- Windows: install MSYS2's own Rust (x86_64-pc-windows-gnu host); the rustup MSVC toolchain is not on the msys2 shell's PATH and the MSVC linker rejects the Unix-style link args the build scripts emit - Linux: libpipewire-0.3-dev + libspa-0.2-dev for libspa-sys (gpui's Linux screen-capture/audio stack)