Codebase Design

Design and evaluate deep modules: cohesive responsibility behind a small, stable caller-facing contract, with information hiding, justified seams, explicit effects, dependency strategy, and behavior-focused tests. Use when designing or changing an in-process module or package contract, consolidating shallow pass-through modules, deciding what to hide, comparing alternative interfaces, or asking whether code should be combined or split for leverage and locality. For physical layout use structure-codebase; for public compatibility use api-design; for a repository-wide scan use improve-codebase-architecture. For an already-selected whole-path requirement to support a calibra…