When working with Power BI Desktop and Git integration for version control, report and semantic model definitions should be saved in the PBIX format. PBIX is the Power BI Desktop file format that contains definitions for reports, data models, and queries, and it can be easily saved and tracked in a version-controlled environment. The solution should minimize development and maintenance effort, and saving in PBIX format allows for the easiest transition from development to deployment, especially when using Azure Pipelines for CI/CD (continuous integration/continuous deployment) practices.
References: The use of PBIX files with Power BI Desktop and Azure Repos for version control is discussed in Microsoft's official Power BI documentation, particularly in the sections covering Power BI Desktop files and Azure DevOps integration.