Add screenshot state flags

App/driver/bk4819.c

@@ -411,6 +411,11 @@ void BK4819_ToggleGpioOut(BK4819_GPIO_PIN_t Pin, bool bSet)
     BK4819_WriteRegister(BK4819_REG_33, gBK4819_GpioOutState);
 }
 
+bool BK4819_IsGpioOutSet(BK4819_GPIO_PIN_t Pin)
+{
+    return (gBK4819_GpioOutState & (0x40u >> Pin)) != 0;
+}
+
 void BK4819_SetCDCSSCodeWord(uint32_t CodeWord)
 {
     // REG_51

App/driver/bk4819.h

@@ -77,6 +77,7 @@ void     BK4819_SetAGC(bool enable);
 void     BK4819_InitAGC(bool amModulation);
 
 void     BK4819_ToggleGpioOut(BK4819_GPIO_PIN_t Pin, bool bSet);
+bool     BK4819_IsGpioOutSet(BK4819_GPIO_PIN_t Pin);
 
 void     BK4819_SetCDCSSCodeWord(uint32_t CodeWord);
 void     BK4819_SetCTCSSFrequency(uint32_t BaudRate);

App/driver/bk4829.c

@@ -441,6 +441,11 @@ void BK4819_ToggleGpioOut(BK4819_GPIO_PIN_t Pin, bool bSet)
     BK4819_WriteRegister(BK4819_REG_33, gBK4819_GpioOutState);
 }
 
+bool BK4819_IsGpioOutSet(BK4819_GPIO_PIN_t Pin)
+{
+    return (gBK4819_GpioOutState & (0x40u >> Pin)) != 0;
+}
+
 void BK4819_SetCDCSSCodeWord(uint32_t CodeWord)
 {
     // REG_51

App/screenshot.c

@@ -20,6 +20,7 @@
 #include "misc.h"
 #include "driver/vcp.h"
 #include "driver/keyboard.h"
+#include "driver/bk4819.h"
 
 // SRAM optimization: minimize static allocations
 // - previousHash: one fingerprint per 8-byte chunk instead of a full
@@ -76,8 +77,30 @@ enum {
     SCREENSHOT_CHUNK_SIZE = 8,
     SCREENSHOT_CHUNKS_PER_LINE = 16,
     SCREENSHOT_HALF_LINE_COLUMNS = LCD_WIDTH / 2,
+    SCREENSHOT_MARKER_BASE = 0xF0,
+    SCREENSHOT_FLAG_DEEP_SLEEP = 1 << 0,
+    SCREENSHOT_FLAG_LED_RED = 1 << 1,
+    SCREENSHOT_FLAG_LED_GREEN = 1 << 2,
 };
 
+static uint8_t SCREENSHOT_StateFlags(void)
+{
+    uint8_t flags = 0;
+
+#ifdef ENABLE_FEAT_F4HWN_SLEEP
+    if (gWakeUp)
+        flags |= SCREENSHOT_FLAG_DEEP_SLEEP;
+#endif
+
+    if (BK4819_IsGpioOutSet(BK4819_GPIO5_PIN1_RED))
+        flags |= SCREENSHOT_FLAG_LED_RED;
+
+    if (BK4819_IsGpioOutSet(BK4819_GPIO6_PIN2_GREEN))
+        flags |= SCREENSHOT_FLAG_LED_GREEN;
+
+    return flags;
+}
+
 // Compute one 8-byte output chunk directly from the display buffers.
 // Frame layout: per line (status + 7 frame lines), 8 bit layers of
 // 16 bytes each. Each bit layer is split into two 64-column chunks.
@@ -149,10 +172,9 @@ void SCREENSHOT_Update(bool force)
     if (gKeyReading0 != KEY_INVALID)
         return;
 
-    // ==== Send version marker (for backward compatibility detection) ====
+    // ==== Send version marker and state flags ====
-    // New format: sends 0xFF before header
+    // 0xF0 keeps a resync-safe marker before the standard AA 55 header.
-    // Old format: doesn't exist, so viewers can differentiate
+    uint8_t versionMarker = SCREENSHOT_MARKER_BASE | SCREENSHOT_StateFlags();
-    uint8_t versionMarker = 0xFF;
     SCREENSHOT_Send(&versionMarker, 1);
 
     // ==== Send header ====