Feature/v2/exportpdf (#4487)

# Description of Changes

<!--
Please provide a summary of the changes, including:

- What was changed
- Why the change was made
- Any challenges encountered

Closes #(issue_number)
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---

## Checklist

### General

- [ ] I have read the [Contribution
Guidelines](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/CONTRIBUTING.md)
- [ ] I have read the [Stirling-PDF Developer
Guide](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/devGuide/DeveloperGuide.md)
(if applicable)
- [ ] I have read the [How to add new languages to
Stirling-PDF](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/devGuide/HowToAddNewLanguage.md)
(if applicable)
- [ ] I have performed a self-review of my own code
- [ ] My changes generate no new warnings

### Documentation

- [ ] I have updated relevant docs on [Stirling-PDF's doc
repo](https://github.com/Stirling-Tools/Stirling-Tools.github.io/blob/main/docs/)
(if functionality has heavily changed)
- [ ] I have read the section [Add New Translation
Tags](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/devGuide/HowToAddNewLanguage.md#add-new-translation-tags)
(for new translation tags only)

### UI Changes (if applicable)

- [ ] Screenshots or videos demonstrating the UI changes are attached
(e.g., as comments or direct attachments in the PR)

### Testing (if applicable)

- [ ] I have tested my changes locally. Refer to the [Testing
Guide](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/devGuide/DeveloperGuide.md#6-testing)
for more details.

frontend/src/components/shared/RightRail.tsx

@@ -66,6 +66,9 @@ export default function RightRail() {
 
   const { totalItems, selectedCount } = getSelectionState();
 
+  // Get export state for viewer mode
+  const exportState = viewerContext?.getExportState?.();
+
   const handleSelectAll = useCallback(() => {
     if (currentView === 'fileEditor' || currentView === 'viewer') {
       // Select all file IDs
@@ -96,7 +99,10 @@ export default function RightRail() {
   }, [currentView, setSelectedFiles, pageEditorFunctions]);
 
   const handleExportAll = useCallback(() => {
-    if (currentView === 'fileEditor' || currentView === 'viewer') {
+    if (currentView === 'viewer') {
+      // Use EmbedPDF export functionality for viewer mode
+      viewerContext?.exportActions?.download();
+    } else if (currentView === 'fileEditor') {
       // Download selected files (or all if none selected)
       const filesToDownload = selectedFiles.length > 0 ? selectedFiles : activeFiles;
 
@@ -113,7 +119,7 @@ export default function RightRail() {
       // Export all pages (not just selected)
       pageEditorFunctions?.onExportAll?.();
     }
-  }, [currentView, activeFiles, selectedFiles, pageEditorFunctions]);
+  }, [currentView, activeFiles, selectedFiles, pageEditorFunctions, viewerContext]);
 
   const handleCloseSelected = useCallback(() => {
     if (currentView !== 'fileEditor') return;
@@ -445,7 +451,9 @@ export default function RightRail() {
                 radius="md"
                 className="right-rail-icon"
                 onClick={handleExportAll}
-                disabled={currentView === 'viewer' || totalItems === 0}
+                disabled={
+                  currentView === 'viewer' ? !exportState?.canExport : totalItems === 0
+                }
               >
                 <LocalIcon icon="download" width="1.5rem" height="1.5rem" />
               </ActionIcon>

frontend/src/components/viewer/ExportAPIBridge.tsx

@@ -0,0 +1,25 @@
+import { useEffect } from 'react';
+import { useExportCapability } from '@embedpdf/plugin-export/react';
+import { useViewer } from '../../contexts/ViewerContext';
+
+/**
+ * Component that runs inside EmbedPDF context and provides export functionality
+ */
+export function ExportAPIBridge() {
+  const { provides: exportApi } = useExportCapability();
+  const { registerBridge } = useViewer();
+
+  useEffect(() => {
+    if (exportApi) {
+      // Register this bridge with ViewerContext
+      registerBridge('export', {
+        state: {
+          canExport: true,
+        },
+        api: exportApi
+      });
+    }
+  }, [exportApi, registerBridge]);
+
+  return null;
+}

frontend/src/components/viewer/LocalEmbedPDF.tsx

@@ -17,6 +17,7 @@ import { SpreadPluginPackage, SpreadMode } from '@embedpdf/plugin-spread/react';
 import { SearchPluginPackage } from '@embedpdf/plugin-search/react';
 import { ThumbnailPluginPackage } from '@embedpdf/plugin-thumbnail/react';
 import { RotatePluginPackage, Rotate } from '@embedpdf/plugin-rotate/react';
+import { ExportPluginPackage } from '@embedpdf/plugin-export/react';
 import { Rotation } from '@embedpdf/models';
 import { CustomSearchLayer } from './CustomSearchLayer';
 import { ZoomAPIBridge } from './ZoomAPIBridge';
@@ -29,6 +30,7 @@ import { SpreadAPIBridge } from './SpreadAPIBridge';
 import { SearchAPIBridge } from './SearchAPIBridge';
 import { ThumbnailAPIBridge } from './ThumbnailAPIBridge';
 import { RotateAPIBridge } from './RotateAPIBridge';
+import { ExportAPIBridge } from './ExportAPIBridge';
 
 interface LocalEmbedPDFProps {
   file?: File | Blob;
@@ -112,6 +114,11 @@ export function LocalEmbedPDF({ file, url }: LocalEmbedPDFProps) {
       createPluginRegistration(RotatePluginPackage, {
         defaultRotation: Rotation.Degree0, // Start with no rotation
       }),
+
+      // Register export plugin for downloading PDFs
+      createPluginRegistration(ExportPluginPackage, {
+        defaultFileName: 'document.pdf',
+      }),
     ];
   }, [pdfUrl]);
 
@@ -170,6 +177,7 @@ export function LocalEmbedPDF({ file, url }: LocalEmbedPDFProps) {
         <SearchAPIBridge />
         <ThumbnailAPIBridge />
         <RotateAPIBridge />
+        <ExportAPIBridge />
         <GlobalPointerProvider>
           <Viewport
             style={{