ss-write-spec

ss-write-spec is a skill for Claude Code, Codex from lbk-open/super-spec. It costs 76 tokens per session (1,035 once invoked), scanned A, original, Apache-2.0.

A tool for writing OpenSpec change specifications from a proposal, PRD, or plain-language requirement. OpenSpec records proposed behavior changes in structured files for review.

In plain words
What is it for?
Use it to create or update delta specifications, including when a repository has no OpenSpec structure yet or when existing deltas need correction.
Why use it?
It lets teams agree on the intended behavior before creating a detailed coding plan or changing implementation code.

Skill for Claude CodeCodex

Part of the super-spec plugin — 20 skills shipped together

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/lbk-open/super-spec/ss-write-spec
Any agent
npx skills add lbk-open/super-spec --skill ss-write-spec
Clone the repo
git clone --depth 1 https://github.com/lbk-open/super-spec

Made for: Claude Code, Codex.

Or install super-spec, the plugin that ships this one along with the rest of its 20 skills.

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.

agentmods badge for ss-write-spec

README.md
[![agentmods](https://agentmods.dev/badge/skills/lbk-open/super-spec/ss-write-spec.svg)](https://agentmods.dev/skills/lbk-open/super-spec/ss-write-spec)
Your own site
<a href="https://agentmods.dev/skills/lbk-open/super-spec/ss-write-spec"><img src="https://agentmods.dev/badge/skills/lbk-open/super-spec/ss-write-spec.svg" alt="Measured on agentmods" height="20"></a>
Per session 76 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,035 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 $0.00076 $0.01035
Opus 5 $0.00038 $0.00517
Sonnet 5 $0.00015 $0.00207
Haiku 4.5 $0.00008 $0.00103

Measured 3d ago against content hash 9c527e681726, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

ss-write-spec 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 3d 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.

skills/ss-write-spec/SKILL.md · 136 lines

How it starts

The opening of the file, as written. The whole thing — 136 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Write OpenSpec Delta

Generate OpenSpec-compatible delta specs under openspec/changes/<change-id>/. This is a plumbing skill: day-to-day development normally goes through the ss-plan skill, whose Phase 0 runs this same logic automatically.

When To Use

  • You need to align capability specs with reviewers before writing a full execution plan.
  • You need to adjust delta specs without regenerating the plan.
  • The ss-coding or ss-create-pr skill reported missing or invalid delta specs.

Inputs

Input Handling
A URL to a hosted doc (wiki, Confluence, Google Docs, etc.) Fetch it with your document-reading tool, or an available doc-integration skill, and convert it to markdown
A local markdown file Read the file directly
Plain text Treat it as the requirement source

If none of these is available, ask the user for the proposal, PRD, or requirement text before continuing.

Language of the deltas: write requirement and scenario prose in the same language as the input document (or the project's existing docs, if that's a clearer signal); default to English when neither gives a signal. SHALL/MUST keywords, code identifiers, and file paths always stay in English.

Step 0: Ensure the OpenSpec Skeleton Exists

Check whether openspec/specs/ and openspec/changes/ already exist. If this repository has no OpenSpec structure yet, create it first by following ../ss-references/openspec-skeleton.md, then continue with Step 1 below.

Process

Step 1: Read Context

Read:

  • openspec/config.yaml, if present
  • all existing openspec/specs/*/spec.md
  • active deltas under openspec/changes/*/specs/*/spec.md, excluding archive/
  • relevant OpenAPI definitions, if API paths are mentioned
  • project guidance files (e.g., AGENTS.md / CLAUDE.md), if present

Step 2: Derive Change ID

Use an explicit --change-id if provided. Otherwise derive a kebab-case id from, in order:

  1. the current branch name, stripped of its type prefix, or
  2. the proposal title, or
  3. the first meaningful requirement sentence.

Read the full file on GitHub · 136 lines

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. 3d ago First seen · 136 lines · 76 tokens per session scan A 9c527e681726

Subscribe to this mod's changes

ss-write-spec is a skill published in the GitHub repository lbk-open/super-spec (1 stars, last pushed 12d ago), licensed Apache-2.0. It adds 76 tokens to every session and 1,035 once invoked, about $0.0004 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 2026-08-31.

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