Spec-driven development
lastmod 2025-10-20created 2025-10-201 edits
About
- Spec-Driven-Development (SDD) is an approach in AI-assisted coding where a specification (spec) is written before the code, with the spec serving as the source of truth for both developers and AI
- SDD is divided into three implementation levels that evolve step by step: spec-first (write the spec first), spec-anchored (keep the spec for maintenance), and spec-as-source (the spec is the main source file and developers do not edit code directly)
- Kiro offers a simple three-step workflow of requirements → design → tasks, spec-kit uses a strong rule-based workflow called a constitution, and Tessl experiments with a spec-as-source approach that maps specs to code 1:1
- All three tools share limitations: they demand excessive process for small bug fixes, reviewing markdown files is more cumbersome than reviewing code, and despite large context windows, the AI does not properly follow all instructions
- SDD recalls the past failures of model-driven development (MDD) and risks having the drawbacks of both sides, non-determinism and inflexibility, so its usefulness in real projects needs to be validated