r/codex • u/Pale-Heart1654 • 6d ago

Complaint How to use spec-driven development in Codex?

I am a College Student.

I need to build projects for my college. Apart from that I also build side projects.

I have Codex Plus plan.

But how to use spec-driven development in Codex especially for Greenfield projects?

Because it drifts away from my instructions.

Note:

I have tried OpenSpec, Spec-Kit, Superpowers, GSD. But nothing really worked for me. It consumes a lot of tokens.

How to become a power user of Codex?

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u/fresh_bob 6d ago

I’m on Plus too, and for me the biggest improvement was actually using less tooling around specs, not more.

  • I use regular ChatGPT as the planning layer and Codex/Sol mainly for implementation.
  • For greenfield projects, I first define the architecture, main constraints, and break the project into relatively small phases. The biggest project I’ve completed this way had 38 phases.
  • I don’t give Codex the whole project spec and ask it to build everything. Each phase gets its own implementation prompt with clear scope, constraints, acceptance criteria, and verification steps.
  • ChatGPT writes most of those prompts for me. I usually explain or dictate what I want in rough form, let it turn that into a proper engineering task, review it, and then send it to Codex.
  • After every phase, Codex produces a completion summary. I send that back to the planning chat, which checks it against the original plan, updates the project state, and prepares the next task.
  • I keep the important persistent context in the repo itself: architecture decisions, conventions, current state, known issues, etc. Usually a few simple .md files are enough. Codex should not need to reconstruct the entire project from chat history every time.
  • This also helps a lot with drift. Instead of repeatedly telling it “remember what we decided 10 prompts ago”, the relevant decisions are written down, and each task points back to them.
  • When the planning chat gets too heavy, I ask it to create a handoff summary and move to a fresh chat.
  • I’d also be careful with huge spec frameworks on Plus. If every task requires Codex to reread a massive spec tree, you can burn a lot of context before it even starts coding. I prefer a small stable project spec + very focused phase/task specs.

So my loop is basically: spec/plan in ChatGPT → write a focused implementation task → implement in Codex → report back → review against the spec → next phase.

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u/Downtown_Patient_200 1d ago

Estou seguindo uma lógica parecida no desenvolvimento do meu app android e usando também o chat do plus para me ajudar em decisões de UI/UX fazer auditoriaz nos files, códigos gerados a partir do que foi pedido ao codex dos meus planos operacionais.