Include What You Use (IWYU) Purpose Guide agents through using IWYU to reduce unnecessary directives, interpret IWYU reports and mapping files, decide between forward declarations and full includes, and integrate IWYU into CMake builds to reduce compilation cascades in large codebases. Triggers - "How do I use include-what-you-use?" - "How do I reduce my C++ compilation times by fixing includes?" - "How do I interpret IWYU output?" - "Should I use a forward declaration or include?" - "How do I integrate IWYU with CMake?" - "What is a compilation cascade and how do I avoid it?" Workflow 1. Ins…