What problem does it solve? Codebases often accumulate shallow modules with large interfaces and thin implementations, making code hard to test, navigate, and maintain. This Skill provides a shared vocabulary and design principles for creating deep modules that hide complexity behind small interfaces. ## Core Features & Use Cases - Deep Module Vocabulary: Defines precise terms (module, interface, seam, adapter, depth, leverage, locality) so teams and AI agents discuss architecture consistently. - Dependency-Aware Deepening: Classifies dependencies (in-process, local-substitutable, remote-owned, true external) and prescribes ports-and-adapters strategies for each, via DEEPENING.md. - Parallel Interface Exploration: Uses a Design-It-Twice pattern that spawns multiple sub-agents to propose radically different interfaces, then compares them on depth, locality, and seam placement. - Use Case: When refactoring a cluster of shallow service classes, use this Skill to merge them into one deep module, define a port at the seam, and rewrite tests against the new interface. ## Quick Start Ask the agent to review a module in your codebase and suggest how to deepen its interface using the codebase-design vocabulary.
