Duplicate/similar web notifications sent

[trwnh]

Follow and mention notifications are being sent twice, with slightly different text:

Mentions:

• "x mentioned you"
• "you were mentioned by x"

Follows:

• "x followed you"
• "x is now following you"

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• I searched or browsed the repo’s other issues to ensure this is not a duplicate.
• This bug happens on v2.4.2 and not on master (If you're a user, don't worry about this).

[renatolond]

I have the same, also in v2.4.2.

[ClearlyClaire]

This has been bugging me for a long time, but I finally understand what's going on.
When the Service Worker receives a push event, it generates a notification.
However, that notification may have sub-par formatting, incomplete information, etc., so the code fetches the missing bits to craft a better notification.

This behavior was introduced in 4b94e9c.

So I guess we have to replace the notification without triggering a new one, if that's possible at all.

EDIT: That's what the tag attribute, already used, should do. So either there is a bug in the browser, or something else is going on.
EDIT2: Well, the tag attribute replaces the notification if it's still there, but will show a new notification if the previous one was discarded!

[renatolond]

Hm, this discarded situation is weird, I have a pebble and what I see is this:

A first notification arrives, in the format of notification_mailer.favourite.subject. Then, almost immediately, I get a second one in the format of notification.favourite. If I turn on the phone, I indeed see only the second one. But it seems to get weird when the notifications collapse, at that point I start to see both.

[ClearlyClaire]

That looks like a bug in the browser, the first notification should be entirely discarded. And it should also not re-notify… I wonder if some properties changing between the two versions cause that…

Alternatively, we could postpone displaying a notification to when the subsequent API call returns…

[renatolond]

It seems the push example by google postpones until the API answers:
https://developers.google.com/web/updates/2015/03/push-notifications-on-the-open-web#a_more_complete_push_event_example