Daily Reminder Message for "Days Since" an Event

[Grumblesmith]

Provide users an option to set a daily reminder for events with text like "Days since EVENT: N". This should be configurable per event. It would be nice if the reminder destination channel could also be specified per event.

Original User Feedback:

a Simpsons-like daily reminder that keeps track of the number of days it has been since an event occurred. Would be nice for it to work similar to the Slackbot reminder app, so that you can set it to specific channels.

[Grumblesmith]

Requested by another user

Do you support the ability to add a custom date? A same usecase would be posting a message every day like this, "It's been 10 days since our last site outage" which of course updates X days appropriately, and is posted every day. I don't want to have to create the /since on the very day of the last outage, I'd want to say something like, /since create "mobile app outage" 08-01-2023.