codebase-designlisted

# Codebase Design Design **deep modules**: a lot of behaviour behind a small interface, placed at a clean seam, testable through that interface. Leverage for callers, locality for maintainers, testability for everyone. This skill merges the deep-module vocabulary with a scan-and-grill workflow: surface architectural friction as deepening opportunities, present them as a visual HTML report, then grill through the one the user picks. ## When to use - Designing a new module or restructuring an existing one — deciding where a seam goes, what hides behind it - Finding refactoring or deepening opportunities across a codebase - Making a codebase more testable or AI-navigable - Consolidating tightly-coupled shallow modules into one deep module - Triggers on "deep module", "seam", "refactoring opportunity", "架构改进", "模块设计", "deepening", "深化模块", "重构架构", "代码库设计" **Not for:** executing the structural change once the design is settled (use `refactoring`); single-file clarity cleanup — naming, nesting, dead code (use `simplify`); greenfield system architecture (use `architecture`); feature-level API contracts (use `api-design`). This skill designs and audits; it does not edit code. ## Steps ### 1. Scan for deepening opportunities Read the project's domain glossary (`CONTEXT.md`) and any ADRs in the area you're touching first — the domain language names good seams; ADRs record decisions not to re-litigate. Scope before you scan — put weight on parts of the codebase that have recently