security-sentinel

security-sentinel is a skill for Claude Code, Codex from CardSorting/LUMI-JOY. It costs 26 tokens per session (145 once invoked), scanned A, original, Apache-2.0.

A code-security checker that examines a program’s structure for injection risks, checks that file paths stay within allowed areas, and detects altered commands.

In plain words
What is it for?
Use it when checking agent actions or code that handles untrusted input, file paths, or shell commands.
Why use it?
It helps catch unsafe input handling and attempts to access files or change commands outside the intended boundaries.

Skill for Claude CodeCodex

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/cardsorting/lumi-joy/security-sentinel
Any agent
npx skills add CardSorting/LUMI-JOY --skill security-sentinel
Clone the repo
git clone --depth 1 https://github.com/CardSorting/LUMI-JOY

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 security-sentinel

README.md
[![agentmods](https://agentmods.dev/badge/skills/cardsorting/lumi-joy/security-sentinel.svg)](https://agentmods.dev/skills/cardsorting/lumi-joy/security-sentinel)
Your own site
<a href="https://agentmods.dev/skills/cardsorting/lumi-joy/security-sentinel"><img src="https://agentmods.dev/badge/skills/cardsorting/lumi-joy/security-sentinel.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 145 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original 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 $0.00026 $0.00145
Opus 5 $0.00013 $0.00072
Sonnet 5 $0.00005 $0.00029
Haiku 4.5 $0.00003 $0.00015

Measured 5d ago against content hash bf3feea5d781, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

security-sentinel 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 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.

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.

skills/security-sentinel/SKILL.md · 20 lines

What it actually says

Security Sentinel

Security sentinel that analyzes ASTs for injection risks, verifies file path sandboxing, and prevents command tampering.

📋 Execution Protocol

  1. Analyze Input: Validate preconditions and inspect operational context.
  2. Execute Actions: Carry out procedures using deterministic tools.
  3. Verify Outcome: Assert correctness and log diagnostic telemetry.

🛡️ Operational Guardrails & Rules

  • Execute with deterministic consistency and verify outputs.
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 · 20 lines · 26 tokens per session scan A bf3feea5d781

Subscribe to this mod's changes

security-sentinel is a skill published in the GitHub repository CardSorting/LUMI-JOY (2 stars, last pushed 7d ago), licensed Apache-2.0. It adds 26 tokens to every session and 145 once invoked, about $0.0001 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 2026-08-31.

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