Yandex Money API - how to check the transfer and refuse?

Question

PHP

Good day to all!
I am filing the form on the site according to the manual:
https://tech.yandex.ru/money/doc/payment-buttons/a...
A number of questions arose. I'll start with the first one.
1) Do I understand correctly that Yandex does not allow transferring the commission to the buyer? On the side of my site, it is necessary to calculate and send for transfer, indicating the amount already with a commission? If so, then the next question arises.
2) The client on my website chooses the payment method via Yandex wallet (0.5% transfer fee). I calculate the transfer amount and send it to the Yandex website. Who prevents the user there from choosing the payment method "Bank card"? I note that the commission from the cards is already 2%. It turns out that if the user changes the payment method on the Yandex side, then I will not receive the funds before? How to deal with it? Is it really possible to set 2% for payment from a Yandex wallet? I don't want to deceive customers.
3) For payment through a mobile operator, the commission generally jumps from 7.86% to 16%! How to be here? Moreover, it is not known in advance how much the commission will be and which operator? How to send a user to pay with an already specified amount?
The first 3 questions disappear if it is possible to transfer the commission to the buyer. If only I could find this option somewhere.
********** I
have another question regarding receiving HTTP notifications.
4) How to check the relevance of the order? Sending the buyer to the Yandex website and waiting for a notification about the transfer is good. But it may take 5 minutes or an hour until the buyer makes the transfer. During this time, the order may "disappear". I did not find a way to pre-send a request from Yandex to me for successful confirmation of receipt of the transfer. It will notify only when the transfer arrives. How to proceed here? Work through the cancellation of the transfer?

Answer 1

I dug a little deeper and figured out how to do it. Yes, calculate the commission at home and send it for transfer.
I noticed that the HTTP notification ( https://tech.yandex.ru/money/doc/payment-buttons/r... Notification parameters) sends a notification_type by which you can understand whether the method chosen by the user matches my website with what came. If they are different, and even more so to increase the commission, then simply reject.
With mobile operators, you will have to take a maximum commission (about 16%), I did not think of another way.
Thanks for the discussions.

Answer 2

xs where did you find 0.5%
https://kassa.yandex.ru/help/payments/fees.html
different tools for different tasks - just increase the invoice by these 3%+

Answer 3

Ask this question in the Yandex.Money TP.