Today at //Build we at Microsoft announced that the long awaited support for Collaborative apps in Teams Personal Tabs and Messaging Extensions now is available for usage in Office.com, Outlook and Outlook on the web. This update to Teams apps is based on the new Promise based Teams JS SDK version 2.0 and the just published Teams Manifest 1.13.
Announcing Yo Teams version 4 Through the Microsoft 365 Platform Community (PnP) we have also released a brand new (preview) version of yo teams that supports both this new Teams JS SDK as well as the updated schema.
