Free Heap when not on Message screen

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