Multi-File Refactoring and Large Codebase Understanding

Previously, we mastered the core mechanics of collaborating with Cascade. We learned how to choose our interaction style using Chat and Write modes, how to provide precise context with @-mentions, and how to work with the AI to debug issues. Now it’s time to apply these foundational skills to solve the kinds of large-scale, professional engineering problems that truly test a developer’s mettle.

This lesson focuses on tackling complexity and scale. We will concentrate on two tasks that are traditionally time-consuming, high-risk, and mentally taxing: performing major, multi-file refactors and getting up to speed on a large, unfamiliar codebase. We will use Windsurf’s deep, whole-codebase awareness to make these challenges manageable, safe, and even enjoyable.

The challenge of large-scale change

Every experienced developer knows the feeling: they need to rename a core function, but it is used in fifty different places across ten different files. They start with a global search, but what if the function is used with different casing? What if they miss one instance? This is the “grep and pray” approach to refactoring a notoriously error-prone process.

Similarly, starting a new job and being handed a million-line legacy codebase can be overwhelming. Building a mental map of its architecture, hidden dependencies, and unspoken conventions can take weeks or months. These are the exact problems where an AI co-pilot with a full view of the entire project can be a revolutionary partner. Let’s see how. ...