feat(metrics): single chart engine + full-width stacked layout

- One engine: go-analyze/charts (grafana theme) for all live metrics
- Server chart: CPU temp, CPU load%, mem load%, power W, fan RPMs
- GPU charts: temp, load%, mem%, power W — one card per GPU, added dynamically
- Charts 1400x280px SVG, rendered at width:100% in single-column layout
- Add CPU load (from /proc/stat) and mem load (from /proc/meminfo) to LiveMetricSample
- Add GPU mem utilization to GPUMetricRow (nvidia-smi utilization.memory)
- Document charting architecture in bible-local/architecture/charting.md

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

audit/internal/platform/gpu_metrics.go

@@ -13,18 +13,19 @@ import (
 
 // GPUMetricRow is one telemetry sample from nvidia-smi during a stress test.
 type GPUMetricRow struct {
-	ElapsedSec float64
-	GPUIndex   int
-	TempC      float64
-	UsagePct   float64
-	PowerW     float64
-	ClockMHz   float64
+	ElapsedSec  float64 `json:"elapsed_sec"`
+	GPUIndex    int     `json:"index"`
+	TempC       float64 `json:"temp_c"`
+	UsagePct    float64 `json:"usage_pct"`
+	MemUsagePct float64 `json:"mem_usage_pct"`
+	PowerW      float64 `json:"power_w"`
+	ClockMHz    float64 `json:"clock_mhz"`
 }
 
 // sampleGPUMetrics runs nvidia-smi once and returns current metrics for each GPU.
 func sampleGPUMetrics(gpuIndices []int) ([]GPUMetricRow, error) {
 	args := []string{
-		"--query-gpu=index,temperature.gpu,utilization.gpu,power.draw,clocks.current.graphics",
+		"--query-gpu=index,temperature.gpu,utilization.gpu,utilization.memory,power.draw,clocks.current.graphics",
 		"--format=csv,noheader,nounits",
 	}
 	if len(gpuIndices) > 0 {
@@ -45,16 +46,17 @@ func sampleGPUMetrics(gpuIndices []int) ([]GPUMetricRow, error) {
 			continue
 		}
 		parts := strings.Split(line, ", ")
-		if len(parts) < 5 {
+		if len(parts) < 6 {
 			continue
 		}
 		idx, _ := strconv.Atoi(strings.TrimSpace(parts[0]))
 		rows = append(rows, GPUMetricRow{
-			GPUIndex: idx,
-			TempC:    parseGPUFloat(parts[1]),
-			UsagePct: parseGPUFloat(parts[2]),
-			PowerW:   parseGPUFloat(parts[3]),
-			ClockMHz: parseGPUFloat(parts[4]),
+			GPUIndex:    idx,
+			TempC:       parseGPUFloat(parts[1]),
+			UsagePct:    parseGPUFloat(parts[2]),
+			MemUsagePct: parseGPUFloat(parts[3]),
+			PowerW:      parseGPUFloat(parts[4]),
+			ClockMHz:    parseGPUFloat(parts[5]),
 		})
 	}
 	return rows, nil

audit/internal/platform/live_metrics.go

@@ -1,15 +1,23 @@
 package platform
 
-import "time"
+import (
+	"bufio"
+	"os"
+	"strconv"
+	"strings"
+	"time"
+)
 
 // LiveMetricSample is a single point-in-time snapshot of server metrics
 // collected for the web UI metrics page.
 type LiveMetricSample struct {
-	Timestamp time.Time       `json:"ts"`
-	Fans      []FanReading    `json:"fans"`
-	Temps     []TempReading   `json:"temps"`
-	PowerW    float64         `json:"power_w"`
-	GPUs      []GPUMetricRow  `json:"gpus"`
+	Timestamp  time.Time      `json:"ts"`
+	Fans       []FanReading   `json:"fans"`
+	Temps      []TempReading  `json:"temps"`
+	PowerW     float64        `json:"power_w"`
+	CPULoadPct float64        `json:"cpu_load_pct"`
+	MemLoadPct float64        `json:"mem_load_pct"`
+	GPUs       []GPUMetricRow `json:"gpus"`
 }
 
 // TempReading is a named temperature sensor value.
@@ -41,5 +49,91 @@ func SampleLiveMetrics() LiveMetricSample {
 	// System power — returns 0 if unavailable
 	s.PowerW = sampleSystemPower()
 
+	// CPU load — from /proc/stat
+	s.CPULoadPct = sampleCPULoadPct()
+
+	// Memory load — from /proc/meminfo
+	s.MemLoadPct = sampleMemLoadPct()
+
 	return s
 }
+
+// sampleCPULoadPct reads two /proc/stat snapshots 200ms apart and returns
+// the overall CPU utilisation percentage.
+var cpuStatPrev [2]uint64 // [total, idle]
+
+func sampleCPULoadPct() float64 {
+	total, idle := readCPUStat()
+	if total == 0 {
+		return 0
+	}
+	prevTotal, prevIdle := cpuStatPrev[0], cpuStatPrev[1]
+	cpuStatPrev = [2]uint64{total, idle}
+	if prevTotal == 0 {
+		return 0
+	}
+	dt := float64(total - prevTotal)
+	di := float64(idle - prevIdle)
+	if dt <= 0 {
+		return 0
+	}
+	pct := (1 - di/dt) * 100
+	if pct < 0 {
+		return 0
+	}
+	if pct > 100 {
+		return 100
+	}
+	return pct
+}
+
+func readCPUStat() (total, idle uint64) {
+	f, err := os.Open("/proc/stat")
+	if err != nil {
+		return 0, 0
+	}
+	defer f.Close()
+	sc := bufio.NewScanner(f)
+	for sc.Scan() {
+		line := sc.Text()
+		if !strings.HasPrefix(line, "cpu ") {
+			continue
+		}
+		fields := strings.Fields(line)[1:] // skip "cpu"
+		var vals [10]uint64
+		for i := 0; i < len(fields) && i < 10; i++ {
+			vals[i], _ = strconv.ParseUint(fields[i], 10, 64)
+		}
+		// idle = idle + iowait
+		idle = vals[3] + vals[4]
+		for _, v := range vals {
+			total += v
+		}
+		return total, idle
+	}
+	return 0, 0
+}
+
+func sampleMemLoadPct() float64 {
+	f, err := os.Open("/proc/meminfo")
+	if err != nil {
+		return 0
+	}
+	defer f.Close()
+	vals := map[string]uint64{}
+	sc := bufio.NewScanner(f)
+	for sc.Scan() {
+		fields := strings.Fields(sc.Text())
+		if len(fields) >= 2 {
+			v, _ := strconv.ParseUint(fields[1], 10, 64)
+			vals[strings.TrimSuffix(fields[0], ":")] = v
+		}
+	}
+	total := vals["MemTotal"]
+	avail := vals["MemAvailable"]
+	if total == 0 {
+		return 0
+	}
+	used := total - avail
+	return float64(used) / float64(total) * 100
+}

audit/internal/webui/api.go

@@ -424,7 +424,7 @@ func (h *handler) handleAPIMetricsStream(w http.ResponseWriter, r *http.Request)
 		case <-ticker.C:
 			sample := platform.SampleLiveMetrics()
 
-			// Feed ring buffers for server-side SVG charts
+			// Feed server ring buffers
 			for _, t := range sample.Temps {
 				if t.Name == "CPU" {
 					h.ringCPUTemp.push(t.Celsius)
@@ -432,6 +432,35 @@ func (h *handler) handleAPIMetricsStream(w http.ResponseWriter, r *http.Request)
 				}
 			}
 			h.ringPower.push(sample.PowerW)
+			h.ringCPULoad.push(sample.CPULoadPct)
+			h.ringMemLoad.push(sample.MemLoadPct)
+
+			// Feed fan ring buffers (grow on first sight)
+			h.ringsMu.Lock()
+			for i, fan := range sample.Fans {
+				for len(h.ringFans) <= i {
+					h.ringFans = append(h.ringFans, newMetricsRing(120))
+					h.fanNames = append(h.fanNames, fan.Name)
+				}
+				h.ringFans[i].push(float64(fan.RPM))
+			}
+			// Feed per-GPU ring buffers (grow on first sight)
+			for _, gpu := range sample.GPUs {
+				idx := gpu.GPUIndex
+				for len(h.gpuRings) <= idx {
+					h.gpuRings = append(h.gpuRings, &gpuRings{
+						Temp:    newMetricsRing(120),
+						Util:    newMetricsRing(120),
+						MemUtil: newMetricsRing(120),
+						Power:   newMetricsRing(120),
+					})
+				}
+				h.gpuRings[idx].Temp.push(gpu.TempC)
+				h.gpuRings[idx].Util.push(gpu.UsagePct)
+				h.gpuRings[idx].MemUtil.push(gpu.MemUsagePct)
+				h.gpuRings[idx].Power.push(gpu.PowerW)
+			}
+			h.ringsMu.Unlock()
 
 			b, err := json.Marshal(sample)
 			if err != nil {

audit/internal/webui/pages.go

@@ -242,28 +242,27 @@ func renderHealthCard(opts HandlerOptions) string {
 // ── Metrics ───────────────────────────────────────────────────────────────────
 
 func renderMetrics() string {
-	return `<p style="color:#64748b;font-size:13px;margin-bottom:16px">Live server metrics, charts updated every 2 seconds.</p>
-<div class="grid2">
-  <div class="card">
-    <div class="card-head">System</div>
-    <div class="card-body">
-      <img id="chart-cpu-temp" src="/api/metrics/chart/cpu-temp.svg" style="width:100%;border-radius:6px" alt="CPU Temp">
-      <img id="chart-power"    src="/api/metrics/chart/power.svg"    style="width:100%;border-radius:6px;margin-top:8px" alt="Power">
-      <div id="sys-table" style="margin-top:8px"></div>
-    </div>
-  </div>
-  <div class="card">
-    <div class="card-head">GPU</div>
-    <div class="card-body">
-      <div id="gpu-table"><p style="color:#64748b;font-size:12px">Waiting for data...</p></div>
-    </div>
+	return `<p style="color:#64748b;font-size:13px;margin-bottom:16px">Live metrics — updated every 2 seconds. Charts use go-analyze/charts (grafana theme).</p>
+
+<div class="card" style="margin-bottom:16px">
+  <div class="card-head">Server</div>
+  <div class="card-body" style="padding:8px">
+    <img id="chart-server" src="/api/metrics/chart/server.svg" style="width:100%;display:block;border-radius:6px" alt="Server metrics">
+    <div id="sys-table" style="margin-top:8px;font-size:12px"></div>
   </div>
 </div>
+
+<div id="gpu-charts"></div>
+
 <script>
+let knownGPUs = [];
+
 function refreshCharts() {
   const t = '?t=' + Date.now();
-  ['chart-cpu-temp','chart-power'].forEach(id => {
-    const el = document.getElementById(id);
+  const srv = document.getElementById('chart-server');
+  if (srv) srv.src = srv.src.split('?')[0] + t;
+  knownGPUs.forEach(idx => {
+    const el = document.getElementById('chart-gpu-' + idx);
     if (el) el.src = el.src.split('?')[0] + t;
   });
 }
@@ -272,21 +271,42 @@ setInterval(refreshCharts, 2000);
 const es = new EventSource('/api/metrics/stream');
 es.addEventListener('metrics', e => {
   const d = JSON.parse(e.data);
-  const gpuRows = (d.gpus||[]).map(g =>
-    '<tr><td>GPU '+g.index+'</td><td>'+g.temp_c+'°C</td><td>'+g.usage_pct+'%</td><td>'+g.power_w+'W</td><td>'+g.clock_mhz+'MHz</td></tr>'
-  ).join('');
-  document.getElementById('gpu-table').innerHTML = gpuRows ?
-    '<table><tr><th>GPU</th><th>Temp</th><th>Usage</th><th>Power</th><th>Clock</th></tr>'+gpuRows+'</table>' :
-    '<p style="color:#64748b;font-size:12px">No NVIDIA GPU detected</p>';
 
+  // Add GPU chart cards as GPUs appear
+  (d.gpus||[]).forEach(g => {
+    if (knownGPUs.includes(g.index)) return;
+    knownGPUs.push(g.index);
+    const div = document.createElement('div');
+    div.className = 'card';
+    div.style.marginBottom = '16px';
+    div.innerHTML = '<div class="card-head">GPU ' + g.index + '</div>' +
+      '<div class="card-body" style="padding:8px">' +
+      '<img id="chart-gpu-' + g.index + '" src="/api/metrics/chart/gpu/' + g.index + '.svg" style="width:100%;display:block;border-radius:6px" alt="GPU ' + g.index + '">' +
+      '<div id="gpu-table-' + g.index + '" style="margin-top:8px;font-size:12px"></div>' +
+      '</div>';
+    document.getElementById('gpu-charts').appendChild(div);
+  });
+
+  // Update numeric tables
   let sysHTML = '';
   const cpuTemp = (d.temps||[]).find(t => t.name==='CPU');
   if (cpuTemp) sysHTML += '<tr><td>CPU Temp</td><td>'+cpuTemp.celsius.toFixed(1)+'°C</td></tr>';
+  if (d.cpu_load_pct) sysHTML += '<tr><td>CPU Load</td><td>'+d.cpu_load_pct.toFixed(1)+'%</td></tr>';
+  if (d.mem_load_pct) sysHTML += '<tr><td>Mem Load</td><td>'+d.mem_load_pct.toFixed(1)+'%</td></tr>';
   (d.fans||[]).forEach(f => sysHTML += '<tr><td>'+f.name+'</td><td>'+f.rpm+' RPM</td></tr>');
-  if (d.power_w) sysHTML += '<tr><td>System Power</td><td>'+d.power_w.toFixed(0)+'W</td></tr>';
-  document.getElementById('sys-table').innerHTML = sysHTML ?
-    '<table>'+sysHTML+'</table>' :
-    '<p style="color:#64748b;font-size:12px">No sensor data (ipmitool/sensors required)</p>';
+  if (d.power_w) sysHTML += '<tr><td>Power</td><td>'+d.power_w.toFixed(0)+' W</td></tr>';
+  const st = document.getElementById('sys-table');
+  if (st) st.innerHTML = sysHTML ? '<table>'+sysHTML+'</table>' : '<p style="color:#64748b">No sensor data (ipmitool/sensors required)</p>';
+
+  (d.gpus||[]).forEach(g => {
+    const t = document.getElementById('gpu-table-' + g.index);
+    if (!t) return;
+    t.innerHTML = '<table>' +
+      '<tr><td>Temp</td><td>'+g.temp_c+'°C</td>' +
+      '<td>Load</td><td>'+g.usage_pct+'%</td>' +
+      '<td>Mem</td><td>'+g.mem_usage_pct+'%</td>' +
+      '<td>Power</td><td>'+g.power_w+' W</td></tr></table>';
+  });
 });
 es.onerror = () => {};
 </script>`

audit/internal/webui/server.go

@@ -62,15 +62,27 @@ func (r *metricsRing) snapshot() ([]float64, []string) {
 	return v, l
 }
 
+// gpuRings holds per-GPU ring buffers.
+type gpuRings struct {
+	Temp    *metricsRing
+	Util    *metricsRing
+	MemUtil *metricsRing
+	Power   *metricsRing
+}
+
 // handler is the HTTP handler for the web UI.
 type handler struct {
-	opts       HandlerOptions
-	mux        *http.ServeMux
+	opts        HandlerOptions
+	mux         *http.ServeMux
+	// server rings
 	ringCPUTemp *metricsRing
+	ringCPULoad *metricsRing
+	ringMemLoad *metricsRing
 	ringPower   *metricsRing
 	ringFans    []*metricsRing
-	ringGPUTemp []*metricsRing
-	ringGPUUtil []*metricsRing
+	fanNames    []string
+	// per-GPU rings (index = GPU index)
+	gpuRings    []*gpuRings
 	ringsMu     sync.Mutex
 }
 
@@ -89,6 +101,8 @@ func NewHandler(opts HandlerOptions) http.Handler {
 	h := &handler{
 		opts:        opts,
 		ringCPUTemp: newMetricsRing(120),
+		ringCPULoad: newMetricsRing(120),
+		ringMemLoad: newMetricsRing(120),
 		ringPower:   newMetricsRing(120),
 	}
 	mux := http.NewServeMux()
@@ -244,48 +258,88 @@ func (h *handler) handleViewer(w http.ResponseWriter, r *http.Request) {
 }
 
 func (h *handler) handleMetricsChartSVG(w http.ResponseWriter, r *http.Request) {
-	name := strings.TrimPrefix(r.URL.Path, "/api/metrics/chart/")
-	name = strings.TrimSuffix(name, ".svg")
+	path := strings.TrimPrefix(r.URL.Path, "/api/metrics/chart/")
+	path = strings.TrimSuffix(path, ".svg")
+
+	var datasets [][]float64
+	var names []string
+	var labels []string
+	var title string
+
+	switch {
+	case path == "server":
+		title = "Server"
+		vCPUTemp, l := h.ringCPUTemp.snapshot()
+		vCPULoad, _ := h.ringCPULoad.snapshot()
+		vMemLoad, _ := h.ringMemLoad.snapshot()
+		vPower, _ := h.ringPower.snapshot()
+		labels = l
+		datasets = [][]float64{vCPUTemp, vCPULoad, vMemLoad, vPower}
+		names = []string{"CPU Temp °C", "CPU Load %", "Mem Load %", "Power W"}
+
+		h.ringsMu.Lock()
+		for i, fr := range h.ringFans {
+			fv, _ := fr.snapshot()
+			datasets = append(datasets, fv)
+			name := "Fan"
+			if i < len(h.fanNames) {
+				name = h.fanNames[i]
+			}
+			names = append(names, name+" RPM")
+		}
+		h.ringsMu.Unlock()
+
+	case strings.HasPrefix(path, "gpu/"):
+		idxStr := strings.TrimPrefix(path, "gpu/")
+		idx := 0
+		fmt.Sscanf(idxStr, "%d", &idx)
+		h.ringsMu.Lock()
+		var gr *gpuRings
+		if idx < len(h.gpuRings) {
+			gr = h.gpuRings[idx]
+		}
+		h.ringsMu.Unlock()
+		if gr == nil {
+			http.NotFound(w, r)
+			return
+		}
+		vTemp, l := gr.Temp.snapshot()
+		vUtil, _ := gr.Util.snapshot()
+		vMemUtil, _ := gr.MemUtil.snapshot()
+		vPower, _ := gr.Power.snapshot()
+		labels = l
+		title = fmt.Sprintf("GPU %d", idx)
+		datasets = [][]float64{vTemp, vUtil, vMemUtil, vPower}
+		names = []string{"Temp °C", "Load %", "Mem %", "Power W"}
 
-	var ring *metricsRing
-	var title, unit string
-	switch name {
-	case "cpu-temp":
-		ring, title, unit = h.ringCPUTemp, "CPU Temperature", "°C"
-	case "power":
-		ring, title, unit = h.ringPower, "System Power", "W"
 	default:
 		http.NotFound(w, r)
 		return
 	}
 
-	vals, labels := ring.snapshot()
-	if len(vals) == 0 {
-		vals = []float64{0}
+	// Ensure all datasets same length as labels
+	n := len(labels)
+	if n == 0 {
+		n = 1
 		labels = []string{""}
 	}
-
-	// Sparse x-axis labels
-	sparse := make([]string, len(labels))
-	step := len(labels) / 6
-	if step < 1 {
-		step = 1
-	}
-	for i := range labels {
-		if i%step == 0 {
-			sparse[i] = labels[i]
+	for i := range datasets {
+		if len(datasets[i]) == 0 {
+			datasets[i] = make([]float64, n)
 		}
 	}
 
-	opt := gocharts.NewLineChartOptionWithData([][]float64{vals})
-	opt.Title = gocharts.TitleOption{Text: title + " (" + unit + ")"}
+	sparse := sparseLabels(labels, 6)
+
+	opt := gocharts.NewLineChartOptionWithData(datasets)
+	opt.Title = gocharts.TitleOption{Text: title}
 	opt.XAxis.Labels = sparse
-	opt.Legend = gocharts.LegendOption{Show: gocharts.Ptr(false)}
+	opt.Legend = gocharts.LegendOption{SeriesNames: names}
 
 	p := gocharts.NewPainter(gocharts.PainterOptions{
 		OutputFormat: gocharts.ChartOutputSVG,
-		Width:        600,
-		Height:       180,
+		Width:        1400,
+		Height:       280,
 	}, gocharts.PainterThemeOption(gocharts.GetTheme("grafana")))
 	if err := p.LineChart(opt); err != nil {
 		http.Error(w, err.Error(), http.StatusInternalServerError)
@@ -301,6 +355,27 @@ func (h *handler) handleMetricsChartSVG(w http.ResponseWriter, r *http.Request)
 	_, _ = w.Write(buf)
 }
 
+func safeIdx(s []float64, i int) float64 {
+	if i < len(s) {
+		return s[i]
+	}
+	return 0
+}
+
+func sparseLabels(labels []string, n int) []string {
+	out := make([]string, len(labels))
+	step := len(labels) / n
+	if step < 1 {
+		step = 1
+	}
+	for i, l := range labels {
+		if i%step == 0 {
+			out[i] = l
+		}
+	}
+	return out
+}
+
 // ── Page handler ─────────────────────────────────────────────────────────────
 
 func (h *handler) handlePage(w http.ResponseWriter, r *http.Request) {