Good point. Perhaps the database api could refuse strings and require Templates.

That’s a big breaking change around a brand new feature. I’m sure it could be done well, but it gives me the shivers.

You add a new API that takes templates only leaving the existing API in place. You (some releases later) deprecate the string API. You (some releases later, with clear advance warning of when it is coming) actually remove the deprecated API. "It's a big breaking change around a brand new feature", yeah, so you don't break anything around a brand new feature, it's not like this kind of transition is a new concept.

much better would be execute_template(t"...")