The fixtures are the live numbers sampled from the box on 02-08-2026, where the
CPT run held 12.8GB of 16 as proc/478104/vram_35881.
The cases that matter are the ones where a mistake is silent: our own
llama-server counting as a contender, an unreadable card reading as free, and
/health hanging or proxying into a closed port instead of answering 503.
The lifecycle rule from Vikunja #488. Not on demand, because a 7-14B takes tens
of seconds to load and a world question would meet a gap every time the card
had been quiet. Not always on, because that is what holds the card.
/health is answered locally and always, so Maven's prober costs nothing and
works while the model is down. Everything else is reverse-proxied to
llama-server, which is what makes the idle window measurable at all.
Yielding is checked before starting, and both transitions are damped by a poll
streak so a short-lived rocm process cannot evict the model.
The workstation cannot keep a 7-14B resident: it would hold 16GB against the
owner's CPT runs, Correx and the manga-recap pipeline. So the process that
stays up costs no VRAM and the model comes and goes under it.
Contention is detected by presence on the KFD, not by a VRAM threshold. A ROCm
process registers under /sys/class/kfd/kfd/proc when it initialises HIP, well
before it allocates, so we see a contender during its startup instead of after
it has already lost an allocation race. rocm-smi is not installed on that box
and a per-second subprocess would get tuned down until useless, so this reads
sysfs and forks nothing.
Free VRAM is read only to decide whether to start. It is never a reason to
stop: by the time free VRAM has dropped, the other job has already failed.
claude