rule-gen

rule-gen is a skill for Claude Code, Codex from ev-flow/quark-engine. It costs 32 tokens per session (1,407 once invoked), scanned A, original, GPL-3.0.

A tool workflow that turns a described software behavior and decompiled Android code into a Quark Engine detection rule. Quark Engine is a framework for finding suspicious behavior in Android apps, and decompiled code is code recovered from an app package.

In plain words
What is it for?
Use it to create and validate Quark Engine rules for detecting specific behaviors in APK files, the installable packages used by Android apps.
Why use it?
It helps turn an observed behavior into a checkable rule and tests the result against an actual Android app before returning it.

Skill for Claude CodeCodex

Installs and runs on its own, but its text points at files inside its plugin — anything it tells you to read at a ${CLAUDE_PLUGIN_ROOT} path is only there once the plugin is installed. Installing the plugin gets both.

Part of the quark plugin — 2 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/ev-flow/quark-engine/rule-gen
Any agent
npx skills add ev-flow/quark-engine --skill rule-gen
Clone the repo
git clone --depth 1 https://github.com/ev-flow/quark-engine

Made for: Claude Code, Codex.

Or install quark, the plugin that ships this one along with the rest of its 2 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 rule-gen

README.md
[![agentmods](https://agentmods.dev/badge/skills/ev-flow/quark-engine/rule-gen.svg)](https://agentmods.dev/skills/ev-flow/quark-engine/rule-gen)
Your own site
<a href="https://agentmods.dev/skills/ev-flow/quark-engine/rule-gen"><img src="https://agentmods.dev/badge/skills/ev-flow/quark-engine/rule-gen.svg" alt="Measured on agentmods" height="20"></a>
Per session 32 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,407 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
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 $0.00032 $0.01407
Opus 5 $0.00016 $0.00704
Sonnet 5 $0.00006 $0.00281
Haiku 4.5 $0.00003 $0.00141

Measured 4d ago against content hash 4dbd684e3cdc, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

rule-gen 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 4d ago.

The scan reads SKILL.md. This mod also ships 1 executable file (scripts/validate_rule.sh), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

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.

quark-ai-plugin/skills/rule-gen/SKILL.md · 163 lines

The source is not reproduced here

Licensed GPL-3.0

The repository is licensed GPL-3.0, which this catalogue does not treat as permission to reproduce the file. Read it at the source.

Read it on GitHub

Files

What ships with it

1 file 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.

  1. 4d ago First seen · 163 lines · 32 tokens per session scan A 4dbd684e3cdc

Subscribe to this mod's changes

rule-gen is a skill published in the GitHub repository ev-flow/quark-engine (1,713 stars, last pushed today), licensed GPL-3.0. It adds 32 tokens to every session and 1,407 once invoked, about $0.0002 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.