What should I do if I see a text message from a girl who is ambiguous with me?

Actually, I don't think you need to worry about texting. Whether she likes you or not is the most important thing. I believe you can also see it from the details of life. Our teacher has always stressed to us that only the details will not be fabricated, even if it is only a very small and subtle feeling. I believe you can feel it. If you feel her feelings for you, don't ask questions. Get along, if you really like her.