limit on eager loaded association ?

ActiveRecord can't currently do that, but it'd be a nice feature given
how difficult it is to customize the eager loading queries.

However, you might be able emulate the functionality by constructing
your own query to fetch the ids of the association that match. Then
you could put them in a big array and pass them into the conditions on
the final query.

There would be a lot of issues, and it might ultimately be slower than
the n+1 queries. There's no direct way to limit the secondary results
although you might be able to cook something up with subselects or
other advanced db features.