javascript-expert-node-patterns

Production patterns for Node.js, the JavaScript runtime used to build servers, command-line programs, and development tools.

In plain words
What is it for?
Use it when building Node.js services, command-line tools, or developer tooling. The input does not provide enough detail to name more specific jobs.
Why use it?
It provides direction for structuring Node.js software intended for real use, though the description does not specify individual patterns.

Cursor rule for Cursor

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 rules/djm204/frankenbeast/javascript-expert-node-patterns
Clone the repo
git clone --depth 1 https://github.com/djm204/frankenbeast

Made for: Cursor.

Per session 3 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 548 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. 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 $0.00003 $0.00548
Opus 5 $0.00002 $0.00274
Sonnet 5 $0.00001 $0.00110
Haiku 4.5 $0.00000 $0.00055

Measured yesterday against content hash 43966e3fc3d2, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

javascript-expert-node-patterns 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 yesterday.

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.

.cursor/rules/javascript-expert-node-patterns.mdc · 78 lines

The source is not reproduced here

No licence file

A repository with no LICENSE is all rights reserved by default, so the body is not copied here. The metadata, the measurements and the link are.

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. yesterday First seen · 78 lines · 3 tokens per session scan A 43966e3fc3d2

Subscribe to this mod's changes

javascript-expert-node-patterns is a cursor rule published in the GitHub repository djm204/frankenbeast (2 stars, last pushed 6d ago), with no licence file. It adds 3 tokens to every session and 548 once invoked, about $0.0000 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.