web-widgets: Skill for Claude Code

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

openspec-onboard is a skill for Claude Code, Codex from mendix/web-widgets. It costs 26 tokens per session (3,349 once invoked), scanned A, a copy of openspec-onboard, Apache-2.0.

A narrated onboarding workflow for OpenSpec, a tool that organizes software changes into proposals, specifications, designs, and implementation tasks. It walks through one complete change using real codebase work.

In plain words
What is it for?
Use it to learn OpenSpec, choose a small codebase task, create its planning documents, implement the change, and archive it.
Why use it?
It teaches the workflow through a practical example and prevents the user from starting before the OpenSpec command-line tool is installed.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one. Also seen: installed under .agents/ (shared by several agents).

This is mendix/web-widgets's own configuration. It tells Claude Code and Codex how to work on web-widgets 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 web-widgets configures →

Reuse

Borrowing it

Nothing to install: this file belongs to mendix/web-widgets. 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/mendix/web-widgets/main/.agents/skills/openspec-onboard/SKILL.md
Clone the repo
git clone --depth 1 https://github.com/mendix/web-widgets

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.

agentmods badge for openspec-onboard

README.md
[![agentmods](https://agentmods.dev/badge/skills/mendix/web-widgets/openspec-onboard/github.svg)](https://agentmods.dev/skills/mendix/web-widgets/openspec-onboard)
Your own site
<a href="https://agentmods.dev/skills/mendix/web-widgets/openspec-onboard"><img src="https://agentmods.dev/badge/skills/mendix/web-widgets/openspec-onboard/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.

agentmods 80×15 button for openspec-onboard

Your own site · 80×15
<a href="https://agentmods.dev/skills/mendix/web-widgets/openspec-onboard"><img src="https://agentmods.dev/badge/skills/mendix/web-widgets/openspec-onboard.svg" alt="Reviewed on agentmods" width="80" 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 3,349 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 73% 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 $0.03349
Opus 5.5 $0.00010 $0.01340
Sonnet 5.5 $0.00005 $0.00670
Haiku 4.5 $0.00003 $0.00335

Measured 1mo ago against content hash 14774213b08f, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, 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 1mo 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

73% identical to openspec-onboard — 180 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.

.agents/skills/openspec-onboard/SKILL.md · 575 lines

How it starts

The opening of the file, as written. The whole thing — 575 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.


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.

Phase 2: Task Selection

Codebase Analysis

Scan the codebase for small improvement opportunities. Look for:

  1. TODO/FIXME comments - Search for TODO, FIXME, HACK, XXX in code files
  2. Missing error handling - catch blocks that swallow errors, risky operations without try-catch
  3. Functions without tests - Cross-reference src/ with test directories
  4. Type issues - any types in TypeScript files (: any, as any)
  5. Debug artifacts - console.log, console.debug, debugger statements in non-debug code
  6. Missing validation - User input handlers without validation

Also check recent git activity:

# Unix/macOS
git log --oneline -10 2>/dev/null || echo "No git history"
# Windows (PowerShell)
# git log --oneline -10 2>$null; if ($LASTEXITCODE -ne 0) { echo "No git history" }

Read the full file on GitHub · 575 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. 1mo ago First seen · 575 lines · 26 tokens per session scan A 14774213b08f

Subscribe to this mod's changes

openspec-onboard is a skill published in the GitHub repository mendix/web-widgets (40 stars, last pushed today), licensed Apache-2.0. It adds 26 tokens to every session and 3,349 once invoked, about $0.0001 per session on Opus 5.5. A static security scan graded it A with 0 findings. It is 73% identical to openspec-onboard, differing in 180 lines, and is treated as a copy.

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