slice 9: GET /host/metrics + CPU/chassis-temp collector (v0.14.0)

Add a host-wide, token-authed GET /host/metrics local-API endpoint that
re-serves the slice-4 collector's host + per-storage view to the customer
(the de-privileged controller can't read the host itself). Add the one new
collector — CPU/chassis temperature via sysfs hwmon/thermal-zones, graceful-
null — to the shared HostMetrics struct, so the hub report carries cpu_temp_c
too. Cross-repo host-report golden updated byte-identical.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

internal/localapi/server.go

@@ -54,6 +54,13 @@ type TokenAuthority interface {
 	Lookup(token string) (int, bool)
 }
 
+// HostMetricsProvider does a FRESH host-metrics collect (cpu%/mem/load/uptime/cpu-temp) for
+// GET /host/metrics (slice 9). Satisfied by *hub.Collector (which reuses the slice-4 collector —
+// no duplicate collection). Optional: when nil, /host/metrics reports "not configured".
+type HostMetricsProvider interface {
+	HostMetricsNow(ctx context.Context) (hub.HostMetrics, error)
+}
+
 // Options configures a Server.
 type Options struct {
 	ListenAddr string // bridge IP:port
@@ -73,7 +80,11 @@ type Options struct {
 	Disks    DiskOps
 	DiskGate StorageGate
 	Guests2  GuestLister
-	Logger   *slog.Logger
+	// HostMetrics serves GET /host/metrics (slice 9) — host-wide health (cpu%/mem/load/uptime/
+	// cpu-temp) + per-storage capacity, host-wide and token-authed (one-customer-per-host). When
+	// nil the endpoint reports "not configured" (host still reports/reconciles).
+	HostMetrics HostMetricsProvider
+	Logger      *slog.Logger
 }
 
 // defaultBackupCadence is the fallback /backup/due window when none is configured.
@@ -117,6 +128,8 @@ type Server struct {
 	diskGate  StorageGate // slice 8C (optional)
 	guestList GuestLister // slice 8C (optional)
 
+	hostMetrics HostMetricsProvider // slice 9 (optional)
+
 	jobsMu sync.Mutex
 	jobs   map[int]*backupJob // per-guest backup job state (slice 8B)
 
@@ -149,10 +162,11 @@ func NewServer(o Options) (*Server, error) {
 		cadence:   cadence,
 		logger:    o.Logger,
 		now:       func() time.Time { return time.Now().UTC() },
-		disks:     o.Disks,
-		diskGate:  o.DiskGate,
-		guestList: o.Guests2,
-		jobs:      map[int]*backupJob{},
+		disks:       o.Disks,
+		diskGate:    o.DiskGate,
+		guestList:   o.Guests2,
+		hostMetrics: o.HostMetrics,
+		jobs:        map[int]*backupJob{},
 	}, nil
 }
 
@@ -166,6 +180,9 @@ func (s *Server) Handler() http.Handler {
 	mux.HandleFunc("GET /backup/due", s.withGuest(s.handleBackupDue))
 	mux.HandleFunc("GET /backup/status", s.withGuest(s.handleBackupStatus))
 	mux.HandleFunc("GET /restore-test/status", s.withGuest(s.handleRestoreTestStatus))
+	// Host metrics (slice 9): host-wide health + per-storage capacity for the customer's monitoring
+	// view. Host-wide, token-authed, fresh (a live collect, not the 15-min hub snapshot).
+	mux.HandleFunc("GET /host/metrics", s.withGuest(s.handleHostMetrics))
 	// Disk management (slice 8C) — self-scoped; format routes through the data-bearing classifier+gate.
 	mux.HandleFunc("GET /disks", s.withGuest(s.handleDisks))
 	mux.HandleFunc("POST /disks/assign", s.withGuest(s.handleDiskAssign))