The CDI generator aborted with "failed to initialize NVML: Driver Not
Loaded", taking docker.service with it (requiredBy) and failing the
switch.
Two causes. The nixpkgs NVIDIA module only adds nvidia/nvidia_modeset/
nvidia_drm to boot.kernelModules when services.xserver.enable is set,
which is false on this Wayland-only host, so load them explicitly.
nvidia_uvm stays out: the module's modprobe softdep loads it once the GPU
device exists.
The generator also runs during activation, when a module rebuilt against a
new kernel cannot be loaded until reboot -- a guaranteed failure after
every kernel bump. Guard it with ConditionPathExists on
/proc/driver/nvidia/version so it skips rather than fails; the toolkit's
udev rule restarts it when the device appears, so the specs are generated
on the next boot.
Claude Code runs on Node, whose V8 build requires SSE4.2 and POPCNT
(x86-64-v2). On an older x86_64 CPU it does not run, so it must not be
installed there in the first place.
Nix cannot detect the CPU (pure evaluation, hosts often built elsewhere),
so add features.cpu.microarchLevel: the psABI level a host declares about
itself, defaulting to 2. features.claudeCode.enable derives from it, and
home/claude.nix reads that through home-manager's osConfig and installs
nothing -- CLI, CLAUDE.md, output style or memory symlink -- when it is
off. Hosts without the option (Darwin, the standalone homeConfigurations)
keep the tool enabled.
An assertion fails evaluation if a host force-enables the flag below the
required level, so the mistake surfaces in nix flake check rather than as
an illegal-instruction crash on the machine.
Emma Thorpe