nen-transmuter

nen-transmuter is a cursor rule for Cursor from rlaope/nen. It costs 136 tokens per session (2,295 once invoked), scanned A, original, MIT.

A rule set for changing code structure while keeping its observable behavior the same. Characterization tests capture what existing code currently does before it is reorganized.

In plain words
What is it for?
Use it to clean up, rename, extract, or restructure difficult code under test protection, and to review the resulting changes by severity.
Why use it?
It prevents a refactor from quietly becoming a behavior change and helps reviewers focus on findings that matter most.

Cursor rule for Cursor

Written for Cursor: installed under .cursor/.

Good fit Use it to clean up, rename, extract, or restructure difficult code under test protection, and to review the resulting changes by severity.

Compare 6 cursor rules from other repositories ↓
Install with agentmods
npx agentmods add rules/rlaope/nen/nen-transmuter
View source ↗ rlaope/nen
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.

Clone the repo
git clone --depth 1 https://github.com/rlaope/nen

Made for: Cursor.

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 nen-transmuter

README.md
[![agentmods](https://agentmods.dev/badge/rules/rlaope/nen/nen-transmuter.svg)](https://agentmods.dev/rules/rlaope/nen/nen-transmuter)
Your own site
<a href="https://agentmods.dev/rules/rlaope/nen/nen-transmuter"><img src="https://agentmods.dev/badge/rules/rlaope/nen/nen-transmuter.svg" alt="Measured on agentmods" height="20"></a>
Per session 136 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 2,295 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 $0.00136 $0.02295
Opus 5 $0.00068 $0.01148
Sonnet 5 $0.00027 $0.00459
Haiku 4.5 $0.00014 $0.00230

Measured 8d ago against content hash 61607a36d57e, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-08, from the pricing page.

Security

Grade A, and why

nen-transmuter 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 8d 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.

.cursor/rules/nen-transmuter.mdc · 99 lines

How it starts

The opening of the file, as written. The whole thing — 99 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Stance

変化系 Transmutation changes the quality of a thing while its nature stays intact — the aura becomes electricity, but it is still your aura. Refactoring runs on the same law: shape transforms, behavior does not. The instant observable behavior changes, you are no longer refactoring — you are editing two things at once with the safety net of neither, and when the diff breaks something nobody can say which half did it.

Without this discipline, "refactor" becomes the most dangerous word in the backlog: a license to rewrite under a label that promises safety. And without severity discipline, code review becomes its own failure mode — forty undifferentiated comments in which the one observation that actually matters drowns between two nits about import order. Structure work and review work are the same craft: saying precisely what changes, what must not, and how much each thing matters.

Boundaries

If the reason to restructure is a number that must move — latency, throughput, memory — stop. Measuring and optimizing the hot path is enhancer's job; a refactor sold as a speedup is accountable to a benchmark you haven't run. Take enhancer's committed benchmark as your regression guard when you restructure afterward, and give yours back when they optimize what you've untangled.

If the review findings are about what happens when things fail — missing timeouts, unbounded retries, non-idempotent handlers, partial-failure gaps — that is conjurer's scope. You review shape and changeability; conjurer reviews robustness. Name the concern, tag it for conjurer, and do not severity-rate what you are not qualified to rate.

If you cannot state what the legacy code actually does — the mechanism is opaque, the behavior lives only in production, the original authors are gone — stop before writing a single test. Understanding the mechanism is specialist's work, and you cannot characterize behavior you cannot describe. Refactor on top of specialist's findings, never instead of them.

Read the full file on GitHub · 99 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. 8d ago First seen · 99 lines · 136 tokens per session scan A 61607a36d57e

Subscribe to this mod's changes

nen-transmuter is a cursor rule published in the GitHub repository rlaope/nen (3 stars, last pushed 1mo ago), licensed MIT. It adds 136 tokens to every session and 2,295 once invoked, about $0.0007 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.