tidying

Development

Guide structural code improvements using Kent Beck's Tidy First methodology. Use when seeing messy code, before making behavioral changes, after completing features, or discussing when to clean up code.

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How to use this skill

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Source SKILL.md: https://github.com/majiayu000/claude-skill-registry/blob/HEAD/skills/development/tidying/SKILL.md

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INSTRUCTIONS

Apply Kent Beck's "Tidy First?" philosophy: small, safe structural changes that improve code without changing behavior. Tidying is separate from feature work and gets its own commits.

Behavior Contract: See behavior-contract.md for complete definition of "behavior" (inputs, validation, outputs, side effects, errors) and structural vs behavioral change examples
Context Boundaries: See context-boundaries.md for what's safe to tidy in frontend/backend/CLI/library contexts (behavior boundary differs by context!)

Core Principle

"Tidying is a special kind of refactoring... tidying is small, and you never need to tidy."

Tidyings are:

Small: Minutes, not hours
Safe: Structure only, no behavior change
Optional: You choose when (or if) to tidy
Separate: Own commits, distinct from behavioral changes

The Three Timings

Timing	Trigger	Flow
Tidy First	Code is hard to change	`/tidy:first` → `refactor:` commit → behavioral change → `feat:/fix:` commit
Tidy After	Feature revealed better structure	behavioral change → `feat:/fix:` commit → `/tidy:after` → `refactor:` commit
Tidy Later	Tidying too big or off-focus	Note opportunity → backlog/TODO → continue current work

Decision Framework

1. Does this code need to change for my current task?
   No  → Tidy Later (or never)
   Yes ↓
2. Would tidying make my change easier/safer?
   No  → Make behavioral change, consider Tidy After
   Yes ↓
3. Is the tidying small (< 15 minutes)?
   No  → Tidy Later, make behavioral change anyway
   Yes → Tidy First, then make behavioral change

When NOT to DRY

"Duplication is far cheaper than the wrong abstraction." — Sandi Metz

Keep code inline when:

Pattern is simple and self-explanatory (vec![], None, error returns)
Abstraction adds indirection without clarity
Repetitions might evolve differently
grep/search is easier with inline code

Reference

Based on: Tidy First? by Kent Beck (2023)