From ca8742821620bc612bcc6a69cd4d3ce3e3b84b9d Mon Sep 17 00:00:00 2001
From: Bohdan Triapitsyn <artmore@protonmail.com>
Date: Sat, 13 Jun 2026 01:44:03 +0300
Subject: [PATCH] fix: harden file previews and downloads

---
 .../components/layout/SidebarFilesTree.tsx    |   5 +-
 .../ui/src/components/views/FilesView.tsx     | 204 +++++++++++++-----
 packages/web/server/lib/fs/DOCUMENTATION.md   |   1 +
 packages/web/server/lib/fs/routes.js          |  93 ++++++++
 packages/web/server/lib/ui-auth/ui-auth.js    |  19 +-
 .../web/server/lib/ui-auth/ui-auth.test.js    |  31 +++
 packages/web/src/api/files.ts                 |  11 +-
 7 files changed, 305 insertions(+), 59 deletions(-)

diff --git a/packages/ui/src/components/layout/SidebarFilesTree.tsx b/packages/ui/src/components/layout/SidebarFilesTree.tsx
index e27e0aaf..94956d5a 100644
--- a/packages/ui/src/components/layout/SidebarFilesTree.tsx
+++ b/packages/ui/src/components/layout/SidebarFilesTree.tsx
@@ -221,7 +221,10 @@ const FileRow: React.FC<FileRowProps> = ({
       {!isDir && downloadFile && (
         <Item onClick={(e: React.MouseEvent) => {
           e.stopPropagation();
-          void downloadFile(node.path);
+          void downloadFile(node.path).catch((error) => {
+            console.error('Download failed:', error);
+            toast.error(t('sidebarFilesTree.toast.operationFailed'));
+          });
         }}>
           <Icon name="download" className="mr-2 h-4 w-4" /> {t('sidebarFilesTree.menu.save')}
         </Item>
diff --git a/packages/ui/src/components/views/FilesView.tsx b/packages/ui/src/components/views/FilesView.tsx
index 5277fcb8..18dff29d 100644
--- a/packages/ui/src/components/views/FilesView.tsx
+++ b/packages/ui/src/components/views/FilesView.tsx
@@ -358,13 +358,13 @@ const isJsonFile = (path: string): boolean => {
   return ext === 'json' || ext === 'jsonc' || ext === 'json5' || ext === 'geojson';
 };
 
-const isHtmlFile = (path: string): boolean => {
-  if (!path) return false;
-  const ext = path.toLowerCase().split('.').pop();
-  return ext === 'html' || ext === 'htm';
-};
-
-interface FileRowProps {
+const isHtmlFile = (path: string): boolean => {
+  if (!path) return false;
+  const ext = path.toLowerCase().split('.').pop();
+  return ext === 'html' || ext === 'htm';
+};
+
+interface FileRowProps {
   node: FileNode;
   root: string;
   isExpanded: boolean;
@@ -478,7 +478,10 @@ const FileRow: React.FC<FileRowProps> = ({
       {!isDir && downloadFile && (
         <Item onClick={(e: React.MouseEvent) => {
           e.stopPropagation();
-          void downloadFile(node.path);
+          void downloadFile(node.path).catch((error) => {
+            console.error('Download failed:', error);
+            toast.error(t('sidebarFilesTree.toast.operationFailed'));
+          });
         }}>
           <Icon name="download" className="mr-2 size-4" /> {t('sidebarFilesTree.menu.save')}
         </Item>
@@ -769,10 +772,28 @@ export const FilesView: React.FC<FilesViewProps> = ({ mode = 'full' }) => {
     };
   }, []);
 
-  const openFiles = React.useMemo(() => openPaths.map(toFileNode), [openPaths, toFileNode]);
-  const effectiveSelectedPath = React.useMemo(() => selectedPath ?? openPaths[0] ?? null, [openPaths, selectedPath]);
+  const openFiles = React.useMemo(() => openPaths.map(toFileNode), [openPaths, toFileNode]);
+  const effectiveSelectedPath = React.useMemo(() => {
+    if (selectedPath) {
+      const comparableSelected = toComparablePath(selectedPath);
+      if (openPaths.some((path) => toComparablePath(path) === comparableSelected)) {
+        return selectedPath;
+      }
+    }
+    return openPaths[0] ?? null;
+  }, [openPaths, selectedPath]);
   const selectedFile = React.useMemo(() => (effectiveSelectedPath ? toFileNode(effectiveSelectedPath) : null), [effectiveSelectedPath, toFileNode]);
   const selectedFilePath = selectedFile?.path ?? '';
+
+  React.useEffect(() => {
+    if (!root || !selectedPath) return;
+    const comparableSelected = toComparablePath(selectedPath);
+    const selectedIsOpen = openPaths.some((path) => toComparablePath(path) === comparableSelected);
+    if (!selectedIsOpen) {
+      setSelectedPath(root, openPaths[0] ?? null);
+    }
+  }, [openPaths, root, selectedPath, setSelectedPath]);
+
   const selectedFileIsOutsideWorkspace = Boolean(root && selectedFilePath && !isPathWithinRoot(selectedFilePath, root));
   const selectedOutsideFileGrant = selectedFileIsOutsideWorkspace ? getOutsideFileGrant(selectedFilePath) : undefined;
   const selectedFileReadOptions = React.useMemo(
@@ -825,7 +846,9 @@ export const FilesView: React.FC<FilesViewProps> = ({ mode = 'full' }) => {
   const [fileLoading, setFileLoading] = React.useState(false);
   const [fileError, setFileError] = React.useState<string | null>(null);
   const [desktopImageSrc, setDesktopImageSrc] = React.useState<string>('');
+  const desktopImageBlobUrlRef = React.useRef<string>('');
   const [imageAssetAuthReadyKey, setImageAssetAuthReadyKey] = React.useState('');
+  const [htmlAssetAuthReadyKey, setHtmlAssetAuthReadyKey] = React.useState('');
   const [pdfAssetAuthReadyKey, setPdfAssetAuthReadyKey] = React.useState('');
 
   const [loadedFilePath, setLoadedFilePath] = React.useState<string | null>(null);
@@ -2835,6 +2858,10 @@ export const FilesView: React.FC<FilesViewProps> = ({ mode = 'full' }) => {
   const pdfAssetAuthKey = selectedFile?.path && isSelectedPdf
     ? `${selectedFile.path}|${selectedFileReadOptions.allowOutsideWorkspace ? 'outside' : 'workspace'}|${selectedFileReadOptions.outsideFileGrant ?? ''}`
     : '';
+
+  const htmlAssetAuthKey = selectedFile?.path && isHtml && htmlViewMode === 'preview' && !runtime.isVSCode
+    ? selectedFile.path
+    : '';
 
   React.useEffect(() => {
     if (!imageAssetAuthKey) {
@@ -2857,6 +2884,33 @@ export const FilesView: React.FC<FilesViewProps> = ({ mode = 'full' }) => {
 
   const isImageAssetAuthLoading = Boolean(imageAssetAuthKey && imageAssetAuthReadyKey !== imageAssetAuthKey);
 
+  React.useEffect(() => {
+    if (!htmlAssetAuthKey) {
+      setHtmlAssetAuthReadyKey('');
+      return;
+    }
+
+    let cancelled = false;
+    setHtmlAssetAuthReadyKey('');
+    void refreshRuntimeUrlAuthToken(getRuntimeApiBaseUrl())
+      .then((token) => {
+        if (!cancelled && token) {
+          setHtmlAssetAuthReadyKey(htmlAssetAuthKey);
+        }
+      })
+      .catch((error) => {
+        if (!cancelled) {
+          setFileError(error instanceof Error ? error.message : t('filesView.error.readFileFailed'));
+        }
+      });
+
+    return () => {
+      cancelled = true;
+    };
+  }, [htmlAssetAuthKey, t]);
+
+  const isHtmlAssetAuthLoading = Boolean(htmlAssetAuthKey && htmlAssetAuthReadyKey !== htmlAssetAuthKey);
+
   React.useEffect(() => {
     if (!pdfAssetAuthKey) {
       setPdfAssetAuthReadyKey('');
@@ -2918,21 +2972,45 @@ export const FilesView: React.FC<FilesViewProps> = ({ mode = 'full' }) => {
   React.useEffect(() => {
     let cancelled = false;
 
-    const resolveDesktopImage = async () => {
-      if (!runtime.isDesktop || !selectedFile?.path || !isSelectedImage || isSelectedSvg) {
-        setDesktopImageSrc('');
-        return;
-      }
-
-      setFileError(null);
-
-      const srcPromise = files.readFileBinary
-        ? files.readFileBinary(selectedFile.path, selectedFileReadOptions).then((result) => result.dataUrl)
-        : Promise.resolve(getRuntimeUrlResolver().authenticatedAsset('/api/fs/raw', {
-          path: selectedFile.path,
-          allowOutsideWorkspace: selectedFileReadOptions.allowOutsideWorkspace ? 'true' : undefined,
-          outsideFileGrant: selectedFileReadOptions.outsideFileGrant,
-        }));
+    const resolveDesktopImage = async () => {
+      if (!runtime.isDesktop || !selectedFile?.path || !isSelectedImage || isSelectedSvg) {
+        if (desktopImageBlobUrlRef.current) {
+          URL.revokeObjectURL(desktopImageBlobUrlRef.current);
+          desktopImageBlobUrlRef.current = '';
+        }
+        setDesktopImageSrc('');
+        return;
+      }
+
+      setFileError(null);
+
+      if (desktopImageBlobUrlRef.current) {
+        URL.revokeObjectURL(desktopImageBlobUrlRef.current);
+        desktopImageBlobUrlRef.current = '';
+      }
+
+      const srcPromise = files.readFileBinary
+        ? files.readFileBinary(selectedFile.path, selectedFileReadOptions).then((result) => result.dataUrl)
+        : (async () => {
+          const response = await runtimeFetch('/api/fs/raw', {
+            query: {
+              path: selectedFile.path,
+              allowOutsideWorkspace: selectedFileReadOptions.allowOutsideWorkspace ? 'true' : undefined,
+              outsideFileGrant: selectedFileReadOptions.outsideFileGrant,
+            },
+          });
+          if (!response.ok) {
+            throw new Error(t('filesView.error.readFileFailed'));
+          }
+          const blob = await response.blob();
+          const url = URL.createObjectURL(blob);
+          if (cancelled) {
+            URL.revokeObjectURL(url);
+            return '';
+          }
+          desktopImageBlobUrlRef.current = url;
+          return url;
+        })();
 
       await srcPromise
         .then((src) => {
@@ -2940,11 +3018,15 @@ export const FilesView: React.FC<FilesViewProps> = ({ mode = 'full' }) => {
             setDesktopImageSrc(src);
             setLoadedFilePath(selectedFile.path);
           }
-        })
-        .catch((error) => {
-          if (!cancelled) {
-            setDesktopImageSrc('');
-            setFileError(error instanceof Error ? error.message : t('filesView.error.readFileFailed'));
+        })
+        .catch((error) => {
+          if (desktopImageBlobUrlRef.current) {
+            URL.revokeObjectURL(desktopImageBlobUrlRef.current);
+            desktopImageBlobUrlRef.current = '';
+          }
+          if (!cancelled) {
+            setDesktopImageSrc('');
+            setFileError(error instanceof Error ? error.message : t('filesView.error.readFileFailed'));
             setLoadedFilePath(null);
           }
         })
@@ -2957,10 +3039,19 @@ export const FilesView: React.FC<FilesViewProps> = ({ mode = 'full' }) => {
 
     void resolveDesktopImage();
 
-    return () => {
-      cancelled = true;
-    };
-  }, [files, isSelectedImage, isSelectedSvg, runtime.isDesktop, selectedFile?.path, selectedFileReadOptions, t]);
+    return () => {
+      cancelled = true;
+    };
+  }, [files, isSelectedImage, isSelectedSvg, runtime.isDesktop, selectedFile?.path, selectedFileReadOptions, t]);
+
+  React.useEffect(() => {
+    return () => {
+      if (desktopImageBlobUrlRef.current) {
+        URL.revokeObjectURL(desktopImageBlobUrlRef.current);
+        desktopImageBlobUrlRef.current = '';
+      }
+    };
+  }, []);
 
   const handleCloseDialog = React.useCallback(() => setActiveDialog(null), []);
 
@@ -3353,7 +3444,10 @@ export const FilesView: React.FC<FilesViewProps> = ({ mode = 'full' }) => {
               size="sm"
               onClick={() => {
                 const fn = files.downloadFile;
-                if (fn) void fn(selectedFile.path);
+                if (fn) void fn(selectedFile.path).catch((error) => {
+                  console.error('Download failed:', error);
+                  toast.error(t('sidebarFilesTree.toast.operationFailed'));
+                });
               }}
               className="size-6 p-0 hover:bg-transparent focus-visible:bg-transparent active:bg-transparent"
               title={t('filesView.editor.saveFile')}
@@ -3702,22 +3796,30 @@ export const FilesView: React.FC<FilesViewProps> = ({ mode = 'full' }) => {
                 />
               </ErrorBoundary>
             </div>
-          ) : selectedFile && isHtml && htmlViewMode === 'preview' ? (
-            <div className="h-full overflow-hidden">
-              <iframe
-                srcDoc={(() => {
-                  // Inject base tag for relative paths (CSS/JS/images) to work
-                  const basePath = selectedFile.path.substring(0, selectedFile.path.lastIndexOf('/') + 1);
-                  if (!basePath) return fileContent;
-                  const baseTag = `<base href="${runtime.isDesktop ? basePath : basePath}">`;
-                  return fileContent.replace(/<head([^>]*)>/i, `<head$1>${baseTag}`);
-                })()}
-                className="w-full h-full border-none"
-                sandbox="allow-scripts allow-same-origin allow-forms"
-                title={t('filesView.editor.htmlPreviewTitle')}
-              />
-            </div>
-          ) : selectedFile && canUseShikiFileView && textViewMode === 'view' ? (
+          ) : selectedFile && isHtml && htmlViewMode === 'preview' ? (
+            isHtmlAssetAuthLoading ? (
+              <div className="flex h-full items-center justify-center text-muted-foreground typography-ui-label">
+                {t('common.loading')}
+              </div>
+            ) : (
+            <div className="h-full overflow-hidden">
+              <iframe
+                src={!runtime.isVSCode && htmlAssetAuthReadyKey === htmlAssetAuthKey ? (() => {
+                  const encoded = selectedFile.path.split('/').map((segment) => encodeURIComponent(segment)).join('/');
+                  return getRuntimeUrlResolver().authenticatedAsset(`/api/fs/serve${encoded.startsWith('/') ? encoded : `/${encoded}`}`);
+                })() : undefined}
+                srcDoc={runtime.isVSCode ? (() => {
+                  const basePath = selectedFile.path.substring(0, selectedFile.path.lastIndexOf('/') + 1);
+                  if (!basePath) return fileContent;
+                  return fileContent.replace(/<head([^>]*)>/i, `<head$1><base href="${basePath}">`);
+                })() : undefined}
+                className="w-full h-full border-none"
+                sandbox="allow-scripts allow-same-origin allow-forms"
+                title={t('filesView.editor.htmlPreviewTitle')}
+              />
+            </div>
+            )
+          ) : selectedFile && canUseShikiFileView && textViewMode === 'view' ? (
             renderShikiFileView(selectedFile, draftContent)
           ) : (
             <div
diff --git a/packages/web/server/lib/fs/DOCUMENTATION.md b/packages/web/server/lib/fs/DOCUMENTATION.md
index dc87c8cd..bc853ce9 100644
--- a/packages/web/server/lib/fs/DOCUMENTATION.md
+++ b/packages/web/server/lib/fs/DOCUMENTATION.md
@@ -14,6 +14,7 @@ Own filesystem API behavior for the web server runtime, including workspace-boun
     - `POST /api/fs/mkdir`
     - `GET /api/fs/read`
     - `GET /api/fs/raw`
+    - `GET /api/fs/serve/:path(*)`
     - `POST /api/fs/write`
     - `POST /api/fs/delete`
     - `POST /api/fs/rename`
diff --git a/packages/web/server/lib/fs/routes.js b/packages/web/server/lib/fs/routes.js
index d2d61a5b..20fb5844 100644
--- a/packages/web/server/lib/fs/routes.js
+++ b/packages/web/server/lib/fs/routes.js
@@ -98,6 +98,38 @@ const createGitCheckIgnoreTimeoutMs = () => {
   return 2500;
 };
 
+const FILE_MIME_MAP = Object.freeze({
+  '.html': 'text/html',
+  '.htm': 'text/html',
+  '.css': 'text/css',
+  '.js': 'application/javascript',
+  '.mjs': 'application/javascript',
+  '.json': 'application/json',
+  '.wasm': 'application/wasm',
+  '.xml': 'application/xml',
+  '.txt': 'text/plain',
+  '.md': 'text/markdown',
+  '.pdf': 'application/pdf',
+  '.csv': 'text/csv',
+  '.woff2': 'font/woff2',
+  '.woff': 'font/woff',
+  '.ttf': 'font/ttf',
+  '.eot': 'application/vnd.ms-fontobject',
+  '.mp3': 'audio/mpeg',
+  '.mp4': 'video/mp4',
+  '.png': 'image/png',
+  '.jpg': 'image/jpeg',
+  '.jpeg': 'image/jpeg',
+  '.gif': 'image/gif',
+  '.svg': 'image/svg+xml',
+  '.webp': 'image/webp',
+  '.ico': 'image/x-icon',
+  '.bmp': 'image/bmp',
+  '.avif': 'image/avif',
+});
+
+const MAX_SERVE_BYTES = 100 * 1024 * 1024;
+
 // Only deterministic, side-effect-free git plumbing path queries are cacheable.
 // Anything outside this allowlist (including any non-git command) runs normally
 // — we never cache arbitrary exec.
@@ -869,6 +901,67 @@ export const registerFsRoutes = (app, dependencies) => {
     }
   });
 
+  app.get(/^\/api\/fs\/serve\/(.+)$/, async (req, res) => {
+    const rawPath = req.params[0] || '';
+    if (!rawPath) {
+      return res.status(400).json({ error: 'Path is required' });
+    }
+
+    try {
+      if (req.query?.allowOutsideWorkspace === 'true') {
+        return res.status(403).json({ error: 'allowOutsideWorkspace is not permitted for this endpoint' });
+      }
+
+      const filePath = path.resolve('/', rawPath);
+      const resolved = await resolveReadPathFromContext({
+        req,
+        targetPath: filePath,
+        resolveProjectDirectory,
+        path,
+        os,
+        normalizeDirectoryPath,
+        openchamberUserConfigRoot,
+      });
+      if (!resolved.ok) {
+        return res.status(400).json({ error: resolved.error });
+      }
+
+      const [canonicalPath, canonicalBase] = await Promise.all([
+        fsPromises.realpath(resolved.resolved),
+        fsPromises.realpath(resolved.base).catch(() => path.resolve(resolved.base)),
+      ]);
+
+      if (!isPathWithinRoot(canonicalPath, canonicalBase, path, os)) {
+        return res.status(403).json({ error: 'Access to file denied' });
+      }
+
+      const stats = await fsPromises.stat(canonicalPath);
+      if (!stats.isFile()) {
+        return res.status(400).json({ error: 'Specified path is not a file' });
+      }
+      if (stats.size > MAX_SERVE_BYTES) {
+        return res.status(413).json({ error: 'File too large to serve' });
+      }
+
+      const ext = path.extname(canonicalPath).toLowerCase();
+      const mimeType = FILE_MIME_MAP[ext] || 'application/octet-stream';
+      const content = await fsPromises.readFile(canonicalPath);
+      res.setHeader('Cache-Control', 'no-store');
+      res.setHeader('X-Content-Type-Options', 'nosniff');
+      return res.type(mimeType).send(content);
+    } catch (error) {
+      const err = error;
+      if (err && typeof err === 'object' && err.code === 'ENOENT') {
+        return res.status(404).json({ error: 'File not found' });
+      }
+      if (err && typeof err === 'object' && err.code === 'EACCES') {
+        return res.status(403).json({ error: 'Access to file denied' });
+      }
+      console.error('Failed to serve file:', error);
+      return res.status(500).json({ error: (error && error.message) || 'Failed to serve file' });
+    }
+  });
+
   app.post('/api/fs/write', async (req, res) => {
     const { path: filePath, content } = req.body || {};
     if (!filePath || typeof filePath !== 'string') {
diff --git a/packages/web/server/lib/ui-auth/ui-auth.js b/packages/web/server/lib/ui-auth/ui-auth.js
index 8c6de09b..926aaae2 100644
--- a/packages/web/server/lib/ui-auth/ui-auth.js
+++ b/packages/web/server/lib/ui-auth/ui-auth.js
@@ -270,14 +270,19 @@ const getUrlAuthTokenFromRequest = (req) => {
 };
 
 const getRequestPathname = (req) => {
-  if (typeof req?.path === 'string' && req.path) return req.path;
   const rawUrl = req?.originalUrl || req?.url;
-  if (typeof rawUrl !== 'string' || !rawUrl) return '';
-  try {
-    return new URL(rawUrl, 'http://localhost').pathname;
-  } catch {
-    return '';
+  if (typeof rawUrl === 'string' && rawUrl) {
+    try {
+      return new URL(rawUrl, 'http://localhost').pathname;
+    } catch {
+      // Fall through to Express' derived path fields.
+    }
   }
+  if (typeof req?.baseUrl === 'string' && req.baseUrl && typeof req?.path === 'string' && req.path) {
+    return `${req.baseUrl}${req.path}`.replace(/\/+/g, '/');
+  }
+  if (typeof req?.path === 'string' && req.path) return req.path;
+  return '';
 };
 
 const isWebSocketUpgrade = (req) => {
@@ -292,6 +297,8 @@ const isUrlAuthReadableHttpPath = (pathname) => {
     || pathname === '/api/openchamber/events'
     || pathname === '/api/notifications/stream'
     || pathname === '/api/fs/raw'
+    || pathname === '/api/fs/serve'
+    || pathname.startsWith('/api/fs/serve/')
     || pathname.startsWith('/api/preview/proxy/')
     || /^\/api\/terminal\/[^/]+\/stream$/.test(pathname)
     || /^\/api\/projects\/[^/]+\/icon$/.test(pathname);
diff --git a/packages/web/server/lib/ui-auth/ui-auth.test.js b/packages/web/server/lib/ui-auth/ui-auth.test.js
index ffb503c3..87a90267 100644
--- a/packages/web/server/lib/ui-auth/ui-auth.test.js
+++ b/packages/web/server/lib/ui-auth/ui-auth.test.js
@@ -182,6 +182,37 @@ describe('ui auth client credential seam', () => {
     expect(await auth.ensureSessionToken(urlReq, urlRes)).toBe('client:device-1');
     expect(await auth.resolveAuthContext(urlReq, urlRes, { allowUrlToken: false })).toBe(null);
 
+    const serveReq = { method: 'GET', path: '/api/fs/serve/tmp/index.html', url: `/api/fs/serve/tmp/index.html?oc_url_token=${encodeURIComponent(urlToken)}`, headers: {} };
+    const serveRes = createResponse();
+    let serveCalled = false;
+    await auth.requireAuth(serveReq, serveRes, () => {
+      serveCalled = true;
+    });
+    expect(serveCalled).toBe(true);
+
+    const absoluteServeReq = { method: 'GET', path: '/api/fs/serve/Users/test/project/preview-test.html', url: `/api/fs/serve/Users/test/project/preview-test.html?oc_url_token=${encodeURIComponent(urlToken)}`, headers: {} };
+    const absoluteServeRes = createResponse();
+    let absoluteServeCalled = false;
+    await auth.requireAuth(absoluteServeReq, absoluteServeRes, () => {
+      absoluteServeCalled = true;
+    });
+    expect(absoluteServeCalled).toBe(true);
+
+    const mountedServeReq = {
+      method: 'GET',
+      baseUrl: '/api',
+      path: '/fs/serve/Users/test/project/preview-test.html',
+      originalUrl: `/api/fs/serve/Users/test/project/preview-test.html?oc_url_token=${encodeURIComponent(urlToken)}`,
+      url: `/fs/serve/Users/test/project/preview-test.html?oc_url_token=${encodeURIComponent(urlToken)}`,
+      headers: {},
+    };
+    const mountedServeRes = createResponse();
+    let mountedServeCalled = false;
+    await auth.requireAuth(mountedServeReq, mountedServeRes, () => {
+      mountedServeCalled = true;
+    });
+    expect(mountedServeCalled).toBe(true);
+
     const arbitraryGetReq = { method: 'GET', path: '/api/config/settings', url: `/api/config/settings?oc_url_token=${encodeURIComponent(urlToken)}`, headers: { accept: 'application/json' } };
     const arbitraryGetRes = createResponse();
     let arbitraryGetCalled = false;
diff --git a/packages/web/src/api/files.ts b/packages/web/src/api/files.ts
index a3fad996..3cb034e5 100644
--- a/packages/web/src/api/files.ts
+++ b/packages/web/src/api/files.ts
@@ -243,12 +243,21 @@ export const createWebFilesAPI = ({ urls }: WebFilesAPIOptions): FilesAPI => ({
 
   async downloadFile(path: string): Promise<void> {
     const target = normalizePath(path);
-    const url = urls.rawFile(target, { download: true });
+    const response = await runtimeFetch('/api/fs/raw', {
+      query: { path: target, download: true },
+    });
+    if (!response.ok) {
+      throw new Error(`Download failed (${response.status})`);
+    }
+
+    const blob = await response.blob();
+    const url = URL.createObjectURL(blob);
     const a = document.createElement('a');
     a.href = url;
     a.download = target.split('/').pop() || 'file';
     document.body.appendChild(a);
     a.click();
     document.body.removeChild(a);
+    setTimeout(() => URL.revokeObjectURL(url), 100);
   },
 });