Addressing the situation politely is essential to maintain a respectful environment. Here's a polite way to address someone who is smoking in your house as a guest:
"Thank you for understanding, but I have a no-smoking policy in my house. I would really appreciate it if you could refrain from smoking indoors. If you need to smoke, there is an area outside where you can do so comfortably. I hope this won't cause any inconvenience, and thank you for your cooperation."
This response sets a clear boundary without being confrontational. It shows appreciation for their understanding and offers an alternative solution, such as an outdoor smoking area, so they can still meet their needs without violating the rules of your house. Remember, it's essential to maintain open communication while being respectful of each other's preferences and boundaries.