diff --git a/app.js b/app.js
index b396094..39ef973 100644
--- a/app.js
+++ b/app.js
@@ -826,6 +826,9 @@ window.addEventListener('status-update', (/** @type {CustomEvent} */ event) => {
 
 window.addEventListener('pr-notification', (/** @type {CustomEvent} */ event) => {
   console.log('[hermes] PR notification:', event.detail);
+  if (event.detail && event.detail.action === 'merged') {
+    triggerMergeFlash();
+  }
 });
 
 // === SOVEREIGNTY EASTER EGG ===
@@ -898,6 +901,62 @@ function triggerSovereigntyEasterEgg() {
   requestAnimationFrame(fadeBack);
 }
 
+/**
+ * Triggers a visual flash effect for merge events: stars pulse bright, lines glow.
+ */
+function triggerMergeFlash() {
+  // Flash constellation lines bright blue-green
+  const originalLineColor = constellationLines.material.color.getHex();
+  constellationLines.material.color.setHex(0x00ffff);
+  constellationLines.material.opacity = 1.0;
+
+  // Stars burst bright blue-green
+  const originalStarColor = starMaterial.color.getHex();
+  const originalStarOpacity = starMaterial.opacity;
+  starMaterial.color.setHex(0x00ffff);
+  starMaterial.opacity = 1.0;
+
+  // Animate fade-out over 2.0s
+  const startTime = performance.now();
+  const DURATION = 2000; // 2 seconds
+
+  function fadeBack() {
+    const t = Math.min((performance.now() - startTime) / DURATION, 1);
+    const eased = t * t; // ease in: slow start, fast end
+
+    // Interpolate star color back
+    const mergeR = 0.0, mergeG = 1.0, mergeB = 1.0; // Cyan
+    const origStarColor = new THREE.Color(originalStarColor);
+    starMaterial.color.setRGB(
+      mergeR + (origStarColor.r - mergeR) * eased,
+      mergeG + (origStarColor.g - mergeG) * eased,
+      mergeB + (origStarColor.b - mergeB) * eased
+    );
+    starMaterial.opacity = 1.0 + (originalStarOpacity - 1.0) * eased;
+
+    // Interpolate line color back
+    const origLineColor = new THREE.Color(originalLineColor);
+    constellationLines.material.color.setRGB(
+      mergeR + (origLineColor.r - mergeR) * eased,
+      mergeG + (origLineColor.g - mergeG) * eased,
+      mergeB + (origLineColor.b - mergeB) * eased
+    );
+    constellationLines.material.opacity = 1.0 + (0.18 - 1.0) * eased; // Assuming original opacity is 0.18 for lines.
+
+    if (t < 1) {
+      requestAnimationFrame(fadeBack);
+    } else {
+      // Restore originals exactly
+      starMaterial.color.setHex(originalStarColor);
+      starMaterial.opacity = originalStarOpacity;
+      constellationLines.material.color.setHex(originalLineColor);
+      constellationLines.material.opacity = 0.18; // Explicitly set to original
+    }
+  }
+
+  requestAnimationFrame(fadeBack);
+}
+
 // Detect 'sovereignty' typed anywhere on the page (cheat-code style)
 document.addEventListener('keydown', (e) => {
   if (e.metaKey || e.ctrlKey || e.altKey) return;