Feature-Sliced Design (FSD) v2.1 Source : fsd.how | Strictness can be adjusted based on project scale and team context. --- 1. Core Philosophy & Layer Overview FSD v2.1 core principle: "Start simple, extract when needed." Place code in first. Duplication across pages is acceptable and does not automatically require extraction to a lower layer. Extract only when the same code is currently being used in multiple places (not hypothetically), the usages do not always change together, and the boundary has a focused responsibility. Not all layers are required. Most projects can start with only , ,…