Two Features, Two Days: What Spec-Driven Development with Spec Kit Taught Me
For most of this year my way of working with an AI coding agent was simple: I wrote a planning document, asked the agent for step 1, reviewed it, then asked for step 2. It worked, but everything important lived in my head and in a chat history that disappeared when the session ended. This month I tried the opposite approach. I adopted Spec Kit , GitHub's open-source toolkit for spec-driven development , and used it with Claude Code to ship two real features into production. People have started calling this kind of workflow an ADLC , an agentic development lifecycle: the classic spec → design → build → verify loop, redrawn so that an agent does most of the writing and a human owns the decisions. This post covers what that looked like over two days. It covers what worked, what surprised me, and where production proved the spec wrong. The setting The project is a domain-name intelligence SaaS: an ASP.NET Core 8 API and a React 19 front end, in two repositories, on top of Azure SQ...