first commit

apps/browser/visual-capture.cjs

@@ -0,0 +1,20 @@
+'use strict';
+const {guardedScreenshot}=require('./page-clipboard-guard.cjs');
+function bounded(operation,ms){let timer;return Promise.race([operation,new Promise((_,reject)=>{timer=setTimeout(()=>reject(Error('Visual capture timed out')),ms);})]).finally(()=>clearTimeout(timer));}
+async function capturePNG(contents,rect){
+  if(rect&&(!['x','y','width','height'].every(key=>Number.isInteger(rect[key]))||rect.x<0||rect.y<0||rect.width<16||rect.height<16||rect.width*rect.height>8*1024*1024))throw Error('Visual capture region invalid');
+  // Use Chromium's current render surface: Windows native capture can return a stale frame.
+  // Share the verified internal page-security connection when present; never detach it.
+  // No debugger endpoint or general command interface is exposed to sites or agents.
+  const parameters={format:'png',fromSurface:true,captureBeyondViewport:false,...(rect?{clip:{...rect,scale:1}}:{})};
+  const owned=guardedScreenshot(contents,parameters);
+  const debuggerAPI=contents.debugger;if(!debuggerAPI||!owned&&debuggerAPI.isAttached())throw Error('Visual capture unavailable');
+  let attached=false;
+  try{
+    if(!owned){debuggerAPI.attach('1.3');attached=true;}
+    const result=await bounded(owned||debuggerAPI.sendCommand('Page.captureScreenshot',parameters),3000);
+    if(typeof result?.data!=='string'||result.data.length>14*1024*1024||!/^[A-Za-z0-9+/]+={0,2}$/.test(result.data))throw Error('Visual capture bytes invalid');
+    return Buffer.from(result.data,'base64');
+  }finally{if(attached)debuggerAPI.detach();}
+}
+module.exports={capturePNG};