I'm developing mud client and I've noticed that CDLib sometimes doesn't send GO AHEAD telnet character after prompt. I think it happens when it already has some more info to send to client, am I correct? Or maybe I'm missing something, and I have an error in my code.
You'd need to first check the mudlib to make sure it doesn't do any secondary caching of output. It's not uncommon for text muds to only emit "full" lines of text, since clients were usually operated in line mode. I know in some cases, the prompt was treated in a special fashion to ensure it got send immediately, in which case you'd need to have to TELNET GO AHEAD sequence be part of the prompt itself.
I'm pretty sure the driver won't do anything odd, as it almost certainly just flushes all available output data on each pass through the loop.