Free Heap when not on Message screen

src/MessageStore.cpp

@@ -251,7 +251,7 @@ void MessageStore::saveToFlash()
 
 void MessageStore::loadFromFlash()
 {
-    liveMessages.clear();
+    std::deque<StoredMessage>().swap(liveMessages);
     resetMessagePool(); // reset pool when loading
 
 #ifdef FSCom
@@ -289,7 +289,7 @@ void MessageStore::loadFromFlash() {}
 // Clear all messages (RAM + persisted queue)
 void MessageStore::clearAllMessages()
 {
-    liveMessages.clear();
+    std::deque<StoredMessage>().swap(liveMessages);
     resetMessagePool();
 
 #ifdef FSCom

src/graphics/Screen.cpp

@@ -715,6 +715,23 @@ int32_t Screen::runOnce()
     if (displayHeight == 0) {
         displayHeight = dispdev->getHeight();
     }
+
+    // Detect frame transitions and clear message cache when leaving text message screen
+    {
+        static int8_t lastFrameIndex = -1;
+        int8_t currentFrameIndex = ui->getUiState()->currentFrame;
+        int8_t textMsgIndex = framesetInfo.positions.textMessage;
+
+        if (lastFrameIndex != -1 && currentFrameIndex != lastFrameIndex) {
+
+            if (lastFrameIndex == textMsgIndex && currentFrameIndex != textMsgIndex) {
+                graphics::MessageRenderer::clearMessageCache();
+            }
+        }
+
+        lastFrameIndex = currentFrameIndex;
+    }
+
     menuHandler::handleMenuSwitch(dispdev);
 
     // Show boot screen for first logo_timeout seconds, then switch to normal operation.
@@ -1320,9 +1337,6 @@ void Screen::showFrame(FrameDirection direction)
 
         lastScreenTransition = millis();
         setFastFramerate();
-
-        // Reset scroll state when switching away from text message screen
-        graphics::MessageRenderer::resetScrollState();
     }
 }
 

src/graphics/draw/MenuHandler.cpp

@@ -481,6 +481,7 @@ void menuHandler::messageResponseMenu()
         } else if (selected == DismissAll) {
             messageStore.clearAllMessages();
             graphics::MessageRenderer::clearThreadRegistries();
+            graphics::MessageRenderer::clearMessageCache();
         } else if (selected == DismissOldest) {
             auto mode = graphics::MessageRenderer::getThreadMode();
             int ch = graphics::MessageRenderer::getThreadChannel();
@@ -919,9 +920,6 @@ void menuHandler::favoriteBaseMenu()
             graphics::MessageRenderer::setThreadMode(graphics::MessageRenderer::ThreadMode::DIRECT, -1,
                                                      graphics::UIRenderer::currentFavoriteNodeNum);
 
-            // Reset scroll state for a fresh view
-            graphics::MessageRenderer::resetScrollState();
-
             // Manually create and send a UIFrameEvent to trigger the jump
             UIFrameEvent evt;
             evt.action = UIFrameEvent::Action::SWITCH_TO_TEXTMESSAGE;

src/graphics/draw/MessageRenderer.cpp

@@ -209,8 +209,19 @@ void resetScrollState()
     scrollStartDelay = millis();
     lastTime = millis();
 
-    didReset = false; // <-- now valid
+    didReset = false;
 }
+
+// Fully free cached message data from heap
+void clearMessageCache()
+{
+    std::vector<std::string>().swap(cachedLines);
+    std::vector<int>().swap(cachedHeights);
+
+    // Reset scroll so we rebuild cleanly next time we enter the screen
+    resetScrollState();
+}
+
 // Current thread state
 static ThreadMode currentMode = ThreadMode::ALL;
 static int currentChannel = -1;

src/graphics/draw/MessageRenderer.h

@@ -60,6 +60,9 @@ void setThreadFor(const StoredMessage &sm, const meshtastic_MeshPacket &packet);
 // Handles a new incoming/outgoing message: banner, wake, thread select, scroll reset
 void handleNewMessage(const StoredMessage &sm, const meshtastic_MeshPacket &packet);
 
+// Clear Message Line Cache from Message Renderer
+void clearMessageCache();
+
 } // namespace MessageRenderer
 } // namespace graphics
 #endif