Panel rebuilt as the heat matrix: verdict header (ring + newest fault named with its age, cable cell top right), one row per check with NOW / last-90s-at-5s-a-cell / since-reset columns, noise as a blue context lane; history.go keeps the 18-slot wall-time ring (per-class fault deltas, SNR minima, rate verdicts, measuring gray) plus since-reset aggregates and fault ages that clear on reset; noise cycle grid-locked to the shared slot clock so cells never straddle a phase and flicker, presence granted at boot until the first up-phase verdict; check/cross stroked as capsule marks (font has neither), line rate is a pure verdict everywhere, footer is a three-line stat stack beside hold-to-reset; old panel/chip/stat-grid machinery deleted; mockups/ gitignored

noise.go

@@ -28,8 +28,6 @@ import (
 const (
 	noiseDriver   = "i40e"
 	noiseFrameLen = 1514
-	noiseUpSpan   = 5 * time.Second
-	noiseDownSpan = 5 * time.Second
 	noiseFrameGap = 10 * time.Millisecond
 
 	noiseEther uint16 = etherBase + numStreams
@@ -94,6 +92,10 @@ func newNoiser() (*noiser, error) {
 	}
 
 	n := &noiser{eps: [2]endpoint{a, b}}
+	// The grid-locked cycle can start mid-down-slot, where absence would be
+	// our own doing: presence is granted until the first up phase delivers a
+	// verdict.
+	n.connected.Store(true)
 	for i, p := range [][2]endpoint{{a, b}, {b, a}} {
 		fd, err := openTxSocket(p[0].idx)
 		if err != nil {
@@ -169,6 +171,10 @@ func (n *noiser) bothUp() bool {
 // comes and goes under the cycle, and a frame this side declined to send is as
 // good as one the wire mangled. What matters is only ever what the test cable
 // counted.
+//
+// The cycle is locked to the panel's history grid — up on even 5 s slots,
+// down on odd, transitions on the shared slot boundaries — so a history cell
+// never straddles a phase and flickers between the two answers.
 func (n *noiser) run(done *atomic.Bool) {
 	fd, err := unix.Socket(unix.AF_INET, unix.SOCK_DGRAM, 0)
 	if err != nil {
@@ -179,29 +185,27 @@ func (n *noiser) run(done *atomic.Bool) {
 	tick := time.NewTicker(noiseFrameGap)
 	defer tick.Stop()
 
+	applied, wasUp, linked := false, false, false
 	for !done.Load() {
-		n.setLinks(fd, true)
-		n.radiating.Store(true)
-		linked := false
-		for end := time.Now().Add(noiseUpSpan); time.Now().Before(end) && !done.Load(); {
-			<-tick.C
-			if !n.bothUp() {
-				continue
-			}
-			linked = true
-			n.connected.Store(true)
-			for i := range n.ports {
-				unix.Write(n.ports[i].fd, n.ports[i].frame)
+		<-tick.C
+		up := (time.Since(rateEpochStart)/histSlotSpan)%2 == 0
+		if !applied || up != wasUp {
+			// A whole up phase with no link is many times the ~1s the wire
+			// needs to train, so at its end the silence is the cable's answer.
+			if applied && wasUp {
+				n.connected.Store(linked)
 			}
+			n.setLinks(fd, up)
+			n.radiating.Store(up)
+			applied, wasUp, linked = true, up, false
 		}
-		// A whole up phase with no link is many times the ~1s the wire needs
-		// to train, so by now the silence is the cable's answer.
-		n.connected.Store(linked)
-
-		n.setLinks(fd, false)
-		n.radiating.Store(false)
-		for end := time.Now().Add(noiseDownSpan); time.Now().Before(end) && !done.Load(); {
-			<-tick.C
+		if !up || !n.bothUp() {
+			continue
+		}
+		linked = true
+		n.connected.Store(true)
+		for i := range n.ports {
+			unix.Write(n.ports[i].fd, n.ports[i].frame)
 		}
 	}
 	// Left up rather than wherever the cycle stopped, so a run never strands