claudegoodies
Skill

spec-driven-development

From addyosmani

Creates specs before coding. Use when starting a new project, feature, or significant change and no specification exists yet. Use when requirements are unclear, ambiguous, or only exist as a vague idea.

Facts

Repository
addyosmani/agent-skills
Status
Actively maintained
Last commit
Source file
skills/spec-driven-development/SKILL.md

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The instructions Claude Code reads when this skill runs.

# Spec-Driven Development

## 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
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