update

examples/companion_radio/main.cpp

@@ -2564,6 +2564,21 @@ void handleKeyboardInput() {
   // Still read the key above to clear the TCA8418 buffer.
   if (ui_task.isLocked()) return;
 
+  // Alt+B backlight toggle (T-Deck Pro MAX — working front-light on IO41)
+  // Cycles: off → low → medium → full → off
+  // Works from any screen; processed before anything else so it never
+  // leaks into compose buffers or screen handlers.
+  #ifdef LilyGo_TDeck_Pro_Max
+  if (key == KB_KEY_BACKLIGHT) {
+    static uint8_t blLevel = 0;  // 0=off, 1=low, 2=med, 3=full
+    blLevel = (blLevel + 1) & 3;
+    const uint8_t levels[] = {0, 64, 160, 255};
+    board.backlightSetBrightness(levels[blLevel]);
+    Serial.printf("Backlight: level %d (%d/255)\n", blLevel, levels[blLevel]);
+    return;
+  }
+  #endif
+
   // Dismiss boot navigation hint on any keypress
   if (ui_task.isHintActive()) {
     ui_task.dismissBootHint();

variants/lilygo_tdeck_pro_max/Tca8418keyboard.h

@@ -22,6 +22,7 @@
 #define KB_KEY_ENTER     '\r'
 #define KB_KEY_SPACE     ' '
 #define KB_KEY_EMOJI     0x01   // Non-printable code for $ key (emoji picker)
+#define KB_KEY_BACKLIGHT 0x02   // Non-printable code for Alt+B (backlight toggle, MAX only)
 
 class TCA8418Keyboard {
 private:
@@ -290,6 +291,13 @@ public:
     // Get the character
     char c = 0;
     
+    // Alt+B -> backlight toggle (T-Deck Pro MAX only — working front-light on IO41)
+    if (_altActive && keyCode == 25) {  // keyCode 25 = B
+      _altActive = false;
+      Serial.println("KB: Alt+B -> backlight toggle");
+      return KB_KEY_BACKLIGHT;
+    }
+
     if (_altActive) {
       c = getAltChar(keyCode);
       _altActive = false;  // Reset sticky alt