Best layer for scripting?

[St4B]

Hello I am thinking about using rhino in order to have some JS functions.
Where do you think is the best part to execute them?

I was thinking about having the following architecture.
Presentation layer triggers the execution of a script.
Domain layer uses the Data layer in order to retrieve the script.
Domain layer executes the script. (The script is possible to do complex calculations and operate over db)

By this approach we do our calculation (aka logic) inside a use case and in a background thread,
but we can not handle UI and we handle data from domain layer which breaks our architecture.
What do you think?