feat: onroad health overlay + 2x tire path in nightrider

System health overlay:
- Lower-right 5-metric panel: LAG (controlsState.cumLagMs), DROP
  (modelV2.frameDropPerc), TEMP (deviceState.maxTempC), CPU (max core of
  deviceState.cpuUsagePercent), MEM (deviceState.memoryUsagePercent)
- Color-coded white→yellow→red by severity (LAG: 50/200ms, DROP: 5/15%,
  TEMP: 75/88°C, CPU: 75/90%, MEM: 70/85%)
- Toggle in ClearPilot → Debug → "System Health Overlay"
- New param ClearpilotShowHealthMetrics, PERSISTENT (disk, survives
  reboots), default false — re-polled every ~2s so toggle takes effect
  without process restart
- InterFont(90, Bold) to match speed limit numeric styling, 30px margin,
  40px between rows, black rounded background

Nightrider center lane path (the "tire track" polygon from
scene.track_vertices) is now drawn at 2x the width of other lines —
highlights the planned path distinctly against the otherwise stark
outline-only rendering.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

selfdrive/ui/qt/home.cc

@@ -338,6 +338,15 @@ ClearPilotPanel::ClearPilotPanel(QWidget* parent) : QFrame(parent) {
   });
   debug_panel->addItem(telemetry_toggle);
 
+  auto *health_metrics_toggle = new ToggleControl("System Health Overlay",
+    "Show controls lag, model frame drops, temperature, CPU, and memory usage "
+    "in the lower-right of the onroad UI. For diagnosing slowdown issues.", "",
+    Params().getBool("ClearpilotShowHealthMetrics"), this);
+  QObject::connect(health_metrics_toggle, &ToggleControl::toggleFlipped, [](bool on) {
+    Params().putBool("ClearpilotShowHealthMetrics", on);
+  });
+  debug_panel->addItem(health_metrics_toggle);
+
   auto *vpn_toggle = new ToggleControl("VPN",
     "Connect to vpn.hanson.xyz for remote SSH access. "
     "Disabling kills the active tunnel and stops reconnection attempts.", "",

selfdrive/ui/qt/onroad.cc

@@ -468,6 +468,9 @@ void AnnotatedCameraWidget::drawHud(QPainter &p) {
   drawSpeedLimitSign(p);
   drawCruiseWarningSign(p);
 
+  // CLEARPILOT: system health metrics in lower-right (debug overlay)
+  drawHealthMetrics(p);
+
   // Draw FrogPilot widgets
   paintFrogPilotWidgets(p);
 }
@@ -727,6 +730,82 @@ void AnnotatedCameraWidget::drawText(QPainter &p, int x, int y, const QString &t
   p.drawText(real_rect.x(), real_rect.bottom(), text);
 }
 
+// CLEARPILOT: System health overlay — shows metrics that indicate the system
+// is overburdened or behind. Toggled via ClearpilotShowHealthMetrics param.
+// Metrics (top→bottom): LAG, DROP, TEMP, CPU, MEM
+//   LAG (ms): controlsd cumLagMs — most direct "is the loop keeping up" indicator
+//   DROP (%): modelV2 frameDropPerc — modeld losing frames; controlsd errors >20%
+//   TEMP (°C): deviceState.maxTempC — thermal throttling starts ~75, serious >88
+//   CPU (%): max core from deviceState.cpuUsagePercent
+//   MEM (%): deviceState.memoryUsagePercent
+// Each value color-codes green/yellow/red by severity.
+void AnnotatedCameraWidget::drawHealthMetrics(QPainter &p) {
+  static bool enabled = Params().getBool("ClearpilotShowHealthMetrics");
+  static int check_counter = 0;
+  // re-check the param every ~2s without a toggle signal path
+  if (++check_counter >= 40) {
+    check_counter = 0;
+    enabled = Params().getBool("ClearpilotShowHealthMetrics");
+  }
+  if (!enabled) return;
+
+  SubMaster &sm = *(uiState()->sm);
+  auto cs = sm["controlsState"].getControlsState();
+  auto ds = sm["deviceState"].getDeviceState();
+  auto mv = sm["modelV2"].getModelV2();
+
+  float lag_ms = cs.getCumLagMs();
+  float drop_pct = mv.getFrameDropPerc();
+  float temp_c = ds.getMaxTempC();
+  int mem_pct = ds.getMemoryUsagePercent();
+  int cpu_pct = 0;
+  for (auto v : ds.getCpuUsagePercent()) cpu_pct = std::max(cpu_pct, (int)v);
+
+  auto color_for = [](float v, float warn, float crit) {
+    if (v >= crit) return QColor(0xff, 0x50, 0x50);   // red
+    if (v >= warn) return QColor(0xff, 0xd0, 0x40);   // yellow
+    return QColor(0xff, 0xff, 0xff);                   // white (ok)
+  };
+
+  struct Row { QString label; QString value; QColor color; };
+  Row rows[] = {
+    {"LAG",  QString::number((int)lag_ms),  color_for(lag_ms,  50.f,  200.f)},
+    {"DROP", QString::number((int)drop_pct),color_for(drop_pct, 5.f,  15.f)},
+    {"TEMP", QString::number((int)temp_c),  color_for(temp_c,  75.f,  88.f)},
+    {"CPU",  QString::number(cpu_pct),      color_for((float)cpu_pct, 75.f, 90.f)},
+    {"MEM",  QString::number(mem_pct),      color_for((float)mem_pct, 70.f, 85.f)},
+  };
+
+  p.save();
+  p.setFont(InterFont(90, QFont::Bold));
+  QFontMetrics fm = p.fontMetrics();
+  int row_h = fm.height();              // natural line height at 90pt bold
+  int gap = 40;                         // requested 40px between values
+  int margin = 30;                      // requested 30px margin
+  int panel_w = 360;                    // fixed width — fits "TEMP 99"
+  int n = sizeof(rows) / sizeof(rows[0]);
+  int panel_h = n * row_h + (n - 1) * gap + 2 * margin;
+  int x = width() - panel_w - margin;
+  int y = height() - panel_h - margin;
+
+  // black background
+  p.setPen(Qt::NoPen);
+  p.setBrush(QColor(0, 0, 0, 200));
+  p.drawRoundedRect(QRect(x, y, panel_w, panel_h), 20, 20);
+
+  // rows
+  int text_y = y + margin + fm.ascent();
+  for (int i = 0; i < n; i++) {
+    p.setPen(rows[i].color);
+    // label left, value right
+    p.drawText(x + margin, text_y, rows[i].label);
+    QRect vrect = fm.boundingRect(rows[i].value);
+    p.drawText(x + panel_w - margin - vrect.width(), text_y, rows[i].value);
+    text_y += row_h + gap;
+  }
+  p.restore();
+}
+
 void AnnotatedCameraWidget::initializeGL() {
   CameraWidget::initializeGL();
   qInfo() << "OpenGL version:" << QString((const char*)glGetString(GL_VERSION));
@@ -867,8 +946,9 @@ void AnnotatedCameraWidget::drawLaneLines(QPainter &painter, const UIState *s) {
     }
 
     if (outlineOnly) {
+      // CLEARPILOT: center path (tire track) is 2x wider than other lines in nightrider
       painter.setPen(QPen(QColor(center_lane_color.red(), center_lane_color.green(),
-                                 center_lane_color.blue(), 180), outlineWidth));
+                                 center_lane_color.blue(), 180), outlineWidth * 2));
       painter.setBrush(Qt::NoBrush);
     } else {
       painter.setPen(Qt::NoPen);

selfdrive/ui/qt/onroad.h

@@ -53,6 +53,7 @@ private:
   void drawSpeedWidget(QPainter &p, int x, int y, const QString &title, const QString &speedLimitStr, QColor colorSpeed, int width = 176);
   void drawSpeedLimitSign(QPainter &p);
   void drawCruiseWarningSign(QPainter &p);
+  void drawHealthMetrics(QPainter &p);
 
   QVBoxLayout *main_layout;
   QPixmap dm_img;