IMO it's nowhere near this cut and dried as you suggest to bring this into a courtroom. A court may well look at the text messages and listen to the claims from both sides and rule that something that was supposedly said that evening at dinner, or in the suggestion to get dinner together was OP's agreement to foot the bill. I'm not saying that is the truth, but it wouldn't prevent grifters from making the claim and a Court deciding the text messages alone aren't enough to make the grifters responsible for their tab.
It also shouldn't go unsaid that if the courts were suddenly called into action to handle every dispute like this one, even small claims, our court systems would collapse under the sheer volume. I've worked in the system almost two decades now, it's straining at the seams in many, many places.
I get not wanting to let lowlifes like this keep taking people for a ride. I shared my own experience upthread on a similar situation and how I went about trying to short circuit the scam to keep going on and balance the social aspects of adult and kid relationships. My solution ended up shutting down a particular scheme and the scammer simply came up with new ones. It's not all that different even when court judgments get involved -- vermin find a way.
Addressing other points upthread, the bar for obtaining a property lien is typically reserved for specific criteria, for good reason.