Who will sue whom in case of violation of the contract between the customer, me and a third party and how to protect yourself?

Question

Law in IT

Good day!
The client in the contract prescribed that the program should not violate the intellectual property rights of third parties and I am responsible.
This is logical.
But there was a need to buy a third-party library from another developer, he agrees to conclude an agreement, with the same conditions, that his library will not violate the intellectual property rights of third parties and responsibility on him.
So, the question is, what will happen if the developer of the library is not actually its developer, but the real author makes claims to my customer?
I think so, in this case, under the contract, the responsibility will be on me and they will sue me, BUT I also have an agreement with the developer about this library, andit turns out that they will sue him directly, but I will not participate? Or, first, the one who has claims to sue my customer, my customer with me, and I am already suing the developer on my own? What if the developer is located in Zimbabwe and how then, do I have full popandos?
I draw such conclusions on the basis of the following clause:
"The Developer undertakes to provide the Buyer with protection from claims of any third parties related to the violation of these warranties, as well as indemnify the Buyer for losses caused by such claims."
In the same way, how would you protect yourself and how would it be most reasonable to change this item, so that the customer would arrange and save yourself from running around and litigation?
PS Let's admit the most extreme case. Please don’t write that “to whom the hell did you give up, there was no such rejoicing” and in that spirit - it’s not necessary at times and it’s better to be prepared. I understand that these are trifles, but suddenly =)

Answer 1

A lawsuit can be brought against someone who violates the rights. According to the plaintiff. Can to several - there will be co-defendants. The defendant may object and prove that he is an improper defendant.
There may be third parties against whom the defendant will then sue and there will be a prejudice.
But I would advise you not to understand now the procedural aspects of who will sue whom, but try to make sure that there are no claims, and if they do, then minimize the consequences.
If possible, indicate in the contract that you are acquiring rights from third parties.
There is no legal aid treaty with Zimbabwe. I just don't understand why you are going to sue the actual developer. Then he'll be more likely to sue you. Moreover, the claim is filed at the place of residence of the plaintiff, that is, he needs to hire a lawyer in the Russian Federation, and you yourself understand that the likelihood that a developer in Zimbabwe will do this is small.
And in case of claims, you will involve the person from whom you bought the IP. If he's from Zimbabwe then problems
You cannot provide protection against claims. Anyone can file a claim and file a claim if the state fee is paid and the claim is properly filed. Even without any reason or evidence. And then the court will decide.
I advise you to write down the procedure in detail: "in the event of a claim, the Buyer immediately notifies the Developer and involves him in the consideration of the claim ..." further depends on your situation. Otherwise, the Buyer will voluntarily satisfy the claim, and then present you with compensation for losses.
Assess the risks in which case there may be a violation of rights. How can this be identified and proven? What could be the losses. And depending on this, discuss with another developer and with the customer