The Pebble watch has a Intent that is globally sended when the Pebble is connected/disconnected. This allow the phone apps to know if the watch is connected or not. I have s
Have you tried NodeApi, you can use getConnectedNodes
Gets a list of Nodes to which this device is currently connected.
or addListener(GoogleApiClient client, NodeApi.NodeListener listener)
which
Registers a listener to receive all node events.
Then you can use callbacks from NodeApi.NodeListener
onPeerConnected(Node peer) and onPeerDisconnected(Node peer)