fix: ensure backlight turns back on during startMcpScreensaver and invalidate canvas on drawText

Tactility/Private/Tactility/service/displayidle/DisplayIdleService.h

@@ -57,6 +57,12 @@ public:
      */
     void startScreensaver();
 
+    /**
+     * Force the MCP screensaver specifically, regardless of the current
+     * screensaver type setting. Safe to call from any thread (acquires LVGL lock).
+     */
+    void startMcpScreensaver();
+
     /**
      * Force the screensaver to stop immediately and restore backlight.
      * @note Not thread-safe. Call from LVGL/main context only, not from

Tactility/Source/mcp/McpSystem.cpp

@@ -78,12 +78,12 @@ static bool display_ready(McpSystemState& state) {
 static bool ensureOverrideScreen() {
     auto& state = getState();
     if (state.drawArea == nullptr) {
-        // Activate the MCP Screen screensaver via DisplayIdle
+        // Activate the MCP screensaver via DisplayIdle (force McpScreensaver type)
         auto idleService = service::displayidle::findService();
         if (idleService) {
-            LOGGER.info("MCP draw triggered: starting MCP screensaver");
-            idleService->startScreensaver();
-            // Wait up to 500ms for the canvas to be registered
+            LOGGER.info("MCP draw triggered: activating MCP screensaver");
+            idleService->startMcpScreensaver();
+            // Wait up to 500ms for the canvas to be registered by McpScreensaver::start()
             for (int i = 0; i < 10; ++i) {
                 vTaskDelay(pdMS_TO_TICKS(50));
                 if (state.drawArea != nullptr) {
@@ -162,6 +162,7 @@ bool drawText(const std::string& text, int x, int y, int size) {
             }
 #endif
 
+            lv_obj_invalidate(state.drawArea);  // Trigger repaint
             state.overrideActive = true;
             success = true;
         }

Tactility/Source/service/displayidle/DisplayIdle.cpp

@@ -16,6 +16,7 @@
 #include <Tactility/service/ServiceContext.h>
 #include <Tactility/service/ServiceManifest.h>
 #include <Tactility/service/ServiceRegistration.h>
+#include <Tactility/mcp/McpSystem.h>
 #include <cstdlib>
 #include <ctime>
 
@@ -263,6 +264,60 @@ void DisplayIdleService::reloadSettings() {
     settingsReloadRequested.store(true, std::memory_order_release);
 }
 
+void DisplayIdleService::startMcpScreensaver() {
+    if (!lvgl::lock(200)) {
+        LOGGER.warn("startMcpScreensaver: failed to acquire LVGL lock");
+        return;
+    }
+
+    if (screensaverOverlay != nullptr) {
+        // Screensaver already active — if drawArea is registered we're done,
+        // otherwise stop the current one so we can replace it with McpScreensaver.
+        const auto& mcpState = mcp::getState();
+        if (mcpState.drawArea != nullptr) {
+            lvgl::unlock();
+            return; // McpScreensaver already running
+        }
+        // Wrong screensaver type active — tear it down first
+        if (screensaver) {
+            screensaver->stop();
+            screensaver.reset();
+        }
+        lv_obj_delete(screensaverOverlay);
+        screensaverOverlay = nullptr;
+    }
+
+    screensaverActiveCounter = 0;
+    backlightOff = false;
+
+    // Ensure backlight is active and set to configured duty cycle
+    auto display = getDisplay();
+    if (display) {
+        display->setBacklightDuty(cachedDisplaySettings.backlightDuty);
+    }
+
+    lv_coord_t screenW = lv_display_get_horizontal_resolution(nullptr);
+
+    lv_coord_t screenH = lv_display_get_vertical_resolution(nullptr);
+
+    lv_obj_t* top = lv_layer_top();
+    screensaverOverlay = lv_obj_create(top);
+    lv_obj_remove_style_all(screensaverOverlay);
+    lv_obj_set_size(screensaverOverlay, LV_PCT(100), LV_PCT(100));
+    lv_obj_set_pos(screensaverOverlay, 0, 0);
+    lv_obj_set_style_bg_color(screensaverOverlay, lv_color_black(), 0);
+    lv_obj_set_style_bg_opa(screensaverOverlay, LV_OPA_COVER, 0);
+    lv_obj_add_flag(screensaverOverlay, LV_OBJ_FLAG_CLICKABLE);
+    lv_obj_add_event_cb(screensaverOverlay, stopScreensaverCb, LV_EVENT_CLICKED, this);
+
+    screensaver = std::make_unique<McpScreensaver>();
+    screensaver->start(screensaverOverlay, screenW, screenH);
+
+    lvgl::unlock();
+    displayDimmed = true;
+    LOGGER.info("MCP screensaver activated");
+}
+
 std::shared_ptr<DisplayIdleService> findService() {
     return std::static_pointer_cast<DisplayIdleService>(
         findServiceById("DisplayIdle")