The latest (tip-of-tree) protocol changes frequently and may break at any time. However it captures the full capabilities of the Protocol, whereas the stable release is a subset. There is no backwards compatibility support guaranteed for the capabilities it introduces.
Latest browser_protocol.json version updated:
Date: Sun Aug 20 15:15:25 2017 -0700
Latest js_protocol.json version updated:
Date: Mon Aug 14 23:15:20 2017 -0700