LoRA adapters on vLLM, loaded on demand with replica affinity: max_loaded_adapters

A vLLM model can carry PEFT adapters, registered at start, or with
max_loaded_adapters held at most N per replica: the router loads an adapter
through vLLM's runtime LoRA API when a request first wants it, sends the
adapter's requests to a replica that holds it while that one is not
saturated, loads each cold adapter once, and unloads the least recently used
idle one to make room. llama.cpp keeps loading every adapter at start.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

internal/control/adminapi/api.go

@@ -1846,8 +1846,12 @@ func (a *API) setAdapters(w http.ResponseWriter, r *http.Request) {
 	for _, ad := range m.Adapters {
 		have[ad.Source] = true
 	}
+	// The file is read only where llama.cpp will load it: a vLLM adapter is
+	// a PEFT directory, which has no header to read, and vLLM itself refuses
+	// one that does not fit the model when it is loaded.
+	ggufs := slices.ContainsFunc(m.Profiles, func(p catalog.Profile) bool { return p.Engine == "llamacpp" })
 	for _, ad := range req.Adapters {
-		if have[ad.Source] {
+		if have[ad.Source] || !ggufs {
 			continue // already checked when it was attached
 		}
 		h, err := gguf.KindFromURL(r.Context(), safedial.Client(safedial.ControlPlane, 30*time.Second), ad.Source)