Reverse-engineers an existing software project into AI Unified Process artifacts: a PlantUML use case diagram, per-use-case specification documents, and an entity model with a Mermaid ER diagram. Use when the user asks to "reverse engineer this codebase", "extract use cases from existing code", "document the system we already have", "generate use case specs from controllers", "derive an entity model from the database", "create AI Unified Process artifacts from a legacy project", or mentions reverse engineering, legacy documentation, or onboarding an inherited codebase. Trigger this skill whenever a user wants to produce use cases, an ER diagram, or a use case diagram from code that already exists rather than from a fresh vision document — even if they don't say "reverse engineer" explicitly.