Hey, add-on devs 
We recently shared a blog post about WebExtensions support for the recently announced Tab Groups feature in Firefox. In short, initial support for this new capability landed in 138 and we expect to expand that support by introducing the Tab Groups API in 139. You can find more details in the full blog post.
Happy coding!
Hi! For the tabGroups.update() mentioned in the blog post (which is said to be in Firefox 139) – is there already a documentation for it somewhere? Trying my hand at these tab groups API to learn these days, and I suppose those are also accessible when testing in Firefox Nightly, right?
We’re are working on adding Tab Groups API docs to the WebExtensions section of MDN (39370).
In the mean time, you can consult Chrome’s Tab Groups API documentation for general information and the tab groups API schema definition in Firefox source for Firefox-specific details.
Super helpful links, especially the last one!! Thank you Simeon!