Strategy for grouped resources

I realize this isn't exclusively a JR question, but I feel it's too common to not bring it up and how one might accomplish it using JR.

My current use case has a type of model that's the basis for summed queries grouped by one or more attributes. In this case, it's a timesheet entry, and I initially need to group them by user_id and project_id, but they could easily be grouped by time periods as well. The aggregated value is SUM(hours). I've created an TimesheetEntryCollection model as an ActiveModel::Model object to handle the aggregated data, but I'm unsure how to serialize them, as JR expects and ActiveRecord::Relation to be returned from the Resource's self.records method and I'm not sure how to force a relation out of a tableless model. Do I just need to override the controller methods, or is there some way to do this through the resource?

Am I thinking about this the wrong way? Should JR maybe allow arrays to be returned from self.records with the understanding that you have to handle pagination/filtering yourself?

Any help would be greatly appreciated!

Start with the Resource's self.records contract and the controller methods mentioned in the report, then trace how JR serializes an ActiveRecord::Relation. Compare that path with the tableless ActiveModel::Model TimesheetEntryCollection and grouped SUM(hours) use case. Done requires an agreed approach for grouped resources, including whether arrays and caller-managed pagination or filtering are supported.