Figure out why Gilda posts `howdy` message before user actually seems to join

[joekr]

We have seen two cases where Gilda posts a message before the user seems to actually join the channel. I'm not sure if there is much we can do about it since Slack is sending the events to us but worth looking into.

History

Oddly enough we see the message at 11:24 ET and the slack event was sent at 1591500248.379100 Sunday, June 7, 2020 3:24:08.379 AM GMT

The function logged it at 2020-06-07 03:24:42,798 UTC
Then I see 3 times the function is sent the event:

1. 2020-06-07 03:24:42,798 UTC
2. 2020-06-07 03:24:42,821 UTC
3. 2020-06-07 03:25:14,212 UTC
   so I’m not sure why slack wouldn’t show in the channel until 12:50 AM ET

[xtoddx]

My theory is that for channels that are auto-joined upon account creation, we're actually seeing the account creation send the channel joined notification. When users boot the app at some later point it actually shows up in the client.

Is there a user presence notification? We can pend the welcome message until we see the user come online, etc.

[joekr]

Possibly use this event: https://api.slack.com/events/user_change given that when they signup/sigin they are updating their user. 🤷

I'm thinking we could subscribe to a few different events, log them and see what is sent

[joekr]

I think I found it. I think the event we want is https://api.slack.com/events/message/channel_join. This could be sent at the same time we see the joined #random. message.

Update: Nope. I don't think that event exists anymore. Or anyway I can't figure out how to add that event.

[xtoddx]

channel_join is RTM (real-time messaging) and not events api.

Side-by-side comparison here: https://api.slack.com/events?nojsmode=1

Which led me to https://api.slack.com/events/member_joined_channel?nojsmode=1