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[Bug]: Web clients can't open chat HTML/PDF file links in a browser #15929
Description
Activity
Note
Grok responding on behalf of Julius.
Triage
Thanks @saphid for the thorough write-up and screenshots across local and remote web clients. Having both menus side by side made the gating easy to follow.
What I found
- The menus in your screenshots match current main (
37de6cb; the file-link logic is unchanged sincea1d9d72). - A chat file chip only gets a browser item when
isPreviewSupportedInRuntime()is true (theonOpenInBrowserprop inapps/web/src/components/ChatMarkdown.tsx). That check iswindow.desktopBridge?.preview(apps/web/src/previewStateStore.ts), so browser clients never get it, and the item it adds today is Open in integrated browser, not the system browser. - Open in Cursor and Reveal in Finder sit behind a separate gate,
canUseMarkdownFileShellActions, which requires a resolved local-exec environment. That's why a Tailscale origin shows only Copy relative path and Copy full path. - Open in system browser on URL links comes from a different menu (
apps/web/src/components/chat/externalLinkContextMenu.ts). File chips don't use it. - On web, the intended rendered view for HTML/PDF links is the Files panel viewer: left-click calls
openFileInPanel, which signs an asset URL and shows the file in a frame, anddocs/user/composer.mddescribes these files opening as rendered pages on web and desktop. That viewer isn't gated on the desktop bridge, so it should work from a remote browser. - In your left-click capture, the
q3-summary.htmltab is open but the panel body is empty: no breadcrumbs, file tree, spinner, "Unable to load file preview", or document. That empty viewer is the clearest failure here; the screenshot doesn't show why the frame failed to load. - Related but different: [Bug]: Local HTML files open to a blank viewer in T3 Code Desktop #11191 (desktop viewer lands on
chrome-error://chromewebdata/while source view works) and fix(web): show an error when a file preview frame fails to load #11588 (adds an error state when a preview frame fails). fix(web): let web clients open chat HTML/PDF file links in the system browser #7641 is closed, so there's no open fix PR for this yet.
Likely fix area
The web file viewer path behind
openFileInPanel(asset URL signing and the preview frame) for HTML/PDF on browser clients, especially over a remote origin. Separately, whether file chips on web should also offer an open-in-system-browser action is a product question. Any console or network errors from that blank panel would help narrow down why the frame doesn't render.A maintainer will decide on the fix direction.
- The menus in your screenshots match current main (
Before submitting
Area
apps/web
Steps to reproduce
[q3-summary.html](/abs/path/reports/q3-summary.html)or[architecture.pdf](/abs/path/reports/architecture.pdf).npx t3/vp run devin a browser, or a remote browser over LAN/Tailscale.Expected behavior
There is some way to view the file rendered, as there is for URL links in the same chat. Those offer Open in system browser (
apps/web/src/components/chat/externalLinkContextMenu.ts) and follow the Open links in setting.Actual behavior
No menu item opens the file in a browser.
Left-clicking the chip opens a Files panel tab instead of a rendered page; in this repro that tab stayed blank after 5 seconds, which I did not investigate further. A browser on another machine also can't reach the environment's filesystem, so on web there is no way to see the agent's HTML report or PDF rendered.
The rendered-view action is gated on the desktop integrated browser:
ChatMarkdown.tsxL2797–2803 only setsonOpenInBrowserwhenisPreviewSupportedInRuntime(). Desktop has the same gap in a smaller form: file links can open only in the integrated browser, never in the OS browser.Impact
Major degradation or frequent failure
Version or commit
main a1d9d72 (reproduced 2026-10-05)
Environment
macOS 26.5.2 (arm64), Google Chrome 154.0.8037.93, Node 24.21.0;
vp run dev --sharewith isolated dev state. Local originhttp://localhost:7720; remote origin is the dev runner's Tailscale Serve HTTPS URL (same Mac).Screenshots, recordings, or supporting files
Local web, right-click on
q3-summary.html:Local web, right-click on
architecture.pdf:Remote web (Tailscale origin), right-click on
q3-summary.html:Local web, left-click on
q3-summary.html(the Files panel opens, but no rendered page):Not verified: hosted app.t3.codes, Safari/Firefox, a client on a separate machine.
Workaround
Copy the full path and open the file some other way on the machine that hosts the environment. That isn't possible from a remote browser.
A fix is proposed in #7641.