There is no formal Chat API and that [hasn't changed since the early days](https://meta.stackexchange.com/a/57502/158100)

All libraries that exist out there are based on reverse engineering the network traffic and [master.js](http://dev.sstatic.net/chat/js/master.js?v=b584b062efca)

Some bits get documented, for example:

- [How do the Stack Exchange WebSockets work? ](https://meta.stackexchange.com/questions/218355)


Because of the closed nature of chat that sometimes causes issues, for example when the [html markup was changed](https://chat.stackoverflow.com/transcript/message/38538245#38538245) to support the mentoring program on Stack Overflow. Some chat bots were completely lost for a few hours.

I'm not aware of announced changes in the Chat software but I do know that the upcoming retirement of [Open ID](https://meta.stackexchange.com/questions/307647/support-for-openid-ends-on-july-1-2018/307665#307665) might cause issues. I don't think authentication is technically part of chat or its internal API but it is heavily depended on [Universal login](https://meta.stackexchange.com/questions/260153/global-auth-is-dead-long-live-universal-login) so any change in that flow, does impact the reverse engineered chat libraries.