websocket

websocket is a skill for Claude Code, Codex from martinholovsky/claude-skills-generator. It costs 22 tokens per session (3,419 once invoked), scanned A, original, Unlicense.

A guide to building and securing WebSocket connections, which let a browser and server exchange messages continuously in both directions.

In plain words
What is it for?
Use it to design authentication, origin checks, per-message permissions, validation, rate limits, and connection lifecycle handling.
Why use it?
It addresses risks specific to long-lived connections, including unauthorised sessions, forged browser connections, invalid messages, and excessive traffic.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one. Also seen: model in frontmatter.

Good fit Use it to design authentication, origin checks, per-message permissions, validation, rate limits, and connection lifecycle handling.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/martinholovsky/claude-skills-generator/websocket
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.

Any agent
npx skills add martinholovsky/claude-skills-generator --skill websocket
Clone the repo
git clone --depth 1 https://github.com/martinholovsky/claude-skills-generator

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 websocket

README.md
[![agentmods](https://agentmods.dev/badge/skills/martinholovsky/claude-skills-generator/websocket/github.svg)](https://agentmods.dev/skills/martinholovsky/claude-skills-generator/websocket)
Your own site
<a href="https://agentmods.dev/skills/martinholovsky/claude-skills-generator/websocket"><img src="https://agentmods.dev/badge/skills/martinholovsky/claude-skills-generator/websocket/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 websocket

Your own site · 80×15
<a href="https://agentmods.dev/skills/martinholovsky/claude-skills-generator/websocket"><img src="https://agentmods.dev/badge/skills/martinholovsky/claude-skills-generator/websocket.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 22 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 3,419 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 $0.00022 $0.03419
Opus 5 $0.00011 $0.01709
Sonnet 5 $0.00004 $0.00684
Haiku 4.5 $0.00002 $0.00342

Measured 9d ago against content hash 2eaf0dc2f61f, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-12, from the pricing page.

Security

Grade A, and why

websocket 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 9d 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/websocket/SKILL.md · 499 lines

How it starts

The opening of the file, as written. The whole thing — 499 lines — stays where its author put it; the contents beside it link to each section on GitHub.

WebSocket Security Skill

File Organization

  • SKILL.md: Core principles, patterns, essential security (this file)
  • references/security-examples.md: CSWSH examples and authentication patterns
  • references/advanced-patterns.md: Connection management, scaling patterns
  • references/threat-model.md: Attack scenarios including CSWSH

Validation Gates

Gate 0.2: PASSED (5+ vulnerabilities documented) - CVE-2024-23898, CVE-2024-26135, CVE-2023-0957


1. Overview

Risk Level: HIGH

Justification: WebSocket connections bypass Same-Origin Policy protections, making them vulnerable to Cross-Site WebSocket Hijacking (CSWSH). Persistent connections require careful authentication, session management, and input validation.

You are an expert in WebSocket security, understanding the unique vulnerabilities of persistent bidirectional connections.

Core Expertise Areas

  • CSWSH (Cross-Site WebSocket Hijacking) prevention
  • Origin header validation and token-based authentication
  • Message validation and per-message authorization
  • Rate limiting and connection lifecycle security

2. Core Responsibilities

Fundamental Principles

  1. TDD First: Write tests before implementation - test security boundaries, connection lifecycle
  2. Performance Aware: Optimize for low latency (<50ms), connection pooling, backpressure
  3. Validate Origin: Always check Origin header against explicit allowlist
  4. Authenticate First: Verify identity before accepting messages
  5. Authorize Each Action: Don't assume connection equals unlimited access
  6. Validate All Messages: Treat WebSocket messages as untrusted input
  7. Limit Resources: Rate limit messages, timeout idle connections

Security Decision Framework

Situation Approach
New connection Validate Origin, require authentication token
Each message Validate format, check authorization for action
Sensitive operations Re-verify session, log action
Idle connection Timeout after inactivity period
Error condition Close connection, log details

Read the full file on GitHub · 499 lines

Files

What ships with it

3 files 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. 9d ago First seen · 499 lines · 22 tokens per session scan A 2eaf0dc2f61f

Subscribe to this mod's changes

websocket is a skill published in the GitHub repository martinholovsky/claude-skills-generator (45 stars, last pushed 9mo ago), licensed Unlicense. It adds 22 tokens to every session and 3,419 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 2026-09-03.

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