What is spec-driven-development?

A guided four-phase process for building software from a specification: discovery, implementation planning, test-driven development, and code review. Test-driven development means writing tests before or alongside the code they verify.

Use it to start a structured development cycle for a feature or module, choose the appropriate phase, write tests during implementation, and complete a final code review.

It gives feature work a defined path from requirements to reviewed implementation, helping catch misunderstandings and defects earlier.

spec-driven-development — Skill for Claude Code and Codex by Ziolson

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.

Any agent

npx skills add Ziolson/ai-context-hub --skill spec-driven-dev

Clone the repo

git clone --depth 1 https://github.com/Ziolson/ai-context-hub

Made for: Claude Code, Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

README.md

[![agentmods](https://agentmods.dev/badge/skills/ziolson/ai-context-hub/spec-driven-dev/github.svg)](https://agentmods.dev/skills/ziolson/ai-context-hub/spec-driven-dev)

Your own site

<a href="https://agentmods.dev/skills/ziolson/ai-context-hub/spec-driven-dev"><img src="https://agentmods.dev/badge/skills/ziolson/ai-context-hub/spec-driven-dev/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

Your own site · 80×15

<a href="https://agentmods.dev/skills/ziolson/ai-context-hub/spec-driven-dev"><img src="https://agentmods.dev/badge/skills/ziolson/ai-context-hub/spec-driven-dev.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 59 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 121 The whole file, excluding the scripts and references it only reads on demand.

Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.

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.

Model	Per session	Once invoked
Fable 5.1	$0.00059	$0.00121
Opus 5.5	$0.00024	$0.00048
Sonnet 5.5	$0.00012	$0.00024
Haiku 4.5	$0.00006	$0.00012

Measured 2mo ago against content hash 15d1f06b6cbd, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, 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 2mo 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.

adapters/antigravity/skills/spec-driven-dev/SKILL.md · 16 lines

What it actually says

Spec-Driven Development

Read and follow the instructions from the following files:

docs/workflows/spec-driven-development.md — Full SDD cycle overview and mandatory rules

Also apply the global rules from rules/global-rules.md.

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.

2mo ago First seen · 16 lines · 59 tokens per session scan A 15d1f06b6cbd

Subscribe to this mod's changes

spec-driven-development is a skill published in the GitHub repository Ziolson/ai-context-hub (2 stars, last pushed 2mo ago), licensed MIT. It adds 59 tokens to every session and 121 once invoked, about $0.0002 per session on Opus 5.5. 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 2026-08-31.

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