A workflow for Spec-Driven Development, a way to define a feature before coding it. It turns an interview into a specification and acceptance criteria, makes a plan, and then carries out the work test first.

Use it to plan and build a feature through a specification, acceptance criteria, implementation plan, and tests. It stores each feature's work in its own project folder.

It removes ambiguity about what a feature must do before implementation begins. The required plan and tests help keep coding aligned with agreed behavior.

sdd — Skill for Claude Code by RobinNorberg/oh-my-copilot

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 RobinNorberg/oh-my-copilot --skill sdd

Clone the repo

git clone --depth 1 https://github.com/RobinNorberg/oh-my-copilot

Made for: Claude Code.

Or install oh-my-copilot, the plugin that ships this one along with the rest of its 99 skills, 21 commands, 20 agents, 11 hooks, 1 MCP server.

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/robinnorberg/oh-my-copilot/sdd/github.svg)](https://agentmods.dev/skills/robinnorberg/oh-my-copilot/sdd)

Your own site

<a href="https://agentmods.dev/skills/robinnorberg/oh-my-copilot/sdd"><img src="https://agentmods.dev/badge/skills/robinnorberg/oh-my-copilot/sdd/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/robinnorberg/oh-my-copilot/sdd"><img src="https://agentmods.dev/badge/skills/robinnorberg/oh-my-copilot/sdd.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 34 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 1,054 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 100% 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.

Model	Per session	Once invoked
Fable 5.1	$0.00034	$0.01054
Opus 5.5	$0.00014	$0.00422
Sonnet 5.5	$0.00007	$0.00211
Haiku 4.5	$0.00003	$0.00105

Measured 2d ago against content hash 097875a6deaf, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

sdd 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.

Origin

This is a copy

100% identical to sdd — 0 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/sdd/SKILL.md · 68 lines

How it starts

The opening of the file, as written. The whole thing — 68 lines — stays where its author put it; the contents beside it link to each section on GitHub.

SDD (lite)

Interview → Spec+AC → Plan → Test-first execute. Artifacts live in spec/<slug>/ at project root (one folder per feature). No implementation code before spec/<slug>/plan.md is approved.

If args start with full: read and follow phases/spec.md, phases/criteria.md, phases/rules.md, phases/review.md, phases/tasks.md, phases/execute.md (relative to this skill's directory) in that order, confirming with the user after each artifact. Pick the slug as in Entry; every phase writes to spec/<slug>/. Then stop reading this file.

Entry

git status --short --branch; list spec/*/.
Pick the slug (kebab-case, max 40 chars, descriptive of the feature):
- On a feature branch, use the branch name without the prefix (feat/csv-export → csv-export) if spec/<that>/ exists or the task matches it.
- Otherwise derive it from the task (add CSV export of reports → csv-report-export) and show it to the user in the first message so they can correct it.
- If several spec/*/ folders exist and the task is unclear, ask which one to resume via AskUserQuestion.
Resume at the first missing artifact in spec/<slug>/ and say where you resume.
Task text comes from args or the user's message. Ask only if there is none.
Skip the flow for tasks prefixed quick:.

1. Interview (no file yet)

Read the code first; never ask what the code answers.
One question at a time via AskUserQuestion: 2-4 concrete options, a recommended pick, one-line reason why it matters.
Ask only if the answer changes behavior, scope, or a safe assumption. Otherwise decide and record it as an assumption.
Stop when an implementer would have no questions left. Typically 3-7 questions; more means the task should be split.

2. Spec → `spec/<slug>/spec.md`

One file, short:

Summary (2-3 sentences)
Decisions and assumptions (bullets, with the reason)
Out of scope
Acceptance criteria: AC-1, AC-2, ... one observable outcome each, EARS form: When <trigger>, the <system> shall <response>. / If <bad trigger>, then the <system> shall <response>. / While <state>, ...
- Bounded values: three ACs (inside, at, beyond the bound).
- Error paths: state the response and whether it is all-or-nothing.
- No implementation details, no "fast"/"correct" without a number.

Read the full file on GitHub · 68 lines

Files

What ships with it

6 files 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.

2d ago First seen · 68 lines · 34 tokens per session scan A 097875a6deaf

Subscribe to this mod's changes

sdd is a skill published in the GitHub repository RobinNorberg/oh-my-copilot (5 stars, last pushed yesterday), licensed MIT. It adds 34 tokens to every session and 1,054 once invoked, about $0.0001 per session on Opus 5.5. A static security scan graded it A with 0 findings. It is 100% identical to sdd, differing in 0 lines, and is treated as a copy.

Planning TDD Testing agentic-coding ai-agents automation copilot copilot-cli copilot-enabled

sdd next to 6 skills from other repositories
Mod	Type	Stars	Last push	Licence	Scan	Tokens	Works with
sddRobinNorberg/oh-my-copilot	Skill	5	yesterday	MIT	A	34	Claude Code
tddYeachan-Heo/oh-my-claudecode	Skill	41k	yesterday	MIT	A	43	Claude Code
windbg-kernel-bugcheck-triagemicrosoft/win-dev-skills	Skill	510	6d ago	MIT	A	50	Claude Code
windbg-user-exception-triagemicrosoft/win-dev-skills	Skill	510	6d ago	MIT	A	69	Claude Code
windbg-user-virtual-memory-exhaustionmicrosoft/win-dev-skills	Skill	510	6d ago	MIT	A	54	Claude Code
windbg-kernel-irp-lifecycle-triagemicrosoft/win-dev-skills	Skill	510	6d ago	MIT	A	58	Claude Code
windbg-kernel-lock-deadlock-triagemicrosoft/win-dev-skills	Skill	510	6d ago	MIT	A	56	Claude Code