ephemeral bot messages

@chrisdickinson mentioned this idea (credit where credit is due!) and I have found that it would be very useful for a plugin I have made.

when a message gets the 📱 emoji reaction, my bot will convert the direct URL to that message into a QR Code and display it as a reply to said message. This way its easy to transfer to the same spot in the thread from your Desktop to your mobile device.

However, after about 30 seconds, the QR Code isn't really all that useful! Not to mention it clutters up the channel quite a bit.

So, if we could set some kind of ephemeral duration on each message a bot sends, OR, have a setting to only make the message visible to the initiating user (emoji reactor), it might be a nice way to declutter the channel.