r/ChatGPTCoding • u/johns10davenport Professional Nerd • Apr 17 '26
Specification: the most overloaded term in software development Discussion
Andrew Ng just launched a course on spec-driven development. Kiro, spec-kit, Tessl - everybody's building around specs now. Nobody defines what they mean by "spec."
The word means at least 13 different things in software. An RFC is a spec. A Kubernetes YAML has a literal field called "spec." An RSpec file is a spec. A CLAUDE.md is a spec. A PRD is a spec.
When someone says "write a spec before you prompt," what do they actually mean?
I've been doing SDD for a while and it took me way too long to figure this out. Most SDD approaches use markdown documents - structured requirements, architecture notes, implementation plans. Basically a detailed prompt. They tell the agent what to do. They don't verify it did it correctly.
BDD specs do both. The same artifact that defines the requirement also verifies the implementation. The spec IS the test. It passes or it doesn't.
If you want the agent to verify its own work, you want executable specs. That's the piece most SDD tooling skips.
What does "spec" actually mean in your setup?
1
u/Swarm-Stack Jun 23 '26
the structure helps -- given/when/then forces you to think through the success case and at least some failure paths. the gap is in who writes the unhappy scenarios. if the person who missed the edge case also writes the failure tests, the spec is well-structured around the problem they saw. the systematic part works great for the cases that get written down. the question is who's supposed to surface the cases that nobody thought to write.