diff --git a/App/apps/app_menu.c b/App/apps/app_menu.c
index b77f6cd0..8ea8f942 100644
--- a/App/apps/app_menu.c
+++ b/App/apps/app_menu.c
@@ -25,6 +25,9 @@
 #include "driver/system.h"
 #include "driver/gpio.h"
 #include "ui/helper.h"
+#ifdef ENABLE_FEAT_F4HWN_K5VIEWER
+#include "k5viewer.h"
+#endif
 
 /* "F4HWN APPS" banner and the same thin separator used by the multiboot
  * selector.  Bit 3 leaves room for the selected-row capsule's top edge. */
@@ -75,6 +78,12 @@ static KEY_Code_t app_get_key(void)
 {
     for (;;)
     {
+#ifdef ENABLE_FEAT_F4HWN_K5VIEWER
+        /* APP_MenuOpen() is modal and does not return to APP_Update(). Keep
+         * serial key injection and the viewer connection alive while waiting. */
+        K5VIEWER_ParseInput();
+        K5VIEWER_Update(false);
+#endif
         KEY_Code_t key = KEYBOARD_Poll();
         if (key != KEY_INVALID)
         {
@@ -179,6 +188,15 @@ _Static_assert(APP_MENU_SLOT_COUNT <= APP_SLOT_COUNT,
 
 void APP_MenuOpen(void)
 {
+#ifdef ENABLE_FEAT_F4HWN_K5VIEWER
+    /* Detach the modal selector from the key state that triggered F+7. The
+     * normal K5Viewer updater suppresses frames while a key is held; without
+     * clearing this stale state, the selector could never publish its first
+     * frame to the viewer. */
+    gKeyReading0 = KEY_INVALID;
+    gKeyReading1 = KEY_INVALID;
+#endif
+
     /* Apps are installed from UV Studio (0x073x) into physical slots 0..N-1,
      * shown here as 1..N.  Keep empty slots in the list so their location is
      * visible and selectable while scrolling. */
@@ -245,6 +263,9 @@ void APP_MenuOpen(void)
 
         ST7565_BlitStatusLine();
         ST7565_BlitFullScreen();
+#ifdef ENABLE_FEAT_F4HWN_K5VIEWER
+        K5VIEWER_Update(false);
+#endif
 
         const KEY_Code_t key = app_get_key();
         if (key == KEY_EXIT)
diff --git a/App/apps/app_overlay.c b/App/apps/app_overlay.c
index 499ea1d0..4291e6da 100644
--- a/App/apps/app_overlay.c
+++ b/App/apps/app_overlay.c
@@ -33,6 +33,9 @@
 #include "driver/st7565.h"
 #include "driver/system.h"
 #include "driver/backlight.h"
+#ifdef ENABLE_FEAT_F4HWN_K5VIEWER
+#include "k5viewer.h"
+#endif
 #include "app/app.h"
 #include "ui/helper.h"
 #include "ui/main.h"
@@ -50,7 +53,25 @@
 _Static_assert(sizeof(app_header_t) == 64, "app_header_t must be 64 bytes");
 
 /* ---- ABI wrappers: the few resident calls that are not a direct signature match ---- */
-static uint8_t app_get_key(void)       { return (uint8_t)KEYBOARD_GetKey(); }
+static uint8_t app_get_key(void)
+{
+#ifdef ENABLE_FEAT_F4HWN_K5VIEWER
+    /* Overlay apps run synchronously outside APP_Update(). Keep serial key
+     * injection alive while an app owns the foreground loop. */
+    K5VIEWER_ParseInput();
+#endif
+    return (uint8_t)KEYBOARD_GetKey();
+}
+
+#ifdef ENABLE_FEAT_F4HWN_K5VIEWER
+static void app_blit_full(void)
+{
+    ST7565_BlitFullScreen();
+    /* The normal loop mirrors completed frames after drawing. Overlay apps
+     * bypass that loop, so publish the frame from this ABI wrapper. */
+    K5VIEWER_Update(false);
+}
+#endif
 static int8_t  app_nav_dir(uint8_t key)
 {
     int8_t direction;
@@ -635,7 +656,11 @@ static const app_api_t app_api = {
     .draw_rect        = UI_DrawRectangleBuffer,
     .print_bold       = UI_PrintStringSmallBold,
     .print_tiny       = GUI_DisplaySmallest,
+#ifdef ENABLE_FEAT_F4HWN_K5VIEWER
+    .blit_full        = app_blit_full,
+#else
     .blit_full        = ST7565_BlitFullScreen,
+#endif
     .blit_line        = ST7565_BlitLine,
     .blit_status      = ST7565_BlitStatusLine,
     .get_key          = app_get_key,
@@ -730,6 +755,14 @@ uint8_t APP_LaunchOverlay(uint8_t slot)
     app_fm_dirty = false;
 #endif
 
+#ifdef ENABLE_FEAT_F4HWN_K5VIEWER
+    /* The caller enters from a debounced key event, so the resident key state
+     * still contains that trigger while the modal app is running. Clear it so
+     * K5Viewer is allowed to mirror overlay frames immediately. */
+    gKeyReading0 = KEY_INVALID;
+    gKeyReading1 = KEY_INVALID;
+#endif
+
     /* Pin RX to the user-selected VFO before the app runs. Under dual watch
      * gRxVfo is whichever VFO the receiver was parked on when F+7 was pressed,
      * so an RF app (FoxHunt, a future S-meter, ...) would measure and display a