Zig's Incremental Compilation Internals

# Summary Zig's incremental compilation feature allows the compiler to detect which functions and declarations have changed, recompile only those parts, and patch the results directly into the binary, enabling rebuild times as fast as 50-70 milliseconds for real applications. The feature has matured from a proof-of-concept to a viable tool used daily by the Zig core team, though full support for complex projects requires Zig's master branch rather than the current 0.16.0 release. The compiler achieves this through a multi-stage pipeline that processes source files into an intermediate representation (ZIR) and uses pure functions to track which files need recompilation.