Learning AI-Native Software Engineering

Chapter 4. Spec-Driven Development

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This will be the 6th chapter of the final book. Please note that the GitHub repo will be made active later on.

If you’d like to be actively involved in reviewing and commenting on this draft, please reach out to the editor at [e-mail].

The next major section of this book is about Spec-Driven Development (SDD). We’ll start not with formats or templates, but with the question that makes everything else make sense: why does writing a specification matter at all when you have an agent that can just start coding?

The answer isn’t obvious until you’ve been burned. Most engineers experience it the same way: you describe what you want, the agent writes code, and the code looks plausible. Then you run it, or review it more carefully, and you realize it has solved a subtly different problem than the one you had in mind. You go back and forth, refining the prompt, asking for corrections, watching the diff grow. Eventually you get something workable, but it takes twice as long as it should, and you’re not entirely sure what the code is doing or why.

That experience has a structural explanation, and this chapter is about understanding it well enough that you stop repeating it. Here’s the other thing: you ...