wait for SteamApp init stage 1 to finish before loading decky's front…

…end bundle

should fix the startup race condition

frontend/src/index.ts

@@ -2,32 +2,22 @@
 interface Window {
   // Shut up TS
   SP_REACTDOM: any;
+  App: any; // TODO type BFinishedInitStageOne in @decky/ui
 }
 
 (async () => {
-  // Wait for main webpack chunks to definitely be loaded
-  console.time('[Decky:Boot] Waiting for main Webpack chunks...');
-  while (!window.webpackChunksteamui || window.webpackChunksteamui.length < 5) {
-    await new Promise((r) => setTimeout(r, 10)); // Can't use DFL sleep here.
-  }
-  console.timeEnd('[Decky:Boot] Waiting for main Webpack chunks...');
+  console.debug('[Decky:Boot] Frontend init');
+
+  console.time('[Decky:Boot] Waiting for SteamApp init stage 1 to finish...');
 
-  // Wait for the React root to be mounted
-  console.time('[Decky:Boot] Waiting for React root mount...');
-  let root;
-  while (
-    // Does React root node exist?
-    !(root = document.getElementById('root')) ||
-    // Does it have a child element?
-    !(root as any)[Object.keys(root).find((k) => k.startsWith('__reactContainer$')) as string].child
-  ) {
-    await new Promise((r) => setTimeout(r, 10)); // Can't use DFL sleep here.
+  while (!window.App?.BFinishedInitStageOne()) {
+    await new Promise((r) => setTimeout(r, 0)); // Can't use DFL sleep here.
   }
-  console.timeEnd('[Decky:Boot] Waiting for React root mount...');
+
+  console.timeEnd('[Decky:Boot] Waiting for SteamApp init stage 1 to finish...');
 
   if (!window.SP_REACT) {
     console.debug('[Decky:Boot] Setting up Webpack & React globals...');
-    await new Promise((r) => setTimeout(r, 500)); // Can't use DFL sleep here.
     // deliberate partial import
     const DFLWebpack = await import('@decky/ui/dist/webpack');
     window.SP_REACT = DFLWebpack.findModule((m) => m.Component && m.PureComponent && m.useLayoutEffect);