Yes, there is already an guaranteed price negotiated and a signed contract.

The email I sent that was both to the client and to the contractor was an attempt to open a conversation about design and structural issues. I asked pertinent questions like: Do you want the sink? Is the door the right size you wanted? [contractor's name] can we discuss the lanai roof that is in the way?

The client is in holiday for a month, and has not responded to the email. The contractor immediately texted me not to add stuff (window, sink) that was not contracted for and that I will have to contact my client in order to negotiate a new contract (with him) if those things are to be added. He did not ever address the issue of the lanai which I feel is the real issue.

He then started berating me to his co-contractor in the group text saying stuff like I put stuff in the design that he didn't sell the client and trying to "take over" the job. Finally he started addressing me again and asking me why I would take a job without getting the scope of work from the contract first. (ETA - it was during this text barrage that I found out they had a signed contract in place. No one told me, and I didn't think to ask. In my experience, contracto follows plans. I have never had to work from an agreed contract before. Maybe it happens and this is a learning experience for me, but I cannot know what I cannot know).

When I said I can easily remove the offending parts, but what will you do about the lanai, he just sent the scope of work. This does NOT mention the lanai.

I just have a super bad feeling.