fix(display): make the USER button click immediate, 3 s hold to power off

Power-off now needs a 3 second hold; any shorter press toggles the display.
MomentaryButton reports a CLICK for any release short of its threshold, so
that single value defines both.

The button also felt unreliable - "a brief press doesn't wake it, more often
than not". MomentaryButton's multi-click detection withholds a CLICK for
MULTI_CLICK_WINDOW_MS (280 ms) after release, and folds a second press
arriving inside that window into a DOUBLE_CLICK. Since the handler only acts
on CLICK, an impatient second press produced nothing at all: press, see
nothing, press again, still nothing. Multi-click is now off for these targets,
so CLICK fires on release.

Both settings are build flags defaulted in variants/heltec_v4_r8/target.cpp
and overridden only on the two TFT observer bases, because the companion
builds share this user_btn and do use double/triple click.

DISPLAY_TOUCH_DEBUG additionally logs which input caused a toggle
("Display: button -> on"), so any remaining flake can be attributed to the
button or to a spurious touch read rather than guessed at.

examples/simple_repeater/UITask.cpp

@@ -326,12 +326,17 @@ void UITask::updateActivityRows() {
 #endif
 
 #ifdef DISPLAY_TOUCH_TOGGLE
-void UITask::toggleDisplay() {
+void UITask::toggleDisplay(const char* source) {
   if (_display->isOn()) {
     _display->turnOff();
   } else {
     _display->turnOn();
   }
+#ifdef DISPLAY_TOUCH_DEBUG
+  Serial.printf("Display: %s -> %s\n", source, _display->isOn() ? "on" : "off");
+#else
+  (void)source;
+#endif
 #ifdef DISPLAY_REDRAW_ON_CHANGE
   _frame_valid = false;   // wake draws one complete current frame
 #endif
@@ -348,7 +353,7 @@ void UITask::loop() {
   int ev = user_btn.check();
   if (ev == BUTTON_EVENT_CLICK) {
 #ifdef DISPLAY_TOUCH_TOGGLE
-    toggleDisplay();   // same action as tapping the panel
+    toggleDisplay("button");   // same action as tapping the panel
 #else
     if (_display->isOn()) {
       // TODO: any action ?
@@ -392,7 +397,7 @@ void UITask::loop() {
     unsigned long now = millis();
     if (millisReached(now, _next_touch)) {
       _next_touch = now + TOUCH_POLL_MILLIS;
-      if (_touch.checkTap(now)) toggleDisplay();
+      if (_touch.checkTap(now)) toggleDisplay("touch");
     }
   }
 #endif

examples/simple_repeater/UITask.h

@@ -48,7 +48,7 @@ class UITask {
   CHSC6XTouch _touch;
   unsigned long _next_touch = 0;
 
-  void toggleDisplay();
+  void toggleDisplay(const char* source);
 #endif
 
 #ifdef WITH_MQTT_BRIDGE

examples/simple_room_server/UITask.cpp

@@ -303,12 +303,17 @@ void UITask::updateActivityRows() {
 #endif
 
 #ifdef DISPLAY_TOUCH_TOGGLE
-void UITask::toggleDisplay() {
+void UITask::toggleDisplay(const char* source) {
   if (_display->isOn()) {
     _display->turnOff();
   } else {
     _display->turnOn();
   }
+#ifdef DISPLAY_TOUCH_DEBUG
+  Serial.printf("Display: %s -> %s\n", source, _display->isOn() ? "on" : "off");
+#else
+  (void)source;
+#endif
 #ifdef DISPLAY_REDRAW_ON_CHANGE
   _frame_valid = false;   // wake draws one complete current frame
 #endif
@@ -327,7 +332,7 @@ void UITask::loop() {
     if (btnState != _prevBtnState) {
       if (btnState == USER_BTN_PRESSED) {  // pressed?
 #ifdef DISPLAY_TOUCH_TOGGLE
-        toggleDisplay();   // same action as tapping the panel
+        toggleDisplay("button");   // same action as tapping the panel
 #else
         if (_display->isOn()) {
           // TODO: any action ?
@@ -371,7 +376,7 @@ void UITask::loop() {
     unsigned long now = millis();
     if (millisReached(now, _next_touch)) {
       _next_touch = now + TOUCH_POLL_MILLIS;
-      if (_touch.checkTap(now)) toggleDisplay();
+      if (_touch.checkTap(now)) toggleDisplay("touch");
     }
   }
 #endif

examples/simple_room_server/UITask.h

@@ -45,7 +45,7 @@ class UITask {
   CHSC6XTouch _touch;
   unsigned long _next_touch = 0;
 
-  void toggleDisplay();
+  void toggleDisplay(const char* source);
 #endif
 
 #ifdef WITH_MQTT_BRIDGE

variants/heltec_v4_r8/platformio.ini

@@ -339,6 +339,10 @@ build_flags =
 ; Blanking is a runtime setting now: `set display.timeout <secs>`, 0 = stay on,
 ; 60 s default. Tap the Expansion Kit panel or press USER to toggle by hand.
   -D DISPLAY_TOUCH_TOGGLE=1
+; Hold 3 s to power off; any shorter press toggles the display, acted on the
+; moment the button is released rather than 280 ms later.
+  -D USER_BTN_LONG_PRESS_MILLIS=3000
+  -D USER_BTN_MULTICLICK=0
 ; Diagnostic: logs the raw CHSC6X frame (and TP_INT) when it changes. Drop this
 ; and PIN_TOUCH_INT once touch is confirmed working.
   -D DISPLAY_TOUCH_DEBUG=1
@@ -414,6 +418,10 @@ build_flags =
 ; Blanking is a runtime setting now: `set display.timeout <secs>`, 0 = stay on,
 ; 60 s default. Tap the Expansion Kit panel or press USER to toggle by hand.
   -D DISPLAY_TOUCH_TOGGLE=1
+; Hold 3 s to power off; any shorter press toggles the display, acted on the
+; moment the button is released rather than 280 ms later.
+  -D USER_BTN_LONG_PRESS_MILLIS=3000
+  -D USER_BTN_MULTICLICK=0
 ; Diagnostic: logs the raw CHSC6X frame (and TP_INT) when it changes. Drop this
 ; and PIN_TOUCH_INT once touch is confirmed working.
   -D DISPLAY_TOUCH_DEBUG=1

variants/heltec_v4_r8/target.cpp

@@ -25,7 +25,19 @@ AutoDiscoverRTCClock rtc_clock(fallback_clock);
 
 #ifdef DISPLAY_CLASS
   DISPLAY_CLASS display(&board.periph_power);
-  MomentaryButton user_btn(PIN_USER_BTN, 1000, true);
+  #ifndef USER_BTN_LONG_PRESS_MILLIS
+    #define USER_BTN_LONG_PRESS_MILLIS 1000
+  #endif
+  // Multi-click detection holds a CLICK back for MULTI_CLICK_WINDOW_MS (280 ms)
+  // after release, and folds a second press inside that window into a
+  // DOUBLE_CLICK. Targets that only want a plain click set this to 0 so the
+  // event fires on release instead of being delayed - or swallowed when an
+  // impatient second press arrives.
+  #ifndef USER_BTN_MULTICLICK
+    #define USER_BTN_MULTICLICK 1
+  #endif
+  MomentaryButton user_btn(PIN_USER_BTN, USER_BTN_LONG_PRESS_MILLIS, true, false,
+                           USER_BTN_MULTICLICK);
 #endif
 
 bool radio_init() {