The form Shall I is used to make offers, in general. For example
Shall I help you?
and one would answer
Yeah, help me
but what's the full answer? I mean, with a question like
You will go for meat, won't you?
Short answer: Yeah.
Full answer: Yes I will.
But shall as a second person has another meaning
Shall I help you?
Yes you shall. <– it's no more a suggestion: I'm requiring you to do that.
and using Yes you will still sounds imperative. Therefore, is there a full answer to that form as there is for normal verbs like do, will, be and so on?
Best Answer
I would say, "Yes, please do."
In other words, if will in a question maps to will in what you are calling a "full answer", then shall in a question maps to do in the "full answer" – at least, that's one way we can look at it.
It's hard to say a mapping like this is 100% reliable, but it does seem to work in a variety of circumstances with a number of verbs. For example, consider these:
All of those questions can be answered with, "Yes, please do."
Of course, if you want to answer the other way, you could simply say, "No, please don't."