Beyond Vibe-Coding: A Practical Guide to Spec-Driven Development

AI has transformed how fast teams can build software, but not how easily they can build the right software. Too often, speed comes through what’s now called vibe-coding: describing an idea in tweet-sized sentences, letting the AI write the code, and fixing things as they break. It feels fast until the system starts to wobble under its own shortcuts.

The gap between “done” and “done right” keeps widening. For leaders, that means missed timelines, creeping scope, and growing maintenance pain.

Spec-Driven Development, or SDD, is the pause that saves you later. It’s taking a moment to define what success actually means before anyone starts coding. Instead of handing an AI a vague prompt and hoping for the best, you give it a clear specification that aligns humans and agents from the start.

This isn’t just a new workflow. It’s a safeguard. Left unguided, AI will vibe-code, producing code that looks fine but misses the point. A solid spec changes that, turning AI from a fast but careless assistant into a partner that truly understands the intent behind the work.

What Is Spec-Driven Development?

At its core, Spec-Driven Development (SDD) is exactly what it sounds like: you start with a specification, not code. Before a single line is written, you lay out what the system or feature should do in detail, including requirements, user flows, behaviors, edge cases, and constraints. That document becomes the north star. Everything else (design, implementation, testing, documentation) lines up behind it.

A few principles define the practice:

• Specification first. You don’t leave the requirements to chance. Expected behaviors, edge cases, and constraints are captured up front.
• One source of truth. The spec anchors the entire project. Tests, documentation, even design decisions all trace back to it.
• Built-in testability. Because the spec defines “what done looks like,” developers, QA, and stakeholders have a shared standard to measure against.
• Iterative by design. Specs aren’t stone tablets. They evolve as teams gather feedback (from design reviews, research, or stakeholder input), but always with traceability.