Worked on the ash-project/ash repository to deliver robust multi-tenancy support by building Tenant-aware Aggregates and introducing a dedicated Tenant resource. The engineering approach involved refactoring aggregate logic in Elixir to ensure all aggregation operations respect tenant boundaries, thereby enhancing data isolation and enabling reliable per-tenant data operations. A targeted patch was applied to fix the aggregates’ to_tenant support, ensuring correct aggregation scope across tenant contexts. The work also included tightening tests around multi-tenant scenarios, improving codebase maintainability and robustness. This effort leveraged backend development skills and a strong focus on testing to address multi-tenancy requirements effectively.