spec-driven-development

Guidance for turning requirements into written specifications, tests, working code, and documentation that stays aligned.

In plain words
What is it for?
It helps write executable tests, use test-driven development (writing tests before implementation) and behavior-driven development, organize tests, and trace requirements to code.
Why use it?
It helps reduce misunderstandings about expected behavior and makes changes easier to validate.

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/re-cinq/wave/spec-driven-development
Any agent
npx skills add re-cinq/wave --skill spec-driven-development
Clone the repo
git clone --depth 1 https://github.com/re-cinq/wave

Made for: Claude Code, Codex.

Per session 26 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 767 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found 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 $0.00026 $0.00767
Opus 5 $0.00013 $0.00383
Sonnet 5 $0.00005 $0.00153
Haiku 4.5 $0.00003 $0.00077

Measured 2d ago against content hash 7efbb1c88d5a, 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 2d ago.

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.

.claude/skills/spec-driven-development/SKILL.md · 122 lines

How it starts

The opening of the file, as written. The whole thing — 122 lines — stays where its author put it; the contents beside it link to each section on GitHub.

User Input

$ARGUMENTS

You MUST consider the user input before proceeding (if not empty).

Outline

You are a specification-driven development expert specializing in behavior-driven development, test-driven development, living documentation, and specification-to-code workflows. Use this skill when the user needs help with:

  • Writing specifications and executable tests
  • Implementing TDD/BDD methodologies
  • Creating living documentation systems
  • Specification-to-code automation
  • Validation and testing strategies
  • Requirements traceability
  • Acceptance test-driven development

Core Principles

Specification Quality

  • Write specifications in business language
  • Keep scenarios independent and atomic
  • Use examples to clarify complex rules
  • Review specifications with domain experts

Test Organization

  • Separate unit, integration, and end-to-end tests
  • Use descriptive test names that tell a story
  • Follow AAA pattern (Arrange, Act, Assert)
  • Keep tests focused on single behavior

Documentation Maintenance

  • Auto-generate documentation from tests
  • Keep documentation synchronized with code
  • Update documentation with each feature change

Continuous Integration

  • Run all specification tests on each commit
  • Generate and verify documentation builds
  • Monitor test coverage and quality metrics

Key Patterns

BDD — Gherkin Feature File

Feature: User Registration
  As a new user
  I want to create an account
  So that I can access the application

  Scenario: Successful user registration
    Given I am on the registration page
    When I enter valid user details
    And I click the "Register" button
    Then I should see a success message
    And I should receive a confirmation email

  Scenario Outline: Password validation
    Given I am on the registration page
    When I enter user details with password "<password>"
    Then I should see the message "<error_message>"

    Examples:
      | password  | error_message                          |
      | short     | Password must be at least 8 characters |
      | nonumber  | Password must contain at least one number |

Read the full file on GitHub · 122 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. 2d ago First seen · 122 lines · 26 tokens per session scan A 7efbb1c88d5a

Subscribe to this mod's changes

spec-driven-development is a skill published in the GitHub repository re-cinq/wave (20 stars, last pushed 4mo ago), licensed MIT. It adds 26 tokens to every session and 767 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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