull/54774))
+- Block Editor: Fix 'isBlockSubtreeDisabled' private selector. ([54618](https://github.com/WordPress/gutenberg/pull/54618))
 
 #### Site Editor
 - Bump the z-index of the rename modal. ([54277](https://github.com/WordPress/gutenberg/pull/54277))
 - Default template lookup should use slug, not the full permalink, in the site editor. ([54599](https://github.com/WordPress/gutenberg/pull/54599))
 - Fix "Blog title" input border radius in Index / Home details panel. ([54192](https://github.com/WordPress/gutenberg/pull/54192))
 - Hide ghost top toolbar. ([54555](https://github.com/WordPress/gutenberg/pull/54555))
+- CreateTemplatePartModal: Disable the 'Create' button while saving. ([54716](https://github.com/WordPress/gutenberg/pull/54716))
 
 #### Plugin
 - Ensure font-face styles are printed in iframe editors. ([54313](https://github.com/WordPress/gutenberg/pull/54313))
 - Font Face & Font Library: Load PHP files only if the main class does not exist. ([54103](https://github.com/WordPress/gutenberg/pull/54103))
 - Gutenberg Plugin: Add hook to allow `writing-mode` as a safe CSS property. ([54581](https://github.com/WordPress/gutenberg/pull/54581))
 - Update readme.txt "tested up to 6.3". ([54072](https://github.com/WordPress/gutenberg/pull/54072))
+- Update cherry-pick script to correctly verify GitHub CLI setup. ([54720](https://github.com/WordPress/gutenberg/pull/54720))
+- Conditionally remove deprecated 'print_emoji_styles'. ([54828](https://github.com/WordPress/gutenberg/pull/54828))
 
 #### Typography
 - Font Library: Ensure merged fontFace data is enconded as an array instead of an object. ([54435](https://github.com/WordPress/gutenberg/pull/54435))
 - Font Library: Fix duplicate variants with different file types. ([54490](https://github.com/WordPress/gutenberg/pull/54490))
 - Font Library: Setting wp_font_family custom post type as _builtin and not plublic. ([54559](https://github.com/WordPress/gutenberg/pull/54559))
+- Font Face: Get name from "fontFamily" setting, not "name". ([54615](https://github.com/WordPress/gutenberg/pull/54615))
+- Font Library: Fix modal width on mobile viewport. ([54518](https://github.com/WordPress/gutenberg/pull/54518))
+- Font Library: Fix space above theme fonts in font library modal. ([54598](https://github.com/WordPress/gutenberg/pull/54598))
+- Font Library: Fix error installing system fonts. ([54713](https://github.com/WordPress/gutenberg/pull/54713))
+- Font Library: Remove font files created by tests after tests run. ([54771](https://github.com/WordPress/gutenberg/pull/54771))
+- Font Library: Avoid rendering font library ui outisde gutenberg plugin. ([54830](https://github.com/WordPress/gutenberg/pull/54830))
 
 #### Widgets Editor
 - Edit Widgets: Fix broken layout. ([54372](https://github.com/WordPress/gutenberg/pull/54372))
@@ -354,12 +278,14 @@ The following contributors merged PRs in this release:
 #### Block API
 - Blocks: Fix incorrect placement for hooked blocks in the parent container. ([54349](https://github.com/WordPress/gutenberg/pull/54349))
 - Pass correct content argument to enter transforms. ([54108](https://github.com/WordPress/gutenberg/pull/54108))
+- Block Hooks: Avoid processing empty content for loaded templates. ([54719](https://github.com/WordPress/gutenberg/pull/54719))
 
 #### Rich Text
 - Revert: Rich text: Copy tag name on internal paste. ([54301](https://github.com/WordPress/gutenberg/pull/54301))
 
 #### Interactivity API
 - Image: Fix block serialization test case to cover deprecation of `behaviors`. ([54570](https://github.com/WordPress/gutenberg/pull/54570))
+- Query Loop: Select first anchor inside Post Template with "enhanced pagination" enabled. ([54730](https://github.com/WordPress/gutenberg/pull/54730))
 
 #### Icons
 - Fix React forwardRef warnings for `TooltipAnchor`s. ([54492](https://github.com/WordPress/gutenberg/pull/54492))
@@ -388,6 +314,15 @@ The following contributors merged PRs in this release:
 #### React i18n
 - Fix: Invalid import in react-i18n documentation. ([54308](https://github.com/WordPress/gutenberg/pull/54308))
 
+#### Design Tools
+- Background Image control: Use consistent button, ensure descriptive text accounts for no image selected. ([54711](https://github.com/WordPress/gutenberg/pull/54711))
+
+#### Collaborative Editing
+- Make sure sync code only runs when experiment is enabled. ([54710](https://github.com/WordPress/gutenberg/pull/54710))
+
+#### Core Data
+- core-data: Fix nested property access with undefined name. ([54790](https://github.com/WordPress/gutenberg/pull/54790))
+
 
 ### Accessibility
 
@@ -399,6 +334,8 @@ The following contributors merged PRs in this release:
 #### Components
 - Improve Notice component accessibility. ([54498](https://github.com/WordPress/gutenberg/pull/54498))
 - Making Circular Option Picker a `listbox`. ([52255](https://github.com/WordPress/gutenberg/pull/52255))
+- Allow Modal to place focus on first element within contents via new API. ([54590](https://github.com/WordPress/gutenberg/pull/54590))
+- Improve the placeholder instructions accessibility. ([45801](https://github.com/WordPress/gutenberg/pull/45801))
 
 #### Site Editor
 - Clarify the "Entity" message of the snackbar. ([54333](https://github.com/WordPress/gutenberg/pull/54333))
@@ -474,6 +411,7 @@ The following contributors merged PRs in this release:
 - [Docs:  Getting Started / Block Development Environment] Updates on the text to improve clarity and preciseness. ([54563](https://github.com/WordPress/gutenberg/pull/54563))
 - documentation - Contribution Triage: Formatted text and changed some titles and structure. ([54258](https://github.com/WordPress/gutenberg/pull/54258))
 - documentation [Block Editor Handbook / Getting Started / Block Development Environment]: Fix links. ([54571](https://github.com/WordPress/gutenberg/pull/54571))
+- Add missing global declaration in DocBlock of interactivity files. ([54683](https://github.com/WordPress/gutenberg/pull/54683))
 
 
 ### Code Quality
@@ -501,6 +439,7 @@ The following contributors merged PRs in this release:
 - Move category map creation out of useSelect. ([54584](https://github.com/WordPress/gutenberg/pull/54584))
 - Remove experimental prefixes from patterns package. ([54338](https://github.com/WordPress/gutenberg/pull/54338))
 - Site editor: Consolidate constants. ([54484](https://github.com/WordPress/gutenberg/pull/54484))
+- Fix sidebar nav screen fallback category. ([54754](https://github.com/WordPress/gutenberg/pull/54754))
 
 #### Post Editor
 - Annotations: Run end-to-end tests with iframe. ([54191](https://github.com/WordPress/gutenberg/pull/54191))
@@ -523,6 +462,8 @@ The following contributors merged PRs in this release:
 #### Site Editor
 - Remove Tooltip workarounds added in the site and block editor. ([54450](https://github.com/WordPress/gutenberg/pull/54450))
 - Revisions: Remove 'gutenberg' query param from revisions.php. ([54166](https://github.com/WordPress/gutenberg/pull/54166))
+- Prune store constants. ([54585](https://github.com/WordPress/gutenberg/pull/54585))
+- Use constants rather than hard coded template strings. ([54586](https://github.com/WordPress/gutenberg/pull/54586))
 
 #### Rich Text
 - RichText: Remove __unstableOnSplitMiddle. ([54183](https://github.com/WordPress/gutenberg/pull/54183))
@@ -530,6 +471,7 @@ The following contributors merged PRs in this release:
 #### Typography
 - Fluid typography: Backporting Core @since annotations. ([54204](https://github.com/WordPress/gutenberg/pull/54204))
 - Font Face: Remove static instance in wp_print_font_faces(). ([54228](https://github.com/WordPress/gutenberg/pull/54228))
+- Font Library: Refactor logic to disable font library in the frontend. ([54748](https://github.com/WordPress/gutenberg/pull/54748))
 
 #### Block Editor
 - Improve code commenting around focus mount behaviour of rich text Link UI. ([54085](https://github.com/WordPress/gutenberg/pull/54085))
@@ -540,6 +482,8 @@ The following contributors merged PRs in this release:
 
 #### Plugin
 - Require minimum WordPress 6.2. ([53451](https://github.com/WordPress/gutenberg/pull/53451))
+- Ensure that Block Hooks work correctly after landing in WP core. ([54651](https://github.com/WordPress/gutenberg/pull/54651))
+- Update uuid package to 9.0.1. ([54725](https://github.com/WordPress/gutenberg/pull/54725))
 
 #### Themes
 - Iframe: Skip scoping styles. ([46752](https://github.com/WordPress/gutenberg/pull/46752))
@@ -563,6 +507,10 @@ The following contributors merged PRs in this release:
 - end-to-end Tests: Fix 'no-useless-not' ESLint warnings. ([54652](https://github.com/WordPress/gutenberg/pull/54652))
 - package(e2e-test-utils): Update fixtures. ([54128](https://github.com/WordPress/gutenberg/pull/54128))
 - wp-scripts: Add support for Playwright. ([53108](https://github.com/WordPress/gutenberg/pull/53108))
+- Font Library: Use resolvable domain in test. ([54763](https://github.com/WordPress/gutenberg/pull/54763))
+- Global styles tests: Fire hooks when updating post. ([54836](https://github.com/WordPress/gutenberg/pull/54836))
+- Remove action to fix tests. ([54806](https://github.com/WordPress/gutenberg/pull/54806))
+- Font Library: Fix set upload dir test. ([54762](https://github.com/WordPress/gutenberg/pull/54762))
 
 #### Build Tooling
 - Backport tools: Filter PRs to be cherry picked by merged date. ([54171](https://github.com/WordPress/gutenberg/pull/54171))
@@ -590,7 +538,7 @@ The following PRs were merged by first time contributors:
 
 The following contributors merged PRs in this release:
 
-@aaronrobertshaw @afercia @alexstine @andrewhayward @andrewserong @annezazu @anomiex @anton-vlasenko @aristath @artemiomorales @atachibana @bangank36 @bfintal @bph @brookewp @c4rl0sbr4v0 @carolinan @chad1008 @chintu51 @ciampo @DAreRodz @dcalhoun @derekblank @draganescu @ediamin @ellatrix @fluiddot @gaambo @geriux @getdave @glendaviesnz @gvgvgvijayan @gziolo @hellofromtonya @jameskoster @jamiemchale @jffng @johnhooks @jordesign @jorgefilipecosta @joshuatf @jrtashjian @jsnajdr @juanmaguitar @kevin940726 @kkoppenhaver @kmanijak @leewillis77 @luisherranz @madhusudhand @Mamaduka @margolisj @masteradhoc @matiasbenedetto @mburridge @mcsf @MericKarabulut @mhimon @michalczaplinski @mikachan @mikejolley @mokagio @ndiego @ntsekouras @Olein-jp @petitphp @Piyush-Deshmukh @Rajinsharwar @ramonjd @richtabor @SantosGuillamot @scruffian @spacedmonkey @stokesman @swissspidy @t-hamano @tellthemachines @thelovekesh @toolstack @torounit @tyxla @vcanales @walbo @WunderBart @youknowriad
+@aaronrobertshaw @afercia @alexstine @andrewhayward @andrewserong @annezazu @anomiex @anton-vlasenko @aristath @artemiomorales @atachibana @bangank36 @bfintal @bph @brookewp @c4rl0sbr4v0 @carolinan @chad1008 @chintu51 @ciampo @DAreRodz @dcalhoun @derekblank @draganescu @ediamin @ellatrix @fluiddot @gaambo @geriux @getdave @glendaviesnz @gvgvgvijayan @gziolo @hellofromtonya @jameskoster @jamiemchale @jeherve @jffng @johnhooks @jordesign @jorgefilipecosta @joshuatf @jrtashjian @jsnajdr @juanmaguitar @kevin940726 @kkoppenhaver @kmanijak @leewillis77 @luisherranz @madhusudhand @MaggieCabrera @Mamaduka @margolisj @masteradhoc @matiasbenedetto @mburridge @mcsf @MericKarabulut @mhimon @michalczaplinski @mikachan @mikejolley @mokagio @ndiego @ntsekouras @Olein-jp @petitphp @Piyush-Deshmukh @Rajinsharwar @ramonjd @richtabor @SantosGuillamot @SaxonF @scruffian @spacedmonkey @stokesman @swissspidy @t-hamano @tellthemachines @thelovekesh @toolstack @torounit @tyxla @vcanales @walbo @WunderBart @youknowriad
 
 
 = 16.6.0 =

From 16e11d4355e499c2b47484c766237c86e383ef48 Mon Sep 17 00:00:00 2001
From: Pascal Birchler <pascalb@google.com>
Date: Wed, 27 Sep 2023 14:32:34 +0200
Subject: [PATCH 4/8] =?UTF-8?q?Don=E2=80=99t=20use=20TypeScript=20files=20?=
 =?UTF-8?q?in=20scripts=20package=20(#54856)?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 .../config/{playwright.config.ts => playwright.config.js} | 0
 .../playwright/{global-setup.ts => global-setup.js}       | 8 ++++++--
 2 files changed, 6 insertions(+), 2 deletions(-)
 rename packages/scripts/config/{playwright.config.ts => playwright.config.js} (100%)
 rename packages/scripts/config/playwright/{global-setup.ts => global-setup.js} (82%)

diff --git a/packages/scripts/config/playwright.config.ts b/packages/scripts/config/playwright.config.js
similarity index 100%
rename from packages/scripts/config/playwright.config.ts
rename to packages/scripts/config/playwright.config.js
diff --git a/packages/scripts/config/playwright/global-setup.ts b/packages/scripts/config/playwright/global-setup.js
similarity index 82%
rename from packages/scripts/config/playwright/global-setup.ts
rename to packages/scripts/config/playwright/global-setup.js
index 10f2822fdfe1a..eace349c6309d 100644
--- a/packages/scripts/config/playwright/global-setup.ts
+++ b/packages/scripts/config/playwright/global-setup.js
@@ -2,14 +2,18 @@
  * External dependencies
  */
 import { request } from '@playwright/test';
-import type { FullConfig } from '@playwright/test';
 
 /**
  * WordPress dependencies
  */
 import { RequestUtils } from '@wordpress/e2e-test-utils-playwright';
 
-async function globalSetup( config: FullConfig ) {
+/**
+ *
+ * @param {import('@playwright/test').FullConfig} config
+ * @return {Promise<void>}
+ */
+async function globalSetup( config ) {
 	const { storageState, baseURL } = config.projects[ 0 ].use;
 	const storageStatePath =
 		typeof storageState === 'string' ? storageState : undefined;

From 3072c985ec62b3f6815643fdf9e27a355d1f57f0 Mon Sep 17 00:00:00 2001
From: David Calhoun <github@davidcalhoun.me>
Date: Wed, 27 Sep 2023 09:02:21 -0400
Subject: [PATCH 5/8] fix: Prevent crash from invalid media URLs (#54834)

* test: Add failing invalid media URL test case

* fix: Prevent crash from invalid media URLs

The `isURL` utility considers URLs using uncommon protocols to be valid,
as constructing `URL` with, say, `h://a-path.com` is valid.
Contrastingly, the `react-native-video` package only considers a URL
using the `http:` or `https:` protocols to be a "network" asset. This
leads to an attempt to load the URL as a local asset, which fails as the
asset does not exist in the app bundle.

https://github.com/react-native-video/react-native-video/blob/81ae785090f5ce3d5e45cc51f68a3360a85be853/Video.js#L277

* docs: Add change log entry
---
 .../block-library/src/audio/edit.native.js    |  4 +-
 .../src/audio/test/edit.native.js             | 42 ++++++++++++-------
 .../block-library/src/video/edit.native.js    |  2 +-
 .../src/video/test/edit.native.js             | 29 +++++++++++++
 packages/react-native-editor/CHANGELOG.md     |  1 +
 5 files changed, 61 insertions(+), 17 deletions(-)
 create mode 100644 packages/block-library/src/video/test/edit.native.js

diff --git a/packages/block-library/src/audio/edit.native.js b/packages/block-library/src/audio/edit.native.js
index fbc39ba190d3e..cbd7f9ff02f8f 100644
--- a/packages/block-library/src/audio/edit.native.js
+++ b/packages/block-library/src/audio/edit.native.js
@@ -30,7 +30,7 @@ import { audio as icon, replace } from '@wordpress/icons';
 import { useState } from '@wordpress/element';
 import { useDispatch, useSelect } from '@wordpress/data';
 import { store as noticesStore } from '@wordpress/notices';
-import { isURL } from '@wordpress/url';
+import { isURL, getProtocol } from '@wordpress/url';
 
 /**
  * Internal dependencies
@@ -73,7 +73,7 @@ function AudioEdit( {
 
 	function onSelectURL( newSrc ) {
 		if ( newSrc !== src ) {
-			if ( isURL( newSrc ) ) {
+			if ( isURL( newSrc ) && /^https?:/.test( getProtocol( newSrc ) ) ) {
 				setAttributes( { src: newSrc, id: undefined } );
 			} else {
 				createErrorNotice( __( 'Invalid URL. Audio file not found.' ) );
diff --git a/packages/block-library/src/audio/test/edit.native.js b/packages/block-library/src/audio/test/edit.native.js
index b59c36db2f66e..c191fd2fff798 100644
--- a/packages/block-library/src/audio/test/edit.native.js
+++ b/packages/block-library/src/audio/test/edit.native.js
@@ -1,13 +1,20 @@
 /**
  * External dependencies
  */
-import { render } from 'test/helpers';
+import {
+	addBlock,
+	dismissModal,
+	fireEvent,
+	initializeEditor,
+	render,
+	screen,
+	setupCoreBlocks,
+} from 'test/helpers';
 
 /**
  * WordPress dependencies
  */
 import { BlockEdit } from '@wordpress/block-editor';
-import { registerBlockType, unregisterBlockType } from '@wordpress/blocks';
 import {
 	subscribeMediaUpload,
 	sendMediaUpload,
@@ -16,7 +23,7 @@ import {
 /**
  * Internal dependencies
  */
-import { metadata, settings, name } from '../index';
+import { name } from '../index';
 
 // react-native-aztec shouldn't be mocked because these tests are based on
 // snapshot testing where we want to keep the original component.
@@ -42,18 +49,9 @@ const getTestComponentWithContent = ( attributes = {} ) => {
 	);
 };
 
-describe( 'Audio block', () => {
-	beforeAll( () => {
-		registerBlockType( name, {
-			...metadata,
-			...settings,
-		} );
-	} );
-
-	afterAll( () => {
-		unregisterBlockType( name );
-	} );
+setupCoreBlocks( [ 'core/audio' ] );
 
+describe( 'Audio block', () => {
 	it( 'renders placeholder without crashing', () => {
 		const component = getTestComponentWithContent();
 		const rendered = component.toJSON();
@@ -86,4 +84,20 @@ describe( 'Audio block', () => {
 		const rendered = component.toJSON();
 		expect( rendered ).toMatchSnapshot();
 	} );
+
+	it( 'should gracefully handle invalid URLs', async () => {
+		await initializeEditor();
+
+		await addBlock( screen, 'Audio' );
+		fireEvent.press( screen.getByText( 'Insert from URL' ) );
+		fireEvent.changeText(
+			screen.getByPlaceholderText( 'Type a URL' ),
+			'h://wordpress.org/audio.mp3'
+		);
+		dismissModal( screen.getByTestId( 'bottom-sheet' ) );
+
+		expect(
+			screen.getByText( 'Invalid URL. Audio file not found.' )
+		).toBeVisible();
+	} );
 } );
diff --git a/packages/block-library/src/video/edit.native.js b/packages/block-library/src/video/edit.native.js
index 48b5692aee3d7..6c1798756b40c 100644
--- a/packages/block-library/src/video/edit.native.js
+++ b/packages/block-library/src/video/edit.native.js
@@ -162,7 +162,7 @@ class VideoEdit extends Component {
 	onSelectURL( url ) {
 		const { createErrorNotice, onReplace, setAttributes } = this.props;
 
-		if ( isURL( url ) ) {
+		if ( isURL( url ) && /^https?:/.test( getProtocol( url ) ) ) {
 			// Check if there's an embed block that handles this URL.
 			const embedBlock = createUpgradedEmbedBlock( {
 				attributes: { url },
diff --git a/packages/block-library/src/video/test/edit.native.js b/packages/block-library/src/video/test/edit.native.js
new file mode 100644
index 0000000000000..9b7f4b0bdffbb
--- /dev/null
+++ b/packages/block-library/src/video/test/edit.native.js
@@ -0,0 +1,29 @@
+/**
+ * External dependencies
+ */
+import {
+	addBlock,
+	dismissModal,
+	fireEvent,
+	initializeEditor,
+	screen,
+	setupCoreBlocks,
+} from 'test/helpers';
+
+setupCoreBlocks( [ 'core/video' ] );
+
+describe( 'Video block', () => {
+	it( 'should gracefully handle invalid URLs', async () => {
+		await initializeEditor();
+
+		await addBlock( screen, 'Video' );
+		fireEvent.press( screen.getByText( 'Insert from URL' ) );
+		fireEvent.changeText(
+			screen.getByPlaceholderText( 'Type a URL' ),
+			'h://wordpress.org/video.mp4'
+		);
+		dismissModal( screen.getByTestId( 'bottom-sheet' ) );
+
+		expect( screen.getByText( 'Invalid URL.' ) ).toBeVisible();
+	} );
+} );
diff --git a/packages/react-native-editor/CHANGELOG.md b/packages/react-native-editor/CHANGELOG.md
index 70f0605599add..504bad70c8057 100644
--- a/packages/react-native-editor/CHANGELOG.md
+++ b/packages/react-native-editor/CHANGELOG.md
@@ -11,6 +11,7 @@ For each user feature we should also add a importance categorization label  to i
 
 ## Unreleased
 -   [*] Limit inner blocks nesting depth to avoid call stack size exceeded crash [#54382]
+-   [*] Prevent crashes when setting an invalid media URL for Video or Audio blocks [#54834]
 
 ## 1.104.0
 -   [*] Fix the obscurred "Insert from URL" input for media blocks when using a device in landscape orientation. [#54096]

From e082f0239bdda0d0e351467f8513b389adc56e2e Mon Sep 17 00:00:00 2001
From: Bernie Reiter <96308+ockham@users.noreply.github.com>
Date: Wed, 27 Sep 2023 15:09:10 +0200
Subject: [PATCH 6/8] Docs: Rename Block Hooks handbook page to Block Filters
 (#54862)

---
 docs/manifest.json                             | 2 +-
 docs/reference-guides/README.md                | 2 +-
 docs/reference-guides/filters/block-filters.md | 2 +-
 3 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/docs/manifest.json b/docs/manifest.json
index 338f2313e6ad1..4108da22296ef 100644
--- a/docs/manifest.json
+++ b/docs/manifest.json
@@ -492,7 +492,7 @@
 		"parent": "reference-guides"
 	},
 	{
-		"title": "Block Hooks",
+		"title": "Block Filters",
 		"slug": "block-filters",
 		"markdown_source": "../docs/reference-guides/filters/block-filters.md",
 		"parent": "filters"
diff --git a/docs/reference-guides/README.md b/docs/reference-guides/README.md
index 33fdd9aa60241..b9725af66f080 100644
--- a/docs/reference-guides/README.md
+++ b/docs/reference-guides/README.md
@@ -18,7 +18,7 @@
 
 ## [Hooks Reference](/docs/reference-guides/filters/README.md)
 
--   [Block Hooks](/docs/reference-guides/filters/block-filters.md)
+-   [Block Filters](/docs/reference-guides/filters/block-filters.md)
 -   [Editor Hooks](/docs/reference-guides/filters/editor-filters.md)
 -   [i18n Hooks](/docs/reference-guides/filters/i18n-filters.md)
 -   [Parser Hooks](/docs/reference-guides/filters/parser-filters.md)
diff --git a/docs/reference-guides/filters/block-filters.md b/docs/reference-guides/filters/block-filters.md
index 66e89b0a1d614..f1784f893ecb2 100644
--- a/docs/reference-guides/filters/block-filters.md
+++ b/docs/reference-guides/filters/block-filters.md
@@ -1,4 +1,4 @@
-# Block Hooks
+# Block Filters
 
 To modify the behavior of existing blocks, WordPress exposes several APIs.
 

From e1a88b33ef10d88da4be6094f2ae8757893e1272 Mon Sep 17 00:00:00 2001
From: Dennis Snell <dennis.snell@automattic.com>
Date: Thu, 14 Sep 2023 15:49:42 -0700
Subject: [PATCH 7/8] HTML API: Backport updates from Core

Pulling over work on the HTML API from Core:

 - bug fix: stop parsing tags inside of STYLE, IFRAME, and other RAWTEXT elements.
 - bug fix: stay on track when document ends in the middle of processing a tag.
 - bug fix: remove all copies of an attribute when duplicates exist on a tag.
 - bug fix: stop processing in the HTML Processor when encountering unsupported markup
 - reverts changes made in #53866 which introduced a bug during a styling refactor.
 - update docblock comments through HTML API.

This patch also excludes the HTML API folders in the compatability
layer from WPCS inspection, since this code is maintained, reviewed,
and accepted into Core and brought back into Gutenberg. Changes to
the code need to be made first in Core and brought over as blessed
backport changes.

Co-authored-by: Ari Stathopoulos <aristath@gmail.com>
Co-authored-by: Bernie Reiter <96308+ockham@users.noreply.github.com>
---
 ...class-gutenberg-html-tag-processor-6-3.php |  125 +-
 ...class-gutenberg-html-tag-processor-6-4.php | 2413 +++++++++++++++++
 .../html-api/class-wp-html-processor.php      |  150 +-
 lib/load.php                                  |    1 +
 phpcs.xml.dist                                |    5 +-
 5 files changed, 2626 insertions(+), 68 deletions(-)
 create mode 100644 lib/compat/wordpress-6.4/html-api/class-gutenberg-html-tag-processor-6-4.php

diff --git a/lib/compat/wordpress-6.3/html-api/class-gutenberg-html-tag-processor-6-3.php b/lib/compat/wordpress-6.3/html-api/class-gutenberg-html-tag-processor-6-3.php
index 73cdb9342490c..3b43d791692a9 100644
--- a/lib/compat/wordpress-6.3/html-api/class-gutenberg-html-tag-processor-6-3.php
+++ b/lib/compat/wordpress-6.3/html-api/class-gutenberg-html-tag-processor-6-3.php
@@ -242,6 +242,8 @@
  * unquoted values will appear in the output with double-quotes.
  *
  * @since 6.2.0
+ * @since 6.2.1 Fix: Support for various invalid comments; attribute updates are case-insensitive.
+ * @since 6.3.2 Fix: Skip HTML-like content inside rawtext elements such as STYLE.
  */
 class Gutenberg_HTML_Tag_Processor_6_3 {
 	/**
@@ -404,6 +406,16 @@ class Gutenberg_HTML_Tag_Processor_6_3 {
 	 */
 	private $attributes = array();
 
+	/**
+	 * Tracks spans of duplicate attributes on a given tag, used for removing
+	 * all copies of an attribute when calling `remove_attribute()`.
+	 *
+	 * @since 6.3.2
+	 *
+	 * @var (WP_HTML_Span[])[]|null
+	 */
+	private $duplicate_attributes = null;
+
 	/**
 	 * Which class names to add or remove from a tag.
 	 *
@@ -546,6 +558,10 @@ public function next_tag( $query = null ) {
 			}
 
 			// Ensure that the tag closes before the end of the document.
+			if ( $this->bytes_already_parsed >= strlen( $this->html ) ) {
+				return false;
+			}
+
 			$tag_ends_at = strpos( $this->html, '>', $this->bytes_already_parsed );
 			if ( false === $tag_ends_at ) {
 				return false;
@@ -564,7 +580,14 @@ public function next_tag( $query = null ) {
 			 * of the tag name as a pre-check avoids a string allocation when it's not needed.
 			 */
 			$t = $this->html[ $this->tag_name_starts_at ];
-			if ( ! $this->is_closing_tag && ( 's' === $t || 'S' === $t || 't' === $t || 'T' === $t ) ) {
+			if (
+				! $this->is_closing_tag &&
+				(
+					'i' === $t || 'I' === $t ||
+					'n' === $t || 'N' === $t ||
+					's' === $t || 'S' === $t ||
+					't' === $t || 'T' === $t
+				) ) {
 				$tag_name = $this->get_tag();
 
 				if ( 'SCRIPT' === $tag_name && ! $this->skip_script_data() ) {
@@ -576,6 +599,25 @@ public function next_tag( $query = null ) {
 				) {
 					$this->bytes_already_parsed = strlen( $this->html );
 					return false;
+				} elseif (
+					(
+						'IFRAME' === $tag_name ||
+						'NOEMBED' === $tag_name ||
+						'NOFRAMES' === $tag_name ||
+						'NOSCRIPT' === $tag_name ||
+						'STYLE' === $tag_name
+					) &&
+					! $this->skip_rawtext( $tag_name )
+				) {
+					/*
+					 * "XMP" should be here too but its rules are more complicated and require the
+					 * complexity of the HTML Processor (it needs to close out any open P element,
+					 * meaning it can't be skipped here or else the HTML Processor will lose its
+					 * place). For now, it can be ignored as it's a rare HTML tag in practice and
+					 * any normative HTML should be using PRE instead.
+					 */
+					$this->bytes_already_parsed = strlen( $this->html );
+					return false;
 				}
 			}
 		} while ( $already_found < $this->sought_match_offset );
@@ -706,15 +748,33 @@ public function release_bookmark( $name ) {
 		return true;
 	}
 
+	/**
+	 * Skips contents of generic rawtext elements.
+	 *
+	 * @since 6.3.2
+	 *
+	 * @see https://html.spec.whatwg.org/#generic-raw-text-element-parsing-algorithm
+	 *
+	 * @param string $tag_name The uppercase tag name which will close the RAWTEXT region.
+	 * @return bool Whether an end to the RAWTEXT region was found before the end of the document.
+	 */
+	private function skip_rawtext( $tag_name ) {
+		/*
+		 * These two functions distinguish themselves on whether character references are
+		 * decoded, and since functionality to read the inner markup isn't supported, it's
+		 * not necessary to implement these two functions separately.
+		 */
+		return $this->skip_rcdata( $tag_name );
+	}
 
 	/**
-	 * Skips contents of title and textarea tags.
+	 * Skips contents of RCDATA elements, namely title and textarea tags.
 	 *
 	 * @since 6.2.0
 	 *
 	 * @see https://html.spec.whatwg.org/multipage/parsing.html#rcdata-state
 	 *
-	 * @param string $tag_name The lowercase tag name which will close the RCDATA region.
+	 * @param string $tag_name The uppercase tag name which will close the RCDATA region.
 	 * @return bool Whether an end to the RCDATA region was found before the end of the document.
 	 */
 	private function skip_rcdata( $tag_name ) {
@@ -947,7 +1007,7 @@ private function parse_next_tag() {
 
 			if ( '/' === $this->html[ $at + 1 ] ) {
 				$this->is_closing_tag = true;
-				++$at;
+				$at++;
 			} else {
 				$this->is_closing_tag = false;
 			}
@@ -1016,7 +1076,7 @@ private function parse_next_tag() {
 					 *
 					 * See https://html.spec.whatwg.org/#parse-error-incorrectly-closed-comment
 					 */
-					--$closer_at; // Pre-increment inside condition below reduces risk of accidental infinite looping.
+					$closer_at--; // Pre-increment inside condition below reduces risk of accidental infinite looping.
 					while ( ++$closer_at < strlen( $html ) ) {
 						$closer_at = strpos( $html, '--', $closer_at );
 						if ( false === $closer_at ) {
@@ -1097,7 +1157,7 @@ private function parse_next_tag() {
 			 * See https://html.spec.whatwg.org/#parse-error-missing-end-tag-name
 			 */
 			if ( '>' === $html[ $at + 1 ] ) {
-				++$at;
+				$at++;
 				continue;
 			}
 
@@ -1236,6 +1296,25 @@ private function parse_next_attribute() {
 				$attribute_end,
 				! $has_value
 			);
+
+			return true;
+		}
+
+		/*
+		 * Track the duplicate attributes so if we remove it, all disappear together.
+		 *
+		 * While `$this->duplicated_attributes` could always be stored as an `array()`,
+		 * which would simplify the logic here, storing a `null` and only allocating
+		 * an array when encountering duplicates avoids needless allocations in the
+		 * normative case of parsing tags with no duplicate attributes.
+		 */
+		$duplicate_span = new WP_HTML_Span( $attribute_start, $attribute_end );
+		if ( null === $this->duplicate_attributes ) {
+			$this->duplicate_attributes = array( $comparable_name => array( $duplicate_span ) );
+		} elseif ( ! array_key_exists( $comparable_name, $this->duplicate_attributes ) ) {
+			$this->duplicate_attributes[ $comparable_name ] = array( $duplicate_span );
+		} else {
+			$this->duplicate_attributes[ $comparable_name ][] = $duplicate_span;
 		}
 
 		return true;
@@ -1257,11 +1336,12 @@ private function skip_whitespace() {
 	 */
 	private function after_tag() {
 		$this->get_updated_html();
-		$this->tag_name_starts_at = null;
-		$this->tag_name_length    = null;
-		$this->tag_ends_at        = null;
-		$this->is_closing_tag     = null;
-		$this->attributes         = array();
+		$this->tag_name_starts_at   = null;
+		$this->tag_name_length      = null;
+		$this->tag_ends_at          = null;
+		$this->is_closing_tag       = null;
+		$this->attributes           = array();
+		$this->duplicate_attributes = null;
 	}
 
 	/**
@@ -1739,7 +1819,7 @@ public function get_attribute( $name ) {
 	 * @param string $prefix Prefix of requested attribute names.
 	 * @return array|null List of attribute names, or `null` when no tag opener is matched.
 	 */
-	public function get_attribute_names_with_prefix( $prefix ) {
+	function get_attribute_names_with_prefix( $prefix ) {
 		if ( $this->is_closing_tag || null === $this->tag_name_starts_at ) {
 			return null;
 		}
@@ -2030,6 +2110,17 @@ public function remove_attribute( $name ) {
 			''
 		);
 
+		// Removes any duplicated attributes if they were also present.
+		if ( null !== $this->duplicate_attributes && array_key_exists( $name, $this->duplicate_attributes ) ) {
+			foreach ( $this->duplicate_attributes[ $name ] as $attribute_token ) {
+				$this->lexical_updates[] = new WP_HTML_Text_Replacement(
+					$attribute_token->start,
+					$attribute_token->end,
+					''
+				);
+			}
+		}
+
 		return true;
 	}
 
@@ -2282,9 +2373,11 @@ private function matches() {
 			 * See https://html.spec.whatwg.org/#attributes-3
 			 * See https://html.spec.whatwg.org/#space-separated-tokens
 			 */
-			do {
-				$class_at = strpos( $this->html, $this->sought_class_name, $class_at );
-
+			while (
+				// phpcs:ignore WordPress.CodeAnalysis.AssignmentInCondition.FoundInWhileCondition
+				false !== ( $class_at = strpos( $this->html, $this->sought_class_name, $class_at ) ) &&
+				$class_at < $class_end
+			) {
 				/*
 				 * Verify this class starts at a boundary.
 				 */
@@ -2310,7 +2403,7 @@ private function matches() {
 				}
 
 				return true;
-			} while ( false !== $class_at && $class_at < $class_end );
+			}
 
 			return false;
 		}
diff --git a/lib/compat/wordpress-6.4/html-api/class-gutenberg-html-tag-processor-6-4.php b/lib/compat/wordpress-6.4/html-api/class-gutenberg-html-tag-processor-6-4.php
new file mode 100644
index 0000000000000..7a87bddd7f1f7
--- /dev/null
+++ b/lib/compat/wordpress-6.4/html-api/class-gutenberg-html-tag-processor-6-4.php
@@ -0,0 +1,2413 @@
+<?php
+/**
+ * HTML API: WP_HTML_Tag_Processor class
+ *
+ * Scans through an HTML document to find specific tags, then
+ * transforms those tags by adding, removing, or updating the
+ * values of the HTML attributes within that tag (opener).
+ *
+ * Does not fully parse HTML or _recurse_ into the HTML structure
+ * Instead this scans linearly through a document and only parses
+ * the HTML tag openers.
+ *
+ * ### Possible future direction for this module
+ *
+ *  - Prune the whitespace when removing classes/attributes: e.g. "a b c" -> "c" not " c".
+ *    This would increase the size of the changes for some operations but leave more
+ *    natural-looking output HTML.
+ *  - Decode HTML character references within class names when matching. E.g. match having
+ *    class `1<"2` needs to recognize `class="1&lt;&quot;2"`. Currently the Tag Processor
+ *    will fail to find the right tag if the class name is encoded as such.
+ *  - Properly decode HTML character references in `get_attribute()`. PHP's
+ *    `html_entity_decode()` is wrong in a couple ways: it doesn't account for the
+ *    no-ambiguous-ampersand rule, and it improperly handles the way semicolons may
+ *    or may not terminate a character reference.
+ *
+ * @package WordPress
+ * @subpackage HTML-API
+ * @since 6.2.0
+ */
+
+/**
+ * Core class used to modify attributes in an HTML document for tags matching a query.
+ *
+ * ## Usage
+ *
+ * Use of this class requires three steps:
+ *
+ *  1. Create a new class instance with your input HTML document.
+ *  2. Find the tag(s) you are looking for.
+ *  3. Request changes to the attributes in those tag(s).
+ *
+ * Example:
+ *
+ *     $tags = new WP_HTML_Tag_Processor( $html );
+ *     if ( $tags->next_tag( 'option' ) ) {
+ *         $tags->set_attribute( 'selected', true );
+ *     }
+ *
+ * ### Finding tags
+ *
+ * The `next_tag()` function moves the internal cursor through
+ * your input HTML document until it finds a tag meeting any of
+ * the supplied restrictions in the optional query argument. If
+ * no argument is provided then it will find the next HTML tag,
+ * regardless of what kind it is.
+ *
+ * If you want to _find whatever the next tag is_:
+ *
+ *     $tags->next_tag();
+ *
+ * | Goal                                                      | Query                                                                           |
+ * |-----------------------------------------------------------|---------------------------------------------------------------------------------|
+ * | Find any tag.                                             | `$tags->next_tag();`                                                            |
+ * | Find next image tag.                                      | `$tags->next_tag( array( 'tag_name' => 'img' ) );`                              |
+ * | Find next image tag (without passing the array).          | `$tags->next_tag( 'img' );`                                                     |
+ * | Find next tag containing the `fullwidth` CSS class.       | `$tags->next_tag( array( 'class_name' => 'fullwidth' ) );`                      |
+ * | Find next image tag containing the `fullwidth` CSS class. | `$tags->next_tag( array( 'tag_name' => 'img', 'class_name' => 'fullwidth' ) );` |
+ *
+ * If a tag was found meeting your criteria then `next_tag()`
+ * will return `true` and you can proceed to modify it. If it
+ * returns `false`, however, it failed to find the tag and
+ * moved the cursor to the end of the file.
+ *
+ * Once the cursor reaches the end of the file the processor
+ * is done and if you want to reach an earlier tag you will
+ * need to recreate the processor and start over, as it's
+ * unable to back up or move in reverse.
+ *
+ * See the section on bookmarks for an exception to this
+ * no-backing-up rule.
+ *
+ * #### Custom queries
+ *
+ * Sometimes it's necessary to further inspect an HTML tag than
+ * the query syntax here permits. In these cases one may further
+ * inspect the search results using the read-only functions
+ * provided by the processor or external state or variables.
+ *
+ * Example:
+ *
+ *     // Paint up to the first five DIV or SPAN tags marked with the "jazzy" style.
+ *     $remaining_count = 5;
+ *     while ( $remaining_count > 0 && $tags->next_tag() ) {
+ *         if (
+ *              ( 'DIV' === $tags->get_tag() || 'SPAN' === $tags->get_tag() ) &&
+ *              'jazzy' === $tags->get_attribute( 'data-style' )
+ *         ) {
+ *             $tags->add_class( 'theme-style-everest-jazz' );
+ *             $remaining_count--;
+ *         }
+ *     }
+ *
+ * `get_attribute()` will return `null` if the attribute wasn't present
+ * on the tag when it was called. It may return `""` (the empty string)
+ * in cases where the attribute was present but its value was empty.
+ * For boolean attributes, those whose name is present but no value is
+ * given, it will return `true` (the only way to set `false` for an
+ * attribute is to remove it).
+ *
+ * ### Modifying HTML attributes for a found tag
+ *
+ * Once you've found the start of an opening tag you can modify
+ * any number of the attributes on that tag. You can set a new
+ * value for an attribute, remove the entire attribute, or do
+ * nothing and move on to the next opening tag.
+ *
+ * Example:
+ *
+ *     if ( $tags->next_tag( array( 'class' => 'wp-group-block' ) ) ) {
+ *         $tags->set_attribute( 'title', 'This groups the contained content.' );
+ *         $tags->remove_attribute( 'data-test-id' );
+ *     }
+ *
+ * If `set_attribute()` is called for an existing attribute it will
+ * overwrite the existing value. Similarly, calling `remove_attribute()`
+ * for a non-existing attribute has no effect on the document. Both
+ * of these methods are safe to call without knowing if a given attribute
+ * exists beforehand.
+ *
+ * ### Modifying CSS classes for a found tag
+ *
+ * The tag processor treats the `class` attribute as a special case.
+ * Because it's a common operation to add or remove CSS classes, this
+ * interface adds helper methods to make that easier.
+ *
+ * As with attribute values, adding or removing CSS classes is a safe
+ * operation that doesn't require checking if the attribute or class
+ * exists before making changes. If removing the only class then the
+ * entire `class` attribute will be removed.
+ *
+ * Example:
+ *
+ *     // from `<span>Yippee!</span>`
+ *     //   to `<span class="is-active">Yippee!</span>`
+ *     $tags->add_class( 'is-active' );
+ *
+ *     // from `<span class="excited">Yippee!</span>`
+ *     //   to `<span class="excited is-active">Yippee!</span>`
+ *     $tags->add_class( 'is-active' );
+ *
+ *     // from `<span class="is-active heavy-accent">Yippee!</span>`
+ *     //   to `<span class="is-active heavy-accent">Yippee!</span>`
+ *     $tags->add_class( 'is-active' );
+ *
+ *     // from `<input type="text" class="is-active rugby not-disabled" length="24">`
+ *     //   to `<input type="text" class="is-active not-disabled" length="24">
+ *     $tags->remove_class( 'rugby' );
+ *
+ *     // from `<input type="text" class="rugby" length="24">`
+ *     //   to `<input type="text" length="24">
+ *     $tags->remove_class( 'rugby' );
+ *
+ *     // from `<input type="text" length="24">`
+ *     //   to `<input type="text" length="24">
+ *     $tags->remove_class( 'rugby' );
+ *
+ * When class changes are enqueued but a direct change to `class` is made via
+ * `set_attribute` then the changes to `set_attribute` (or `remove_attribute`)
+ * will take precedence over those made through `add_class` and `remove_class`.
+ *
+ * ### Bookmarks
+ *
+ * While scanning through the input HTMl document it's possible to set
+ * a named bookmark when a particular tag is found. Later on, after
+ * continuing to scan other tags, it's possible to `seek` to one of
+ * the set bookmarks and then proceed again from that point forward.
+ *
+ * Because bookmarks create processing overhead one should avoid
+ * creating too many of them. As a rule, create only bookmarks
+ * of known string literal names; avoid creating "mark_{$index}"
+ * and so on. It's fine from a performance standpoint to create a
+ * bookmark and update it frequently, such as within a loop.
+ *
+ *     $total_todos = 0;
+ *     while ( $p->next_tag( array( 'tag_name' => 'UL', 'class_name' => 'todo' ) ) ) {
+ *         $p->set_bookmark( 'list-start' );
+ *         while ( $p->next_tag( array( 'tag_closers' => 'visit' ) ) ) {
+ *             if ( 'UL' === $p->get_tag() && $p->is_tag_closer() ) {
+ *                 $p->set_bookmark( 'list-end' );
+ *                 $p->seek( 'list-start' );
+ *                 $p->set_attribute( 'data-contained-todos', (string) $total_todos );
+ *                 $total_todos = 0;
+ *                 $p->seek( 'list-end' );
+ *                 break;
+ *             }
+ *
+ *             if ( 'LI' === $p->get_tag() && ! $p->is_tag_closer() ) {
+ *                 $total_todos++;
+ *             }
+ *         }
+ *     }
+ *
+ * ## Design and limitations
+ *
+ * The Tag Processor is designed to linearly scan HTML documents and tokenize
+ * HTML tags and their attributes. It's designed to do this as efficiently as
+ * possible without compromising parsing integrity. Therefore it will be
+ * slower than some methods of modifying HTML, such as those incorporating
+ * over-simplified PCRE patterns, but will not introduce the defects and
+ * failures that those methods bring in, which lead to broken page renders
+ * and often to security vulnerabilities. On the other hand, it will be faster
+ * than full-blown HTML parsers such as DOMDocument and use considerably
+ * less memory. It requires a negligible memory overhead, enough to consider
+ * it a zero-overhead system.
+ *
+ * The performance characteristics are maintained by avoiding tree construction
+ * and semantic cleanups which are specified in HTML5. Because of this, for
+ * example, it's not possible for the Tag Processor to associate any given
+ * opening tag with its corresponding closing tag, or to return the inner markup
+ * inside an element. Systems may be built on top of the Tag Processor to do
+ * this, but the Tag Processor is and should be constrained so it can remain an
+ * efficient, low-level, and reliable HTML scanner.
+ *
+ * The Tag Processor's design incorporates a "garbage-in-garbage-out" philosophy.
+ * HTML5 specifies that certain invalid content be transformed into different forms
+ * for display, such as removing null bytes from an input document and replacing
+ * invalid characters with the Unicode replacement character `U+FFFD` (visually "�").
+ * Where errors or transformations exist within the HTML5 specification, the Tag Processor
+ * leaves those invalid inputs untouched, passing them through to the final browser
+ * to handle. While this implies that certain operations will be non-spec-compliant,
+ * such as reading the value of an attribute with invalid content, it also preserves a
+ * simplicity and efficiency for handling those error cases.
+ *
+ * Most operations within the Tag Processor are designed to minimize the difference
+ * between an input and output document for any given change. For example, the
+ * `add_class` and `remove_class` methods preserve whitespace and the class ordering
+ * within the `class` attribute; and when encountering tags with duplicated attributes,
+ * the Tag Processor will leave those invalid duplicate attributes where they are but
+ * update the proper attribute which the browser will read for parsing its value. An
+ * exception to this rule is that all attribute updates store their values as
+ * double-quoted strings, meaning that attributes on input with single-quoted or
+ * unquoted values will appear in the output with double-quotes.
+ *
+ * @since 6.2.0
+ * @since 6.2.1 Fix: Support for various invalid comments; attribute updates are case-insensitive.
+ * @since 6.3.2 Fix: Skip HTML-like content inside rawtext elements such as STYLE.
+ */
+class Gutenberg_HTML_Tag_Processor_6_4 {
+	/**
+	 * The maximum number of bookmarks allowed to exist at
+	 * any given time.
+	 *
+	 * @since 6.2.0
+	 * @var int
+	 *
+	 * @see WP_HTML_Tag_Processor::set_bookmark()
+	 */
+	const MAX_BOOKMARKS = 10;
+
+	/**
+	 * Maximum number of times seek() can be called.
+	 * Prevents accidental infinite loops.
+	 *
+	 * @since 6.2.0
+	 * @var int
+	 *
+	 * @see WP_HTML_Tag_Processor::seek()
+	 */
+	const MAX_SEEK_OPS = 1000;
+
+	/**
+	 * The HTML document to parse.
+	 *
+	 * @since 6.2.0
+	 * @var string
+	 */
+	protected $html;
+
+	/**
+	 * The last query passed to next_tag().
+	 *
+	 * @since 6.2.0
+	 * @var array|null
+	 */
+	private $last_query;
+
+	/**
+	 * The tag name this processor currently scans for.
+	 *
+	 * @since 6.2.0
+	 * @var string|null
+	 */
+	private $sought_tag_name;
+
+	/**
+	 * The CSS class name this processor currently scans for.
+	 *
+	 * @since 6.2.0
+	 * @var string|null
+	 */
+	private $sought_class_name;
+
+	/**
+	 * The match offset this processor currently scans for.
+	 *
+	 * @since 6.2.0
+	 * @var int|null
+	 */
+	private $sought_match_offset;
+
+	/**
+	 * Whether to visit tag closers, e.g. </div>, when walking an input document.
+	 *
+	 * @since 6.2.0
+	 * @var bool
+	 */
+	private $stop_on_tag_closers;
+
+	/**
+	 * How many bytes from the original HTML document have been read and parsed.
+	 *
+	 * This value points to the latest byte offset in the input document which
+	 * has been already parsed. It is the internal cursor for the Tag Processor
+	 * and updates while scanning through the HTML tokens.
+	 *
+	 * @since 6.2.0
+	 * @var int
+	 */
+	private $bytes_already_parsed = 0;
+
+	/**
+	 * Byte offset in input document where current tag name starts.
+	 *
+	 * Example:
+	 *
+	 *     <div id="test">...
+	 *     01234
+	 *      - tag name starts at 1
+	 *
+	 * @since 6.2.0
+	 * @var int|null
+	 */
+	private $tag_name_starts_at;
+
+	/**
+	 * Byte length of current tag name.
+	 *
+	 * Example:
+	 *
+	 *     <div id="test">...
+	 *     01234
+	 *      --- tag name length is 3
+	 *
+	 * @since 6.2.0
+	 * @var int|null
+	 */
+	private $tag_name_length;
+
+	/**
+	 * Byte offset in input document where current tag token ends.
+	 *
+	 * Example:
+	 *
+	 *     <div id="test">...
+	 *     0         1   |
+	 *     01234567890123456
+	 *      --- tag name ends at 14
+	 *
+	 * @since 6.2.0
+	 * @var int|null
+	 */
+	private $tag_ends_at;
+
+	/**
+	 * Whether the current tag is an opening tag, e.g. <div>, or a closing tag, e.g. </div>.
+	 *
+	 * @var bool
+	 */
+	private $is_closing_tag;
+
+	/**
+	 * Lazily-built index of attributes found within an HTML tag, keyed by the attribute name.
+	 *
+	 * Example:
+	 *
+	 *     // Supposing the parser is working through this content
+	 *     // and stops after recognizing the `id` attribute.
+	 *     // <div id="test-4" class=outline title="data:text/plain;base64=asdk3nk1j3fo8">
+	 *     //                 ^ parsing will continue from this point.
+	 *     $this->attributes = array(
+	 *         'id' => new WP_HTML_Attribute_Match( 'id', null, 6, 17 )
+	 *     );
+	 *
+	 *     // When picking up parsing again, or when asking to find the
+	 *     // `class` attribute we will continue and add to this array.
+	 *     $this->attributes = array(
+	 *         'id'    => new WP_HTML_Attribute_Match( 'id', null, 6, 17 ),
+	 *         'class' => new WP_HTML_Attribute_Match( 'class', 'outline', 18, 32 )
+	 *     );
+	 *
+	 *     // Note that only the `class` attribute value is stored in the index.
+	 *     // That's because it is the only value used by this class at the moment.
+	 *
+	 * @since 6.2.0
+	 * @var WP_HTML_Attribute_Token[]
+	 */
+	private $attributes = array();
+
+	/**
+	 * Tracks spans of duplicate attributes on a given tag, used for removing
+	 * all copies of an attribute when calling `remove_attribute()`.
+	 *
+	 * @since 6.3.2
+	 *
+	 * @var (WP_HTML_Span[])[]|null
+	 */
+	private $duplicate_attributes = null;
+
+	/**
+	 * Which class names to add or remove from a tag.
+	 *
+	 * These are tracked separately from attribute updates because they are
+	 * semantically distinct, whereas this interface exists for the common
+	 * case of adding and removing class names while other attributes are
+	 * generally modified as with DOM `setAttribute` calls.
+	 *
+	 * When modifying an HTML document these will eventually be collapsed
+	 * into a single `set_attribute( 'class', $changes )` call.
+	 *
+	 * Example:
+	 *
+	 *     // Add the `wp-block-group` class, remove the `wp-group` class.
+	 *     $classname_updates = array(
+	 *         // Indexed by a comparable class name.
+	 *         'wp-block-group' => WP_HTML_Tag_Processor::ADD_CLASS,
+	 *         'wp-group'       => WP_HTML_Tag_Processor::REMOVE_CLASS
+	 *     );
+	 *
+	 * @since 6.2.0
+	 * @var bool[]
+	 */
+	private $classname_updates = array();
+
+	/**
+	 * Tracks a semantic location in the original HTML which
+	 * shifts with updates as they are applied to the document.
+	 *
+	 * @since 6.2.0
+	 * @var WP_HTML_Span[]
+	 */
+	protected $bookmarks = array();
+
+	const ADD_CLASS    = true;
+	const REMOVE_CLASS = false;
+	const SKIP_CLASS   = null;
+
+	/**
+	 * Lexical replacements to apply to input HTML document.
+	 *
+	 * "Lexical" in this class refers to the part of this class which
+	 * operates on pure text _as text_ and not as HTML. There's a line
+	 * between the public interface, with HTML-semantic methods like
+	 * `set_attribute` and `add_class`, and an internal state that tracks
+	 * text offsets in the input document.
+	 *
+	 * When higher-level HTML methods are called, those have to transform their
+	 * operations (such as setting an attribute's value) into text diffing
+	 * operations (such as replacing the sub-string from indices A to B with
+	 * some given new string). These text-diffing operations are the lexical
+	 * updates.
+	 *
+	 * As new higher-level methods are added they need to collapse their
+	 * operations into these lower-level lexical updates since that's the
+	 * Tag Processor's internal language of change. Any code which creates
+	 * these lexical updates must ensure that they do not cross HTML syntax
+	 * boundaries, however, so these should never be exposed outside of this
+	 * class or any classes which intentionally expand its functionality.
+	 *
+	 * These are enqueued while editing the document instead of being immediately
+	 * applied to avoid processing overhead, string allocations, and string
+	 * copies when applying many updates to a single document.
+	 *
+	 * Example:
+	 *
+	 *     // Replace an attribute stored with a new value, indices
+	 *     // sourced from the lazily-parsed HTML recognizer.
+	 *     $start = $attributes['src']->start;
+	 *     $end   = $attributes['src']->end;
+	 *     $modifications[] = new WP_HTML_Text_Replacement( $start, $end, $new_value );
+	 *
+	 *     // Correspondingly, something like this will appear in this array.
+	 *     $lexical_updates = array(
+	 *         WP_HTML_Text_Replacement( 14, 28, 'https://my-site.my-domain/wp-content/uploads/2014/08/kittens.jpg' )
+	 *     );
+	 *
+	 * @since 6.2.0
+	 * @var WP_HTML_Text_Replacement[]
+	 */
+	protected $lexical_updates = array();
+
+	/**
+	 * Tracks and limits `seek()` calls to prevent accidental infinite loops.
+	 *
+	 * @since 6.2.0
+	 * @var int
+	 *
+	 * @see WP_HTML_Tag_Processor::seek()
+	 */
+	protected $seek_count = 0;
+
+	/**
+	 * Constructor.
+	 *
+	 * @since 6.2.0
+	 *
+	 * @param string $html HTML to process.
+	 */
+	public function __construct( $html ) {
+		$this->html = $html;
+	}
+
+	/**
+	 * Finds the next tag matching the $query.
+	 *
+	 * @since 6.2.0
+	 *
+	 * @param array|string|null $query {
+	 *     Optional. Which tag name to find, having which class, etc. Default is to find any tag.
+	 *
+	 *     @type string|null $tag_name     Which tag to find, or `null` for "any tag."
+	 *     @type int|null    $match_offset Find the Nth tag matching all search criteria.
+	 *                                     1 for "first" tag, 3 for "third," etc.
+	 *                                     Defaults to first tag.
+	 *     @type string|null $class_name   Tag must contain this whole class name to match.
+	 *     @type string|null $tag_closers  "visit" or "skip": whether to stop on tag closers, e.g. </div>.
+	 * }
+	 * @return bool Whether a tag was matched.
+	 */
+	public function next_tag( $query = null ) {
+		$this->parse_query( $query );
+		$already_found = 0;
+
+		do {
+			if ( $this->bytes_already_parsed >= strlen( $this->html ) ) {
+				return false;
+			}
+
+			// Find the next tag if it exists.
+			if ( false === $this->parse_next_tag() ) {
+				$this->bytes_already_parsed = strlen( $this->html );
+
+				return false;
+			}
+
+			// Parse all of its attributes.
+			while ( $this->parse_next_attribute() ) {
+				continue;
+			}
+
+			// Ensure that the tag closes before the end of the document.
+			if ( $this->bytes_already_parsed >= strlen( $this->html ) ) {
+				return false;
+			}
+
+			$tag_ends_at = strpos( $this->html, '>', $this->bytes_already_parsed );
+			if ( false === $tag_ends_at ) {
+				return false;
+			}
+			$this->tag_ends_at          = $tag_ends_at;
+			$this->bytes_already_parsed = $tag_ends_at;
+
+			// Finally, check if the parsed tag and its attributes match the search query.
+			if ( $this->matches() ) {
+				++$already_found;
+			}
+
+			/*
+			 * For non-DATA sections which might contain text that looks like HTML tags but
+			 * isn't, scan with the appropriate alternative mode. Looking at the first letter
+			 * of the tag name as a pre-check avoids a string allocation when it's not needed.
+			 */
+			$t = $this->html[ $this->tag_name_starts_at ];
+			if (
+				! $this->is_closing_tag &&
+				(
+					'i' === $t || 'I' === $t ||
+					'n' === $t || 'N' === $t ||
+					's' === $t || 'S' === $t ||
+					't' === $t || 'T' === $t
+				) ) {
+				$tag_name = $this->get_tag();
+
+				if ( 'SCRIPT' === $tag_name && ! $this->skip_script_data() ) {
+					$this->bytes_already_parsed = strlen( $this->html );
+					return false;
+				} elseif (
+					( 'TEXTAREA' === $tag_name || 'TITLE' === $tag_name ) &&
+					! $this->skip_rcdata( $tag_name )
+				) {
+					$this->bytes_already_parsed = strlen( $this->html );
+					return false;
+				} elseif (
+					(
+						'IFRAME' === $tag_name ||
+						'NOEMBED' === $tag_name ||
+						'NOFRAMES' === $tag_name ||
+						'NOSCRIPT' === $tag_name ||
+						'STYLE' === $tag_name
+					) &&
+					! $this->skip_rawtext( $tag_name )
+				) {
+					/*
+					 * "XMP" should be here too but its rules are more complicated and require the
+					 * complexity of the HTML Processor (it needs to close out any open P element,
+					 * meaning it can't be skipped here or else the HTML Processor will lose its
+					 * place). For now, it can be ignored as it's a rare HTML tag in practice and
+					 * any normative HTML should be using PRE instead.
+					 */
+					$this->bytes_already_parsed = strlen( $this->html );
+					return false;
+				}
+			}
+		} while ( $already_found < $this->sought_match_offset );
+
+		return true;
+	}
+
+
+	/**
+	 * Sets a bookmark in the HTML document.
+	 *
+	 * Bookmarks represent specific places or tokens in the HTML
+	 * document, such as a tag opener or closer. When applying
+	 * edits to a document, such as setting an attribute, the
+	 * text offsets of that token may shift; the bookmark is
+	 * kept updated with those shifts and remains stable unless
+	 * the entire span of text in which the token sits is removed.
+	 *
+	 * Release bookmarks when they are no longer needed.
+	 *
+	 * Example:
+	 *
+	 *     <main><h2>Surprising fact you may not know!</h2></main>
+	 *           ^  ^
+	 *            \-|-- this `H2` opener bookmark tracks the token
+	 *
+	 *     <main class="clickbait"><h2>Surprising fact you may no…
+	 *                             ^  ^
+	 *                              \-|-- it shifts with edits
+	 *
+	 * Bookmarks provide the ability to seek to a previously-scanned
+	 * place in the HTML document. This avoids the need to re-scan
+	 * the entire document.
+	 *
+	 * Example:
+	 *
+	 *     <ul><li>One</li><li>Two</li><li>Three</li></ul>
+	 *                                 ^^^^
+	 *                                 want to note this last item
+	 *
+	 *     $p = new WP_HTML_Tag_Processor( $html );
+	 *     $in_list = false;
+	 *     while ( $p->next_tag( array( 'tag_closers' => $in_list ? 'visit' : 'skip' ) ) ) {
+	 *         if ( 'UL' === $p->get_tag() ) {
+	 *             if ( $p->is_tag_closer() ) {
+	 *                 $in_list = false;
+	 *                 $p->set_bookmark( 'resume' );
+	 *                 if ( $p->seek( 'last-li' ) ) {
+	 *                     $p->add_class( 'last-li' );
+	 *                 }
+	 *                 $p->seek( 'resume' );
+	 *                 $p->release_bookmark( 'last-li' );
+	 *                 $p->release_bookmark( 'resume' );
+	 *             } else {
+	 *                 $in_list = true;
+	 *             }
+	 *         }
+	 *
+	 *         if ( 'LI' === $p->get_tag() ) {
+	 *             $p->set_bookmark( 'last-li' );
+	 *         }
+	 *     }
+	 *
+	 * Bookmarks intentionally hide the internal string offsets
+	 * to which they refer. They are maintained internally as
+	 * updates are applied to the HTML document and therefore
+	 * retain their "position" - the location to which they
+	 * originally pointed. The inability to use bookmarks with
+	 * functions like `substr` is therefore intentional to guard
+	 * against accidentally breaking the HTML.
+	 *
+	 * Because bookmarks allocate memory and require processing
+	 * for every applied update, they are limited and require
+	 * a name. They should not be created with programmatically-made
+	 * names, such as "li_{$index}" with some loop. As a general
+	 * rule they should only be created with string-literal names
+	 * like "start-of-section" or "last-paragraph".
+	 *
+	 * Bookmarks are a powerful tool to enable complicated behavior.
+	 * Consider double-checking that you need this tool if you are
+	 * reaching for it, as inappropriate use could lead to broken
+	 * HTML structure or unwanted processing overhead.
+	 *
+	 * @since 6.2.0
+	 *
+	 * @param string $name Identifies this particular bookmark.
+	 * @return bool Whether the bookmark was successfully created.
+	 */
+	public function set_bookmark( $name ) {
+		if ( null === $this->tag_name_starts_at ) {
+			return false;
+		}
+
+		if ( ! array_key_exists( $name, $this->bookmarks ) && count( $this->bookmarks ) >= static::MAX_BOOKMARKS ) {
+			_doing_it_wrong(
+				__METHOD__,
+				__( 'Too many bookmarks: cannot create any more.' ),
+				'6.2.0'
+			);
+			return false;
+		}
+
+		$this->bookmarks[ $name ] = new WP_HTML_Span(
+			$this->tag_name_starts_at - ( $this->is_closing_tag ? 2 : 1 ),
+			$this->tag_ends_at
+		);
+
+		return true;
+	}
+
+
+	/**
+	 * Removes a bookmark that is no longer needed.
+	 *
+	 * Releasing a bookmark frees up the small
+	 * performance overhead it requires.
+	 *
+	 * @param string $name Name of the bookmark to remove.
+	 * @return bool Whether the bookmark already existed before removal.
+	 */
+	public function release_bookmark( $name ) {
+		if ( ! array_key_exists( $name, $this->bookmarks ) ) {
+			return false;
+		}
+
+		unset( $this->bookmarks[ $name ] );
+
+		return true;
+	}
+
+	/**
+	 * Skips contents of generic rawtext elements.
+	 *
+	 * @since 6.3.2
+	 *
+	 * @see https://html.spec.whatwg.org/#generic-raw-text-element-parsing-algorithm
+	 *
+	 * @param string $tag_name The uppercase tag name which will close the RAWTEXT region.
+	 * @return bool Whether an end to the RAWTEXT region was found before the end of the document.
+	 */
+	private function skip_rawtext( $tag_name ) {
+		/*
+		 * These two functions distinguish themselves on whether character references are
+		 * decoded, and since functionality to read the inner markup isn't supported, it's
+		 * not necessary to implement these two functions separately.
+		 */
+		return $this->skip_rcdata( $tag_name );
+	}
+
+	/**
+	 * Skips contents of RCDATA elements, namely title and textarea tags.
+	 *
+	 * @since 6.2.0
+	 *
+	 * @see https://html.spec.whatwg.org/multipage/parsing.html#rcdata-state
+	 *
+	 * @param string $tag_name The uppercase tag name which will close the RCDATA region.
+	 * @return bool Whether an end to the RCDATA region was found before the end of the document.
+	 */
+	private function skip_rcdata( $tag_name ) {
+		$html       = $this->html;
+		$doc_length = strlen( $html );
+		$tag_length = strlen( $tag_name );
+
+		$at = $this->bytes_already_parsed;
+
+		while ( false !== $at && $at < $doc_length ) {
+			$at = strpos( $this->html, '</', $at );
+
+			// If there is no possible tag closer then fail.
+			if ( false === $at || ( $at + $tag_length ) >= $doc_length ) {
+				$this->bytes_already_parsed = $doc_length;
+				return false;
+			}
+
+			$closer_potentially_starts_at = $at;
+			$at                          += 2;
+
+			/*
+			 * Find a case-insensitive match to the tag name.
+			 *
+			 * Because tag names are limited to US-ASCII there is no
+			 * need to perform any kind of Unicode normalization when
+			 * comparing; any character which could be impacted by such
+			 * normalization could not be part of a tag name.
+			 */
+			for ( $i = 0; $i < $tag_length; $i++ ) {
+				$tag_char  = $tag_name[ $i ];
+				$html_char = $html[ $at + $i ];
+
+				if ( $html_char !== $tag_char && strtoupper( $html_char ) !== $tag_char ) {
+					$at += $i;
+					continue 2;
+				}
+			}
+
+			$at                        += $tag_length;
+			$this->bytes_already_parsed = $at;
+
+			/*
+			 * Ensure that the tag name terminates to avoid matching on
+			 * substrings of a longer tag name. For example, the sequence
+			 * "</textarearug" should not match for "</textarea" even
+			 * though "textarea" is found within the text.
+			 */
+			$c = $html[ $at ];
+			if ( ' ' !== $c && "\t" !== $c && "\r" !== $c && "\n" !== $c && '/' !== $c && '>' !== $c ) {
+				continue;
+			}
+
+			while ( $this->parse_next_attribute() ) {
+				continue;
+			}
+			$at = $this->bytes_already_parsed;
+			if ( $at >= strlen( $this->html ) ) {
+				return false;
+			}
+
+			if ( '>' === $html[ $at ] || '/' === $html[ $at ] ) {
+				$this->bytes_already_parsed = $closer_potentially_starts_at;
+				return true;
+			}
+		}
+
+		return false;
+	}
+
+	/**
+	 * Skips contents of script tags.
+	 *
+	 * @since 6.2.0
+	 *
+	 * @return bool Whether the script tag was closed before the end of the document.
+	 */
+	private function skip_script_data() {
+		$state      = 'unescaped';
+		$html       = $this->html;
+		$doc_length = strlen( $html );
+		$at         = $this->bytes_already_parsed;
+
+		while ( false !== $at && $at < $doc_length ) {
+			$at += strcspn( $html, '-<', $at );
+
+			/*
+			 * For all script states a "-->"  transitions
+			 * back into the normal unescaped script mode,
+			 * even if that's the current state.
+			 */
+			if (
+				$at + 2 < $doc_length &&
+				'-' === $html[ $at ] &&
+				'-' === $html[ $at + 1 ] &&
+				'>' === $html[ $at + 2 ]
+			) {
+				$at   += 3;
+				$state = 'unescaped';
+				continue;
+			}
+
+			// Everything of interest past here starts with "<".
+			if ( $at + 1 >= $doc_length || '<' !== $html[ $at++ ] ) {
+				continue;
+			}
+
+			/*
+			 * Unlike with "-->", the "<!--" only transitions
+			 * into the escaped mode if not already there.
+			 *
+			 * Inside the escaped modes it will be ignored; and
+			 * should never break out of the double-escaped
+			 * mode and back into the escaped mode.
+			 *
+			 * While this requires a mode change, it does not
+			 * impact the parsing otherwise, so continue
+			 * parsing after updating the state.
+			 */
+			if (
+				$at + 2 < $doc_length &&
+				'!' === $html[ $at ] &&
+				'-' === $html[ $at + 1 ] &&
+				'-' === $html[ $at + 2 ]
+			) {
+				$at   += 3;
+				$state = 'unescaped' === $state ? 'escaped' : $state;
+				continue;
+			}
+
+			if ( '/' === $html[ $at ] ) {
+				$closer_potentially_starts_at = $at - 1;
+				$is_closing                   = true;
+				++$at;
+			} else {
+				$is_closing = false;
+			}
+
+			/*
+			 * At this point the only remaining state-changes occur with the
+			 * <script> and </script> tags; unless one of these appears next,
+			 * proceed scanning to the next potential token in the text.
+			 */
+			if ( ! (
+				$at + 6 < $doc_length &&
+				( 's' === $html[ $at ] || 'S' === $html[ $at ] ) &&
+				( 'c' === $html[ $at + 1 ] || 'C' === $html[ $at + 1 ] ) &&
+				( 'r' === $html[ $at + 2 ] || 'R' === $html[ $at + 2 ] ) &&
+				( 'i' === $html[ $at + 3 ] || 'I' === $html[ $at + 3 ] ) &&
+				( 'p' === $html[ $at + 4 ] || 'P' === $html[ $at + 4 ] ) &&
+				( 't' === $html[ $at + 5 ] || 'T' === $html[ $at + 5 ] )
+			) ) {
+				++$at;
+				continue;
+			}
+
+			/*
+			 * Ensure that the script tag terminates to avoid matching on
+			 * substrings of a non-match. For example, the sequence
+			 * "<script123" should not end a script region even though
+			 * "<script" is found within the text.
+			 */
+			if ( $at + 6 >= $doc_length ) {
+				continue;
+			}
+			$at += 6;
+			$c   = $html[ $at ];
+			if ( ' ' !== $c && "\t" !== $c && "\r" !== $c && "\n" !== $c && '/' !== $c && '>' !== $c ) {
+				++$at;
+				continue;
+			}
+
+			if ( 'escaped' === $state && ! $is_closing ) {
+				$state = 'double-escaped';
+				continue;
+			}
+
+			if ( 'double-escaped' === $state && $is_closing ) {
+				$state = 'escaped';
+				continue;
+			}
+
+			if ( $is_closing ) {
+				$this->bytes_already_parsed = $closer_potentially_starts_at;
+				if ( $this->bytes_already_parsed >= $doc_length ) {
+					return false;
+				}
+
+				while ( $this->parse_next_attribute() ) {
+					continue;
+				}
+
+				if ( '>' === $html[ $this->bytes_already_parsed ] ) {
+					$this->bytes_already_parsed = $closer_potentially_starts_at;
+					return true;
+				}
+			}
+
+			++$at;
+		}
+
+		return false;
+	}
+
+	/**
+	 * Parses the next tag.
+	 *
+	 * This will find and start parsing the next tag, including
+	 * the opening `<`, the potential closer `/`, and the tag
+	 * name. It does not parse the attributes or scan to the
+	 * closing `>`; these are left for other methods.
+	 *
+	 * @since 6.2.0
+	 * @since 6.2.1 Support abruptly-closed comments, invalid-tag-closer-comments, and empty elements.
+	 *
+	 * @return bool Whether a tag was found before the end of the document.
+	 */
+	private function parse_next_tag() {
+		$this->after_tag();
+
+		$html       = $this->html;
+		$doc_length = strlen( $html );
+		$at         = $this->bytes_already_parsed;
+
+		while ( false !== $at && $at < $doc_length ) {
+			$at = strpos( $html, '<', $at );
+			if ( false === $at ) {
+				return false;
+			}
+
+			if ( '/' === $this->html[ $at + 1 ] ) {
+				$this->is_closing_tag = true;
+				++$at;
+			} else {
+				$this->is_closing_tag = false;
+			}
+
+			/*
+			 * HTML tag names must start with [a-zA-Z] otherwise they are not tags.
+			 * For example, "<3" is rendered as text, not a tag opener. If at least
+			 * one letter follows the "<" then _it is_ a tag, but if the following
+			 * character is anything else it _is not a tag_.
+			 *
+			 * It's not uncommon to find non-tags starting with `<` in an HTML
+			 * document, so it's good for performance to make this pre-check before
+			 * continuing to attempt to parse a tag name.
+			 *
+			 * Reference:
+			 * * https://html.spec.whatwg.org/multipage/parsing.html#data-state
+			 * * https://html.spec.whatwg.org/multipage/parsing.html#tag-open-state
+			 */
+			$tag_name_prefix_length = strspn( $html, 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ', $at + 1 );
+			if ( $tag_name_prefix_length > 0 ) {
+				++$at;
+				$this->tag_name_length      = $tag_name_prefix_length + strcspn( $html, " \t\f\r\n/>", $at + $tag_name_prefix_length );
+				$this->tag_name_starts_at   = $at;
+				$this->bytes_already_parsed = $at + $this->tag_name_length;
+				return true;
+			}
+
+			/*
+			 * Abort if no tag is found before the end of
+			 * the document. There is nothing left to parse.
+			 */
+			if ( $at + 1 >= strlen( $html ) ) {
+				return false;
+			}
+
+			/*
+			 * <! transitions to markup declaration open state
+			 * https://html.spec.whatwg.org/multipage/parsing.html#markup-declaration-open-state
+			 */
+			if ( '!' === $html[ $at + 1 ] ) {
+				/*
+				 * <!-- transitions to a bogus comment state – skip to the nearest -->
+				 * https://html.spec.whatwg.org/multipage/parsing.html#tag-open-state
+				 */
+				if (
+					strlen( $html ) > $at + 3 &&
+					'-' === $html[ $at + 2 ] &&
+					'-' === $html[ $at + 3 ]
+				) {
+					$closer_at = $at + 4;
+					// If it's not possible to close the comment then there is nothing more to scan.
+					if ( strlen( $html ) <= $closer_at ) {
+						return false;
+					}
+
+					// Abruptly-closed empty comments are a sequence of dashes followed by `>`.
+					$span_of_dashes = strspn( $html, '-', $closer_at );
+					if ( '>' === $html[ $closer_at + $span_of_dashes ] ) {
+						$at = $closer_at + $span_of_dashes + 1;
+						continue;
+					}
+
+					/*
+					 * Comments may be closed by either a --> or an invalid --!>.
+					 * The first occurrence closes the comment.
+					 *
+					 * See https://html.spec.whatwg.org/#parse-error-incorrectly-closed-comment
+					 */
+					--$closer_at; // Pre-increment inside condition below reduces risk of accidental infinite looping.
+					while ( ++$closer_at < strlen( $html ) ) {
+						$closer_at = strpos( $html, '--', $closer_at );
+						if ( false === $closer_at ) {
+							return false;
+						}
+
+						if ( $closer_at + 2 < strlen( $html ) && '>' === $html[ $closer_at + 2 ] ) {
+							$at = $closer_at + 3;
+							continue 2;
+						}
+
+						if ( $closer_at + 3 < strlen( $html ) && '!' === $html[ $closer_at + 2 ] && '>' === $html[ $closer_at + 3 ] ) {
+							$at = $closer_at + 4;
+							continue 2;
+						}
+					}
+				}
+
+				/*
+				 * <![CDATA[ transitions to CDATA section state – skip to the nearest ]]>
+				 * The CDATA is case-sensitive.
+				 * https://html.spec.whatwg.org/multipage/parsing.html#tag-open-state
+				 */
+				if (
+					strlen( $html ) > $at + 8 &&
+					'[' === $html[ $at + 2 ] &&
+					'C' === $html[ $at + 3 ] &&
+					'D' === $html[ $at + 4 ] &&
+					'A' === $html[ $at + 5 ] &&
+					'T' === $html[ $at + 6 ] &&
+					'A' === $html[ $at + 7 ] &&
+					'[' === $html[ $at + 8 ]
+				) {
+					$closer_at = strpos( $html, ']]>', $at + 9 );
+					if ( false === $closer_at ) {
+						return false;
+					}
+
+					$at = $closer_at + 3;
+					continue;
+				}
+
+				/*
+				 * <!DOCTYPE transitions to DOCTYPE state – skip to the nearest >
+				 * These are ASCII-case-insensitive.
+				 * https://html.spec.whatwg.org/multipage/parsing.html#tag-open-state
+				 */
+				if (
+					strlen( $html ) > $at + 8 &&
+					( 'D' === $html[ $at + 2 ] || 'd' === $html[ $at + 2 ] ) &&
+					( 'O' === $html[ $at + 3 ] || 'o' === $html[ $at + 3 ] ) &&
+					( 'C' === $html[ $at + 4 ] || 'c' === $html[ $at + 4 ] ) &&
+					( 'T' === $html[ $at + 5 ] || 't' === $html[ $at + 5 ] ) &&
+					( 'Y' === $html[ $at + 6 ] || 'y' === $html[ $at + 6 ] ) &&
+					( 'P' === $html[ $at + 7 ] || 'p' === $html[ $at + 7 ] ) &&
+					( 'E' === $html[ $at + 8 ] || 'e' === $html[ $at + 8 ] )
+				) {
+					$closer_at = strpos( $html, '>', $at + 9 );
+					if ( false === $closer_at ) {
+						return false;
+					}
+
+					$at = $closer_at + 1;
+					continue;
+				}
+
+				/*
+				 * Anything else here is an incorrectly-opened comment and transitions
+				 * to the bogus comment state - skip to the nearest >.
+				 */
+				$at = strpos( $html, '>', $at + 1 );
+				continue;
+			}
+
+			/*
+			 * </> is a missing end tag name, which is ignored.
+			 *
+			 * See https://html.spec.whatwg.org/#parse-error-missing-end-tag-name
+			 */
+			if ( '>' === $html[ $at + 1 ] ) {
+				++$at;
+				continue;
+			}
+
+			/*
+			 * <? transitions to a bogus comment state – skip to the nearest >
+			 * See https://html.spec.whatwg.org/multipage/parsing.html#tag-open-state
+			 */
+			if ( '?' === $html[ $at + 1 ] ) {
+				$closer_at = strpos( $html, '>', $at + 2 );
+				if ( false === $closer_at ) {
+					return false;
+				}
+
+				$at = $closer_at + 1;
+				continue;
+			}
+
+			/*
+			 * If a non-alpha starts the tag name in a tag closer it's a comment.
+			 * Find the first `>`, which closes the comment.
+			 *
+			 * See https://html.spec.whatwg.org/#parse-error-invalid-first-character-of-tag-name
+			 */
+			if ( $this->is_closing_tag ) {
+				$closer_at = strpos( $html, '>', $at + 3 );
+				if ( false === $closer_at ) {
+					return false;
+				}
+
+				$at = $closer_at + 1;
+				continue;
+			}
+
+			++$at;
+		}
+
+		return false;
+	}
+
+	/**
+	 * Parses the next attribute.
+	 *
+	 * @since 6.2.0
+	 *
+	 * @return bool Whether an attribute was found before the end of the document.
+	 */
+	private function parse_next_attribute() {
+		// Skip whitespace and slashes.
+		$this->bytes_already_parsed += strspn( $this->html, " \t\f\r\n/", $this->bytes_already_parsed );
+		if ( $this->bytes_already_parsed >= strlen( $this->html ) ) {
+			return false;
+		}
+
+		/*
+		 * Treat the equal sign as a part of the attribute
+		 * name if it is the first encountered byte.
+		 *
+		 * @see https://html.spec.whatwg.org/multipage/parsing.html#before-attribute-name-state
+		 */
+		$name_length = '=' === $this->html[ $this->bytes_already_parsed ]
+			? 1 + strcspn( $this->html, "=/> \t\f\r\n", $this->bytes_already_parsed + 1 )
+			: strcspn( $this->html, "=/> \t\f\r\n", $this->bytes_already_parsed );
+
+		// No attribute, just tag closer.
+		if ( 0 === $name_length || $this->bytes_already_parsed + $name_length >= strlen( $this->html ) ) {
+			return false;
+		}
+
+		$attribute_start             = $this->bytes_already_parsed;
+		$attribute_name              = substr( $this->html, $attribute_start, $name_length );
+		$this->bytes_already_parsed += $name_length;
+		if ( $this->bytes_already_parsed >= strlen( $this->html ) ) {
+			return false;
+		}
+
+		$this->skip_whitespace();
+		if ( $this->bytes_already_parsed >= strlen( $this->html ) ) {
+			return false;
+		}
+
+		$has_value = '=' === $this->html[ $this->bytes_already_parsed ];
+		if ( $has_value ) {
+			++$this->bytes_already_parsed;
+			$this->skip_whitespace();
+			if ( $this->bytes_already_parsed >= strlen( $this->html ) ) {
+				return false;
+			}
+
+			switch ( $this->html[ $this->bytes_already_parsed ] ) {
+				case "'":
+				case '"':
+					$quote                      = $this->html[ $this->bytes_already_parsed ];
+					$value_start                = $this->bytes_already_parsed + 1;
+					$value_length               = strcspn( $this->html, $quote, $value_start );
+					$attribute_end              = $value_start + $value_length + 1;
+					$this->bytes_already_parsed = $attribute_end;
+					break;
+
+				default:
+					$value_start                = $this->bytes_already_parsed;
+					$value_length               = strcspn( $this->html, "> \t\f\r\n", $value_start );
+					$attribute_end              = $value_start + $value_length;
+					$this->bytes_already_parsed = $attribute_end;
+			}
+		} else {
+			$value_start   = $this->bytes_already_parsed;
+			$value_length  = 0;
+			$attribute_end = $attribute_start + $name_length;
+		}
+
+		if ( $attribute_end >= strlen( $this->html ) ) {
+			return false;
+		}
+
+		if ( $this->is_closing_tag ) {
+			return true;
+		}
+
+		/*
+		 * > There must never be two or more attributes on
+		 * > the same start tag whose names are an ASCII
+		 * > case-insensitive match for each other.
+		 *     - HTML 5 spec
+		 *
+		 * @see https://html.spec.whatwg.org/multipage/syntax.html#attributes-2:ascii-case-insensitive
+		 */
+		$comparable_name = strtolower( $attribute_name );
+
+		// If an attribute is listed many times, only use the first declaration and ignore the rest.
+		if ( ! array_key_exists( $comparable_name, $this->attributes ) ) {
+			$this->attributes[ $comparable_name ] = new WP_HTML_Attribute_Token(
+				$attribute_name,
+				$value_start,
+				$value_length,
+				$attribute_start,
+				$attribute_end,
+				! $has_value
+			);
+
+			return true;
+		}
+
+		/*
+		 * Track the duplicate attributes so if we remove it, all disappear together.
+		 *
+		 * While `$this->duplicated_attributes` could always be stored as an `array()`,
+		 * which would simplify the logic here, storing a `null` and only allocating
+		 * an array when encountering duplicates avoids needless allocations in the
+		 * normative case of parsing tags with no duplicate attributes.
+		 */
+		$duplicate_span = new WP_HTML_Span( $attribute_start, $attribute_end );
+		if ( null === $this->duplicate_attributes ) {
+			$this->duplicate_attributes = array( $comparable_name => array( $duplicate_span ) );
+		} elseif ( ! array_key_exists( $comparable_name, $this->duplicate_attributes ) ) {
+			$this->duplicate_attributes[ $comparable_name ] = array( $duplicate_span );
+		} else {
+			$this->duplicate_attributes[ $comparable_name ][] = $duplicate_span;
+		}
+
+		return true;
+	}
+
+	/**
+	 * Move the internal cursor past any immediate successive whitespace.
+	 *
+	 * @since 6.2.0
+	 */
+	private function skip_whitespace() {
+		$this->bytes_already_parsed += strspn( $this->html, " \t\f\r\n", $this->bytes_already_parsed );
+	}
+
+	/**
+	 * Applies attribute updates and cleans up once a tag is fully parsed.
+	 *
+	 * @since 6.2.0
+	 */
+	private function after_tag() {
+		$this->get_updated_html();
+		$this->tag_name_starts_at   = null;
+		$this->tag_name_length      = null;
+		$this->tag_ends_at          = null;
+		$this->is_closing_tag       = null;
+		$this->attributes           = array();
+		$this->duplicate_attributes = null;
+	}
+
+	/**
+	 * Converts class name updates into tag attributes updates
+	 * (they are accumulated in different data formats for performance).
+	 *
+	 * @since 6.2.0
+	 *
+	 * @see WP_HTML_Tag_Processor::$lexical_updates
+	 * @see WP_HTML_Tag_Processor::$classname_updates
+	 */
+	private function class_name_updates_to_attributes_updates() {
+		if ( count( $this->classname_updates ) === 0 ) {
+			return;
+		}
+
+		$existing_class = $this->get_enqueued_attribute_value( 'class' );
+		if ( null === $existing_class || true === $existing_class ) {
+			$existing_class = '';
+		}
+
+		if ( false === $existing_class && isset( $this->attributes['class'] ) ) {
+			$existing_class = substr(
+				$this->html,
+				$this->attributes['class']->value_starts_at,
+				$this->attributes['class']->value_length
+			);
+		}
+
+		if ( false === $existing_class ) {
+			$existing_class = '';
+		}
+
+		/**
+		 * Updated "class" attribute value.
+		 *
+		 * This is incrementally built while scanning through the existing class
+		 * attribute, skipping removed classes on the way, and then appending
+		 * added classes at the end. Only when finished processing will the
+		 * value contain the final new value.
+
+		 * @var string $class
+		 */
+		$class = '';
+
+		/**
+		 * Tracks the cursor position in the existing
+		 * class attribute value while parsing.
+		 *
+		 * @var int $at
+		 */
+		$at = 0;
+
+		/**
+		 * Indicates if there's any need to modify the existing class attribute.
+		 *
+		 * If a call to `add_class()` and `remove_class()` wouldn't impact
+		 * the `class` attribute value then there's no need to rebuild it.
+		 * For example, when adding a class that's already present or
+		 * removing one that isn't.
+		 *
+		 * This flag enables a performance optimization when none of the enqueued
+		 * class updates would impact the `class` attribute; namely, that the
+		 * processor can continue without modifying the input document, as if
+		 * none of the `add_class()` or `remove_class()` calls had been made.
+		 *
+		 * This flag is set upon the first change that requires a string update.
+		 *
+		 * @var bool $modified
+		 */
+		$modified = false;
+
+		// Remove unwanted classes by only copying the new ones.
+		$existing_class_length = strlen( $existing_class );
+		while ( $at < $existing_class_length ) {
+			// Skip to the first non-whitespace character.
+			$ws_at     = $at;
+			$ws_length = strspn( $existing_class, " \t\f\r\n", $ws_at );
+			$at       += $ws_length;
+
+			// Capture the class name – it's everything until the next whitespace.
+			$name_length = strcspn( $existing_class, " \t\f\r\n", $at );
+			if ( 0 === $name_length ) {
+				// If no more class names are found then that's the end.
+				break;
+			}
+
+			$name = substr( $existing_class, $at, $name_length );
+			$at  += $name_length;
+
+			// If this class is marked for removal, start processing the next one.
+			$remove_class = (
+				isset( $this->classname_updates[ $name ] ) &&
+				self::REMOVE_CLASS === $this->classname_updates[ $name ]
+			);
+
+			// If a class has already been seen then skip it; it should not be added twice.
+			if ( ! $remove_class ) {
+				$this->classname_updates[ $name ] = self::SKIP_CLASS;
+			}
+
+			if ( $remove_class ) {
+				$modified = true;
+				continue;
+			}
+
+			/*
+			 * Otherwise, append it to the new "class" attribute value.
+			 *
+			 * There are options for handling whitespace between tags.
+			 * Preserving the existing whitespace produces fewer changes
+			 * to the HTML content and should clarify the before/after
+			 * content when debugging the modified output.
+			 *
+			 * This approach contrasts normalizing the inter-class
+			 * whitespace to a single space, which might appear cleaner
+			 * in the output HTML but produce a noisier change.
+			 */
+			$class .= substr( $existing_class, $ws_at, $ws_length );
+			$class .= $name;
+		}
+
+		// Add new classes by appending those which haven't already been seen.
+		foreach ( $this->classname_updates as $name => $operation ) {
+			if ( self::ADD_CLASS === $operation ) {
+				$modified = true;
+
+				$class .= strlen( $class ) > 0 ? ' ' : '';
+				$class .= $name;
+			}
+		}
+
+		$this->classname_updates = array();
+		if ( ! $modified ) {
+			return;
+		}
+
+		if ( strlen( $class ) > 0 ) {
+			$this->set_attribute( 'class', $class );
+		} else {
+			$this->remove_attribute( 'class' );
+		}
+	}
+
+	/**
+	 * Applies attribute updates to HTML document.
+	 *
+	 * @since 6.2.0
+	 * @since 6.2.1 Accumulates shift for internal cursor and passed pointer.
+	 * @since 6.3.0 Invalidate any bookmarks whose targets are overwritten.
+	 *
+	 * @param int $shift_this_point Accumulate and return shift for this position.
+	 * @return int How many bytes the given pointer moved in response to the updates.
+	 */
+	private function apply_attributes_updates( $shift_this_point = 0 ) {
+		if ( ! count( $this->lexical_updates ) ) {
+			return 0;
+		}
+
+		$accumulated_shift_for_given_point = 0;
+
+		/*
+		 * Attribute updates can be enqueued in any order but updates
+		 * to the document must occur in lexical order; that is, each
+		 * replacement must be made before all others which follow it
+		 * at later string indices in the input document.
+		 *
+		 * Sorting avoid making out-of-order replacements which
+		 * can lead to mangled output, partially-duplicated
+		 * attributes, and overwritten attributes.
+		 */
+		usort( $this->lexical_updates, array( self::class, 'sort_start_ascending' ) );
+
+		$bytes_already_copied = 0;
+		$output_buffer        = '';
+		foreach ( $this->lexical_updates as $diff ) {
+			$shift = strlen( $diff->text ) - ( $diff->end - $diff->start );
+
+			// Adjust the cursor position by however much an update affects it.
+			if ( $diff->start <= $this->bytes_already_parsed ) {
+				$this->bytes_already_parsed += $shift;
+			}
+
+			// Accumulate shift of the given pointer within this function call.
+			if ( $diff->start <= $shift_this_point ) {
+				$accumulated_shift_for_given_point += $shift;
+			}
+
+			$output_buffer       .= substr( $this->html, $bytes_already_copied, $diff->start - $bytes_already_copied );
+			$output_buffer       .= $diff->text;
+			$bytes_already_copied = $diff->end;
+		}
+
+		$this->html = $output_buffer . substr( $this->html, $bytes_already_copied );
+
+		/*
+		 * Adjust bookmark locations to account for how the text
+		 * replacements adjust offsets in the input document.
+		 */
+		foreach ( $this->bookmarks as $bookmark_name => $bookmark ) {
+			/*
+			 * Each lexical update which appears before the bookmark's endpoints
+			 * might shift the offsets for those endpoints. Loop through each change
+			 * and accumulate the total shift for each bookmark, then apply that
+			 * shift after tallying the full delta.
+			 */
+			$head_delta = 0;
+			$tail_delta = 0;
+
+			foreach ( $this->lexical_updates as $diff ) {
+				if ( $bookmark->start < $diff->start && $bookmark->end < $diff->start ) {
+					break;
+				}
+
+				if ( $bookmark->start >= $diff->start && $bookmark->end < $diff->end ) {
+					$this->release_bookmark( $bookmark_name );
+					continue 2;
+				}
+
+				$delta = strlen( $diff->text ) - ( $diff->end - $diff->start );
+
+				if ( $bookmark->start >= $diff->start ) {
+					$head_delta += $delta;
+				}
+
+				if ( $bookmark->end >= $diff->end ) {
+					$tail_delta += $delta;
+				}
+			}
+
+			$bookmark->start += $head_delta;
+			$bookmark->end   += $tail_delta;
+		}
+
+		$this->lexical_updates = array();
+
+		return $accumulated_shift_for_given_point;
+	}
+
+	/**
+	 * Checks whether a bookmark with the given name exists.
+	 *
+	 * @since 6.3.0
+	 *
+	 * @param string $bookmark_name Name to identify a bookmark that potentially exists.
+	 * @return bool Whether that bookmark exists.
+	 */
+	public function has_bookmark( $bookmark_name ) {
+		return array_key_exists( $bookmark_name, $this->bookmarks );
+	}
+
+	/**
+	 * Move the internal cursor in the Tag Processor to a given bookmark's location.
+	 *
+	 * In order to prevent accidental infinite loops, there's a
+	 * maximum limit on the number of times seek() can be called.
+	 *
+	 * @since 6.2.0
+	 *
+	 * @param string $bookmark_name Jump to the place in the document identified by this bookmark name.
+	 * @return bool Whether the internal cursor was successfully moved to the bookmark's location.
+	 */
+	public function seek( $bookmark_name ) {
+		if ( ! array_key_exists( $bookmark_name, $this->bookmarks ) ) {
+			_doing_it_wrong(
+				__METHOD__,
+				__( 'Unknown bookmark name.' ),
+				'6.2.0'
+			);
+			return false;
+		}
+
+		if ( ++$this->seek_count > static::MAX_SEEK_OPS ) {
+			_doing_it_wrong(
+				__METHOD__,
+				__( 'Too many calls to seek() - this can lead to performance issues.' ),
+				'6.2.0'
+			);
+			return false;
+		}
+
+		// Flush out any pending updates to the document.
+		$this->get_updated_html();
+
+		// Point this tag processor before the sought tag opener and consume it.
+		$this->bytes_already_parsed = $this->bookmarks[ $bookmark_name ]->start;
+		return $this->next_tag( array( 'tag_closers' => 'visit' ) );
+	}
+
+	/**
+	 * Compare two WP_HTML_Text_Replacement objects.
+	 *
+	 * @since 6.2.0
+	 *
+	 * @param WP_HTML_Text_Replacement $a First attribute update.
+	 * @param WP_HTML_Text_Replacement $b Second attribute update.
+	 * @return int Comparison value for string order.
+	 */
+	private static function sort_start_ascending( $a, $b ) {
+		$by_start = $a->start - $b->start;
+		if ( 0 !== $by_start ) {
+			return $by_start;
+		}
+
+		$by_text = isset( $a->text, $b->text ) ? strcmp( $a->text, $b->text ) : 0;
+		if ( 0 !== $by_text ) {
+			return $by_text;
+		}
+
+		/*
+		 * This code should be unreachable, because it implies the two replacements
+		 * start at the same location and contain the same text.
+		 */
+		return $a->end - $b->end;
+	}
+
+	/**
+	 * Return the enqueued value for a given attribute, if one exists.
+	 *
+	 * Enqueued updates can take different data types:
+	 *  - If an update is enqueued and is boolean, the return will be `true`
+	 *  - If an update is otherwise enqueued, the return will be the string value of that update.
+	 *  - If an attribute is enqueued to be removed, the return will be `null` to indicate that.
+	 *  - If no updates are enqueued, the return will be `false` to differentiate from "removed."
+	 *
+	 * @since 6.2.0
+	 *
+	 * @param string $comparable_name The attribute name in its comparable form.
+	 * @return string|boolean|null Value of enqueued update if present, otherwise false.
+	 */
+	private function get_enqueued_attribute_value( $comparable_name ) {
+		if ( ! isset( $this->lexical_updates[ $comparable_name ] ) ) {
+			return false;
+		}
+
+		$enqueued_text = $this->lexical_updates[ $comparable_name ]->text;
+
+		// Removed attributes erase the entire span.
+		if ( '' === $enqueued_text ) {
+			return null;
+		}
+
+		/*
+		 * Boolean attribute updates are just the attribute name without a corresponding value.
+		 *
+		 * This value might differ from the given comparable name in that there could be leading
+		 * or trailing whitespace, and that the casing follows the name given in `set_attribute`.
+		 *
+		 * Example:
+		 *
+		 *     $p->set_attribute( 'data-TEST-id', 'update' );
+		 *     'update' === $p->get_enqueued_attribute_value( 'data-test-id' );
+		 *
+		 * Detect this difference based on the absence of the `=`, which _must_ exist in any
+		 * attribute containing a value, e.g. `<input type="text" enabled />`.
+		 *                                            ¹           ²
+		 *                                       1. Attribute with a string value.
+		 *                                       2. Boolean attribute whose value is `true`.
+		 */
+		$equals_at = strpos( $enqueued_text, '=' );
+		if ( false === $equals_at ) {
+			return true;
+		}
+
+		/*
+		 * Finally, a normal update's value will appear after the `=` and
+		 * be double-quoted, as performed incidentally by `set_attribute`.
+		 *
+		 * e.g. `type="text"`
+		 *           ¹²    ³
+		 *        1. Equals is here.
+		 *        2. Double-quoting starts one after the equals sign.
+		 *        3. Double-quoting ends at the last character in the update.
+		 */
+		$enqueued_value = substr( $enqueued_text, $equals_at + 2, -1 );
+		return html_entity_decode( $enqueued_value );
+	}
+
+	/**
+	 * Returns the value of a requested attribute from a matched tag opener if that attribute exists.
+	 *
+	 * Example:
+	 *
+	 *     $p = new WP_HTML_Tag_Processor( '<div enabled class="test" data-test-id="14">Test</div>' );
+	 *     $p->next_tag( array( 'class_name' => 'test' ) ) === true;
+	 *     $p->get_attribute( 'data-test-id' ) === '14';
+	 *     $p->get_attribute( 'enabled' ) === true;
+	 *     $p->get_attribute( 'aria-label' ) === null;
+	 *
+	 *     $p->next_tag() === false;
+	 *     $p->get_attribute( 'class' ) === null;
+	 *
+	 * @since 6.2.0
+	 *
+	 * @param string $name Name of attribute whose value is requested.
+	 * @return string|true|null Value of attribute or `null` if not available. Boolean attributes return `true`.
+	 */
+	public function get_attribute( $name ) {
+		if ( null === $this->tag_name_starts_at ) {
+			return null;
+		}
+
+		$comparable = strtolower( $name );
+
+		/*
+		 * For every attribute other than `class` it's possible to perform a quick check if
+		 * there's an enqueued lexical update whose value takes priority over what's found in
+		 * the input document.
+		 *
+		 * The `class` attribute is special though because of the exposed helpers `add_class`
+		 * and `remove_class`. These form a builder for the `class` attribute, so an additional
+		 * check for enqueued class changes is required in addition to the check for any enqueued
+		 * attribute values. If any exist, those enqueued class changes must first be flushed out
+		 * into an attribute value update.
+		 */
+		if ( 'class' === $name ) {
+			$this->class_name_updates_to_attributes_updates();
+		}
+
+		// Return any enqueued attribute value updates if they exist.
+		$enqueued_value = $this->get_enqueued_attribute_value( $comparable );
+		if ( false !== $enqueued_value ) {
+			return $enqueued_value;
+		}
+
+		if ( ! isset( $this->attributes[ $comparable ] ) ) {
+			return null;
+		}
+
+		$attribute = $this->attributes[ $comparable ];
+
+		/*
+		 * This flag distinguishes an attribute with no value
+		 * from an attribute with an empty string value. For
+		 * unquoted attributes this could look very similar.
+		 * It refers to whether an `=` follows the name.
+		 *
+		 * e.g. <div boolean-attribute empty-attribute=></div>
+		 *           ¹                 ²
+		 *        1. Attribute `boolean-attribute` is `true`.
+		 *        2. Attribute `empty-attribute` is `""`.
+		 */
+		if ( true === $attribute->is_true ) {
+			return true;
+		}
+
+		$raw_value = substr( $this->html, $attribute->value_starts_at, $attribute->value_length );
+
+		return html_entity_decode( $raw_value );
+	}
+
+	/**
+	 * Gets lowercase names of all attributes matching a given prefix in the current tag.
+	 *
+	 * Note that matching is case-insensitive. This is in accordance with the spec:
+	 *
+	 * > There must never be two or more attributes on
+	 * > the same start tag whose names are an ASCII
+	 * > case-insensitive match for each other.
+	 *     - HTML 5 spec
+	 *
+	 * Example:
+	 *
+	 *     $p = new WP_HTML_Tag_Processor( '<div data-ENABLED class="test" DATA-test-id="14">Test</div>' );
+	 *     $p->next_tag( array( 'class_name' => 'test' ) ) === true;
+	 *     $p->get_attribute_names_with_prefix( 'data-' ) === array( 'data-enabled', 'data-test-id' );
+	 *
+	 *     $p->next_tag() === false;
+	 *     $p->get_attribute_names_with_prefix( 'data-' ) === null;
+	 *
+	 * @since 6.2.0
+	 *
+	 * @see https://html.spec.whatwg.org/multipage/syntax.html#attributes-2:ascii-case-insensitive
+	 *
+	 * @param string $prefix Prefix of requested attribute names.
+	 * @return array|null List of attribute names, or `null` when no tag opener is matched.
+	 */
+	public function get_attribute_names_with_prefix( $prefix ) {
+		if ( $this->is_closing_tag || null === $this->tag_name_starts_at ) {
+			return null;
+		}
+
+		$comparable = strtolower( $prefix );
+
+		$matches = array();
+		foreach ( array_keys( $this->attributes ) as $attr_name ) {
+			if ( str_starts_with( $attr_name, $comparable ) ) {
+				$matches[] = $attr_name;
+			}
+		}
+		return $matches;
+	}
+
+	/**
+	 * Returns the uppercase name of the matched tag.
+	 *
+	 * Example:
+	 *
+	 *     $p = new WP_HTML_Tag_Processor( '<div class="test">Test</div>' );
+	 *     $p->next_tag() === true;
+	 *     $p->get_tag() === 'DIV';
+	 *
+	 *     $p->next_tag() === false;
+	 *     $p->get_tag() === null;
+	 *
+	 * @since 6.2.0
+	 *
+	 * @return string|null Name of currently matched tag in input HTML, or `null` if none found.
+	 */
+	public function get_tag() {
+		if ( null === $this->tag_name_starts_at ) {
+			return null;
+		}
+
+		$tag_name = substr( $this->html, $this->tag_name_starts_at, $this->tag_name_length );
+
+		return strtoupper( $tag_name );
+	}
+
+	/**
+	 * Indicates if the currently matched tag contains the self-closing flag.
+	 *
+	 * No HTML elements ought to have the self-closing flag and for those, the self-closing
+	 * flag will be ignored. For void elements this is benign because they "self close"
+	 * automatically. For non-void HTML elements though problems will appear if someone
+	 * intends to use a self-closing element in place of that element with an empty body.
+	 * For HTML foreign elements and custom elements the self-closing flag determines if
+	 * they self-close or not.
+	 *
+	 * This function does not determine if a tag is self-closing,
+	 * but only if the self-closing flag is present in the syntax.
+	 *
+	 * @since 6.3.0
+	 *
+	 * @return bool Whether the currently matched tag contains the self-closing flag.
+	 */
+	public function has_self_closing_flag() {
+		if ( ! $this->tag_name_starts_at ) {
+			return false;
+		}
+
+		return '/' === $this->html[ $this->tag_ends_at - 1 ];
+	}
+
+	/**
+	 * Indicates if the current tag token is a tag closer.
+	 *
+	 * Example:
+	 *
+	 *     $p = new WP_HTML_Tag_Processor( '<div></div>' );
+	 *     $p->next_tag( array( 'tag_name' => 'div', 'tag_closers' => 'visit' ) );
+	 *     $p->is_tag_closer() === false;
+	 *
+	 *     $p->next_tag( array( 'tag_name' => 'div', 'tag_closers' => 'visit' ) );
+	 *     $p->is_tag_closer() === true;
+	 *
+	 * @since 6.2.0
+	 *
+	 * @return bool Whether the current tag is a tag closer.
+	 */
+	public function is_tag_closer() {
+		return $this->is_closing_tag;
+	}
+
+	/**
+	 * Updates or creates a new attribute on the currently matched tag with the passed value.
+	 *
+	 * For boolean attributes special handling is provided:
+	 *  - When `true` is passed as the value, then only the attribute name is added to the tag.
+	 *  - When `false` is passed, the attribute gets removed if it existed before.
+	 *
+	 * For string attributes, the value is escaped using the `esc_attr` function.
+	 *
+	 * @since 6.2.0
+	 * @since 6.2.1 Fix: Only create a single update for multiple calls with case-variant attribute names.
+	 *
+	 * @param string      $name  The attribute name to target.
+	 * @param string|bool $value The new attribute value.
+	 * @return bool Whether an attribute value was set.
+	 */
+	public function set_attribute( $name, $value ) {
+		if ( $this->is_closing_tag || null === $this->tag_name_starts_at ) {
+			return false;
+		}
+
+		/*
+		 * WordPress rejects more characters than are strictly forbidden
+		 * in HTML5. This is to prevent additional security risks deeper
+		 * in the WordPress and plugin stack. Specifically the
+		 * less-than (<) greater-than (>) and ampersand (&) aren't allowed.
+		 *
+		 * The use of a PCRE match enables looking for specific Unicode
+		 * code points without writing a UTF-8 decoder. Whereas scanning
+		 * for one-byte characters is trivial (with `strcspn`), scanning
+		 * for the longer byte sequences would be more complicated. Given
+		 * that this shouldn't be in the hot path for execution, it's a
+		 * reasonable compromise in efficiency without introducing a
+		 * noticeable impact on the overall system.
+		 *
+		 * @see https://html.spec.whatwg.org/#attributes-2
+		 *
+		 * @TODO as the only regex pattern maybe we should take it out? are
+		 *       Unicode patterns available broadly in Core?
+		 */
+		if ( preg_match(
+			'~[' .
+				// Syntax-like characters.
+				'"\'>&</ =' .
+				// Control characters.
+				'\x{00}-\x{1F}' .
+				// HTML noncharacters.
+				'\x{FDD0}-\x{FDEF}' .
+				'\x{FFFE}\x{FFFF}\x{1FFFE}\x{1FFFF}\x{2FFFE}\x{2FFFF}\x{3FFFE}\x{3FFFF}' .
+				'\x{4FFFE}\x{4FFFF}\x{5FFFE}\x{5FFFF}\x{6FFFE}\x{6FFFF}\x{7FFFE}\x{7FFFF}' .
+				'\x{8FFFE}\x{8FFFF}\x{9FFFE}\x{9FFFF}\x{AFFFE}\x{AFFFF}\x{BFFFE}\x{BFFFF}' .
+				'\x{CFFFE}\x{CFFFF}\x{DFFFE}\x{DFFFF}\x{EFFFE}\x{EFFFF}\x{FFFFE}\x{FFFFF}' .
+				'\x{10FFFE}\x{10FFFF}' .
+			']~Ssu',
+			$name
+		) ) {
+			_doing_it_wrong(
+				__METHOD__,
+				__( 'Invalid attribute name.' ),
+				'6.2.0'
+			);
+
+			return false;
+		}
+
+		/*
+		 * > The values "true" and "false" are not allowed on boolean attributes.
+		 * > To represent a false value, the attribute has to be omitted altogether.
+		 *     - HTML5 spec, https://html.spec.whatwg.org/#boolean-attributes
+		 */
+		if ( false === $value ) {
+			return $this->remove_attribute( $name );
+		}
+
+		if ( true === $value ) {
+			$updated_attribute = $name;
+		} else {
+			$escaped_new_value = esc_attr( $value );
+			$updated_attribute = "{$name}=\"{$escaped_new_value}\"";
+		}
+
+		/*
+		 * > There must never be two or more attributes on
+		 * > the same start tag whose names are an ASCII
+		 * > case-insensitive match for each other.
+		 *     - HTML 5 spec
+		 *
+		 * @see https://html.spec.whatwg.org/multipage/syntax.html#attributes-2:ascii-case-insensitive
+		 */
+		$comparable_name = strtolower( $name );
+
+		if ( isset( $this->attributes[ $comparable_name ] ) ) {
+			/*
+			 * Update an existing attribute.
+			 *
+			 * Example – set attribute id to "new" in <div id="initial_id" />:
+			 *
+			 *     <div id="initial_id"/>
+			 *          ^-------------^
+			 *          start         end
+			 *     replacement: `id="new"`
+			 *
+			 *     Result: <div id="new"/>
+			 */
+			$existing_attribute                        = $this->attributes[ $comparable_name ];
+			$this->lexical_updates[ $comparable_name ] = new WP_HTML_Text_Replacement(
+				$existing_attribute->start,
+				$existing_attribute->end,
+				$updated_attribute
+			);
+		} else {
+			/*
+			 * Create a new attribute at the tag's name end.
+			 *
+			 * Example – add attribute id="new" to <div />:
+			 *
+			 *     <div/>
+			 *         ^
+			 *         start and end
+			 *     replacement: ` id="new"`
+			 *
+			 *     Result: <div id="new"/>
+			 */
+			$this->lexical_updates[ $comparable_name ] = new WP_HTML_Text_Replacement(
+				$this->tag_name_starts_at + $this->tag_name_length,
+				$this->tag_name_starts_at + $this->tag_name_length,
+				' ' . $updated_attribute
+			);
+		}
+
+		/*
+		 * Any calls to update the `class` attribute directly should wipe out any
+		 * enqueued class changes from `add_class` and `remove_class`.
+		 */
+		if ( 'class' === $comparable_name && ! empty( $this->classname_updates ) ) {
+			$this->classname_updates = array();
+		}
+
+		return true;
+	}
+
+	/**
+	 * Remove an attribute from the currently-matched tag.
+	 *
+	 * @since 6.2.0
+	 *
+	 * @param string $name The attribute name to remove.
+	 * @return bool Whether an attribute was removed.
+	 */
+	public function remove_attribute( $name ) {
+		if ( $this->is_closing_tag ) {
+			return false;
+		}
+
+		/*
+		 * > There must never be two or more attributes on
+		 * > the same start tag whose names are an ASCII
+		 * > case-insensitive match for each other.
+		 *     - HTML 5 spec
+		 *
+		 * @see https://html.spec.whatwg.org/multipage/syntax.html#attributes-2:ascii-case-insensitive
+		 */
+		$name = strtolower( $name );
+
+		/*
+		 * Any calls to update the `class` attribute directly should wipe out any
+		 * enqueued class changes from `add_class` and `remove_class`.
+		 */
+		if ( 'class' === $name && count( $this->classname_updates ) !== 0 ) {
+			$this->classname_updates = array();
+		}
+
+		/*
+		 * If updating an attribute that didn't exist in the input
+		 * document, then remove the enqueued update and move on.
+		 *
+		 * For example, this might occur when calling `remove_attribute()`
+		 * after calling `set_attribute()` for the same attribute
+		 * and when that attribute wasn't originally present.
+		 */
+		if ( ! isset( $this->attributes[ $name ] ) ) {
+			if ( isset( $this->lexical_updates[ $name ] ) ) {
+				unset( $this->lexical_updates[ $name ] );
+			}
+			return false;
+		}
+
+		/*
+		 * Removes an existing tag attribute.
+		 *
+		 * Example – remove the attribute id from <div id="main"/>:
+		 *    <div id="initial_id"/>
+		 *         ^-------------^
+		 *         start         end
+		 *    replacement: ``
+		 *
+		 *    Result: <div />
+		 */
+		$this->lexical_updates[ $name ] = new WP_HTML_Text_Replacement(
+			$this->attributes[ $name ]->start,
+			$this->attributes[ $name ]->end,
+			''
+		);
+
+		// Removes any duplicated attributes if they were also present.
+		if ( null !== $this->duplicate_attributes && array_key_exists( $name, $this->duplicate_attributes ) ) {
+			foreach ( $this->duplicate_attributes[ $name ] as $attribute_token ) {
+				$this->lexical_updates[] = new WP_HTML_Text_Replacement(
+					$attribute_token->start,
+					$attribute_token->end,
+					''
+				);
+			}
+		}
+
+		return true;
+	}
+
+	/**
+	 * Adds a new class name to the currently matched tag.
+	 *
+	 * @since 6.2.0
+	 *
+	 * @param string $class_name The class name to add.
+	 * @return bool Whether the class was set to be added.
+	 */
+	public function add_class( $class_name ) {
+		if ( $this->is_closing_tag ) {
+			return false;
+		}
+
+		if ( null !== $this->tag_name_starts_at ) {
+			$this->classname_updates[ $class_name ] = self::ADD_CLASS;
+		}
+
+		return true;
+	}
+
+	/**
+	 * Removes a class name from the currently matched tag.
+	 *
+	 * @since 6.2.0
+	 *
+	 * @param string $class_name The class name to remove.
+	 * @return bool Whether the class was set to be removed.
+	 */
+	public function remove_class( $class_name ) {
+		if ( $this->is_closing_tag ) {
+			return false;
+		}
+
+		if ( null !== $this->tag_name_starts_at ) {
+			$this->classname_updates[ $class_name ] = self::REMOVE_CLASS;
+		}
+
+		return true;
+	}
+
+	/**
+	 * Returns the string representation of the HTML Tag Processor.
+	 *
+	 * @since 6.2.0
+	 *
+	 * @see WP_HTML_Tag_Processor::get_updated_html()
+	 *
+	 * @return string The processed HTML.
+	 */
+	public function __toString() {
+		return $this->get_updated_html();
+	}
+
+	/**
+	 * Returns the string representation of the HTML Tag Processor.
+	 *
+	 * @since 6.2.0
+	 * @since 6.2.1 Shifts the internal cursor corresponding to the applied updates.
+	 *
+	 * @return string The processed HTML.
+	 */
+	public function get_updated_html() {
+		$requires_no_updating = 0 === count( $this->classname_updates ) && 0 === count( $this->lexical_updates );
+
+		/*
+		 * When there is nothing more to update and nothing has already been
+		 * updated, return the original document and avoid a string copy.
+		 */
+		if ( $requires_no_updating ) {
+			return $this->html;
+		}
+
+		/*
+		 * Keep track of the position right before the current tag. This will
+		 * be necessary for reparsing the current tag after updating the HTML.
+		 */
+		$before_current_tag = $this->tag_name_starts_at - 1;
+
+		/*
+		 * 1. Apply the enqueued edits and update all the pointers to reflect those changes.
+		 */
+		$this->class_name_updates_to_attributes_updates();
+		$before_current_tag += $this->apply_attributes_updates( $before_current_tag );
+
+		/*
+		 * 2. Rewind to before the current tag and reparse to get updated attributes.
+		 *
+		 * At this point the internal cursor points to the end of the tag name.
+		 * Rewind before the tag name starts so that it's as if the cursor didn't
+		 * move; a call to `next_tag()` will reparse the recently-updated attributes
+		 * and additional calls to modify the attributes will apply at this same
+		 * location.
+		 *
+		 * <p>Previous HTML<em>More HTML</em></p>
+		 *                 ^  | back up by the length of the tag name plus the opening <
+		 *                 \<-/ back up by strlen("em") + 1 ==> 3
+		 */
+
+		// Store existing state so it can be restored after reparsing.
+		$previous_parsed_byte_count = $this->bytes_already_parsed;
+		$previous_query             = $this->last_query;
+
+		// Reparse attributes.
+		$this->bytes_already_parsed = $before_current_tag;
+		$this->next_tag();
+
+		// Restore previous state.
+		$this->bytes_already_parsed = $previous_parsed_byte_count;
+		$this->parse_query( $previous_query );
+
+		return $this->html;
+	}
+
+	/**
+	 * Parses tag query input into internal search criteria.
+	 *
+	 * @since 6.2.0
+	 *
+	 * @param array|string|null $query {
+	 *     Optional. Which tag name to find, having which class, etc. Default is to find any tag.
+	 *
+	 *     @type string|null $tag_name     Which tag to find, or `null` for "any tag."
+	 *     @type int|null    $match_offset Find the Nth tag matching all search criteria.
+	 *                                     1 for "first" tag, 3 for "third," etc.
+	 *                                     Defaults to first tag.
+	 *     @type string|null $class_name   Tag must contain this class name to match.
+	 *     @type string      $tag_closers  "visit" or "skip": whether to stop on tag closers, e.g. </div>.
+	 * }
+	 */
+	private function parse_query( $query ) {
+		if ( null !== $query && $query === $this->last_query ) {
+			return;
+		}
+
+		$this->last_query          = $query;
+		$this->sought_tag_name     = null;
+		$this->sought_class_name   = null;
+		$this->sought_match_offset = 1;
+		$this->stop_on_tag_closers = false;
+
+		// A single string value means "find the tag of this name".
+		if ( is_string( $query ) ) {
+			$this->sought_tag_name = $query;
+			return;
+		}
+
+		// An empty query parameter applies no restrictions on the search.
+		if ( null === $query ) {
+			return;
+		}
+
+		// If not using the string interface, an associative array is required.
+		if ( ! is_array( $query ) ) {
+			_doing_it_wrong(
+				__METHOD__,
+				__( 'The query argument must be an array or a tag name.' ),
+				'6.2.0'
+			);
+			return;
+		}
+
+		if ( isset( $query['tag_name'] ) && is_string( $query['tag_name'] ) ) {
+			$this->sought_tag_name = $query['tag_name'];
+		}
+
+		if ( isset( $query['class_name'] ) && is_string( $query['class_name'] ) ) {
+			$this->sought_class_name = $query['class_name'];
+		}
+
+		if ( isset( $query['match_offset'] ) && is_int( $query['match_offset'] ) && 0 < $query['match_offset'] ) {
+			$this->sought_match_offset = $query['match_offset'];
+		}
+
+		if ( isset( $query['tag_closers'] ) ) {
+			$this->stop_on_tag_closers = 'visit' === $query['tag_closers'];
+		}
+	}
+
+
+	/**
+	 * Checks whether a given tag and its attributes match the search criteria.
+	 *
+	 * @since 6.2.0
+	 *
+	 * @return bool Whether the given tag and its attribute match the search criteria.
+	 */
+	private function matches() {
+		if ( $this->is_closing_tag && ! $this->stop_on_tag_closers ) {
+			return false;
+		}
+
+		// Does the tag name match the requested tag name in a case-insensitive manner?
+		if ( null !== $this->sought_tag_name ) {
+			/*
+			 * String (byte) length lookup is fast. If they aren't the
+			 * same length then they can't be the same string values.
+			 */
+			if ( strlen( $this->sought_tag_name ) !== $this->tag_name_length ) {
+				return false;
+			}
+
+			/*
+			 * Check each character to determine if they are the same.
+			 * Defer calls to `strtoupper()` to avoid them when possible.
+			 * Calling `strcasecmp()` here tested slowed than comparing each
+			 * character, so unless benchmarks show otherwise, it should
+			 * not be used.
+			 *
+			 * It's expected that most of the time that this runs, a
+			 * lower-case tag name will be supplied and the input will
+			 * contain lower-case tag names, thus normally bypassing
+			 * the case comparison code.
+			 */
+			for ( $i = 0; $i < $this->tag_name_length; $i++ ) {
+				$html_char = $this->html[ $this->tag_name_starts_at + $i ];
+				$tag_char  = $this->sought_tag_name[ $i ];
+
+				if ( $html_char !== $tag_char && strtoupper( $html_char ) !== $tag_char ) {
+					return false;
+				}
+			}
+		}
+
+		$needs_class_name = null !== $this->sought_class_name;
+
+		if ( $needs_class_name && ! isset( $this->attributes['class'] ) ) {
+			return false;
+		}
+
+		/*
+		 * Match byte-for-byte (case-sensitive and encoding-form-sensitive) on the class name.
+		 *
+		 * This will overlook certain classes that exist in other lexical variations
+		 * than was supplied to the search query, but requires more complicated searching.
+		 */
+		if ( $needs_class_name ) {
+			$class_start = $this->attributes['class']->value_starts_at;
+			$class_end   = $class_start + $this->attributes['class']->value_length;
+			$class_at    = $class_start;
+
+			/*
+			 * Ensure that boundaries surround the class name to avoid matching on
+			 * substrings of a longer name. For example, the sequence "not-odd"
+			 * should not match for the class "odd" even though "odd" is found
+			 * within the class attribute text.
+			 *
+			 * See https://html.spec.whatwg.org/#attributes-3
+			 * See https://html.spec.whatwg.org/#space-separated-tokens
+			 */
+			while (
+				// phpcs:ignore WordPress.CodeAnalysis.AssignmentInCondition.FoundInWhileCondition
+				false !== ( $class_at = strpos( $this->html, $this->sought_class_name, $class_at ) ) &&
+				$class_at < $class_end
+			) {
+				/*
+				 * Verify this class starts at a boundary.
+				 */
+				if ( $class_at > $class_start ) {
+					$character = $this->html[ $class_at - 1 ];
+
+					if ( ' ' !== $character && "\t" !== $character && "\f" !== $character && "\r" !== $character && "\n" !== $character ) {
+						$class_at += strlen( $this->sought_class_name );
+						continue;
+					}
+				}
+
+				/*
+				 * Verify this class ends at a boundary as well.
+				 */
+				if ( $class_at + strlen( $this->sought_class_name ) < $class_end ) {
+					$character = $this->html[ $class_at + strlen( $this->sought_class_name ) ];
+
+					if ( ' ' !== $character && "\t" !== $character && "\f" !== $character && "\r" !== $character && "\n" !== $character ) {
+						$class_at += strlen( $this->sought_class_name );
+						continue;
+					}
+				}
+
+				return true;
+			}
+
+			return false;
+		}
+
+		return true;
+	}
+}
diff --git a/lib/compat/wordpress-6.4/html-api/class-wp-html-processor.php b/lib/compat/wordpress-6.4/html-api/class-wp-html-processor.php
index b348a982a4686..2e4b5a47589e8 100644
--- a/lib/compat/wordpress-6.4/html-api/class-wp-html-processor.php
+++ b/lib/compat/wordpress-6.4/html-api/class-wp-html-processor.php
@@ -31,6 +31,7 @@
  *  - Unwrapping a tag by removing its parent.
  *  - Inserting and removing nodes.
  *  - Reading and changing inner content.
+ *  - Navigating up or around HTML structure.
  *
  * ## Usage
  *
@@ -70,7 +71,7 @@
  * `array( 'IMG' )` matches all IMG elements and `array( 'P', 'IMG' )`
  * matches all IMG elements directly inside a P element. To ensure that no
  * partial matches erroneously match it's possible to specify in a query
- * the full breadcrumb match.
+ * the full breadcrumb match all the way down from the root HTML element.
  *
  * Example:
  *
@@ -80,7 +81,7 @@
  *
  *     $html = '<figure><img><figcaption>A <em>lovely</em> day outside</figcaption></figure>';
  *     //                                  ---- Matches here.
- *     $processor->next_tag( array( 'breadcrumbs' => array( 'FIGURE', 'IMG', 'FIGCAPTION', 'EM' ) ) );
+ *     $processor->next_tag( array( 'breadcrumbs' => array( 'FIGURE', 'FIGCAPTION', 'EM' ) ) );
  *
  *     $html = '<div><img></div><img>';
  *     //                       ----- Matches here, because IMG must be a direct child of the implicit BODY.
@@ -104,7 +105,8 @@
  *
  *  - Links: A.
  *  - The formatting elements: B, BIG, CODE, EM, FONT, I, SMALL, STRIKE, STRONG, TT, U.
- *  - Containers: DIV, FIGCAPTION, FIGURE.
+ *  - Containers: DIV, FIGCAPTION, FIGURE, SPAN.
+ *  - Form elements: BUTTON.
  *  - Paragraph: P.
  *  - Void elements: IMG.
  *
@@ -120,7 +122,9 @@
  *  - Markup involving only those tags listed above.
  *  - Fully-balanced and non-overlapping tags.
  *  - HTML with unexpected tag closers.
+ *  - Some unbalanced or overlapping tags.
  *  - P tags after unclosed P tags.
+ *  - BUTTON tags after unclosed BUTTON tags.
  *  - A tags after unclosed A tags that don't involve any active formatting elements.
  *
  * @since 6.4.0
@@ -128,9 +132,12 @@
  * @see WP_HTML_Tag_Processor
  * @see https://html.spec.whatwg.org/
  */
-class WP_HTML_Processor extends WP_HTML_Tag_Processor {
+class WP_HTML_Processor extends Gutenberg_HTML_Tag_Processor_6_4 {
 	/**
-	 * HTML processing requires more bookmarks than basic tag processing.
+	 * The maximum number of bookmarks allowed to exist at any given time.
+	 *
+	 * HTML processing requires more bookmarks than basic tag processing,
+	 * so this class constant from the Tag Processor is overwritten.
 	 *
 	 * @since 6.4.0
 	 *
@@ -141,6 +148,8 @@ class WP_HTML_Processor extends WP_HTML_Tag_Processor {
 	/**
 	 * Static query for instructing the Tag Processor to visit every token.
 	 *
+	 * @access private
+	 *
 	 * @since 6.4.0
 	 *
 	 * @var array
@@ -162,21 +171,19 @@ class WP_HTML_Processor extends WP_HTML_Tag_Processor {
 	/**
 	 * Used to create unique bookmark names.
 	 *
+	 * This class sets a bookmark for every tag in the HTML document that it encounters.
+	 * The bookmark name is auto-generated and increments, starting with `1`. These are
+	 * internal bookmarks and are automatically released when the referring WP_HTML_Token
+	 * goes out of scope and is garbage-collected.
+	 *
 	 * @since 6.4.0
 	 *
+	 * @see WP_HTML_Processor::$release_internal_bookmark_on_destruct
+	 *
 	 * @var int
 	 */
 	private $bookmark_counter = 0;
 
-	/**
-	 * Refers to the currently-matched tag, if any.
-	 *
-	 * @since 6.4.0
-	 *
-	 * @var WP_HTML_Token|null
-	 */
-	private $current_token = null;
-
 	/**
 	 * Stores an explanation for why something failed, if it did.
 	 *
@@ -199,7 +206,7 @@ class WP_HTML_Processor extends WP_HTML_Tag_Processor {
 	 *
 	 * @var closure
 	 */
-	private $release_internal_bookmark = null;
+	private $release_internal_bookmark_on_destruct = null;
 
 	/*
 	 * Public Interface Functions
@@ -271,10 +278,14 @@ public static function createFragment( $html, $context = '<body>', $encoding = '
 	/**
 	 * Constructor.
 	 *
+	 * Do not use this method. Use the static creator methods instead.
+	 *
 	 * @access private
 	 *
 	 * @since 6.4.0
 	 *
+	 * @see WP_HTML_Processor::createFragment()
+	 *
 	 * @param string      $html                                  HTML to process.
 	 * @param string|null $use_the_static_create_methods_instead This constructor should not be called manually.
 	 */
@@ -300,7 +311,7 @@ public function __construct( $html, $use_the_static_create_methods_instead = nul
 		 * a private method into WP_HTML_Token classes without
 		 * exposing it to any public API.
 		 */
-		$this->release_internal_bookmark = function ( $name ) {
+		$this->release_internal_bookmark_on_destruct = function ( $name ) {
 			parent::release_bookmark( $name );
 		};
 	}
@@ -311,13 +322,15 @@ public function __construct( $html, $use_the_static_create_methods_instead = nul
 	 * Various situations lead to parsing failure but this class will
 	 * return `false` in all those cases. To determine why something
 	 * failed it's possible to request the last error. This can be
-	 * helpful to know if it's possible to fix something or to give up.
+	 * helpful to know to distinguish whether a given tag couldn't
+	 * be found or if content in the document caused the processor
+	 * to give up and abort processing.
 	 *
 	 * Example
 	 *
-	 *     $p = WP_HTML_Processor::createFragment( '<template><strong><button><em><p><em>' );
-	 *     false === $p->next_tag();
-	 *     WP_HTML_Processor::ERROR_UNSUPPORTED === $p->get_last_error();
+	 *     $processor = WP_HTML_Processor::createFragment( '<template><strong><button><em><p><em>' );
+	 *     false === $processor->next_tag();
+	 *     WP_HTML_Processor::ERROR_UNSUPPORTED === $processor->get_last_error();
 	 *
 	 * @since 6.4.0
 	 *
@@ -436,7 +449,26 @@ public function next_tag( $query = null ) {
 	 * @return bool Whether a tag was matched.
 	 */
 	public function step( $node_to_process = self::PROCESS_NEXT_NODE ) {
+		// Refuse to proceed if there was a previous error.
+		if ( null !== $this->last_error ) {
+			return false;
+		}
+
 		if ( self::PROCESS_NEXT_NODE === $node_to_process ) {
+			/*
+			 * Void elements still hop onto the stack of open elements even though
+			 * there's no corresponding closing tag. This is important for managing
+			 * stack-based operations such as "navigate to parent node" or checking
+			 * on an element's breadcrumbs.
+			 *
+			 * When moving on to the next node, therefore, if the bottom-most element
+			 * on the stack is a void element, it must be closed.
+			 *
+			 * @TODO: Once self-closing foreign elements and BGSOUND are supported,
+			 *        they must also be implicitly closed here too. BGSOUND is
+			 *        special since it's only self-closing if the self-closing flag
+			 *        is provided in the opening tag, otherwise it expects a tag closer.
+			 */
 			$top_node = $this->state->stack_of_open_elements->current_node();
 			if ( $top_node && self::is_void( $top_node->node_name ) ) {
 				$this->state->stack_of_open_elements->pop();
@@ -450,11 +482,11 @@ public function step( $node_to_process = self::PROCESS_NEXT_NODE ) {
 			return false;
 		}
 
-		$this->current_token = new WP_HTML_Token(
+		$this->state->current_token = new WP_HTML_Token(
 			$this->bookmark_tag(),
 			$this->get_tag(),
 			$this->is_tag_closer(),
-			$this->release_internal_bookmark
+			$this->release_internal_bookmark_on_destruct
 		);
 
 		try {
@@ -464,7 +496,7 @@ public function step( $node_to_process = self::PROCESS_NEXT_NODE ) {
 
 				default:
 					$this->last_error = self::ERROR_UNSUPPORTED;
-					throw new WP_HTML_Unsupported_Exception( 'Cannot parse outside of the IN BODY insertion mode.' );
+					throw new WP_HTML_Unsupported_Exception( "No support for parsing in the '{$this->state->insertion_mode}' state." );
 			}
 		} catch ( WP_HTML_Unsupported_Exception $e ) {
 			/*
@@ -478,17 +510,22 @@ public function step( $node_to_process = self::PROCESS_NEXT_NODE ) {
 	/**
 	 * Computes the HTML breadcrumbs for the currently-matched node, if matched.
 	 *
-	 * Breadcrumbs start at the outer-most parent and descend toward the matched element.
+	 * Breadcrumbs start at the outermost parent and descend toward the matched element.
+	 * They always include the entire path from the root HTML node to the matched element.
+	 *
+	 * @TODO: It could be more efficient to expose a generator-based version of this function
+	 *        to avoid creating the array copy on tag iteration. If this is done, it would likely
+	 *        be more useful to walk up the stack when yielding instead of starting at the top.
 	 *
 	 * Example
 	 *
-	 *     $p = WP_HTML_Processor::createFragment( '<p><strong><em><img></em></strong></p>' );
-	 *     $p->next_tag( 'IMG' );
-	 *     $p->get_breadcrumbs() === array( 'HTML', 'BODY', 'P', 'STRONG', 'EM', 'IMG' );
+	 *     $processor = WP_HTML_Processor::createFragment( '<p><strong><em><img></em></strong></p>' );
+	 *     $processor->next_tag( 'IMG' );
+	 *     $processor->get_breadcrumbs() === array( 'HTML', 'BODY', 'P', 'STRONG', 'EM', 'IMG' );
 	 *
 	 * @since 6.4.0
 	 *
-	 * @return string[]|null Array of tag-names representing path to matched node, if matched, otherwise null.
+	 * @return string[]|null Array of tag names representing path to matched node, if matched, otherwise NULL.
 	 */
 	public function get_breadcrumbs() {
 		if ( ! $this->get_tag() ) {
@@ -507,16 +544,14 @@ public function get_breadcrumbs() {
 	 * Parses next element in the 'in body' insertion mode.
 	 *
 	 * This internal function performs the 'in body' insertion mode
-	 * logic for the generalized `self::step()` function.
-	 *
-	 * @access private
+	 * logic for the generalized WP_HTML_Processor::step() function.
 	 *
 	 * @since 6.4.0
 	 *
 	 * @throws WP_HTML_Unsupported_Exception When encountering unsupported HTML input.
 	 *
 	 * @see https://html.spec.whatwg.org/#parsing-main-inbody
-	 * @see self::step
+	 * @see WP_HTML_Processor::step
 	 *
 	 * @return bool Whether an element was found.
 	 */
@@ -537,7 +572,7 @@ private function step_in_body() {
 				}
 
 				$this->reconstruct_active_formatting_elements();
-				$this->insert_html_element( $this->current_token );
+				$this->insert_html_element( $this->state->current_token );
 				$this->state->frameset_ok = false;
 
 				return true;
@@ -557,7 +592,7 @@ private function step_in_body() {
 					$this->close_a_p_element();
 				}
 
-				$this->insert_html_element( $this->current_token );
+				$this->insert_html_element( $this->state->current_token );
 				return true;
 
 			/*
@@ -589,7 +624,7 @@ private function step_in_body() {
 			 */
 			case '-P':
 				if ( ! $this->state->stack_of_open_elements->has_p_in_button_scope() ) {
-					$this->insert_html_element( $this->current_token );
+					$this->insert_html_element( $this->state->current_token );
 				}
 
 				$this->close_a_p_element();
@@ -611,8 +646,8 @@ private function step_in_body() {
 				}
 
 				$this->reconstruct_active_formatting_elements();
-				$this->insert_html_element( $this->current_token );
-				$this->state->active_formatting_elements->push( $this->current_token );
+				$this->insert_html_element( $this->state->current_token );
+				$this->state->active_formatting_elements->push( $this->state->current_token );
 				return true;
 
 			/*
@@ -632,8 +667,8 @@ private function step_in_body() {
 			case '+TT':
 			case '+U':
 				$this->reconstruct_active_formatting_elements();
-				$this->insert_html_element( $this->current_token );
-				$this->state->active_formatting_elements->push( $this->current_token );
+				$this->insert_html_element( $this->state->current_token );
+				$this->state->active_formatting_elements->push( $this->state->current_token );
 				return true;
 
 			/*
@@ -661,7 +696,7 @@ private function step_in_body() {
 			 */
 			case '+IMG':
 				$this->reconstruct_active_formatting_elements();
-				$this->insert_html_element( $this->current_token );
+				$this->insert_html_element( $this->state->current_token );
 				return true;
 
 			/*
@@ -669,7 +704,7 @@ private function step_in_body() {
 			 */
 			case '+SPAN':
 				$this->reconstruct_active_formatting_elements();
-				$this->insert_html_element( $this->current_token );
+				$this->insert_html_element( $this->state->current_token );
 				return true;
 
 			/*
@@ -706,7 +741,7 @@ private function step_in_body() {
 	 */
 
 	/**
-	 * Creates a new bookmark for the currently-matched tag and returns generated name.
+	 * Creates a new bookmark for the currently-matched tag and returns the generated name.
 	 *
 	 * @since 6.4.0
 	 *
@@ -734,20 +769,29 @@ private function bookmark_tag() {
 	/**
 	 * Returns the uppercase name of the matched tag.
 	 *
+	 * The semantic rules for HTML specify that certain tags be reprocessed
+	 * with a different tag name. Because of this, the tag name presented
+	 * by the HTML Processor may differ from the one reported by the HTML
+	 * Tag Processor, which doesn't apply these semantic rules.
+	 *
 	 * Example:
 	 *
-	 *     $p = new WP_HTML_Tag_Processor( '<div class="test">Test</div>' );
-	 *     $p->next_tag() === true;
-	 *     $p->get_tag() === 'DIV';
+	 *     $processor = new WP_HTML_Tag_Processor( '<div class="test">Test</div>' );
+	 *     $processor->next_tag() === true;
+	 *     $processor->get_tag() === 'DIV';
 	 *
-	 *     $p->next_tag() === false;
-	 *     $p->get_tag() === null;
+	 *     $processor->next_tag() === false;
+	 *     $processor->get_tag() === null;
 	 *
 	 * @since 6.4.0
 	 *
 	 * @return string|null Name of currently matched tag in input HTML, or `null` if none found.
 	 */
 	public function get_tag() {
+		if ( null !== $this->last_error ) {
+			return null;
+		}
+
 		$tag_name = parent::get_tag();
 
 		switch ( $tag_name ) {
@@ -779,11 +823,13 @@ public function release_bookmark( $bookmark_name ) {
 	}
 
 	/**
-	 * Moves the internal cursor in the Tag Processor to a given bookmark's location.
+	 * Moves the internal cursor in the HTML Processor to a given bookmark's location.
 	 *
 	 * In order to prevent accidental infinite loops, there's a
 	 * maximum limit on the number of times seek() can be called.
 	 *
+	 * @throws Exception When unable to allocate a bookmark for the next token in the input HTML document.
+	 *
 	 * @since 6.4.0
 	 *
 	 * @param string $bookmark_name Jump to the place in the document identified by this bookmark name.
@@ -791,7 +837,9 @@ public function release_bookmark( $bookmark_name ) {
 	 */
 	public function seek( $bookmark_name ) {
 		$actual_bookmark_name = "_{$bookmark_name}";
-		$processor_started_at = $this->current_token ? $this->bookmarks[ $this->current_token->bookmark_name ]->start : 0;
+		$processor_started_at = $this->state->current_token
+			? $this->bookmarks[ $this->state->current_token->bookmark_name ]->start
+			: 0;
 		$bookmark_starts_at   = $this->bookmarks[ $actual_bookmark_name ]->start;
 		$direction            = $bookmark_starts_at > $processor_started_at ? 'forward' : 'backward';
 
@@ -799,7 +847,7 @@ public function seek( $bookmark_name ) {
 			case 'forward':
 				// When moving forwards, re-parse the document until reaching the same location as the original bookmark.
 				while ( $this->step() ) {
-					if ( $bookmark_starts_at === $this->bookmarks[ $this->current_token->bookmark_name ]->start ) {
+					if ( $bookmark_starts_at === $this->bookmarks[ $this->state->current_token->bookmark_name ]->start ) {
 						return true;
 					}
 				}
@@ -1350,6 +1398,8 @@ public static function is_void( $tag_name ) {
 	 *
 	 * This unlock code is used to ensure that anyone calling the constructor is
 	 * doing so with a full understanding that it's intended to be a private API.
+	 *
+	 * @access private
 	 */
 	const CONSTRUCTOR_UNLOCK_CODE = 'Use WP_HTML_Processor::createFragment instead of calling the class constructor directly.';
 }
diff --git a/lib/load.php b/lib/load.php
index 0d442302450ea..0da7be481fefa 100644
--- a/lib/load.php
+++ b/lib/load.php
@@ -74,6 +74,7 @@ function gutenberg_is_experiment_enabled( $name ) {
 require __DIR__ . '/compat/plugin/edit-site-routes-backwards-compat.php';
 
 if ( ! class_exists( 'WP_HTML_Processor' ) ) {
+	require __DIR__ . '/compat/wordpress-6.4/html-api/class-gutenberg-html-tag-processor-6-4.php';
 	require __DIR__ . '/compat/wordpress-6.4/html-api/class-wp-html-active-formatting-elements.php';
 	require __DIR__ . '/compat/wordpress-6.4/html-api/class-wp-html-open-elements.php';
 	require __DIR__ . '/compat/wordpress-6.4/html-api/class-wp-html-processor-state.php';
diff --git a/phpcs.xml.dist b/phpcs.xml.dist
index d383de10726d2..56cd6734e4f3e 100644
--- a/phpcs.xml.dist
+++ b/phpcs.xml.dist
@@ -59,6 +59,9 @@
 	<exclude-pattern>./vendor/*</exclude-pattern>
 	<exclude-pattern>./test/php/gutenberg-coding-standards/*</exclude-pattern>
 
+	<!-- Exclude files maintained in WordPress Core and backported to Gutenberg -->
+	<exclude-pattern>./lib/compat/wordpress-*/html-api/*.php</exclude-pattern>
+
 	<!-- These special comments are markers for the build process -->
 	<rule ref="Squiz.Commenting.InlineComment.WrongStyle">
 		<exclude-pattern>gutenberg.php</exclude-pattern>
@@ -92,8 +95,6 @@
 		<exclude-pattern>phpunit/*</exclude-pattern>
 	</rule>
 	<rule ref="Squiz.Commenting.FunctionCommentThrowTag.Missing">
-		<!-- Ignore until squizlabs/PHP_CodeSniffer#3685 is fixed: it thinks that a caught exception escapes the function. -->
-		<exclude-pattern>lib/compat/wordpress-6.4/html-api/class-wp-html-processor.php</exclude-pattern>
 		<exclude-pattern>phpunit/*</exclude-pattern>
 	</rule>
 

From 937d51e7721b891ff86581242e36311f2286e062 Mon Sep 17 00:00:00 2001
From: George Mamadashvili <georgemamadashvili@gmail.com>
Date: Wed, 27 Sep 2023 18:06:20 +0400
Subject: [PATCH 8/8] E2E Tests: Revert temporary fixes (#54865)

---
 packages/e2e-tests/specs/editor/various/datepicker.test.js | 4 +---
 packages/e2e-tests/specs/editor/various/scheduling.test.js | 4 +---
 2 files changed, 2 insertions(+), 6 deletions(-)

diff --git a/packages/e2e-tests/specs/editor/various/datepicker.test.js b/packages/e2e-tests/specs/editor/various/datepicker.test.js
index 057418d3eacc3..b0fc3bf898d4a 100644
--- a/packages/e2e-tests/specs/editor/various/datepicker.test.js
+++ b/packages/e2e-tests/specs/editor/various/datepicker.test.js
@@ -61,9 +61,7 @@ async function getPublishingDate() {
 	);
 }
 
-// @todo: Change `UTC+1` back to `UTC` once the core regressions is resolved.
-// See: https://github.com/WordPress/gutenberg/pull/54806#issuecomment-1734840171.
-describe.each( [ [ 'UTC-10' ], [ 'UTC+1' ], [ 'UTC+10' ] ] )(
+describe.each( [ [ 'UTC-10' ], [ 'UTC' ], [ 'UTC+10' ] ] )(
 	`Datepicker %s`,
 	( timezone ) => {
 		let oldTimezone;
diff --git a/packages/e2e-tests/specs/editor/various/scheduling.test.js b/packages/e2e-tests/specs/editor/various/scheduling.test.js
index 87cc6e52a048c..61c3541c1f47e 100644
--- a/packages/e2e-tests/specs/editor/various/scheduling.test.js
+++ b/packages/e2e-tests/specs/editor/various/scheduling.test.js
@@ -23,9 +23,7 @@ describe( 'Scheduling', () => {
 		} );
 	};
 
-	// @todo: Change `UTC+1` back to `UTC` once the core regressions is resolved.
-	// See: https://github.com/WordPress/gutenberg/pull/54806#issuecomment-1734840171.
-	describe.each( [ [ 'UTC-10' ], [ 'UTC+1' ], [ 'UTC+10' ] ] )(
+	describe.each( [ [ 'UTC-10' ], [ 'UTC' ], [ 'UTC+10' ] ] )(
 		`Timezone %s`,
 		( timezone ) => {
 			let oldTimezone;