duplication-check

duplication-check is a skill for Claude Code, Codex from iansmith/slopstop. It costs 81 tokens per session (1,707 once invoked), scanned C, original, no licence file.

A code-duplication check for a branch difference, using syntax-aware code search to find repeated code sections. It reports clone groups that meet a configured minimum line count.

In plain words
What is it for?
Use it to inspect duplicate code within one file or across files, including its locations, size, hash, scope, and varying identifiers.
Why use it?
It shows where duplicated code exists, whether it was already present in the base commit, and which repeated parts may be candidates for a shared helper.

Skill for Claude CodeCodex

Part of the slopstop plugin — 19 skills, 5 agents 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/iansmith/slopstop/duplication-check
Any agent
npx skills add iansmith/slopstop --skill duplication-check
Clone the repo
git clone --depth 1 https://github.com/iansmith/slopstop

Made for: Claude Code, Codex.

Or install slopstop, the plugin that ships this one along with the rest of its 19 skills, 5 agents.

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 duplication-check

README.md
[![agentmods](https://agentmods.dev/badge/skills/iansmith/slopstop/duplication-check.svg)](https://agentmods.dev/skills/iansmith/slopstop/duplication-check)
Your own site
<a href="https://agentmods.dev/skills/iansmith/slopstop/duplication-check"><img src="https://agentmods.dev/badge/skills/iansmith/slopstop/duplication-check.svg" alt="Measured on agentmods" height="20"></a>
Per session 81 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,707 The whole file, excluding the scripts and references it only reads on demand.
Security scan C 1 finding. 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 5.1 $0.00081 $0.01707
Opus 5 $0.00041 $0.00853
Sonnet 5 $0.00016 $0.00341
Haiku 4.5 $0.00008 $0.00171

Measured 5d ago against content hash 82869bb18a4c, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-05, from the pricing page.

Security

Grade C, and why

duplication-check scanned grade C with 1 finding 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 5d 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.

Recursive force deletehighDestructive command

rm -rf with a variable or a broad path is one typo away from removing the wrong tree.

git worktree remove --force "$BASE_WT" 2>/dev/null || rm -rf "$BASE_WT"
skills/duplication-check/SKILL.md · 148 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. 5d ago First seen · 148 lines · 81 tokens per session scan C 82869bb18a4c

Subscribe to this mod's changes

duplication-check is a skill published in the GitHub repository iansmith/slopstop (2 stars, last pushed yesterday), with no licence file. It adds 81 tokens to every session and 1,707 once invoked, about $0.0004 per session on Opus 5. A static security scan graded it C with 1 finding (recursive force delete). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

Related

Other skills, from other repositories