I think you're right, and I can see that what I wrote is confusing. I meant, "in this altruistic act, I place your interests above my own." It says nothing about what you might do in return. It's not a moral precept.

On the other hand, there are many different kinds of reciprocity, in various contexts. If my survival depends on your survival, personally - then of course I am going to help you in any way I can, and I am repaid in the long term by your continued well being. This is the interdependence hypothesis of human non-kin altruism. It was the situation for the human family tree for most of 2 million years. So, unconditional altruism does exist in some circumstances.

But tit-for-tat belongs in a more impersonal environment where I depend on you only indirectly and there is no great reason for us to trust each other beyond the enforcement of our reciprocal agreement.