Settings: one window for how far back every graph reaches, 1 minute to 24 hours

Each machine keeps 300 points per curve whatever the window, so memory doesn't follow it;
a wider window means wider points, each the average of its bucket rather than one instant
out of it. The hub passes the setting to every machine it manages.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

internal/api/status_sensors.go

@@ -27,12 +27,21 @@ type statusSensors struct {
 	cpuPrev map[string]cpuMark // container ID → CPU time at the previous read
 
 	hist map[string]*sensors.Series // numeric sensors only, statusHistory points each
+	acc  map[string]*bucket         // the point being built for each, when the window is wider than the read rate
 }
 
 // statusHistory is how many readings each status sensor keeps: at 15 s that is over an
 // hour of container memory; at 10 min, two days of drive wear.
 const statusHistory = 300
 
+// A point being averaged, the same idea as the sampler's: these sources are read every 15 to
+// 300 seconds, so a wide window keeps one point per stride rather than one per read.
+type bucket struct {
+	start int64
+	sum   float64
+	n     float64
+}
+
 const (
 	servicesEvery   = 30 * time.Second
 	containersEvery = 15 * time.Second
@@ -42,7 +51,7 @@ const (
 )
 
 func newStatusSensors(s *Server) *statusSensors {
-	p := &statusSensors{s: s, by: map[string][]sensors.Sensor{}, hist: map[string]*sensors.Series{}}
+	p := &statusSensors{s: s, by: map[string][]sensors.Sensor{}, hist: map[string]*sensors.Series{}, acc: map[string]*bucket{}}
 	go p.loop("services", servicesEvery, p.services)
 	go p.loop("containers", containersEvery, p.containers)
 	go p.loop("updates", updatesEvery, p.updates)
@@ -58,6 +67,8 @@ func (p *statusSensors) loop(name string, every time.Duration, read func(context
 		cancel()
 		p.mu.Lock()
 		p.by[name] = got
+		window := p.s.metrics.Window()
+		stride := window.Milliseconds() / statusHistory
 		live := map[string]bool{}
 		for _, x := range got {
 			v, ok := x.Value.(float64)
@@ -70,14 +81,32 @@ func (p *statusSensors) loop(name string, every time.Duration, read func(context
 				h = &sensors.Series{ID: x.ID, Unit: x.Unit}
 				p.hist[x.ID] = h
 			}
-			h.T, h.V = append(h.T, x.T), append(h.V, v)
+			b := p.acc[x.ID]
+			if b == nil {
+				b = &bucket{start: x.T}
+				p.acc[x.ID] = b
+			}
+			b.sum, b.n = b.sum+v, b.n+1
+			if x.T-b.start < stride && b.n > 1 {
+				continue // still filling this point
+			}
+			h.T, h.V = append(h.T, x.T), append(h.V, b.sum/b.n)
+			*b = bucket{start: x.T + 1}
 			if len(h.T) > statusHistory {
 				h.T, h.V = h.T[len(h.T)-statusHistory:], h.V[len(h.V)-statusHistory:]
 			}
+			if cut := x.T - window.Milliseconds(); h.T[0] < cut { // and nothing older than the window
+				i := 0
+				for i < len(h.T) && h.T[i] < cut {
+					i++
+				}
+				h.T, h.V = h.T[i:], h.V[i:]
+			}
 		}
 		for id := range p.hist { // a container that is gone takes its history with it
 			if strings.HasPrefix(id, prefixOf[name]) && !live[id] && prefixOf[name] != "" {
 				delete(p.hist, id)
+				delete(p.acc, id)
 			}
 		}
 		p.mu.Unlock()