wasm improvements

interfaces/Crafter.Graphics-Window.cppm

@@ -121,7 +121,22 @@ export namespace Crafter {
         ~Window();
         #endif
 
+        // Enter the platform event loop and never return. In DOM mode this
+        // hands the loop to requestAnimationFrame and _Exit(0)s so the wasm
+        // instance survives without running static destructors. No caller
+        // code after this point ever runs, on any target.
         void StartSync();
+
+        // As StartSync, but does NOT start the animation-frame loop in DOM
+        // mode — for event-driven pages that only touch the DOM and never
+        // draw. A rAF tick running forever to do nothing costs battery in
+        // every open tab. Still never returns.
+        //
+        // On native this is identical to StartSync: the event loop is what
+        // keeps a window alive there, so there is no cheaper option. Call it
+        // unconditionally and get the browser saving without an #ifdef.
+        void StayAlive();
+
         void StartUpdate();
         void StopUpdate();
         void SetTitle(const std::string_view title);