diff --git a/cmd/mavgpud/gpu.go b/cmd/mavgpud/gpu.go
new file mode 100644
index 0000000..89120c6
--- /dev/null
+++ b/cmd/mavgpud/gpu.go
@@ -0,0 +1,117 @@
+package main
+
+import (
+	"os"
+	"path/filepath"
+	"strconv"
+	"strings"
+)
+
+// The card is an AMD 7900 GRE with 16GB, driven by amdgpu and ROCm. Everything
+// here reads sysfs and forks nothing: rocm-smi is not even installed on the
+// workstation, and a poll that costs a subprocess every second is a poll that
+// gets tuned down until it is useless.
+
+// gpuProc — one process holding the compute engine.
+type gpuProc struct {
+	PID  int
+	Comm string
+	VRAM int64 // bytes, as the kernel accounts them to this process
+}
+
+// probe reads the two sysfs trees the supervisor decides from.
+//
+// kfdRoot is /sys/class/kfd/kfd/proc, one directory per ROCm process. The
+// directory appears when the process initialises HIP, which is well before it
+// allocates anything large. That is the whole reason this works: the job that
+// is about to want the card announces itself while it is still starting up,
+// so we see the contender rather than only the winner of an allocation race.
+//
+// drmDev is /sys/class/drm/cardN/device, which reports total and used VRAM for
+// the card as a whole.
+type probe struct {
+	kfdRoot string
+	drmDev  string
+}
+
+// foreign lists every ROCm process that is not ours. selfPID is the supervisor's
+// llama-server child, or 0 when it is not running.
+//
+// An unreadable kfd tree returns no processes and no error. That is deliberate
+// and it is the safe direction only because startVRAM also has to agree before
+// anything launches: a supervisor that cannot see the KFD never sees free VRAM
+// either, because the CPT run holding the card shows up in the drm totals.
+func (p probe) foreign(selfPID int) []gpuProc {
+	entries, err := os.ReadDir(p.kfdRoot)
+	if err != nil {
+		return nil
+	}
+	var out []gpuProc
+	for _, e := range entries {
+		pid, err := strconv.Atoi(e.Name())
+		if err != nil || pid == selfPID {
+			continue
+		}
+		out = append(out, gpuProc{
+			PID:  pid,
+			Comm: readComm(pid),
+			VRAM: p.procVRAM(e.Name()),
+		})
+	}
+	return out
+}
+
+// procVRAM sums the per-node vram_* files under one process directory. The
+// suffix is the KFD topology node id (vram_35881 on this card), so it is
+// globbed rather than named, and a machine with two cards sums both.
+func (p probe) procVRAM(pid string) int64 {
+	matches, err := filepath.Glob(filepath.Join(p.kfdRoot, pid, "vram_*"))
+	if err != nil {
+		return 0
+	}
+	var total int64
+	for _, m := range matches {
+		total += readInt(m)
+	}
+	return total
+}
+
+// freeVRAM reports the bytes the card has left. Used only to decide whether to
+// start: a shortfall here means llama-server would refuse to load anyway. It is
+// never used to decide to stop, because by the time free VRAM has dropped the
+// other job has already failed its allocation, which is exactly the outcome
+// yielding exists to prevent.
+func (p probe) freeVRAM() int64 {
+	total := readInt(filepath.Join(p.drmDev, "mem_info_vram_total"))
+	used := readInt(filepath.Join(p.drmDev, "mem_info_vram_used"))
+	if total <= 0 {
+		return 0
+	}
+	if free := total - used; free > 0 {
+		return free
+	}
+	return 0
+}
+
+func readInt(path string) int64 {
+	b, err := os.ReadFile(path)
+	if err != nil {
+		return 0
+	}
+	n, err := strconv.ParseInt(strings.TrimSpace(string(b)), 10, 64)
+	if err != nil {
+		return 0
+	}
+	return n
+}
+
+// readComm names the contender for the log. The log is the instrument for the
+// open question in Vikunja #488: whether a process can want this card without
+// ever registering on the KFD, which a Vulkan or video-decode job would.
+func readComm(pid int) string {
+	b, err := os.ReadFile(filepath.Join("/proc", strconv.Itoa(pid), "comm"))
+	if err != nil {
+		return "?"
+	}
+	return strings.TrimSpace(string(b))
+}
diff --git a/cmd/mavgpud/runner.go b/cmd/mavgpud/runner.go
new file mode 100644
index 0000000..39ce341
--- /dev/null
+++ b/cmd/mavgpud/runner.go
@@ -0,0 +1,132 @@
+package main
+
+import (
+	"context"
+	"log"
+	"net/http"
+	"os/exec"
+	"sync"
+	"syscall"
+	"time"
+)
+
+// runner owns one llama-server process. Owning it is the point of the daemon:
+// the workstation cannot keep a 7-14B resident, because that holds 16GB against
+// the owner's CPT runs, Correx and the manga-recap pipeline. So the thing that
+// stays up is this, which costs no VRAM, and the model comes and goes under it.
+type runner struct {
+	bin  string
+	args []string
+	// ready is llama-server's own /health, which answers "is a model loaded".
+	// Loading a 7-14B takes tens of seconds, so started is not ready.
+	readyURL string
+
+	mu    sync.Mutex
+	cmd   *exec.Cmd
+	ready bool
+	http  *http.Client
+}
+
+func newRunner(bin string, args []string, readyURL string) *runner {
+	return &runner{
+		bin: bin, args: args, readyURL: readyURL,
+		http: &http.Client{Timeout: 2 * time.Second},
+	}
+}
+
+// pid is the child's, or 0. The GPU probe needs it to tell our own model apart
+// from a contender.
+func (r *runner) pid() int {
+	r.mu.Lock()
+	defer r.mu.Unlock()
+	if r.cmd == nil || r.cmd.Process == nil {
+		return 0
+	}
+	return r.cmd.Process.Pid
+}
+
+func (r *runner) running() bool { return r.pid() != 0 }
+
+// isReady reports the cached readiness. The supervisor loop refreshes it; the
+// health handler only reads, so answering /health never costs a round trip.
+func (r *runner) isReady() bool {
+	r.mu.Lock()
+	defer r.mu.Unlock()
+	return r.ready
+}
+
+// start launches llama-server. It returns as soon as the process exists, not
+// when the model is loaded.
+func (r *runner) start() error {
+	r.mu.Lock()
+	defer r.mu.Unlock()
+	if r.cmd != nil {
+		return nil
+	}
+	cmd := exec.Command(r.bin, r.args...)
+	// Own process group, so stop kills anything llama-server spawned rather
+	// than leaving it holding VRAM after we have declared the card yielded.
+	cmd.SysProcAttr = &syscall.SysProcAttr{Setpgid: true}
+	if err := cmd.Start(); err != nil {
+		return err
+	}
+	r.cmd, r.ready = cmd, false
+	log.Printf("mavgpud: started llama-server pid=%d", cmd.Process.Pid)
+	go func() {
+		err := cmd.Wait()
+		r.mu.Lock()
+		r.cmd, r.ready = nil, false
+		r.mu.Unlock()
+		log.Printf("mavgpud: llama-server exited: %v", err)
+	}()
+	return nil
+}
+
+// stop ends llama-server and waits for the VRAM to come back. SIGTERM first so
+// it unmaps cleanly, SIGKILL after the grace window. Returning before the
+// process is gone would let the supervisor report a free card while 14GB is
+// still mapped, which is the one lie that would make yielding useless.
+func (r *runner) stop(grace time.Duration) {
+	r.mu.Lock()
+	cmd := r.cmd
+	r.ready = false
+	r.mu.Unlock()
+	if cmd == nil || cmd.Process == nil {
+		return
+	}
+	pgid := -cmd.Process.Pid
+	_ = syscall.Kill(pgid, syscall.SIGTERM)
+	deadline := time.Now().Add(grace)
+	for time.Now().Before(deadline) {
+		if !r.running() {
+			return
+		}
+		time.Sleep(100 * time.Millisecond)
+	}
+	log.Printf("mavgpud: llama-server did not exit in %s, killing", grace)
+	_ = syscall.Kill(pgid, syscall.SIGKILL)
+}
+
+// refreshReady asks llama-server whether the model is loaded. Called once per
+// supervisor tick, never per request.
+func (r *runner) refreshReady(ctx context.Context) {
+	if !r.running() {
+		return
+	}
+	ok := false
+	req, err := http.NewRequestWithContext(ctx, http.MethodGet, r.readyURL, nil)
+	if err == nil {
+		resp, err := r.http.Do(req)
+		if err == nil {
+			ok = resp.StatusCode == http.StatusOK
+			resp.Body.Close()
+		}
+	}
+	r.mu.Lock()
+	was := r.ready
+	r.ready = ok
+	r.mu.Unlock()
+	if ok && !was {
+		log.Printf("mavgpud: model ready")
+	}
+}