argentum-engine: Skill for Claude Code

.agents/skills/add-feature/SKILL.md

add-feature is a skill for Claude Code from wingedsheep/argentum-engine. It costs 87 tokens per session (3,939 once invoked), scanned A, original, no licence file.

A workflow for adding a new feature or game mechanic to the Argentum Engine beyond a single Magic: The Gathering card. It covers engine, SDK, server, and client functionality such as effects, triggers, and conditions.

In plain words
What is it for?
Use it when building a reusable engine or SDK capability, or adding related server or client behavior.
Why use it?
It helps place broader functionality in the project's existing architecture instead of treating it as a one-off card implementation.

Skill for Claude Code

Written for Claude Code: argument-hint in frontmatter. Also seen: installed under .agents/ (shared by several agents).

This is wingedsheep/argentum-engine's own configuration. It tells Claude Code how to work on argentum-engine 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 argentum-engine configures →

Reuse

Borrowing it

Nothing to install: this file belongs to wingedsheep/argentum-engine. 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/wingedsheep/argentum-engine/main/.agents/skills/add-feature/SKILL.md
Clone the repo
git clone --depth 1 https://github.com/wingedsheep/argentum-engine

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 add-feature

README.md
[![agentmods](https://agentmods.dev/badge/skills/wingedsheep/argentum-engine/add-feature.svg)](https://agentmods.dev/skills/wingedsheep/argentum-engine/add-feature)
Your own site
<a href="https://agentmods.dev/skills/wingedsheep/argentum-engine/add-feature"><img src="https://agentmods.dev/badge/skills/wingedsheep/argentum-engine/add-feature.svg" alt="Measured on agentmods" height="20"></a>
Per session 87 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 3,939 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 unknown 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 5.1 $0.00087 $0.03939
Opus 5 $0.00044 $0.01969
Sonnet 5 $0.00017 $0.00788
Haiku 4.5 $0.00009 $0.00394

Measured 8d ago against content hash 1cfc05f298dc, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-07, from the pricing page.

Security

Grade A, and why

add-feature 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 8d 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.

.agents/skills/add-feature/SKILL.md · 250 lines

The source is not reproduced here

A licence we could not identify

The repository carries a LICENSE file, but it is custom or dual enough that GitHub cannot name it and neither can this catalogue. Unknown terms are not permission, so the body is not copied here. Read the licence at the source and decide for yourself.

Read it on GitHub

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. 8d ago First seen · 250 lines · 87 tokens per session scan A 1cfc05f298dc

Subscribe to this mod's changes

add-feature is a skill published in the GitHub repository wingedsheep/argentum-engine (64 stars, last pushed 2d ago), with no licence file. It adds 87 tokens to every session and 3,939 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 2026-08-30.

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