Mergify Monorepo CI is an innovative solution for optimizing continuous integration (CI) in monorepos by detecting which parts of a repository each pull request affects and triggering only the relevant GitHub Actions jobs. This approach addresses the inefficiencies and costs associated with traditional CI processes that run unnecessary tests when minor changes are made, especially in large repositories. By introducing the concept of "scopes," which are specific areas of a repository, Mergify allows for precise CI execution, reducing redundant tests and ensuring faster feedback for pull requests. It integrates seamlessly with GitHub Actions, enabling a single CI gate for branch protection and enhancing merge workflows through its Merge Queue feature. This system not only lowers CI costs but also simplifies workflows, ensuring that CI is only tied to actual code ownership, which is crucial for maintaining efficiency and speed in collaborative development environments.