Hello,
Hope it’s OK for you to let me add my 2 cents to this discussion.
My understanding is IG aims to reduce alerting noise and have a better relationship between incidents (ie: tickets, here in PagerDuty) and real disruptions (ie: only one incident to ack/resolve for the same cause, even if many probes detect the disruption).
Not grouping an alert because the incident is acknowledged is not the sense. And for us will increase noise.
But: I agree with this: as the incident responder I want to be able to decide (optional) to be informed when a new alert is added/resolved into an incident
eg: be notified via my 1st notifications rules (or the last notification channel used for the incident) when an alert is added/resolved
eg: have a message into the linked Slack channel (if I set it) when an alert is added/resolved
And to be sure the incident responder checked all the alerts - even only to define if he had to split them into a new incident - until it becomes a habit, maybe add a confirmation when closing an incident with more than 1 alert.
Regards,
SĂ©bastien
PS: you should not have alerts added indefinitely as you should not have indefinitely new probes detecting the same issue, and the ones which trigger the incident should send the same event (using dedup key) until they resolve.