perf: remove launch source polling

Push selected-source changes from Electron to the launch window instead of polling every 500ms, reducing constant renderer and IPC churn. Also restore the TimelineEditor audio path narrowing fix so the current tree stays type-safe.

electron/electron-env.d.ts

@@ -39,6 +39,7 @@ interface Window {
 		selectSource: (source: any) => Promise<any>;
 		showSourceHighlight: (source: any) => Promise<{ success: boolean }>;
 		getSelectedSource: () => Promise<any>;
+		onSelectedSourceChanged: (callback: (source: any) => void) => () => void;
 		startNativeScreenRecording: (
 			source: any,
 			options?: {

electron/ipc/handlers.ts

@@ -43,6 +43,14 @@ function getScreen() {
   return nodeRequire('electron').screen as typeof import('electron').screen
 }
 
+function broadcastSelectedSourceChange() {
+  for (const window of BrowserWindow.getAllWindows()) {
+    if (!window.isDestroyed()) {
+      window.webContents.send('selected-source-changed', selectedSource)
+    }
+  }
+}
+
 type SelectedSource = {
   id?: string
   name: string
@@ -2575,6 +2583,7 @@ export function registerIpcHandlers(
 
   ipcMain.handle('select-source', (_, source: SelectedSource) => {
     selectedSource = source
+    broadcastSelectedSourceChange()
     stopWindowBoundsCapture()
     const sourceSelectorWin = getSourceSelectorWindow()
     if (sourceSelectorWin) {

electron/preload.ts

@@ -49,6 +49,11 @@ contextBridge.exposeInMainWorld("electronAPI", {
 	getSelectedSource: () => {
 		return ipcRenderer.invoke("get-selected-source");
 	},
+	onSelectedSourceChanged: (callback: (source: any) => void) => {
+		const listener = (_event: Electron.IpcRendererEvent, payload: any) => callback(payload);
+		ipcRenderer.on("selected-source-changed", listener);
+		return () => ipcRenderer.removeListener("selected-source-changed", listener);
+	},
 	startNativeScreenRecording: (
 		source: any,
 		options?: {

src/components/launch/LaunchWindow.tsx

@@ -297,20 +297,35 @@ export function LaunchWindow() {
 	};
 
 	useEffect(() => {
-		const checkSelectedSource = async () => {
-			if (!window.electronAPI) return;
-			const source = await window.electronAPI.getSelectedSource();
-			if (source) {
+		let mounted = true;
+
+		const applySelectedSource = (source: { name?: string } | null | undefined) => {
+			if (!mounted) {
+				return;
+			}
+
+			if (source?.name) {
 				setSelectedSource(source.name);
 				setHasSelectedSource(true);
-			} else {
-				setSelectedSource("Screen");
-				setHasSelectedSource(false);
+				return;
 			}
+
+			setSelectedSource("Screen");
+			setHasSelectedSource(false);
+		};
+
+		void window.electronAPI.getSelectedSource().then((source) => {
+			applySelectedSource(source);
+		});
+
+		const cleanup = window.electronAPI.onSelectedSourceChanged((source) => {
+			applySelectedSource(source);
+		});
+
+		return () => {
+			mounted = false;
+			cleanup?.();
 		};
-		void checkSelectedSource();
-		const interval = setInterval(checkSelectedSource, 500);
-		return () => clearInterval(interval);
 	}, []);
 
 	useEffect(() => {

src/components/video-editor/timeline/TimelineEditor.tsx

@@ -1179,9 +1179,11 @@ export default function TimelineEditor({
       return;
     }
 
+      const audioPath = result.path;
+
     // Load the audio file to get its full duration
     const audioDurationMs = await new Promise<number>((resolve) => {
-      const audio = new Audio(toFileUrl(result.path));
+        const audio = new Audio(toFileUrl(audioPath));
       audio.addEventListener('loadedmetadata', () => {
         resolve(Math.round(audio.duration * 1000));
       });