yajl (needed by conmon, bootstrapped from source since Slackware ships no package for it) builds via CMake, not the cmake-free autoconf script its ./configure wrapper name suggests. Tracing the failure through the actual vbatts/slackware:15.0 image on the runner host surfaced a chain of packages slackpkg does not auto-resolve (Slackware packages carry no dependency metadata at all): cmake needs libarchive, which needs lz4 and libxml2; the patched make/gmake this mirror serves needs guile, which needs gc; compiling anything needs kernel-headers for <linux/errno.h>; and this build's binutils (ar/ranlib) needs flex, while objdump needs elfutils. All added to the same slackpkg install list as the rest of the toolchain, keeping everything on one mutually consistent version set. Verified end-to-end against vbatts/slackware:15.0 on the actual runner host at each step of this dependency chain. Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>