Chapter 30: Understanding Spec-Driven Development
Spec-Driven Development bridges human creativity and AI precision: it turns vague ideas into executable contracts so coding agents can operate within clear boundaries and shared truths. By starting with specs — not vibes — we ensure AI coding agents build systems that are correct by design, traceable by memory, and governed by principle.
As AI-driven development matures, one thing is clear: its future will be written not in code, but in specs.
Throughout this chapter you’ll collaborate with your AI companion to co-create specifications, use those specs to generate code, and evaluate the practical trade-offs of a “spec-as-source” workflow.
How to Work Through This Chapter
You'll need: Your AI coding assistant open alongside this book.
The workflow: When you see "Tell your companion:" or "Ask your companion:" prompts:
- Copy the prompt and paste it into your AI tool
- Review the response - does it make sense? Does it raise questions?
- Refine through dialogue - ask follow-up questions, request clarifications
- Capture the results - save the collaborative spec in a file (we'll show you where)
This isn't passive reading—it's active collaboration. By the end, you'll have real specification documents you created with AI, not just read about.
What You'll Learn
By the end of this chapter you will be able to:
- Diagnose vagueness: identify and quantify the real costs (time, rework, debugging, debt) caused by unclear requirements.
- Write your first production-ready spec: produce a single, executable spec with intent, requirements, acceptance criteria, and test scenarios.
- Use AI as a spec partner: run the prompts and dialogues that reveal missing requirements, edge cases, and testable acceptance criteria.
- Evaluate tools & patterns: choose the right tooling strategy for your team’s scale and constraints.
- Apply organizational patterns: understand how “Constitutions” or domain-level rules can embed governance and speed coordination across many engineers.