diff --git a/third_party/astrolabe/src/App.vue b/third_party/astrolabe/src/App.vue
index 7c646bf..6886cd9 100644
--- a/third_party/astrolabe/src/App.vue
+++ b/third_party/astrolabe/src/App.vue
@@ -394,18 +394,6 @@ import MarkdownViewer from './components/MarkdownViewer.vue'
 import axios from '@nextcloud/axios'
 import { generateUrl } from '@nextcloud/router'
 import Plotly from 'plotly.js-dist-min'
-import * as pdfjsLib from 'pdfjs-dist'
-
-// Set worker source with error handling
-try {
-	pdfjsLib.GlobalWorkerOptions.workerSrc = new URL(
-		'pdfjs-dist/build/pdf.worker.mjs',
-		import.meta.url,
-	).toString()
-} catch (e) {
-	console.warn('Failed to set PDF.js worker, will use fallback', e)
-	// PDF.js will use fake worker automatically
-}
 
 export default {
 	name: 'App',
diff --git a/third_party/astrolabe/src/components/PDFViewer.vue b/third_party/astrolabe/src/components/PDFViewer.vue
index 60d6611..ac81f91 100644
--- a/third_party/astrolabe/src/components/PDFViewer.vue
+++ b/third_party/astrolabe/src/components/PDFViewer.vue
@@ -15,11 +15,14 @@
 </template>
 
 <script setup>
-import { ref, watch, onMounted, onBeforeUnmount, nextTick } from 'vue'
-import * as pdfjsLib from 'pdfjs-dist'
+import { ref, shallowRef, watch, onMounted, onBeforeUnmount, nextTick } from 'vue'
 import { generateUrl } from '@nextcloud/router'
 import { translate as t } from '@nextcloud/l10n'
 import { NcLoadingIcon } from '@nextcloud/vue'
+
+// Use global pdfjsLib loaded by pdfjs-loader.mjs (external, not bundled)
+// This avoids Vite transforming ES private fields which breaks fake worker compatibility
+const pdfjsLib = window.pdfjsLib
 import AlertCircle from 'vue-material-design-icons/AlertCircle.vue'
 
 const props = defineProps({
@@ -40,7 +43,9 @@ const props = defineProps({
 const emit = defineEmits(['loaded', 'error', 'page-rendered'])
 
 // Reactive state
-const pdfDoc = ref(null)
+// Use shallowRef for pdfDoc because PDFDocumentProxy uses ES private fields
+// which can't be accessed through Vue's Proxy wrapper
+const pdfDoc = shallowRef(null)
 const loading = ref(true)
 const error = ref(null)
 const totalPages = ref(0)
@@ -60,6 +65,10 @@ async function loadPDF() {
 		const encodedPath = cleanPath.split('/').map(encodeURIComponent).join('/')
 		const downloadUrl = generateUrl(`/remote.php/webdav/${encodedPath}`)
 
+		// Set worker source using OC.linkTo for correct app webroot path
+		// Must be done here (not at module load time) because _oc_appswebroots isn't populated until after page load
+		pdfjsLib.GlobalWorkerOptions.workerSrc = window.OC.linkTo('astrolabe', 'js/pdf.worker.mjs')
+
 		// Load PDF document
 		const loadingTask = pdfjsLib.getDocument({
 			url: downloadUrl,
diff --git a/third_party/astrolabe/templates/index.php b/third_party/astrolabe/templates/index.php
index a2ca69f..07688a5 100644
--- a/third_party/astrolabe/templates/index.php
+++ b/third_party/astrolabe/templates/index.php
@@ -2,10 +2,15 @@
 
 declare(strict_types=1);
 
+use OCA\Astrolabe\AppInfo\Application;
 use OCP\Util;
 
-Util::addScript(OCA\Astrolabe\AppInfo\Application::APP_ID, OCA\Astrolabe\AppInfo\Application::APP_ID . '-main');
-Util::addStyle(OCA\Astrolabe\AppInfo\Application::APP_ID, OCA\Astrolabe\AppInfo\Application::APP_ID . '-main');
+// Load PDF.js loader first (must be external, not bundled by Vite,
+// to avoid ES private field transformation issues with fake worker fallback)
+// The loader imports pdf.mjs and sets window.pdfjsLib before the main app runs
+Util::addScript(Application::APP_ID, 'pdfjs-loader');
+Util::addScript(Application::APP_ID, Application::APP_ID . '-main');
+Util::addStyle(Application::APP_ID, Application::APP_ID . '-main');
 
 ?>
 
diff --git a/third_party/astrolabe/vite.config.js b/third_party/astrolabe/vite.config.js
index e8f1239..22e5d41 100644
--- a/third_party/astrolabe/vite.config.js
+++ b/third_party/astrolabe/vite.config.js
@@ -1,7 +1,40 @@
 import { defineConfig } from 'vite'
 import vue from '@vitejs/plugin-vue'
 import { resolve } from 'path'
-import { readFileSync } from 'fs'
+import { readFileSync, copyFileSync, writeFileSync, mkdirSync } from 'fs'
+
+// Plugin to copy PDF.js files to output directory
+// Both pdf.mjs and pdf.worker.mjs are loaded externally to avoid Vite transforming
+// ES private fields, which breaks compatibility with the fake worker fallback
+function copyPdfFiles() {
+  return {
+    name: 'copy-pdf-files',
+    writeBundle() {
+      mkdirSync(resolve(__dirname, 'js'), { recursive: true })
+      // Copy main library
+      copyFileSync(
+        resolve(__dirname, 'node_modules/pdfjs-dist/build/pdf.mjs'),
+        resolve(__dirname, 'js/pdf.mjs')
+      )
+      console.log('Copied pdf.mjs to js/')
+      // Copy worker (loaded by pdfjs at runtime)
+      copyFileSync(
+        resolve(__dirname, 'node_modules/pdfjs-dist/build/pdf.worker.mjs'),
+        resolve(__dirname, 'js/pdf.worker.mjs')
+      )
+      console.log('Copied pdf.worker.mjs to js/')
+      // Create loader script that imports pdf.mjs and sets window.pdfjsLib
+      // This is loaded via script tag before the main app
+      const loaderScript = `// PDF.js loader - imports pdf.mjs and exposes it globally
+// Loaded before main app to make pdfjsLib available as window.pdfjsLib
+import * as pdfjsLib from './pdf.mjs';
+window.pdfjsLib = pdfjsLib;
+`
+      writeFileSync(resolve(__dirname, 'js/pdfjs-loader.mjs'), loaderScript)
+      console.log('Created pdfjs-loader.mjs in js/')
+    }
+  }
+}
 
 // Read app info from info.xml for @nextcloud/vue
 const infoXml = readFileSync(resolve(__dirname, 'appinfo/info.xml'), 'utf-8')
@@ -9,7 +42,7 @@ const appName = infoXml.match(/<id>([^<]+)<\/id>/)?.[1] || 'astrolabe'
 const appVersion = infoXml.match(/<version>([^<]+)<\/version>/)?.[1] || ''
 
 export default defineConfig({
-  plugins: [vue()],
+  plugins: [vue(), copyPdfFiles()],
   define: {
     appName: JSON.stringify(appName),
     appVersion: JSON.stringify(appVersion),