¡Trato hecho!

¡Trato hecho!
 

I'm trying to figure out when to use this expression. Am I right assuming that it means something like 'Deal!' or 'Agreed!'?
For example if we go for dinner and my friend says if we can't eat at xy tonight we'll go there next time, could I answer with 'Trato hecho'?

Done deal.
It's a done deal.

So more business related? Like an actual deal?

It isn't always used that way. It's used just like in English-an agreement.

Oh ok, so the above example would work then? Thanks Rusty

It's a deal.=Trato hecho.
It's just a saying we use to mean
an agreement. An iformal saying.
Let's make a deal. Hacemos un trato.

My Costa Rican family adds the following to it "........, jamás deshecho, y cuando lo busques ya está en el techo"

"Trato hecho" means "Deal".
Although we dont use "Trato hecho" to answer on the example, If you want to use a more Native Spanish expression to answer, you can use "De acuerdo" (all right) or "está bien" (it's ok).

Great, thanks!

It's a deal

Español :

¡Trato hecho! : could be used for busiiness too. o como afirmación enfática.
de acuerdo
Listo!