No longer map zh_TW language to zh language code in dev translations.

.changelog/20260721132553_ck_10480.md

@@ -0,0 +1,14 @@
+---
+type: Major breaking change
+scope:
+  - ckeditor5-dev-translations
+see:
+  - https://github.com/ckeditor/ckeditor5-commercial/issues/10480
+---
+
+The `languageCode` returned for the `zh_CN` and `zh_TW` locales is no longer the ambiguous `zh` for both. It is now `zh-Hans` for `zh_CN` (Simplified Chinese) and `zh-Hant` for `zh_TW` (Traditional Chinese).
+
+As a result:
+
+* The `zh_TW` language code is no longer mapped to the `zh.po` file. It now emits `zh-hant.po` instead.
+* The `zh_CN` language code now emits `zh-hans.po` instead of `zh-cn.po`.

packages/ckeditor5-dev-translations/lib/utils/getlanguages.js

@@ -78,12 +78,12 @@ const SUPPORTED_LOCALES = [
 	'uz', // Uzbek
 	'vi' // Vietnamese
 ];
-
 const LOCALES_FILENAME_MAP = {
 	'ne_NP': 'ne',
 	'si_LK': 'si',
 	'sr@latin': 'sr-latn',
-	'zh_TW': 'zh'
+	'zh_CN': 'zh-hans',
+	'zh_TW': 'zh-hant'
 };
 
 /**

packages/ckeditor5-dev-translations/tests/utils/getlanguages.js

@@ -55,14 +55,25 @@ describe( 'getLanguages()', () => {
 		} );
 	} );
 
-	it( 'should use predefined filename if defined', () => {
+	it( 'should return Chinese (Simplified) language', () => {
 		const languages = getLanguages();
-		const languageChineseTaiwan = languages.find( l => l.localeCode === 'zh_TW' );
+		const languageChineseSimplified = languages.find( l => l.localeCode === 'zh_CN' );
 
-		expect( languageChineseTaiwan ).toEqual( {
+		expect( languageChineseSimplified ).toEqual( {
+			localeCode: 'zh_CN',
+			languageCode: 'zh',
+			languageFileName: 'zh-hans'
+		} );
+	} );
+
+	it( 'should return Chinese (Traditional) language', () => {
+		const languages = getLanguages();
+		const languageChineseTraditional = languages.find( l => l.localeCode === 'zh_TW' );
+
+		expect( languageChineseTraditional ).toEqual( {
 			localeCode: 'zh_TW',
 			languageCode: 'zh',
-			languageFileName: 'zh'
+			languageFileName: 'zh-hant'
 		} );
 	} );
 } );