background.js

@@ -10,6 +10,19 @@ function errMsg(err) {
   return String((err && err.message) || err);
 }
 
+// Build a download URL from PDF bytes. Chrome MV3 runs the background as a
+// service worker, where URL.createObjectURL is NOT available, so we use a
+// base64 data URL (works in both Firefox and Chrome). PDFs here are small
+// (~150KB), well within data-URL length limits.
+function pdfDataUrl(bytes) {
+  let binary = '';
+  const chunk = 0x8000;
+  for (let i = 0; i < bytes.length; i += chunk) {
+    binary += String.fromCharCode.apply(null, bytes.subarray(i, i + chunk));
+  }
+  return 'data:application/pdf;base64,' + btoa(binary);
+}
+
 browser.runtime.onMessage.addListener((msg, sender, sendResponse) => {
   if (msg && msg.type === 'generate-pdf') {
     generatePdf(msg.data)
@@ -32,8 +45,9 @@ function formatPeriod(period) {
 
 async function generatePdf(data) {
   const bytes = await ISMIStools.buildStudyLoadPdf(data);
-  const blob = new Blob([bytes], { type: 'application/pdf' });
+  // Chrome MV3 background is a service worker (no URL.createObjectURL), so we
-  const url = URL.createObjectURL(blob);
+  // use a base64 data URL that works in both browsers.
+  const url = pdfDataUrl(bytes);
   const header = data.header || {};
   const year = parseInt(data.year, 10);
   const period = formatPeriod(data.period || header.semester || '');
@@ -55,12 +69,10 @@ async function generatePdf(data) {
     const onChanged = (delta) => {
       if (delta.id === id && delta.state && (delta.state.current === 'complete' || delta.state.current === 'interrupted')) {
         browser.downloads.onChanged.removeListener(onChanged);
-        URL.revokeObjectURL(url);
       }
     };
     browser.downloads.onChanged.addListener(onChanged);
   } catch (err) {
-    URL.revokeObjectURL(url);
     throw err;
   }
 }