Marco Russo and Alberto Ferrari redline a few things:
Contract. As a DAX developer, you will use this term frequently; indeed, when developing code with an AI assistant, defining the contract is the most important task you need to complete to obtain a useful semantic model.
First things first: what is a contract? In simple terms, it is a text that identifies the rules at work in a specific semantic model. It is not just an algorithm definition: a contract can define multiple measures and multiple algorithms at the same time. However, it is not even a vague description of the model in terms of entities and relationships. It sits somewhere between the two: documentation that defines how to perform calculations in a specific model.
Read on to understand what they mean by a contract in this sense, and what has changed with the proliferation of language models generating DAX code.