spec-driven-development

A workflow that writes a clear specification before code is written. A specification describes what to build, why it is needed, and how to decide whether it is finished.

In plain words
What is it for?
Use it to clarify an idea, agree on requirements, plan significant changes, and define completion checks before coding.
Why use it?
It reduces guesswork when a project, feature, or larger change starts with unclear requirements.

Skill for Claude CodeCodex

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add skills/codoop/codoop-flow/spec-driven-development
Any agent
npx skills add Codoop/codoop-flow --skill spec-driven-development
Clone the repo
git clone --depth 1 https://github.com/Codoop/codoop-flow

Made for: Claude Code, Codex.

Per session 43 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,977 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin 92% copy Near-identical to another mod in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00043 $0.01977
Opus 5 $0.00022 $0.00988
Sonnet 5 $0.00009 $0.00395
Haiku 4.5 $0.00004 $0.00198

Measured yesterday against content hash c4b3bc41eef5, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

spec-driven-development scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured yesterday.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

Origin

This is a copy

92% identical to as-spec-driven-development — 20 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

skills/spec-driven-development/SKILL.md · 217 lines

How it starts

The opening of the file, as written. The whole thing — 217 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Spec-Driven Development

Conversation Profile

When codoop_flow.toml is available, read user_role; a missing value means general. It applies only to this conversation: use normal professional terms inside the user's field, and explain cross-field topics in plain language. The user may override it for the current conversation by asking for simpler or more professional language. Never apply the profile to code, PRD, Spec, Plan, Todo, reports, agent prompts, or other generated files; those stay precise and professional.

Overview

Write a structured specification before writing any code. The spec is the shared source of truth between you and the human engineer — it defines what we're building, why, and how we'll know it's done. Code without a spec is guessing.

When to Use

  • Starting a new project or feature
  • Requirements are ambiguous or incomplete
  • The change touches multiple files or modules
  • You're about to make an architectural decision
  • The task would take more than 30 minutes to implement

When NOT to use: Single-line fixes, typo corrections, or changes where requirements are unambiguous and self-contained.

The Gated Workflow

Spec-driven development has four phases. Do not advance to the next phase until the current one is validated.

SPECIFY ──→ PLAN ──→ TASKS ──→ IMPLEMENT
   │          │        │          │
   ▼          ▼        ▼          ▼
 Human      Human    Human      Human
 reviews    reviews  reviews    reviews

Phase 1: Specify

Start with a high-level vision. Ask the human clarifying questions until requirements are concrete.

Surface assumptions immediately. Before writing any spec content, list what you're assuming:

ASSUMPTIONS I'M MAKING:
1. This is a web application (not native mobile)
2. Authentication uses session-based cookies (not JWT)
3. The database is PostgreSQL (based on existing Prisma schema)
4. We're targeting modern browsers only (no IE11)
→ Correct me now or I'll proceed with these.

Read the full file on GitHub · 217 lines

Files

What ships with it

1 file beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. yesterday First seen · 217 lines · 43 tokens per session scan A c4b3bc41eef5

Subscribe to this mod's changes

spec-driven-development is a skill published in the GitHub repository Codoop/codoop-flow (5 stars, last pushed 8d ago), licensed MIT. It adds 43 tokens to every session and 1,977 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. It is 92% identical to as-spec-driven-development, differing in 20 lines, and is treated as a copy.

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