I’m not sure how up-to-date this all is as I have switched all my ESP8266 integration over to MQTT using the MQTT bridge as I’ve found it to be more reliable and far more flexible for all sorts of use cases. Moreover, the authors of that bridge don’t seem as inclined to take their ball and go home which is pretty important for my own projects as I don’t want to have to redevelop my own code in response to someone else’s rage against the machine.
Anyway, here’s what I have saved. This was originally released under the Apache License so share and share alike:
SmartThingsContactSensor.ino
esp8266-contact-sensor.groovy