building dexi, an assistant that lives in imessage, no app, the whole surface is a text thread. one prompt-design problem from it is worth sharing because it's non-obvious when your only surface is messages, you can't show a spinner or stream tokens. there's silence, then a reply. anything over ~10 seconds reads as being ignored and the user starts typing again, which forks the conversation. so you have to acknowledge fast. the trap: a generic "working on it!" reads as a bot instantl...