What problem does it solve? Drawing accurate database ER diagrams or data-flow diagrams by hand is slow and error-prone: foreign keys dangle, cardinality goes unmarked, and processes end up with no inputs or outputs. This Skill produces a validated ER or DFD diagram in Excalidraw, enforcing referential integrity, flow conservation, and a minimum quality score before saving. ## Core Features & Use Cases - ER diagram generation: Renders each table as a card with columns, PK/FK/UK markers, and crow's-foot or Chen cardinality on relation arrows, routing many-to-many relations through explicit junction tables. - Data-flow diagram generation: Places external entities, processes, and cylinder-shaped data stores connected by labelled data flows, validating that every process has at least one input and one output. - Reverse engineering from code: Derives tables, columns, and foreign keys from migrations, ORM models, or Prisma schemas via repository analysis. - Quality loop: Runs lint, score, repair, polish, and architecture validation until the drawing scores at least 95 with zero hard blockers, then saves, versions, and exports to SVG/PNG. - Use Case: Ask to reverse-engineer a Prisma schema into an ER diagram; the Skill builds the table cards, flags any FK missing an index, redacts database connection strings, and exports a clean diagram. ## Quick Start Ask the agent to draw the ER diagram for your orders service with users, orders, products, and an order_items junction table, marking PKs, FKs, and cardinality.
