score:7
The most likely candidate is the Regulation on common rules ensuring basic air connectivity with regard to the withdrawal of the United Kingdom from the Union. This sets out the EU's position over air travel in the case of a no deal Brexit, which amounts to freezing the situation at the state in 2018 for at least 7 months, with most provisions holding until 30th March 2020, or an actual deal.
I'm not an expert on EU legalese, but based on my own reading and media coverage, this is unilateral, but with suitable provisions for the Commission to act quickly to revoke it in the unlikely situation that the UK's unilateral declaration did something unexpected like closing UK airspace to EU carriers.