I know that we use "yet" with Present Perfect in interrogative and negative sentences. And "already" is used in affirmative statements. Despite that fact I have found one sentence:
"What have you already done today?"
Is it correct?
Learn English – Using “already” in interrogative sentences
present-perfect
Best Answer
An NPI (negative polarity item) is a term restricted to negative contexts, and a PPI (positive polarity item) is one restricted to positive contexts.
Yet is the NPI corresponding to the PPI already.
Questions may be positive or negative; for instance, if you are asking about the status of a completed task:
Haven't you done that yet? is what you would ask if you expected the task to be finished but had reason to believe that it was not.
Have you done that yet? is what you would ask if you had no expectation and no evidence that in fact it was completed.
Have you done that already? is what you would ask if you expected the task to be unfinished but had evidence that in fact it was finished.
In your example, the question is positive: it asks about what you have done, not what you have left undone.