Note that if you mean the contract between a publisher and a writer, the proper term is publishing contract.

https://en.wikipedia.org/wiki/Publishing_contract


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Note added at 1 hr (2023-11-12 16:34:57 GMT)
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Work for hire agreement:
Work for hire is a type of agreement in which an author is hired to create a book, article, or other written material in exchange for a flat fee. The work is for a client or employer who will own the copyright of the finished product. In publishing, these agreements are often used by companies or individuals who want to write such materials but do not have the necessary expertise or resources to create them.

https://publishdrive.com/glossary-what-is-a-work-for-hire.ht...


Buyout agreement:
Buyout agreement (also known as a buy-sell agreement) refers to a contract that gives rights to at least one party of the contract to buy the share, assets, or rights of another party given a specific event.

Buyout agreements play the biggest role in partnership and corporate ownership contexts where the parties agree that a leaving party will sell their ownership for a specified price to the other parties to the agreement.

https://www.law.cornell.edu/wex/buyout_agreement