security-engineer

Security review guidance for applications, covering checks such as input validation, authentication, permissions, rate limits, and protection against common web attacks.

In plain words
What is it for?
It helps review authentication, role-based access, user input, file uploads, secrets, database queries, browser attacks, API protection, and secure headers.
Why use it?
It gives developers a consistent checklist for finding security weaknesses while changing or reviewing code.

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/mtnyilmaz/agents/security-engineer
Any agent
npx skills add mtnyilmaz/agents --skill security-engineer
Clone the repo
git clone --depth 1 https://github.com/mtnyilmaz/agents

Made for: Claude Code, Codex.

Per session 63 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 483 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 $0.00063 $0.00483
Opus 5 $0.00032 $0.00242
Sonnet 5 $0.00013 $0.00097
Haiku 4.5 $0.00006 $0.00048

Measured 3d ago against content hash b0d848c88077, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

security-engineer 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 3d 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/security-engineer/SKILL.md · 39 lines

What it actually says

Security Engineer

Expert in application security for this monorepo.

Reference Documentation

Read the full security guide before making security-related decisions:

  • .agents/rules/security-patterns.md — Complete security architecture (input validation, auth, rate limiting, CORS, headers, XSS, SQL injection, secrets, file uploads, audit trail)
  • .agents/rules/auth-patterns.md — Authentication flows, RBAC roles, multi-app session
  • .agents/rules/config-patterns.md — Secrets management, environment variables
  • .agents/rules/api-patterns.md — API middleware chain, request validation

Quick Security Checklist

Before approving any code:

  1. Input validated with Zod on both client AND server
  2. Auth middleware checks session/JWT before route handler
  3. RBAC middleware checks role for protected routes
  4. No secrets in code, logs, or error responses
  5. No any types — use unknown and narrow
  6. No $queryRawUnsafe — use parameterized queries only
  7. No dangerouslySetInnerHTML without DOMPurify
  8. No console.log — use @repo/logger (it redacts sensitive fields)
  9. Rate limiting on auth endpoints (login, register, forgot-password)
  10. Soft delete — never hard delete user data

Security Patterns by Area

Authentication — see .agents/rules/security-patterns.md and .agents/rules/auth-patterns.md

Rate Limiting — see .agents/rules/security-patterns.md (Rate Limiting section)

CORS & Headers — see .agents/rules/security-patterns.md (CORS and HTTP Security Headers sections)

File Uploads — see .agents/rules/security-patterns.md (File Upload Security section)

Audit Trail — see .agents/rules/security-patterns.md (Audit Trail section)

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. 3d ago First seen · 39 lines · 63 tokens per session scan A b0d848c88077

Subscribe to this mod's changes

security-engineer is a skill published in the GitHub repository mtnyilmaz/agents (6 stars, last pushed 3mo ago), licensed MIT. It adds 63 tokens to every session and 483 once invoked, about $0.0003 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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