I'd agree with that except the part about mentioning Slack compatibility. I wouldn't mention Slack at all without their permission. Since the OP says that this

I'd agree with that except the part about mentioning Slack compatibility. I wouldn't mention Slack at all without their permission. Since the OP says that this is for another project, they might get not only a C&D for the chat code, but the original project might be infringing as well. Even if it's not actually infringing, it might result in some legal fees.