72-refactoring

A set of rules for improving existing code while keeping its behavior the same. Refactoring means changing code structure, such as splitting a large function, without changing what the program does.

In plain words
What is it for?
Use it to extract functions, rename code, remove duplication, simplify conditionals, reorganize files, or address other structural problems.
Why use it?
It lowers the risk of accidental behavior changes by requiring tests, understanding of the code, small focused changes, and checks after each step.

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/luxvil/ai-coding-rules/72-refactoring
Clone the repo
git clone --depth 1 https://github.com/Luxvil/ai-coding-rules

Made for: Cursor.

Per session 7 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 253 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin 100% copy Near-identical to another mod 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 $0.00007 $0.00253
Opus 5 $0.00003 $0.00127
Sonnet 5 $0.00001 $0.00051
Haiku 4.5 $0.00001 $0.00025

Measured yesterday against content hash f4977dbfeaa2, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

72-refactoring 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.

Origin

This is a copy

100% identical to 72-refactoring — 0 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

.cursor/rules/72-refactoring.mdc · 41 lines

What it actually says

Refactoring Rules

Pre-Refactor Checklist

  • Tests exist for current behavior
  • All tests are passing
  • You understand the code's purpose
  • Changes are approved (if >200 LOC)

Principles

  • Make it work → Make it right → Make it fast
  • One refactor type per commit
  • Keep behavior unchanged (unless fixing bugs)
  • Run tests after each step

Common Refactors

  1. Extract Function - Split large functions
  2. Rename - Clarify intent
  3. Extract Variable - Explain complex expressions
  4. Inline - Remove unnecessary indirection
  5. Move - Better file organization

Anti-Patterns to Fix

  • Magic numbers → Named constants
  • Nested conditionals → Early returns
  • Long functions → Extract helpers
  • Duplicate code → DRY it up
  • God objects → Single responsibility

When NOT to Refactor

  • Under time pressure (unless blocking)
  • Without tests
  • Without understanding the code
  • When it's "good enough"
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 · 41 lines · 7 tokens per session scan A f4977dbfeaa2

Subscribe to this mod's changes

72-refactoring is a cursor rule published in the GitHub repository Luxvil/ai-coding-rules (3 stars, last pushed 2d ago), licensed MIT. It adds 7 tokens to every session and 253 once invoked, about $0.0000 per session on Opus 5. A static security scan graded it A with 0 findings. It is 100% identical to 72-refactoring, differing in 0 lines, and is treated as a copy.