Spec-Driven Development Puts a Blueprint Under AI-Generated Code
As code generation gets cheaper, the bottleneck shifts from typing to deciding. SDD gives a team a single, version-controlled artifact that an AI agent can read to understand what to build, how to build it, and how to know when it's done—cutting the rework that makes AI-assisted projects net-negative after the first week.
Vibe Coding's chat-driven loop collapses under its own weight once a project grows beyond a single session. Without a durable record of decisions, AI agents guess at architecture, silently break existing features, and force developers into cycles of rework that erase the early speed gains. SDD addresses this by making a specification—not the chat log—the authoritative artifact that defines scope, design, tasks, and acceptance criteria.
The process follows a Spec → Plan → Tasks → Implement sequence. A proposal document locks down what the MVP will and won't do, a design document resolves technical risks like API surface and security constraints before a single line of code exists, and a task list breaks the work into small, verifiable units that keep an agent's context focused. When requirements change, the specification changes first, and any drift between the document and the codebase is treated as a defect.
A walkthrough using a Chrome translation plugin shows the method in practice: extracting article text, calling an OpenAI-compatible model, and rendering Markdown in a Side Panel. The upfront investment in writing clear, falsifiable acceptance criteria—"translation results display in a sidebar with independently scrollable body text" instead of "the interface should look good"—eliminates the guessing that causes AI-generated projects to unravel.
The core failure mode of Vibe Coding isn't the AI's capability but the absence of a durable, shared context that survives across sessions and feature additions.
SDD reframes documentation from a passive artifact that rots after implementation to an active constraint that governs what the AI generates, making it closer to a type system for intent.
The 'ten-minute spec' tradeoff—pausing before the first prompt to write why, what, how, and how-to-verify—is a leverage point that compounds as project complexity grows.
Treating specification drift as a defect rather than a documentation debt item changes the team's relationship with AI-generated code: the spec is the product, and the code is one of its outputs.