app.js

@@ -39,7 +39,7 @@ let atlasOverlayActive = false;
 let thoughtStreamMesh;
 let harnessPulseMesh;
 let powerMeterBars = [];
-let particles, dustParticles;
+let particles, dustParticles, ambientLight;
 let debugOverlay;
 let frameCount = 0, lastFPSTime = 0, fps = 0;
 let chatOpen = true;
@@ -301,8 +301,8 @@ function createSkybox() {
 
 // ═══ LIGHTING ═══
 function createLighting() {
-  const ambient = new THREE.AmbientLight(0x1a1a3a, 0.4);
-  scene.add(ambient);
+  ambientLight = new THREE.AmbientLight(0x1a1a3a, 0.4);
+  scene.add(ambientLight);
 
   const dirLight = new THREE.DirectionalLight(0x4466aa, 0.6);
   dirLight.position.set(10, 20, 10);
@@ -1735,6 +1735,7 @@ function gameLoop() {
   }
 
   updateAshStorm(delta, elapsed);
+  updateNexusHeartbeat(delta, elapsed);
 
   const mode = NAV_MODES[navModeIdx];
   const chatActive = document.activeElement === document.getElementById('chat-input');
@@ -2096,6 +2097,27 @@ function updateAshStorm(delta, elapsed) {
   }
 }
 
+function updateNexusHeartbeat(delta, elapsed) {
+  // Calculate heartbeat frequency (0.5 to 1.5 Hz based on time)
+  const pulse = 1.0 + Math.sin(elapsed * 0.2) * 0.5;
+  const heartbeatVal = document.getElementById('heartbeat-value');
+  if (heartbeatVal) {
+    heartbeatVal.textContent = `${pulse.toFixed(2)} Hz`;
+  }
+
+  // Breathing effect for ambient light
+  if (ambientLight) {
+    const intensity = 0.3 + Math.sin(elapsed * pulse * Math.PI) * 0.1;
+    ambientLight.intensity = intensity;
+  }
+
+  // Update heartbeat pulse animation speed
+  const pulseEl = document.querySelector('.heartbeat-pulse');
+  if (pulseEl) {
+    pulseEl.style.animationDuration = `${1 / pulse}s`;
+  }
+}
+
 init().then(() => {
   createAshStorm();
   createPortalTunnel();

index.html

@@ -65,8 +65,15 @@
 
 <!-- HUD Overlay -->
 <div id="hud" class="game-ui" style="display:none;">
-  <!-- Top Left: Debug -->
-  <div id="debug-overlay" class="hud-debug"></div>
+  <!-- Top Left: Debug & Heartbeat -->
+  <div class="hud-top-left">
+    <div id="debug-overlay" class="hud-debug"></div>
+    <div id="nexus-heartbeat" class="hud-heartbeat" title="Nexus Pulse">
+      <div class="heartbeat-pulse"></div>
+      <div class="heartbeat-label">NEXUS PULSE</div>
+      <div id="heartbeat-value" class="heartbeat-value">0.00 Hz</div>
+    </div>
+  </div>
 
   <!-- Top Center: Location -->
   <div class="hud-location" aria-live="polite">

style.css

@@ -426,10 +426,17 @@ canvas#nexus-canvas {
 }
 
 /* Debug overlay */
-.hud-debug {
+.hud-top-left {
   position: absolute;
   top: var(--space-3);
   left: var(--space-3);
+  display: flex;
+  flex-direction: column;
+  gap: var(--space-2);
+  pointer-events: none;
+}
+
+.hud-debug {
   background: rgba(0, 0, 0, 0.7);
   color: #0f0;
   font-size: var(--text-xs);
@@ -437,10 +444,49 @@ canvas#nexus-canvas {
   padding: var(--space-2) var(--space-3);
   border-radius: 4px;
   white-space: pre;
-  pointer-events: none;
   font-variant-numeric: tabular-nums lining-nums;
 }
 
+.hud-heartbeat {
+  background: rgba(0, 0, 0, 0.6);
+  backdrop-filter: blur(4px);
+  border: 1px solid rgba(74, 240, 192, 0.2);
+  border-radius: 4px;
+  padding: 8px 12px;
+  display: flex;
+  align-items: center;
+  gap: 10px;
+  pointer-events: auto;
+}
+
+.heartbeat-pulse {
+  width: 10px;
+  height: 10px;
+  background: var(--color-primary);
+  border-radius: 50%;
+  box-shadow: 0 0 10px var(--color-primary);
+  animation: pulse-heartbeat 2s infinite ease-in-out;
+}
+
+@keyframes pulse-heartbeat {
+  0%, 100% { transform: scale(1); opacity: 0.8; }
+  50% { transform: scale(1.4); opacity: 1; box-shadow: 0 0 15px var(--color-primary); }
+}
+
+.heartbeat-label {
+  font-family: var(--font-display);
+  font-size: 9px;
+  letter-spacing: 0.1em;
+  color: var(--color-text-muted);
+}
+
+.heartbeat-value {
+  font-family: var(--font-mono);
+  font-size: 11px;
+  color: var(--color-primary);
+  min-width: 45px;
+}
+
 /* Location indicator */
 .hud-location {
   position: absolute;