refactor-safely

A guide for renaming, moving, extracting, or restructuring code while keeping its behavior unchanged. It treats a refactor as an organizational change, not a feature or bug fix.

In plain words
What is it for?
Use it when changing names, moving files, extracting code, or reorganizing a codebase, with searches and checks between each step.
Why use it?
It helps prevent missed references, broken runtime strings, and large mixed changes that are difficult to review or debug.

Skill for Claude CodeCodex

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 skills/zfinix/aster/refactor-safely
Any agent
npx skills add Zfinix/aster --skill refactor-safely
Clone the repo
git clone --depth 1 https://github.com/Zfinix/aster

Made for: Claude Code, Codex.

Per session 44 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 324 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
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 $0.00044 $0.00324
Opus 5 $0.00022 $0.00162
Sonnet 5 $0.00009 $0.00065
Haiku 4.5 $0.00004 $0.00032

Measured 2d ago against content hash 1a5c5ac38461, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

refactor-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 2d 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.

crates/aster-skills/optional-skills/refactor-safely/SKILL.md · 25 lines

What it actually says

Refactor safely

  1. Map the blast radius first. Search every reference before changing one: the definition, call sites, tests, docs, config strings, serialization. A rename that misses a string reference compiles and then breaks at runtime.
  2. Green between every step. Refactor in compilable increments: move, check, rename, check. A ten-step refactor with one check at the end turns one mistake into an hour of archaeology.
  3. Never mix behavior change into a refactor. If you spot a bug mid refactor, note it, finish the neutral change, then fix the bug as its own change. Mixed diffs are unreviewable and unbisectable.
  4. Let the compiler drive mechanical renames. Change the definition first, then fix every error it reports; the error list is your checklist.
  5. Match the destination's conventions. Moved code adopts the naming, error handling, and comment density of the file it lands in.
  6. Prove neutrality at the end. The same tests that passed before must pass after, with no test edits beyond imports and paths. Any test that had to change semantically means it was not a refactor.
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. 2d ago First seen · 25 lines · 44 tokens per session scan A 1a5c5ac38461

Subscribe to this mod's changes

refactor-safely is a skill published in the GitHub repository Zfinix/aster (40 stars, last pushed 8d ago), licensed Apache-2.0. It adds 44 tokens to every session and 324 once invoked, about $0.0002 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 2026-08-30.

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