DDD、SDD、TDD：三個維度的邊際效益矩陣
軟體團隊常把 DDD、SDD 與 TDD 當成三選一的方法論，但它們其實分別處理領域語言、介面契約與重構風險。本文用三軸矩陣拆解三者在不同複雜度、協作邊界與變更成本下的邊際效益，提供判斷何時投資建模、規格或測試的實用框架，避免把方法論討論變成宗教戰爭。
Software Architecture
DDD, SDD, TDD: A Three-Axis Marginal Return Matrix
DDD, SDD, and TDD address different risks: domain language, interface contracts, and change safety. This matrix shows where each method pays off.
Design-First、API-First 與 Code-First：你是在選誰先付出代價？
PM 丟 Figma，工程師回 API spec。起點選錯，後期重構成本可能翻倍。拆解 Design-First、API-First、Code-First 的取捨，並提供 AI 時代的混合實戰框架。
Design-First, API-First, and Code-First: Which One Pays the Price First?
A PM drops a Figma link, and an engineer replies with an API spec. Pick the wrong starting point, and later refactor costs may double. This post breaks down the tradeoffs among Design-First, API-First, and Code-First, and offers a practical hybrid framework for the AI era.