Disclaimer? I do not know ...
You are coding the manual trading system/idea which was developed/elaborated by your client, right? Coding according to his idea?In this case - he is responsible for his own losses.
You can use Freelance service for example.This is from Freelance service rules:
Forex is a high risk market. You may lose substantial amount of money by taking the risk of live trading. I shall not be held responsible for any loss.
So, if you are coding to the client to be outside Freelance service - write simple disclaimer in EA.But I am recommending to use Freelance service, and in this case -any "diffucult situations" will be solved according to the rules which your client signed/agreed with.
I can not tell you more because I am not a coder sorry (other members are having more experience with it for example).
Ok, thanks for the advice Sergey.
Good idea - thanks Stanislav.