kolea: Skill for Claude Code

.claude/skills/security-web/SKILL.md

security-web is a skill for Claude Code from robconery/kolea. It costs 207 tokens per session (3,019 once invoked), scanned A, original, MIT.

A security-review guide for TypeScript and JavaScript web applications. It covers risks such as cross-site scripting, forged requests, leaked secrets, broken permissions, injection, unsafe file handling, and requests to internal services.

In plain words
What is it for?
Use it when reviewing or securely implementing web frontends, backends, HTTP handlers, forms, file uploads, server actions, or outbound network requests.
Why use it?
It makes reviewers trace where untrusted data enters the system and where security decisions are enforced. This helps uncover vulnerabilities hidden by web frameworks or client-side checks.

Skill for Claude Code

Written for Claude Code: installed under .claude/.

This is robconery/kolea's own configuration. It tells Claude Code how to work on kolea 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 kolea configures →

Reuse

Borrowing it

Nothing to install: this file belongs to robconery/kolea. 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/robconery/kolea/main/.claude/skills/security-web/SKILL.md
Clone the repo
git clone --depth 1 https://github.com/robconery/kolea

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 security-web

README.md
[![agentmods](https://agentmods.dev/badge/skills/robconery/kolea/security-web/github.svg)](https://agentmods.dev/skills/robconery/kolea/security-web)
Your own site
<a href="https://agentmods.dev/skills/robconery/kolea/security-web"><img src="https://agentmods.dev/badge/skills/robconery/kolea/security-web/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for security-web

Your own site · 80×15
<a href="https://agentmods.dev/skills/robconery/kolea/security-web"><img src="https://agentmods.dev/badge/skills/robconery/kolea/security-web.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 207 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 3,019 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 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 5.1 $0.00207 $0.03019
Opus 5.5 $0.00083 $0.01208
Sonnet 5.5 $0.00041 $0.00604
Haiku 4.5 $0.00021 $0.00302

Measured 2mo ago against content hash e9026350da7e, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

security-web 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 2mo ago.

The scan reads SKILL.md. This mod also ships 1 executable file (templates/input-validation.ts), 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.

Origin

Copies of this mod

2 near-identical copies found in the catalogue:

.claude/skills/security-web/SKILL.md · 208 lines

How it starts

The opening of the file, as written. The whole thing — 208 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Web Application Security Review

Treat every byte that crossed a network boundary as hostile until proven otherwise, and prove it on the server. The client is an untrusted rendering surface you do not control. Frameworks add convenience (Server Actions, Nitro routes, Bun.serve, Hono middleware) that hides the trust boundary — this skill's job is to make the reviewer see the boundary the framework obscured.

🎯 Why: Design for Change

The goal of writing software is to be able to change it safely. Secure-by-default config (CSP, cookie flags, parameterized queries, authz-at-the-edge) means the next feature ships without re-litigating the threat model. Every insecure default you accept becomes a foothold the next change has to step around.

This skill is for security review and secure implementation. For general TypeScript correctness use typescript-best-practices; for schema-level integrity use postgres-dba. This skill never assumes another layer will catch it.

How to use this skill (review workflow)

  1. Map the attack surface first. Identify every trust boundary: HTTP handlers, Server Actions, form posts, websocket frames, file uploads, outbound fetches, postMessage, process.env reaching the client, third-party script tags. A vuln you didn't enumerate is a vuln you didn't find.
  2. Triage each input against the decision guide below; open the matching references/*.md for the exploit, the vulnerable pattern, the fix, and the false-positive caveat.
  3. Apply the framework reference (references/nextjs.md, nuxt.md, bun.md, hono.md) — the generic finding almost always has a framework-specific trap or a framework-specific fix.
  4. Report findings in the standard format (templates/finding.md): severity, location (file:line), a concrete exploit walkthrough, and the minimal fix. No exploit path stated → it is an observation, not a finding; say which.
  5. Recommend the secure default, not a bespoke patch. The templates/ configs (CSP, security headers, cookies, CORS) are the target state; a one-off escape is a stopgap.

Read the full file on GitHub · 208 lines

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. 2mo ago First seen · 208 lines · 207 tokens per session scan A e9026350da7e

Subscribe to this mod's changes

security-web is a skill published in the GitHub repository robconery/kolea (11 stars, last pushed 28d ago), licensed MIT. It adds 207 tokens to every session and 3,019 once invoked, about $0.0008 per session on Opus 5.5. 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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