Add centralized saveMedia helpers for image, video, and file downloads.

Platforms can register a custom saver; viewers share one download/save path instead of FileSaver call sites.

src/app/components/Pdf-viewer/PdfViewer.tsx

@@ -5,7 +5,7 @@ import classNames from 'classnames';
 import { Box, Button, Chip, Header, IconButton, Input, Menu, PopOut, RectCords, Scroll, Spinner, Text, as, config } from 'folds';
 import { Icon, Icons } from '../icons';
 import FocusTrap from 'focus-trap-react';
-import FileSaver from 'file-saver';
+import { saveMediaBlob } from '../../utils/saveMedia';
 import * as css from './PdfViewer.css';
 import { AsyncStatus } from '../../hooks/useAsyncCallback';
 import { useZoom } from '../../hooks/useZoom';
@@ -61,8 +61,14 @@ export const PdfViewer = as<'div', PdfViewerProps>(
       }
     }, [docState, pageNo, zoom]);
 
-    const handleDownload = () => {
-      FileSaver.saveAs(src, name);
+    const handleDownload = async () => {
+      try {
+        const res = await fetch(src);
+        if (!res.ok) throw new Error('Failed to fetch PDF');
+        await saveMediaBlob(await res.blob(), name);
+      } catch (error) {
+        console.warn('[PdfViewer] Failed to download:', error);
+      }
     };
 
     const handleJumpSubmit: FormEventHandler<HTMLFormElement> = (evt) => {

src/app/components/image-viewer/ImageViewer.tsx

@@ -6,12 +6,11 @@ import React, {
   useRef,
   useState,
 } from 'react';
-import FileSaver from 'file-saver';
 import classNames from 'classnames';
 import { as } from 'folds';
 import { Icon, Icons } from '../icons';
 import * as css from './ImageViewer.css';
-import { downloadMedia } from '../../utils/matrix';
+import { downloadAndSaveMedia } from '../../utils/saveMedia';
 import { getCurrentAccessToken } from '../../utils/auth';
 
 const ZOOM_MIN = 1;
@@ -270,18 +269,13 @@ export const ImageViewer = as<'div', ImageViewerProps>(
 
     const handleDownload = async () => {
       try {
-        const fileContent = await downloadMedia(src, getCurrentAccessToken());
-        FileSaver.saveAs(fileContent, alt);
+        await downloadAndSaveMedia(src, alt, getCurrentAccessToken());
       } catch (error) {
         console.warn('[ImageViewer] Failed to download media:', error);
         try {
-          const response = await fetch(src);
-          if (response.ok) {
-            const blob = await response.blob();
-            FileSaver.saveAs(blob, alt);
-          }
-        } catch {
           window.open(src, '_blank');
+        } catch {
+          // ignore
         }
       }
     };

src/app/components/message/FileHeader.tsx

@@ -2,7 +2,6 @@ import { Badge, Box, IconButton, Spinner, Text, as, toRem } from 'folds';
 import { Icon, Icons } from '../icons';
 import React, { ReactNode, useCallback } from 'react';
 import { EncryptedAttachmentInfo } from 'browser-encrypt-attachment';
-import FileSaver from 'file-saver';
 import { mimeTypeToExt } from '../../utils/mimeTypes';
 import { useMatrixClient } from '../../hooks/useMatrixClient';
 import { useMediaAuthentication } from '../../hooks/useMediaAuthentication';
@@ -14,6 +13,7 @@ import {
   mxcUrlToHttp,
 } from '../../utils/matrix';
 import { getCurrentAccessToken } from '../../utils/auth';
+import { saveMediaBlob } from '../../utils/saveMedia';
 
 const badgeStyles = { maxWidth: toRem(100) };
 
@@ -36,9 +36,8 @@ export function FileDownloadButton({ filename, url, mimeType, encInfo }: FileDow
         ? await downloadEncryptedMedia(mediaUrl, (encBuf) => decryptFile(encBuf, mimeType, encInfo), accessToken)
         : await downloadMedia(mediaUrl, accessToken);
 
-      const fileURL = URL.createObjectURL(fileContent);
-      FileSaver.saveAs(fileURL, filename);
-      return fileURL;
+      await saveMediaBlob(fileContent, filename);
+      return true;
     }, [mx, url, useAuthentication, mimeType, encInfo, filename])
   );
 

src/app/components/message/content/FileContent.tsx

@@ -1,8 +1,8 @@
 import React, { ReactNode, useCallback, useState } from 'react';
 import { Box, Button, Modal, Overlay, OverlayBackdrop, OverlayCenter, Spinner, Text, Tooltip, TooltipProvider, as } from 'folds';
 import { Icon, Icons } from '../../icons';
-import FileSaver from 'file-saver';
 import { EncryptedAttachmentInfo } from 'browser-encrypt-attachment';
+import { saveMediaBlob } from '../../../utils/saveMedia';
 import FocusTrap from 'focus-trap-react';
 import { IFileInfo } from '../../../../types/matrix/common';
 import { AsyncStatus, useAsyncCallback } from '../../../hooks/useAsyncCallback';
@@ -252,9 +252,8 @@ export function DownloadFile({ body, mimeType, url, info, encInfo }: DownloadFil
         ? await downloadEncryptedMedia(mediaUrl, (encBuf) => decryptFile(encBuf, mimeType, encInfo), accessToken)
         : await downloadMedia(mediaUrl, accessToken);
 
-      const fileURL = URL.createObjectURL(fileContent);
-      FileSaver.saveAs(fileURL, body);
-      return fileURL;
+      await saveMediaBlob(fileContent, body);
+      return fileContent;
     }, [mx, url, useAuthentication, mimeType, encInfo, body])
   );
 
@@ -268,7 +267,7 @@ export function DownloadFile({ body, mimeType, url, info, encInfo }: DownloadFil
       size="400"
       onClick={() =>
         downloadState.status === AsyncStatus.Success
-          ? FileSaver.saveAs(downloadState.data, body)
+          ? saveMediaBlob(downloadState.data, body)
           : download()
       }
       disabled={downloadState.status === AsyncStatus.Loading}

src/app/components/video-viewer/VideoViewer.tsx

@@ -1,10 +1,9 @@
 import React from 'react';
-import FileSaver from 'file-saver';
 import classNames from 'classnames';
 import { Box, Chip, Header, IconButton, Text, as } from 'folds';
 import { Icon, Icons } from '../icons';
 import * as css from './VideoViewer.css';
-import { downloadMedia } from '../../utils/matrix';
+import { downloadAndSaveMedia } from '../../utils/saveMedia';
 import { getCurrentAccessToken } from '../../utils/auth';
 
 export type VideoViewerProps = {
@@ -14,20 +13,16 @@ export type VideoViewerProps = {
 };
 
 export const VideoViewer = as<'div', VideoViewerProps>(
-  ({ className, alt, src, requestClose, ...props }, ref) => {    const handleDownload = async () => {
+  ({ className, alt, src, requestClose, ...props }, ref) => {
+    const handleDownload = async () => {
       try {
-        const fileContent = await downloadMedia(src, getCurrentAccessToken());
-        FileSaver.saveAs(fileContent, alt);
+        await downloadAndSaveMedia(src, alt, getCurrentAccessToken());
       } catch (error) {
         console.warn('[VideoViewer] Failed to download media:', error);
         try {
-          const response = await fetch(src);
-          if (response.ok) {
-            const blob = await response.blob();
-            FileSaver.saveAs(blob, alt);
-          }
-        } catch {
           window.open(src, '_blank');
+        } catch {
+          // ignore
         }
       }
     };

src/app/utils/saveMedia.ts

@@ -0,0 +1,55 @@
+import FileSaver from 'file-saver';
+import { downloadMedia } from './matrix';
+import { getCurrentAccessToken } from './auth';
+
+export type MediaSaver = (blob: Blob, filename: string) => void | Promise<void>;
+
+let customMediaSaver: MediaSaver | null = null;
+
+const defaultMediaSaver: MediaSaver = (blob, filename) => {
+  FileSaver.saveAs(blob, filename);
+};
+
+/**
+ * Register a platform-specific media saver (Android MediaStore, Electron dialog, etc.).
+ * Pass null to restore the default FileSaver path.
+ *
+ * Platforms should call this once at startup (mobile overlay / desktop shell entry).
+ */
+export const registerMediaSaver = (saver: MediaSaver | null): void => {
+  customMediaSaver = saver;
+};
+
+/**
+ * Persist a Blob to disk via the registered platform saver, or FileSaver by default.
+ */
+export const saveMediaBlob = async (blob: Blob, filename: string): Promise<void> => {
+  const saver = customMediaSaver ?? defaultMediaSaver;
+  await saver(blob, filename);
+};
+
+/**
+ * Fetch media (auth download or blob:/data:/http URL) and save it via [saveMediaBlob].
+ */
+export const downloadAndSaveMedia = async (
+  src: string,
+  filename: string,
+  accessToken?: string | null
+): Promise<void> => {
+  let blob: Blob;
+  try {
+    if (src.startsWith('blob:') || src.startsWith('data:')) {
+      const res = await fetch(src);
+      if (!res.ok) throw new Error(`Failed to fetch ${src}`);
+      blob = await res.blob();
+    } else {
+      blob = await downloadMedia(src, accessToken ?? getCurrentAccessToken());
+    }
+  } catch (error) {
+    console.warn('[saveMedia] downloadMedia failed, trying fetch fallback:', error);
+    const res = await fetch(src);
+    if (!res.ok) throw error;
+    blob = await res.blob();
+  }
+  await saveMediaBlob(blob, filename);
+};