FCIS Architect & Refactoring Guide

소개

This skill implements the 'Functional Core, Imperative Shell' (FCIS) pattern to improve code testability and reduce architectural debt. It provides Claude with a strict framework for classifying files as either pure logic containers or I/O orchestrators, mandating pattern comments on all modified files. By separating computational complexity from environment-dependent side-effects, it ensures that business logic remains deterministic and easy to unit test without complex mocks, while isolating external dependencies in thin imperative shells. It is particularly useful when refactoring legacy code or architecting new features that require high reliability.

주요 기능

• Mandatory file classification using pattern comments for every code file
• Isolated I/O and orchestration handling via the Imperative Shell pattern
• Comprehensive decision framework for determining function placement
• 45 GitHub stars
• Strict enforcement of pure, side-effect-free Functional Core logic
• Standardized refactoring patterns for converting mixed logic into clean architectures

사용 사례

• Refactoring monolithic functions that mix database calls with complex business rules
• Decoupling application logic from external dependencies like APIs, file systems, and environment variables
• Establishing high-testability architectural standards for new project modules