The Protocol on Ireland is quite breathtaking in its level of detail. It establishes a "common regulatory area" between north-south, covering customs, VAT, energy, env, agri, product markets and more. This is the enforcement section -- full ECJ jurisdiction over Northern Ireland 
Here is the free movement of goods section (which basically describes a customs union). Note the need for joint EU-UK customs checks on goods coming from the UK mainland
One VAT regime between EU and NI
More on the EU-UK joint customs checks on goods crossing the Irish Sea. Remember the EU institutions would have direct enforcement authority within NI
EU state aid rules apply to NI.
Automatic rule taking for NI on all policies covered by the common regulatory area
UK regulators would not have the authority to approve products -- like say car parts -- that are part of the NI-Ireland regulatory area
Some interesting safeguard provisions
This is important. It states the fallback plan in the protocol can be superseded. But it also makes clear that this would be decided AFTER Brexit day -- so the fallback plan would have to be in the withdrawal agreement, regardless of what is agreed this year
No fudge here -- this is the summary of the annexes detailing all the EU regulations, directives and implementing acts that are covered under the north-south regulatory area.
The official document is now out so no more selective leaks from me.... ec.europa.eu/commission/sit…
