Invaliating browser cache after UI selection change

wled00/set.cpp

@@ -193,6 +193,10 @@ void handleSettingsSet(AsyncWebServerRequest *request, byte subPage)
     strlcpy(serverDescription, request->arg(F("DS")).c_str(), 33);
     syncToggleReceive = request->hasArg(F("ST"));
   #ifndef WLED_DISABLE_SIMPLE_UI
+    if (simplifiedUI ^ request->hasArg(F("SU"))) {
+      // UI selection changed, invalidate browser cache
+      cacheInvalidate++;
+    }
     simplifiedUI = request->hasArg(F("SU"));
   #endif
   }

wled00/wled.h

@@ -8,7 +8,7 @@
  */
 
 // version code in format yymmddb (b = daily build)
-#define VERSION 2108091
+#define VERSION 2108101
 
 //uncomment this if you have a "my_config.h" file you'd like to use
 //#define WLED_USE_MY_CONFIG
@@ -282,6 +282,7 @@ WLED_GLOBAL byte briMultiplier _INIT(100);          // % of brightness to set (t
 WLED_GLOBAL char serverDescription[33] _INIT("WLED");  // Name of module
 WLED_GLOBAL bool syncToggleReceive     _INIT(false);   // UIs which only have a single button for sync should toggle send+receive if this is true, only send otherwise
 WLED_GLOBAL bool simplifiedUI          _INIT(false);   // enable simplified UI
+WLED_GLOBAL byte cacheInvalidate       _INIT(0);       // used to invalidate browser cache when switching from regular to simplified UI
 
 // Sync CONFIG
 WLED_GLOBAL NodesMap Nodes;

wled00/wled_server.cpp

@@ -285,12 +285,14 @@ bool handleIfNoneMatchCacheHeader(AsyncWebServerRequest* request)
 
 void setStaticContentCacheHeaders(AsyncWebServerResponse *response)
 {
+  char tmp[12];
   #ifndef WLED_DEBUG
   response->addHeader(F("Cache-Control"),"max-age=604800");     // 7 day caching
   #else
   response->addHeader(F("Cache-Control"),"no-store,max-age=0"); // prevent caching if debug build
   #endif
-  response->addHeader(F("ETag"), String(VERSION));
+  sprintf_P(tmp, PSTR("%8d-%02x"), VERSION, cacheInvalidate);
+  response->addHeader(F("ETag"), tmp);
 }
 
 void serveIndex(AsyncWebServerRequest* request)