tabGroups API release note

files/en-us/mozilla/firefox/releases/139/index.md

@@ -63,6 +63,7 @@ This article provides information about the changes in Firefox 139 that affect d
 
 - Localized extensions now cascade through locale subtags to find translations before reverting to the extension's default language. Previously, the extension used the extension default if a translation couldn't be found for a language with subtags. See [Localized string selection](/en-US/docs/Mozilla/Add-ons/WebExtensions/Internationalization#localized_string_selection) in the Internationalization article for more details of the new behavior. ([Firefox bug 1381580](https://bugzil.la/1381580))
 - Content scripts and styles are now guaranteed to execute in the order of registration (i.e., their order in the [`content_scripts` manifest key array](/en-US/docs/Mozilla/Add-ons/WebExtensions/manifest.json/content_scripts)). Previously, the order was only guaranteed for scripts within the same `js` array. ([Firefox bug 1792685](https://bugzil.la/1792685))
+- The {{WebExtAPIRef("tabGroups")}} API is now available. This API enables extensions to modify and rearrange tab groups. The [tab groups](https://support.mozilla.org/en-US/kb/tab-groups) feature was made available to users in Firefox 137. For more information, see [WebExtensions Support for Tab Groups](https://blog.mozilla.org/addons/2025/04/30/webextensions-support-for-tab-groups/). ([Firefox bug 1940631](https://bugzil.la/1940631))
 
 ### Removals