Currently if you're looking at a Zulip message that contains an uploaded file (other than an image or video, which we handle directly in the message feed) — for example a PDF — and you click the link to try to open the file, you get a Zulip login page.

This ultimately works; you just have to do the login, and then you can see the file. But it'd be smoother if the file opened without that step; after all, you were already logged in in the Zulip app.

The legacy app had this feature; see zulip/zulip-mobile#3303 where it was requested, and zulip/zulip-mobile#4089 for the implementation. We'll use the same feature of the Zulip server API as the legacy app did for this; see getFileTemporaryUrl.js.

References

• Chat thread: #mobile > can't open uploaded PDF
• Old zulip-mobile issue: Viewing uploaded files fails, or requires logging in again zulip-mobile#3303
• Implementation in zulip-mobile: View uploaded files without needing to be logged in to the realm in the browser. zulip-mobile#4089
• API documentation: partial docs at https://zulip.com/api/get-file-temporary-url ; additional details in zulip-mobile's API binding at zulip-mobile:src/api/messages/getFileTemporaryUrl.js.