I developed TextSender for Pebble, a jailbreak tweak that enables text sending and actionable notification functionality for Pebble users. The tweak hooks directly into Pebble's app and modifies it in order to allow the user to send texts or perform actions on notifications. TextSender for Pebble is for sale on Cydia, the jailbreak community's equivalent of the App Store. TextSender has over a thousand users. You can view the source code here.