The rise of AI coding assistants has reignited interest in an old idea: what if specifications-not code-were the primary artifact of software development? Spec-driven development (SDD) inverts the traditional workflow by treating specifications as the source of truth and code as a generated or verified secondary artifact. This paper provides practitioners with a comprehensive guide to SDD, covering its principles, workflow patterns, and supporting tools. We present three levels of specification rigor-spec-first, spec-anchored, and spec-as-source-with clear guidance on when each applies. Through analysis of tools ranging from Behavior-Driven Development frameworks to modern AI-assisted toolkits like GitHub Spec Kit, we demonstrate how the spec-first philosophy maps to real implementations. We present case studies from API development, enterprise systems, and embedded software, illustrating how different domains apply SDD. We conclude with a decision framework helping practitioners determine when SDD provides value and when simpler approaches suffice.

翻译：AI编码助手的兴起重新点燃了一个古老理念的兴趣：如果规范——而非代码——成为软件开发的主要产物会怎样？规范驱动开发通过将规范视为唯一可信源，并将代码视为生成或验证的次级产物，从而颠覆了传统工作流程。本文为从业者提供了关于SDD的全面指南，涵盖其基本原则、工作流模式及支持工具。我们提出了规范严谨性的三个层级——规范优先、规范锚定与规范即源码，并明确了各层级的适用场景。通过对从行为驱动开发框架到现代AI辅助工具包（如GitHub Spec Kit）等工具的分析，我们展示了规范优先理念如何映射到实际实现中。我们呈现了来自API开发、企业系统和嵌入式软件领域的案例研究，阐明不同领域如何应用SDD。最后我们提出一个决策框架，帮助从业者判断SDD何时能创造价值，以及何时更简单的方法即可满足需求。