As a former user of Kafka, this is awesome and it would have been a huge help for our company if this was available then. I'm glad to hear that a company is offering Kafka as opposed to other propriety versions(AWS Kinesis etc).
One thing is odd though, there is no mention of disk space at all and only a configuration of retention time. One of Kafka's best features is the use of disk to store large amounts of messages, you are not RAM bound. Heroku seems to only allows you to set retention times? This could be awesome if they are giving you "unlimited" disk space, but could also be a beta oversight. Interested to see how this progresses.
That is very cool idea. I love saving the context there. It may be really cool to send an SMS contact too. That would make it one step less than the copy and paste.
I'm rolling out that feature in a few hours. I was a bit ambitions, but it will be `send to {{number}}`. Glad to hear that you found this as an important feature. I think it will be valuable too :)
I also think a lot has to do with language and deployment. Etsy uses PHP for their entire codebase. PHP can be easily hot swapped without any overhead. It's all scaffolded and thrown out every pageview. This provides a much simpler deploy process and has much less impact.
Java on the other hand takes time to warm up. It just isn't practical to redeploy the whole app when you are just updated one aspect.
I made a port of some Scala Monads to Javascript. Mostly, Option and Either. Makes for some really nice, and you won't find yourself doing (typeof foobar === "undefined").