All feature flags now use positive naming (enabled by default): - PIP_HAS_FILESYSTEM, PIP_HAS_THREADS, PIP_HAS_SOCKET - PIP_HAS_PROCESS, PIP_HAS_DYNLIB, PIP_HAS_FFT, PIP_HAS_SERIAL Preprocessor guards inverted: - #ifndef PIP_NO_X → #ifdef PIP_HAS_X - #ifdef PIP_NO_X → #ifndef PIP_HAS_X CMake options default ON instead of OFF. Platform blocks set flags OFF to disable features. 85 files transformed via Python script + 2 manual fixes.