backend-data-layer

@lookatitude

Designs database schemas, access patterns, indexes, and query shapes for a single storage boundary. Output: DDL (SQL) or schema fragment plus query-pattern notes and indexing plan. Pulled by the `backend` specialist. TRIGGER: "design the schema for X", "what tables do we need for X", "model the data for X", "draft the DDL for X", "what indexes should we add for X queries", "how should we store X". DO NOT TRIGGER for: writing the actual migration file (use `backend-migration-writer`), external API shape (use `backend-api-contract`), third-party integration (use `backend-service-integration`), picking a DB engine at vendor level (architect-tradeoff-matrix or researcher-comparison-table), cross-service data-flow architecture (architect-systems-design).