diff --git a/package-lock.json b/package-lock.json
index f031cdaf0..8032aea98 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -56,9 +56,9 @@
 				"@wordpress/server-side-render": "^6.14.0",
 				"@wordpress/shortcode": "^4.38.0",
 				"@wordpress/style-engine": "^2.43.0",
-				"@wordpress/sync": "^2.0.0",
 				"@wordpress/theme": "^2.1.0",
 				"@wordpress/token-list": "^3.38.0",
+				"@wordpress/undo-manager": "^1.57.0",
 				"@wordpress/upload-media": "^0.42.0",
 				"@wordpress/url": "^4.42.0",
 				"@wordpress/viewport": "^6.57.0",
diff --git a/package.json b/package.json
index 7b96d9579..094a967a6 100644
--- a/package.json
+++ b/package.json
@@ -90,9 +90,9 @@
 		"@wordpress/server-side-render": "^6.14.0",
 		"@wordpress/shortcode": "^4.38.0",
 		"@wordpress/style-engine": "^2.43.0",
-		"@wordpress/sync": "^2.0.0",
 		"@wordpress/theme": "^2.1.0",
 		"@wordpress/token-list": "^3.38.0",
+		"@wordpress/undo-manager": "^1.57.0",
 		"@wordpress/upload-media": "^0.42.0",
 		"@wordpress/url": "^4.42.0",
 		"@wordpress/viewport": "^6.57.0",
diff --git a/src/utils/wordpress-globals.js b/src/utils/wordpress-globals.js
index dfe575f73..d87c16c38 100644
--- a/src/utils/wordpress-globals.js
+++ b/src/utils/wordpress-globals.js
@@ -47,9 +47,9 @@ import * as router from '@wordpress/router';
 import * as serverSideRender from '@wordpress/server-side-render';
 import * as shortcode from '@wordpress/shortcode';
 import * as styleEngine from '@wordpress/style-engine';
-import * as sync from '@wordpress/sync';
 import * as theme from '@wordpress/theme';
 import * as tokenList from '@wordpress/token-list';
+import * as undoManager from '@wordpress/undo-manager';
 import * as uploadMedia from '@wordpress/upload-media';
 import * as url from '@wordpress/url';
 import * as viewport from '@wordpress/viewport';
@@ -124,9 +124,9 @@ export async function initializeWordPressGlobals() {
 	window.wp.serverSideRender = serverSideRender.default || serverSideRender;
 	window.wp.shortcode = shortcode.default || shortcode;
 	window.wp.styleEngine = toCommonJS( styleEngine );
-	window.wp.sync = toCommonJS( sync );
 	window.wp.theme = toCommonJS( theme );
 	window.wp.tokenList = tokenList.default || tokenList;
+	window.wp.undoManager = toCommonJS( undoManager );
 	window.wp.uploadMedia = toCommonJS( uploadMedia );
 	window.wp.url = toCommonJS( url );
 	window.wp.viewport = toCommonJS( viewport );
diff --git a/src/utils/wordpress-globals.test.js b/src/utils/wordpress-globals.test.js
new file mode 100644
index 000000000..7a9c85112
--- /dev/null
+++ b/src/utils/wordpress-globals.test.js
@@ -0,0 +1,114 @@
+import { existsSync, readdirSync, readFileSync } from 'node:fs';
+import { join } from 'node:path';
+import { describe, expect, it } from 'vitest';
+import { camelCaseDash } from '@wordpress/dependency-extraction-webpack-plugin/lib/util';
+
+// Packages flagged `wpScript` that WP Admin's post editor doesn't expose,
+// keyed to the reason.
+const EXCLUDED_PACKAGES = {
+	'@wordpress/base-styles':
+		'Flagged only to build its stylesheet; the editor never loads its empty script.',
+};
+
+// Modules that assign `window.wp` globals. Importing them would load every
+// `@wordpress` package, which Node can't evaluate, so read their source.
+const GLOBALS_MODULES = [ './wordpress-globals.js', './wordpress-i18n.js' ];
+
+const SCRIPT_PACKAGES = getInstalledScriptPackages();
+
+describe( 'WordPress globals', () => {
+	const assignments = getAssignments();
+	const scriptNames = SCRIPT_PACKAGES.map( ( { name } ) => name );
+	const scriptGlobals = SCRIPT_PACKAGES.map( ( { global } ) => global );
+
+	// WordPress builds a `window.wp` global for each package flagged `wpScript`,
+	// so the flag approximates the globals plugins expect. A missing global
+	// breaks every plugin script that reads it. Core exposes the default export
+	// of packages flagged `wpScriptDefaultExport`, and the namespace of the rest.
+	it.each(
+		SCRIPT_PACKAGES.filter( ( { name } ) => ! EXCLUDED_PACKAGES[ name ] )
+	)(
+		'exposes $name in the shape core does',
+		( { global, defaultExport } ) => {
+			expect( assignments ).toHaveProperty( global );
+			expect( assignments[ global ] ).toMatch(
+				defaultExport
+					? /^(\w+)\.default \|\| \1$/
+					: /^toCommonJS\( \w+ \)$|^undefined$/
+			);
+		}
+	);
+
+	// A global without a flagged package is one core no longer exposes, like
+	// `wp.sync` after WordPress/gutenberg#81999.
+	it.each( Object.keys( assignments ) )(
+		'exposes window.wp.%s only while a package is flagged `wpScript`',
+		( global ) => {
+			expect( scriptGlobals ).toContain( global );
+		}
+	);
+
+	it.each( Object.keys( EXCLUDED_PACKAGES ) )(
+		'excludes %s only while it is flagged `wpScript`',
+		( name ) => {
+			expect( scriptNames ).toContain( name );
+		}
+	);
+} );
+
+/**
+ * List the installed `@wordpress` packages that WordPress builds as scripts.
+ *
+ * @return {Array<{name: string, global: string, defaultExport: boolean}>}
+ *         Packages, with the `window.wp` member core assigns each.
+ */
+function getInstalledScriptPackages() {
+	const root = join( import.meta.dirname, '../../node_modules/@wordpress' );
+
+	return readdirSync( root ).flatMap( ( directory ) => {
+		const path = join( root, directory, 'package.json' );
+
+		// Skip entries that aren't packages, e.g. `.DS_Store` or npm's
+		// temporary directories from an interrupted install.
+		if ( ! existsSync( path ) ) {
+			return [];
+		}
+
+		const { name, wpScript, wpScriptDefaultExport } = JSON.parse(
+			readFileSync( path )
+		);
+
+		return wpScript
+			? [
+					{
+						name,
+						global: camelCaseDash( directory ),
+						defaultExport: !! wpScriptDefaultExport,
+					},
+			  ]
+			: [];
+	} );
+}
+
+/**
+ * Map each `window.wp` member the globals modules assign to its value's source.
+ *
+ * @return {Object<string, string>} Source keyed by global, e.g.
+ *                                  `{ blockEditor: 'toCommonJS( blockEditor )' }`.
+ */
+function getAssignments() {
+	return Object.fromEntries(
+		GLOBALS_MODULES.flatMap( ( path ) => {
+			const source = readFileSync(
+				join( import.meta.dirname, path ),
+				'utf8'
+			);
+			return [
+				...source.matchAll( /window\.wp\.(\w+)\s*=\s*([^;]+);/g ),
+			].map( ( [ , global, value ] ) => [
+				global,
+				value.replace( /\s+/g, ' ' ).trim(),
+			] );
+		} )
+	);
+}