When submitting a message:
response "[phpBB Debug] PHP Warning: in file [ROOT]/ext/spaceace/ajaxchat/controller/chat.php on line 606: file_get_contents(./ext/spaceace/ajaxchat/styles/latte/template/chat_body.html): failed to open stream: No such file or directory
Had to dig through the AJAX response to figure this one out since the response was being discarded (maybe you should write it to the console?). You should probably deal with that a little better and fall back to whatever you have in the "all" or "prosilver" directory if you really need to do this plus having every single style included with your extension is probably not something you'll want to do as there are many that will work just fine with prosilver. Not really sure why this would come up since the chat loads up with prosilver as the default style. Even stranger is that it would work fine if you change to popup mode.
I've worked around the error by just copying the prosilver folder and renaming it to latte.
P.S. I've changed your code for another client quite a bit to accommodate their needs. While doing that I noticed there's quite a lot of code duplication between the three controllers. Might be a good idea to consolidate some of that.
Also, as part of changing your code for that client, I added notifications of entry/exit into the chat room. Any chance you have the appropriate sounds for those actions? Seems a little weird that it's playing the "messaging" sound instead of the "door open/close" sounds (based on your use of old AIM sounds).