[Feature] Mobile: show when a large upload was interrupted instead of restarting it silently

[teconomix]

I have searched the existing feature requests, both open and closed, to make sure this is not a duplicate request.

• Yes

The feature

Make it visible in the mobile app when a foreground upload was cancelled and restarted, instead of retrying silently.

Background. When the app leaves the foreground (screen off, switching apps) during a foreground upload, the in-flight POST /assets is cancelled and starts again from 0 % when the app is resumed. According to #32422 and #29005 this is by design, and resumable/chunked uploads are already tracked in #1674 and #22385. This request is about neither of those.

The problem is that the user is never told. For a large video (several GB), what happens today is:

• the upload is cancelled and restarted from zero, again and again, with no message
• the asset simply stays "not backed up"; nothing shows that it was attempted, how far it got, or why it was dropped
• the only way to find the cause is the reverse proxy log (499 / client closed the request after a few seconds) or the app log (Foreground backup cancelled: restarting the backup)

In #32422 a 4.8 GB video never made it through the app, while the same file uploaded from the same phone through the web UI in 133 s. File, network, proxy and server were fine. A single hint from the app would have explained it immediately; instead it looked like a bug and took proxy and app log analysis to understand.

Proposal. Keep an interrupted upload as a visible state rather than a silent restart, for example:

• in the backup screen / on the asset: "Upload interrupted at 37 % because the app was closed. Large files only upload while the app stays open."
• once the same asset has been interrupted a few times, or for files above a size that is unlikely to finish in one session: a hint to keep the app open with the screen on, or to use the web upload

This would not change the upload behaviour at all, only tell the user what is going on. It would remain useful after resumable uploads land, since an interruption would still be worth showing.

Platform

• Server
• Web
• Mobile