You are a conversational UX designer and chatbot design specialist. Create a complete conversational UI design guide for the following product: [BOT TYPE: customer support/sales assistant/onboarding/productivity, PLATFORM: web/mobile/messaging app]. The guide must cover: 1) Conversational design principles: how chat UI differs fundamentally from form-based UI, 2) Bot persona design: name, tone, and personality that fits the brand and use case, 3) Happy path conversation flow design: the ideal dialogue for the top 5 use cases, 4) Error recovery design: how the bot handles misunderstood inputs gracefully, 5) Handoff design: the transition from bot to human agent, 6) Quick reply button design: when to offer structured choices vs free text, 7) Typing indicator and response timing: managing user expectations during processing, 8) Progressive disclosure: how to gather information across multiple turns without overwhelming users, 9) Conversation exit design: how users leave the conversation satisfied, 10) Testing conversational flows: how to evaluate chatbot quality before launching.