Someone says 'about to push this potentially breaking change to a shared resource, is that ok?'. Then everyone else posts a :thumbsup:

Obviously, this could be done differently. But it's easy to do it like this and come to depend on it.

While that use case is certainly an example of a convenience, I don’t think it passes the “mission critical” bar.

I can’t think of any way that emoji reactions would be mission critical unless they are part of an API that can be used for automated execution of tasks. But maybe that sort of thing does exist?

And is that an acceptable paper trail? If you break something can you show your bosses "look, Jack thumbs-upped me on Slack!"

It is a perfectly adequate paper trail. It's much easier to check in a postmortem than shouting something across the desk. Like code review, because you know your approval will be recorded irrevocably, you just think it through that little bit extra before approving.

Well, you can undo your own reactions, so not 'irrevocably'.

We typically do something similar in Hipchat - "Hey, I'm about to push to prod, any objections?" "No, go for it."

This is what I don't get; for someone wanting to use an irc client ":thumbs-up:" is as least as good as the actual graphic. Nothing is lost. And that goes for all the built-in emojis in slack.

Now if it was :4677: it'd be a different story - without some support it'd be hard to understand the constant identifiers.

/shrug

We use it for an on the spot estimation outside of our normal grooming sessions.