What problem does it solve? Codebases accumulate shallow modules whose interfaces are nearly as complex as their implementations, making code hard to test, navigate, and change. This Skill provides a shared vocabulary and decision framework for designing deep modules that hide complexity behind small interfaces. ## Core Features & Use Cases - Deep-module vocabulary: Precise definitions of module, interface, seam, adapter, depth, leverage, and locality so teams and AI agents name things consistently. - Dependency-aware deepening: Classifies dependencies (in-process, local-substitutable, remote-owned, true external) and prescribes ports-and-adapters strategies for each, per DEEPENING.md. - Parallel interface exploration: DESIGN-IT-TWICE.md 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 identify the right seam, define a port with production and in-memory test adapters, and rewrite tests against the new deep interface. ## Quick Start Ask the AI to review a module in your codebase and suggest how to deepen its interface using the codebase-design vocabulary.
