Improve Codebase Architecture Surface architectural friction and propose deepening opportunities : refactors that turn shallow modules into deep ones. The aim is testability and AI-navigability. This command is informed by the project's domain model and built on a shared design vocabulary: - Call the Skill tool with "codebase-design" for the architecture vocabulary ( module , interface , depth , seam , adapter , leverage , locality ) and its principles (the deletion test, "the interface is the test surface", "one adapter = hypothetical seam, two = real"). Use these terms exactly in every sugg…