refactor

A guide for the refactoring step in test-driven development (TDD), where you improve code after tests pass. It requires trying an improvement while keeping the tests passing.

In plain words
What is it for?
Use it to review names, structure, and code size during refactoring, compare the code before and after, and explain why no useful improvement was possible.
Why use it?
It helps improve messy or unclear code without losing the behavior that existing tests check. It also records what changed and why.

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/marcoemrich/agentic_coding_lab/refactor
Any agent
npx skills add marcoemrich/agentic_coding_lab --skill refactor
Clone the repo
git clone --depth 1 https://github.com/marcoemrich/agentic_coding_lab

Made for: Claude Code, Codex.

Per session 22 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,408 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 $0.00022 $0.02408
Opus 5 $0.00011 $0.01204
Sonnet 5 $0.00004 $0.00482
Haiku 4.5 $0.00002 $0.00241

Measured 2d ago against content hash 7bda94ec9601, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

refactor 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.

experiments/runs/2026-05-25_08-16-22_claim-office-example-mapping_v5.1-testlist-scope-fix-oc_opus-4-7-portkey/.opencode/skills/refactor/SKILL.md · 328 lines

How it starts

The opening of the file, as written. The whole thing — 328 lines — stays where its author put it; the contents beside it link to each section on GitHub.

TDD Refactor Phase

You are now in the Refactor Phase of TDD. Follow these instructions to improve the code while keeping tests green.

Your Mission

Guide developers through the Refactor phase of TDD by helping them:

  1. MUST attempt at least one refactoring - mandatory, not optional
  2. Apply the Four Rules of Simple Design in priority order
  3. Use Absolute Priority Premise (APP) to measure code improvements
  4. Improve code quality while keeping all tests green
  5. Document refactoring decisions and mass calculations
  6. If no improvement is possible, explicitly document why

Context: $ARGUMENTS

Refactor Phase Rules

  • Mandatory refactoring attempt: MUST try at least one improvement
  • Tests must stay green: Never break passing tests
  • Apply Simple Design Rules: In priority order (1 -> 2 -> 3 -> 4)
  • Calculate APP mass: Before and after refactoring
  • Document decisions: Explain improvements or why none were possible
  • Naming is first priority: Evaluate if function name still fits its purpose

Simple Design Rules (Priority Order)

Rule 1: Tests Pass
  • Highest priority - never compromise working code
  • All tests must pass before and after refactoring
  • If tests fail, revert and try different approach
Rule 2: Reveals Intent
  • Second priority - clarity trumps everything else (including APP)
  • Use meaningful names for variables, functions, classes
  • Structure code to be self-documenting
  • Prefer explicit over clever code
  • Naming Evaluation (First Refactoring Priority):
    • Ask: "Does this name clearly describe what the function actually does based on all tests we have so far?"
    • Ask: "Has the function's purpose become clearer/more specific through the latest test?"
    • Rename if the name doesn't capture the current full intent
    • Especially critical when new functionality changes the nature of what the function does
Rule 3: No Duplication (DRY)
  • Third priority - extract common functionality
  • Look for obvious and conceptual duplication
  • Knowledge should have single representation
  • Balance with Rule 2: If DRY hurts clarity, choose clarity

Read the full file on GitHub · 328 lines

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 · 328 lines · 22 tokens per session scan A 7bda94ec9601

Subscribe to this mod's changes

refactor is a skill published in the GitHub repository marcoemrich/agentic_coding_lab (11 stars, last pushed 15d ago), licensed MIT. It adds 22 tokens to every session and 2,408 once invoked, about $0.0001 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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