v0.94.0: serialize per-disk SMART into the /disks payload

Additive, backward-compatible (MinAgent floor unchanged). The SMART is already
computed on the request path (storage.Observe -> enrich); this copies the target's
Smart into localapi.DiskInfo (pointer, omitempty) only when Health != "", so an
unread/absent summary stays omitted and the controller renders "Nincs adat".
No new smartctl load, endpoint, or sudoers change.

Test TestDisks_SmartSerialized + red-proof (drop the copy -> fails).

internal/localapi/disks.go

@@ -8,6 +8,7 @@ import (
 	"strings"
 	"time"
 
+	"gitea.dooplex.hu/admin/felhom-agent/internal/hub"
 	"gitea.dooplex.hu/admin/felhom-agent/internal/proxmox"
 	"gitea.dooplex.hu/admin/felhom-agent/internal/storage"
 )
@@ -151,6 +152,12 @@ type DiskInfo struct {
 	// at GuestPath (a host mount-table check) — i.e. live + usable in the guest in the intermediary model.
 	// The controller's drive-absent gate + auto-restart key on this (and State).
 	BoundUnderParent bool `json:"bound_under_parent"`
+	// Smart is the already-computed per-disk SMART health summary (v0.94.0), serialized here so the
+	// controller can render a disk-health card + degradation alert WITHOUT any new smartctl load — the
+	// value is copied straight from the target's Observe-time enrichment. omitempty + a pointer so a
+	// device that exposes no SMART (USB bridge, unread) is ABSENT, not a misleading zero-value UNKNOWN;
+	// the controller feature-detects presence and renders "Nincs adat" when nil (never alarms).
+	Smart *hub.SmartSummary `json:"smart,omitempty"`
 }
 
 // handleDisks lists the host's drives + data-bearing flags (read-only/benign).
@@ -206,6 +213,13 @@ func (s *Server) handleDisks(w http.ResponseWriter, r *http.Request, vmid int) {
 				di.WipeDurableID = wid
 			}
 		}
+		// v0.94.0: surface the already-computed SMART only when it was actually read (Health set).
+		// A zero-value summary (enrich skipped / no smartctl device) has Health "" → stays omitted, so
+		// the controller sees "absent" and renders "Nincs adat" rather than a false UNKNOWN.
+		if t.Smart.Health != "" {
+			sm := t.Smart
+			di.Smart = &sm
+		}
 		out = append(out, di)
 	}
 	// Impl-2a: union in registry+units drives that Observe() does NOT surface (a drive with no PVE

internal/localapi/disks_smart_test.go

@@ -0,0 +1,64 @@
+package localapi
+
+import (
+	"net/http"
+	"testing"
+
+	"gitea.dooplex.hu/admin/felhom-agent/internal/hub"
+	"gitea.dooplex.hu/admin/felhom-agent/internal/storage"
+)
+
+func smartIP(v int) *int { return &v }
+
+// TestDisks_SmartSerialized (v0.94.0) — the already-computed SMART summary is copied into the /disks
+// payload for a target that has it (Health set), including the SATA counters + temperature; a target
+// whose SMART was never read (zero-value summary, Health "") omits the field entirely.
+//
+// Red-proof: drop the `di.Smart = &sm` copy in handleDisks → the "data" disk's Smart is nil → this fails.
+func TestDisks_SmartSerialized(t *testing.T) {
+	d := &fakeDiskOps{probe: storage.DeviceProbe{Probed: true, HasFilesystem: true, FSType: "ext4"}}
+	sv := fakeStorage{targets: []hub.StorageTarget{
+		{
+			Name: "data", Type: hub.StorageTypeUSB, BackingDevice: "/dev/sdb1", MountPath: "/mnt/data",
+			Smart: hub.SmartSummary{
+				Health:             hub.SmartPassed,
+				TemperatureC:       smartIP(34),
+				ReallocatedSectors: smartIP(3),
+				PendingSectors:     smartIP(0),
+			},
+		},
+		// Zero-value SMART (never read) — Health "" → must be omitted from the payload.
+		{Name: "nosmart", Type: hub.StorageTypeUSB, BackingDevice: "/dev/sdc1", MountPath: "/mnt/nosmart"},
+	}}
+	h := newDiskServer(t, d, &fakeGate{}, sv, nil)
+
+	w := do(t, h, "GET", "/disks", "A", "")
+	if w.Code != http.StatusOK {
+		t.Fatalf("GET /disks: %d (%s)", w.Code, w.Body.String())
+	}
+	byName := map[string]DiskInfo{}
+	for _, di := range decodeDisks(t, w.Body.Bytes()) {
+		byName[di.Name] = di
+	}
+
+	ds := byName["data"].Smart
+	if ds == nil {
+		t.Fatal("data disk: smart summary was not serialized")
+	}
+	if ds.Health != hub.SmartPassed {
+		t.Errorf("data smart Health = %q, want PASSED", ds.Health)
+	}
+	if ds.ReallocatedSectors == nil || *ds.ReallocatedSectors != 3 {
+		t.Errorf("data ReallocatedSectors = %v, want 3", ds.ReallocatedSectors)
+	}
+	if ds.PendingSectors == nil || *ds.PendingSectors != 0 {
+		t.Errorf("data PendingSectors = %v, want 0 (a real zero, not null)", ds.PendingSectors)
+	}
+	if ds.TemperatureC == nil || *ds.TemperatureC != 34 {
+		t.Errorf("data TemperatureC = %v, want 34", ds.TemperatureC)
+	}
+
+	if byName["nosmart"].Smart != nil {
+		t.Errorf("nosmart disk: smart must be omitted when Health is empty, got %+v", byName["nosmart"].Smart)
+	}
+}