Mostly, guidelines talk about Grice’s maxims, or speak in generalities. Greg Bennett says to fit the closing to the context, fitting the style of your bot. Google doesn’t address closings specifically. A contact center blog says not to leave the conversation before the user; 1) if wrapping up, say thank you and goodbye; 2) if transferring, notify the user; 3) if chat is left open (or a long delay?), ask if the user needs more assistance. Another live chat blog emphasizes the importance of the pre-closing (without using that term), including a last topic check, gratitude, and future contact orientation. One blog post encourages including an exit button, recognizing a user’s “exit” intent, and a task completion closing flow.