Spec-driven development

AI Spec-Driven Development (AI-SDD) in 2026 | Why SDD Is Back, the Four Documents (Requirements, Spec, Basic Design, Detailed Design), and How Progress and Memory Docs Are Becoming Code

Since GitHub's Spec Kit and AWS's Kiro arrived in autumn 2025, spec-driven development (SDD) has become the standard discipline for AI coding. Written for corporate new-business teams, this article explains why "fix the documents before writing code" made a comeback, how to write the four documents (requirements, specification, basic design, detailed design) with a coding agent, and why development docs, progress docs and memory docs now play a role close to code, quoting Andrej Karpathy's statements along the way. A full rewrite of the March 2026 original. Part 3 of the AI-native new business development series.