fix(voice): reuse the Linux audio capture across routing changes (#2440)

fluxer_desktop/src/main/NativeAudio.ts

@@ -40,6 +40,7 @@ interface NativeCaptureInstance {
 	removeListener(event: 'closed', listener: () => void): this;
 	start(): Promise<void> | void;
 	stop(): Promise<void> | void;
+	setRoutingRule?: (target: {linuxRule: NonNullable<NativeAudioStartOptions['linuxRule']>}) => boolean;
 	routingGraph?: () => VirtmicRoutingGraph | null;
 }
 
@@ -631,6 +632,23 @@ async function stopCaptureById(
 	await stopActiveSession(session, reason, detail);
 }
 
+function reconfigureCaptureById(
+	senderId: number,
+	captureId: string,
+	linuxRule: NonNullable<NativeAudioStartOptions['linuxRule']>,
+): boolean {
+	const session = activeSessions.get(captureId);
+	if (!session || session.sender.id !== senderId) return false;
+	if (session.finalized || session.stopping) return false;
+	if (typeof session.capture.setRoutingRule !== 'function') return false;
+	try {
+		return session.capture.setRoutingRule({linuxRule});
+	} catch (error) {
+		logger.warn('Failed to reconfigure native audio routing in place', {captureId, error});
+		return false;
+	}
+}
+
 async function makeRoomForSenderSession(senderId: number): Promise<void> {
 	const senderSessions = activeSessionIdsBySenderId.get(senderId);
 	if (!senderSessions) return;
@@ -885,6 +903,15 @@ export function registerNativeAudioHandlers(): void {
 		(event, options: NativeAudioStartOptions): Promise<NativeAudioStartResult> =>
 			startNativeAudioCapture(event.sender, options),
 	);
+	ipcMain.handle(
+		'native-audio:set-rule',
+		(event, captureId: unknown, linuxRule: NativeAudioStartOptions['linuxRule']): boolean => {
+			if (typeof captureId !== 'string' || !isValidLinuxRule(linuxRule)) {
+				return false;
+			}
+			return reconfigureCaptureById(event.sender.id, captureId, linuxRule);
+		},
+	);
 	ipcMain.handle('native-audio:stop', async (event, captureId: string): Promise<void> => {
 		const session = activeSessions.get(captureId);
 		if (!session || session.sender.id !== event.sender.id) {
@@ -904,6 +931,7 @@ export function cleanupNativeAudio(): void {
 	ipcMain.removeHandler('native-audio:list-applications');
 	ipcMain.removeHandler('native-audio:resolve-root-pid');
 	ipcMain.removeHandler('native-audio:start');
+	ipcMain.removeHandler('native-audio:set-rule');
 	ipcMain.removeHandler('native-audio:stop');
 	ipcMain.removeHandler('native-audio:get-routing-graph');
 	handlersRegistered = false;