Liveness spinner: a 30-degree gap punched through the status ring band orbits on the wall clock (one turn per 2 s, all states including link-dead and MEASURING), so a static GOOD panel can never be mistaken for a hung app; one bg-colour stroke capsule at the byte-counter-free clock phase, no new primitives

ui.go

@@ -75,6 +75,10 @@ const (
 	btnBorder    = 2
 	holdDuration = time.Second
 
+	spinGap    = math.Pi / 6
+	spinPunch  = 9
+	spinPeriod = 2 * time.Second
+
 	versionSpotSide = 200
 )
 
@@ -386,6 +390,12 @@ func (d *display) drawHeader(phy phyDisplay, hv histView, measuring bool,
 	d.fb.roundRect(rx, ry, ringD, ringD, ringD/2, col)
 	d.fb.roundRect(rx+ringEdge, ry+ringEdge, ringD-2*ringEdge, ringD-2*ringEdge,
 		ringD/2-ringEdge, uiBg)
+	spin := float64(now.UnixNano()%int64(spinPeriod)) / float64(spinPeriod)
+	cx, cy := float64(rx)+ringD/2, float64(ry)+ringD/2
+	cr := (ringD - ringEdge) / 2.0
+	a0, a1 := 2*math.Pi*spin-spinGap/2, 2*math.Pi*spin+spinGap/2
+	d.fb.stroke(cx+cr*math.Sin(a0), cy-cr*math.Cos(a0),
+		cx+cr*math.Sin(a1), cy-cr*math.Cos(a1), spinPunch, uiBg)
 	switch {
 	case measuring:
 	case good: