Refactoring Safely

Refactoring Safely is a skill for Claude Code from obra/clank. It costs 27 tokens per session (3,041 once invoked), scanned A, original, no licence file.

A coding practice for changing existing code in small steps while tests check that its behavior stays the same. Refactoring means improving code structure without changing what it does.

In plain words
What is it for?
Use it when cleaning up or reorganizing working code. It helps plan test coverage, make one refactoring at a time, and keep unrelated changes separate.
Why use it?
Large structural changes can hide new bugs, especially when mixed with feature work or bug fixes. Tests and separate changes make problems easier to detect and review.

Skill for Claude Code

Written for Claude Code: when-to-use in frontmatter.

Good fit Use it when cleaning up or reorganizing working code. It helps plan test coverage, make one refactoring at a time, and keep unrelated changes separate.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/obra/clank/refactoring-safely
View source ↗ obra/clank
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.

Any agent
npx skills add obra/clank --skill refactoring-safely
Clone the repo
git clone --depth 1 https://github.com/obra/clank

Made for: Claude Code.

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 Refactoring Safely

README.md
[![agentmods](https://agentmods.dev/badge/skills/obra/clank/refactoring-safely/github.svg)](https://agentmods.dev/skills/obra/clank/refactoring-safely)
Your own site
<a href="https://agentmods.dev/skills/obra/clank/refactoring-safely"><img src="https://agentmods.dev/badge/skills/obra/clank/refactoring-safely/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for Refactoring Safely

Your own site · 80×15
<a href="https://agentmods.dev/skills/obra/clank/refactoring-safely"><img src="https://agentmods.dev/badge/skills/obra/clank/refactoring-safely.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 27 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 3,041 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 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 5.1 $0.00027 $0.03041
Opus 5.5 $0.00011 $0.01216
Sonnet 5.5 $0.00005 $0.00608
Haiku 4.5 $0.00003 $0.00304

Measured 2mo ago against content hash 94517f009256, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

Refactoring Safely 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 2mo 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.

skills/coding/refactoring-safely/SKILL.md · 475 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. 2mo ago First seen · 475 lines · 27 tokens per session scan A 94517f009256

Subscribe to this mod's changes

Refactoring Safely is a skill published in the GitHub repository obra/clank (43 stars, last pushed 1y ago), with no licence file. It adds 27 tokens to every session and 3,041 once invoked, about $0.0001 per session on Opus 5.5. 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 2026-08-30.

Related

Refactoring Safely compared with skills from other repositories

Refactoring Safely next to 6 skills from other repositories
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