Fix: Move scroll injection to service worker

Offscreen documents can only use chrome.runtime API, not chrome.scripting.
This was likely causing the Chrome crash when reloading the extension.

- offscreen.js now sends 'injectScroll' message to service worker
- background.js handles scroll script injection via chrome.scripting.executeScript

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: MaxGhenis

background.js

@@ -6,9 +6,44 @@ chrome.runtime.onMessage.addListener((message, sender, sendResponse) => {
     startRecording(message.tabId, message.duration, message.delay);
     sendResponse({ status: 'started' });
   }
+  if (message.action === 'injectScroll') {
+    injectScrollScript(message.tabId, message.duration);
+    sendResponse({ status: 'injected' });
+  }
   if (message.action === 'recordingComplete') {
     handleRecordingComplete();
     console.log('Recording saved!');
   }
   return true;
 });
+
+// Inject scroll script into target tab (called by offscreen document)
+async function injectScrollScript(tabId, duration) {
+  try {
+    console.log('Injecting scroll script for', duration, 'seconds');
+    await chrome.scripting.executeScript({
+      target: { tabId },
+      func: (scrollDuration) => {
+        const totalHeight = document.documentElement.scrollHeight - window.innerHeight;
+        const startTime = Date.now();
+        const endTime = startTime + (scrollDuration * 1000);
+
+        function smoothScroll() {
+          const now = Date.now();
+          if (now >= endTime) return;
+
+          const progress = (now - startTime) / (scrollDuration * 1000);
+          const targetY = totalHeight * progress;
+          window.scrollTo({ top: targetY, behavior: 'instant' });
+
+          requestAnimationFrame(smoothScroll);
+        }
+
+        smoothScroll();
+      },
+      args: [duration],
+    });
+  } catch (error) {
+    console.error('Failed to inject scroll script:', error);
+  }
+}

offscreen.js

@@ -31,58 +31,64 @@ async function startCapture(streamId, tabId, duration, delay) {
     });
 
     mediaRecorder.ondataavailable = (event) => {
+      console.log('Data available:', event.data.size, 'bytes');
       if (event.data.size > 0) {
         recordedChunks.push(event.data);
       }
     };
 
     mediaRecorder.onstop = async () => {
+      console.log('MediaRecorder stopped, chunks:', recordedChunks.length);
       stream.getTracks().forEach(track => track.stop());
 
       const blob = new Blob(recordedChunks, { type: 'video/webm' });
+      console.log('Blob size:', blob.size, 'bytes');
+
+      if (blob.size === 0) {
+        console.error('Empty recording - no data captured');
+        chrome.runtime.sendMessage({ action: 'recordingComplete' });
+        return;
+      }
+
       const url = URL.createObjectURL(blob);
+      console.log('Blob URL:', url);
 
       // Download the video
       const timestamp = new Date().toISOString().replace(/[:.]/g, '-').slice(0, 19);
-      await chrome.downloads.download({
-        url: url,
-        filename: `scrollywood-${timestamp}.webm`,
-        saveAs: true,
-      });
+      const filename = `scrollywood-${timestamp}.webm`;
+      console.log('Downloading as:', filename);
+
+      try {
+        const downloadId = await chrome.downloads.download({
+          url: url,
+          filename: filename,
+          saveAs: true,
+        });
+        console.log('Download started, ID:', downloadId);
+      } catch (err) {
+        console.error('Download error:', err);
+      }
 
       chrome.runtime.sendMessage({ action: 'recordingComplete' });
     };
 
+    mediaRecorder.onerror = (event) => {
+      console.error('MediaRecorder error:', event.error);
+    };
+
     // Start recording
     mediaRecorder.start(1000);
     console.log('Recording started, waiting for delay...');
 
     // Wait for initial delay
     await sleep(delay * 1000);
 
-    // Inject scroll script
-    console.log('Starting scroll...');
-    await chrome.scripting.executeScript({
-      target: { tabId },
-      func: (scrollDuration) => {
-        const totalHeight = document.documentElement.scrollHeight - window.innerHeight;
-        const startTime = Date.now();
-        const endTime = startTime + (scrollDuration * 1000);
-
-        function smoothScroll() {
-          const now = Date.now();
-          if (now >= endTime) return;
-
-          const progress = (now - startTime) / (scrollDuration * 1000);
-          const targetY = totalHeight * progress;
-          window.scrollTo({ top: targetY, behavior: 'instant' });
-
-          requestAnimationFrame(smoothScroll);
-        }
-
-        smoothScroll();
-      },
-      args: [duration],
+    // Ask service worker to inject scroll script (scripting API not available in offscreen)
+    console.log('Requesting scroll injection...');
+    chrome.runtime.sendMessage({
+      action: 'injectScroll',
+      tabId,
+      duration,
     });
 
     // Wait for scroll to complete plus extra time at the end