first pass implementation

js/src/preload.ts

@@ -41,6 +41,21 @@ contextBridge.exposeInMainWorld('electronAutoplay', {
   },
 });
 
+contextBridge.exposeInMainWorld('electronScreen', {
+  getScreenSources: () => ipcRenderer.invoke('screen:get-sources'),
+  startRecordingWindow: () => ipcRenderer.send('screen-record:start'),
+  stopRecordingWindow: () => ipcRenderer.send('screen-record:cancel'),
+  onStopRequested: (callback: () => void) => {
+    const handler = () => callback();
+    ipcRenderer.on('screen-record:stopped', handler);
+    return () => { ipcRenderer.removeListener('screen-record:stopped', handler); };
+  },
+});
+
+contextBridge.exposeInMainWorld('electronScreenRecord', {
+  stop: () => ipcRenderer.send('screen-record:stop'),
+});
+
 contextBridge.exposeInMainWorld('electronLink', {
   fetchMetadata: (url: string) => ipcRenderer.invoke('link:fetch-metadata', url),
   openExternal: (url: string) => ipcRenderer.invoke('link:open-external', url),