can I pass lambdas as task inputs?

Afair, no

I think we may have fixed it some time ago, but I don't have a reference at hand

thank you, will take a look

The Kobweb Gradle plugin uses

Property<(String) -> String>

and other lambda properties as task inputs with no issues. The trick is to annotate them with

@Nested

instead of

@Input

, this makes the task rerun when the lambda changes as expected.