Completion needs a proactive notification
Aliases: completion alert · call-back on done · task-finished notice
What it is
The person has gone to do something else. At some moment the job ends. If ending only swaps a spinner for a checkmark on the original screen, the message is delivered into an empty room. A proactive completion notification is the system calling the person back from the other task on success or failure: an OS notice, an in-app banner, a badge, a sound or a vibration — some channel that can cross current attention. It is not a decorative success motion. It is a cross-task call.
This leaf covers completion when the person is not looking. If they are still watching, an in-place change is enough; another notification is noise.
Why it happens
Once attention has left, the original window is outside perception. The completion event happens where the person is not, so to be noticed it must occupy the channel they are now using, or a channel that is allowed to interrupt (notification centre, status bar). Changing only the original window is writing a signal on an unwatched monitor.
Calls have a cost. Notify on every completion and people disable that class of notice; the channel is dead when a real return is needed. So the trigger is “the person is probably gone at completion”, not “notify on every done”. Failure often needs the call more than success: success can be discovered at the next open; failure leaves people thinking it is still running.
Where it stops holding
When the app is foreground and the wait is under the attention ceiling, do not send a second notice. If notification permission has been denied, the fallback is a prominent entry on next open, not an unsilienceable full-screen ad. Multiple completions at once should merge; five “Done” notices exhaust the channel. Privacy-sensitive completions (a payslip is ready) must not spell the content on the lock screen — only “a task finished”. Sound and vibration in public must be muteable.
Applying it
- For tasks expected to exceed ten seconds and allowed to leave, send a notification on both completion and failure that deep-links to the task object. Failure copy must be distinguishable from success.
- If the person is still in that UI in the foreground, suppress the notice and use an in-place completion state only.
- Tapping the notice should return to that task, not the app home.
- How to check: start a long export, switch apps, wait until it finishes. A notice should arrive that opens onto the file. A control group that watched the progress the whole time should not get an extra system notice.