book-refactoring-nano

name	book--refactoring--nano
description	Refactoring (Martin Fowler) — Minimal rules — essential one-liners only. Use when asked to apply Refactoring principles or review code against Refactoring standards.
origin	github.com/ciembor/agent-rules-books (MIT)
license	MIT
version	1.0.0
compatibility	yana-ai >= 0.14.0

OBEY Refactoring by Martin Fowler

When to use

Use as a compact always-on rule set for changing existing code under tight context.

Primary bias to correct

Cleanup must preserve behavior and move in small verified steps, not become a rewrite.

Decision rules

• Preserve observable behavior; isolate feature changes, migrations, redesign, and cleanup.
• Work in small buildable, testable, reviewable steps; split changes that are too large to reason about locally.
• Get a safety net or record the verification gap before risky structural edits.
• Refactor the smell that blocks the current change, not every smell nearby.
• Prefer simple named moves: rename, extract, inline, move, split phases, encapsulate mutation, decompose conditionals, and remove duplication.
• Put behavior, state, and validation with the concept that owns them; avoid vague utilities, pass-through layers, and just-in-case abstractions.
• Keep mutation and call contracts clear: avoid boolean flags, parameter reassignment, public mutable data, unnecessary setters, and hidden side effects.
• Stop when the change is easy, the code is clearer, and further cleanup would be speculative.

Trigger rules

• When behavior is unclear or tests are weak, characterize current behavior before broader refactoring.
• When adding a feature is awkward, make the smallest preparatory refactor that makes it straightforward.
• When the same edit appears for a third time, centralize ownership instead of copying again.
• When conditionals or type codes grow, decompose intent before reaching for polymorphism, state, strategy, or lookup tables.
• When a patch mixes cleanup with behavior or broad code motion, split it where practical.
• When tempted to rewrite, choose the next small behavior-preserving transformation.

Final checklist

• Same behavior?
• Safety net or verification gap?
• Small runnable step?
• Clearer names, ownership, and control flow?
• No speculative abstraction or mixed patch?