diff --git a/freeink-sdk b/freeink-sdk
index 26e3dac6..e7d33619 160000
--- a/freeink-sdk
+++ b/freeink-sdk
@@ -1 +1 @@
-Subproject commit 26e3dac6662639ad7790a4f101df7759b6176e6a
+Subproject commit e7d336191b5e45aa0ea9908fda7294fdd82a60b5
diff --git a/src/activities/boot_sleep/SleepActivity.cpp b/src/activities/boot_sleep/SleepActivity.cpp
index e7ff4317..a181df16 100644
--- a/src/activities/boot_sleep/SleepActivity.cpp
+++ b/src/activities/boot_sleep/SleepActivity.cpp
@@ -149,6 +149,10 @@ void SleepActivity::renderCustomSleepScreen() const {
   renderDefaultSleepScreen();
 }
 
+// Sleep screens paint with a single HALF refresh (stock parity): the OEM X4
+// firmware's only clean refresh in normal operation is the single-pass 0xD7
+// sequence, used once for the sleep image. It never runs the multi-flash GC
+// waveform (0xF7) that FULL_REFRESH selects (#2471's blinking complaint).
 void SleepActivity::renderDefaultSleepScreen() const {
   const auto pageWidth = renderer.getScreenWidth();
   const auto pageHeight = renderer.getScreenHeight();
@@ -163,7 +167,7 @@ void SleepActivity::renderDefaultSleepScreen() const {
     renderer.invertScreen();
   }
 
-  renderer.displayBuffer(HalDisplay::FULL_REFRESH);
+  renderer.displayBuffer(HalDisplay::HALF_REFRESH);
 }
 
 void SleepActivity::renderBitmapSleepScreen(const Bitmap& bitmap) const {
@@ -219,11 +223,13 @@ void SleepActivity::renderBitmapSleepScreen(const Bitmap& bitmap) const {
   }
 
   if (hasGreyscale) {
-    // OEM grayscale pipeline base: use a full sleep-screen paint so the panel
-    // enters deep sleep from a clean B/W baseline before the gray nudge refresh.
-    renderer.displayGrayscaleBase(HalDisplay::FULL_REFRESH);
+    // OEM grayscale pipeline base. Must stay HALF: the gray nudge LUT is
+    // calibrated against the pixel state the single-pass HALF waveform leaves
+    // behind. A FULL (GC) base parks pixels in a different charge state and
+    // the differential nudge then lands unevenly (blotchy noise in gray areas).
+    renderer.displayGrayscaleBase(HalDisplay::HALF_REFRESH);
   } else {
-    renderer.displayBuffer(HalDisplay::FULL_REFRESH);
+    renderer.displayBuffer(HalDisplay::HALF_REFRESH);
   }
 
   if (hasGreyscale) {
@@ -331,5 +337,5 @@ void SleepActivity::renderLastScreenSleepScreen() const {
 
 void SleepActivity::renderBlankSleepScreen() const {
   renderer.clearScreen();
-  renderer.displayBuffer(HalDisplay::FULL_REFRESH);
+  renderer.displayBuffer(HalDisplay::HALF_REFRESH);
 }