set-core: Skill for Claude Code

.claude/skills/openspec-onboard/SKILL.md

openspec-onboard is a skill for Claude Code from tatargabor/set-core. It costs 26 tokens per session (3,759 once invoked), scanned A, a copy of openspec-onboard, MIT.

A guided introduction to OpenSpec that walks through a complete change workflow while explaining each step and working in the real codebase.

In plain words
What is it for?
Use it to learn OpenSpec, check its command-line tool, and complete a first proposal-to-implementation cycle.
Why use it?
It helps someone new learn how OpenSpec works without having to understand the process beforehand. The explanations accompany an actual workflow rather than a purely theoretical example.

Skill for Claude Code

Written for Claude Code: allowed-tools in frontmatter.

This is tatargabor/set-core's own configuration. It tells Claude Code how to work on set-core itself, so it is not a mod to install elsewhere. Copy it as a starting point and replace the rules that are about this project. Everything set-core configures →

Reuse

Borrowing it

Nothing to install: this file belongs to tatargabor/set-core. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file
curl -O https://raw.githubusercontent.com/tatargabor/set-core/main/.claude/skills/openspec-onboard/SKILL.md
Clone the repo
git clone --depth 1 https://github.com/tatargabor/set-core

Made for: Claude Code.

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 openspec-onboard

README.md
[![agentmods](https://agentmods.dev/badge/skills/tatargabor/set-core/openspec-onboard.svg)](https://agentmods.dev/skills/tatargabor/set-core/openspec-onboard)
Your own site
<a href="https://agentmods.dev/skills/tatargabor/set-core/openspec-onboard"><img src="https://agentmods.dev/badge/skills/tatargabor/set-core/openspec-onboard.svg" alt="Measured on agentmods" height="20"></a>
Per session 26 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 3,759 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 94% 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.

ModelPer sessionOnce invoked
Fable 5.1 $0.00026 $0.03759
Opus 5 $0.00013 $0.01879
Sonnet 5 $0.00005 $0.00752
Haiku 4.5 $0.00003 $0.00376

Measured today against content hash d389cc98dba8, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-06, from the pricing page.

Security

Grade A, and why

openspec-onboard 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 today.

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

94% identical to openspec-onboard — 53 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.

.claude/skills/openspec-onboard/SKILL.md · 562 lines

How it starts

The opening of the file, as written. The whole thing — 562 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Guide the user through their first complete OpenSpec workflow cycle. This is a teaching experience—you'll do real work in their codebase while explaining each step.

Store selection: If the user names a store (a store is a standalone OpenSpec repo registered on this machine) or the work lives in one, run openspec store list --json to discover registered store ids, then pass --store <id> on the commands that read or write specs and changes (new change, status, instructions, list, show, validate, archive, doctor, context, schemas, view). Once selected, treat --store <id> as sticky for the rest of the workflow. Every unscoped example of those commands below is shorthand: before running it, append the flag. For example, run openspec status --change "<name>" --json --store "<id>", not the unscoped form shown below. Other commands do not take the flag. Hints printed by commands already carry the flag; keep it on follow-ups. Without a store, commands act on the nearest local openspec/ root.


Preflight

Before starting, check if the OpenSpec CLI is installed:

# Unix/macOS
openspec --version 2>&1 || echo "CLI_NOT_INSTALLED"
# Windows (PowerShell)
# if (Get-Command openspec -ErrorAction SilentlyContinue) { openspec --version } else { echo "CLI_NOT_INSTALLED" }

If CLI not installed:

OpenSpec CLI is not installed. Install it first, then come back to /opsx:onboard.

Stop here if not installed.


Phase 1: Welcome

Display:

## Welcome to OpenSpec!

I'll walk you through a complete change cycle—from idea to implementation—using a real task in your codebase. Along the way, you'll learn the workflow by doing it.

**What we'll do:**
1. Pick a small, real task in your codebase
2. Explore the problem briefly
3. Create a change (the container for our work)
4. Build the artifacts: proposal → specs → design → tasks
5. Implement the tasks
6. Archive the completed change

**Time:** ~15-20 minutes

Let's start by finding something to work on.

Read the full file on GitHub · 562 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. today First seen · 562 lines · 26 tokens per session scan A d389cc98dba8

Subscribe to this mod's changes

openspec-onboard is a skill published in the GitHub repository tatargabor/set-core (35 stars, last pushed yesterday), licensed MIT. It adds 26 tokens to every session and 3,759 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it A with 0 findings. It is 94% identical to openspec-onboard, differing in 53 lines, and is treated as a copy.