rein: Skill for Codex

.codex/skills/rein-cleanup/SKILL.md

rein-cleanup is a skill for Codex from jstxn/rein. It costs 17 tokens per session (860 once invoked), scanned A, original, MIT.

A structured workflow for simplifying code that works but is bloated, repetitive, noisy, or over-abstracted. Regression tests are checks that confirm existing behavior still works after changes.

In plain words
What is it for?
Plan and perform focused refactoring, remove duplication or dead code, improve boundaries, and add narrow tests where existing behavior lacks coverage.
Why use it?
It reduces unnecessary code while protecting behavior with tests and keeping the cleanup limited to the requested scope.

Skill for Codex

Written for Codex: installed under .codex/.

This is jstxn/rein's own configuration. It tells Codex how to work on rein itself, so it is not a mod to install elsewhere. Copy it as a starting point and replace the rules that are about this project. Everything rein configures →

View source ↗ jstxn/rein
Reuse

Borrowing it

Nothing to install: this file belongs to jstxn/rein. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file
curl -O https://raw.githubusercontent.com/jstxn/rein/main/.codex/skills/rein-cleanup/SKILL.md
Clone the repo
git clone --depth 1 https://github.com/jstxn/rein

Made for: Codex.

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 rein-cleanup

README.md
[![agentmods](https://agentmods.dev/badge/skills/jstxn/rein/rein-cleanup/github.svg)](https://agentmods.dev/skills/jstxn/rein/rein-cleanup)
Your own site
<a href="https://agentmods.dev/skills/jstxn/rein/rein-cleanup"><img src="https://agentmods.dev/badge/skills/jstxn/rein/rein-cleanup/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 rein-cleanup

Your own site · 80×15
<a href="https://agentmods.dev/skills/jstxn/rein/rein-cleanup"><img src="https://agentmods.dev/badge/skills/jstxn/rein/rein-cleanup.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 17 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 860 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 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 5.1 $0.00017 $0.00860
Opus 5 $0.00009 $0.00430
Sonnet 5 $0.00003 $0.00172
Haiku 4.5 $0.00002 $0.00086

Measured 11d ago against content hash 50d6f93023bf, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-11, from the pricing page.

Security

Grade A, and why

rein-cleanup 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 11d 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.

.codex/skills/rein-cleanup/SKILL.md · 97 lines

How it starts

The opening of the file, as written. The whole thing — 97 lines — stays where its author put it; the contents beside it link to each section on GitHub.

rein-cleanup

Reduce bloated, noisy, repetitive, or over-abstracted code with a regression-tests-first, smell-by-smell cleanup workflow that preserves behavior and raises signal quality.

When to Use

Use this skill when:

  • A code path works but feels bloated, noisy, repetitive, or over-abstracted
  • A user asks to "cleanup", "refactor", or "deslop" output
  • Follow-up implementation left duplicate code, dead code, weak boundaries, missing tests, or unnecessary wrapper layers
  • You need a disciplined cleanup workflow without broad rewrites

Scoped File Lists

  • This skill can accept a file list scope instead of a whole feature area.
  • When the caller provides a changed-files list, keep the cleanup strictly bounded to those files.

Procedure

  1. Lock behavior with regression tests first

    • Identify the behavior that must not change
    • Add or run targeted regression tests before editing cleanup candidates
    • If behavior is currently untested, create the narrowest test coverage needed first
  2. Create a cleanup plan before code

    • List the specific smells to remove
    • Bound the pass to the requested files or scope
    • If a file list scope is provided, keep the pass restricted to that changed-files list
    • Order fixes from safest and highest-signal to riskiest
    • Prefer deletion or local simplification before helper extraction
    • Do not start coding until the cleanup plan is explicit
  3. Categorize issues before editing

    • Duplication: repeated logic, copy-paste branches, redundant helpers
    • Dead code: unused code, unreachable branches, stale flags, debug leftovers
    • Needless abstraction: pass-through wrappers, speculative indirection, single-use helper layers
    • Boundary violations: hidden coupling, leaky responsibilities, wrong-layer imports or side effects
    • Missing tests: behavior not locked, weak regression coverage, gaps around edge cases
  4. Execute passes one smell at a time

    • Pass 1: dead code deletion
    • Pass 2: duplicate removal
    • Before adding a helper or abstraction, confirm that deletion or local simplification is not enough
    • Pass 3: naming and error handling cleanup
    • Pass 4: test reinforcement
    • Re-run targeted verification after each pass
    • Avoid bundling unrelated refactors into the same edit set
    • Do not use cleanup as permission for unrelated refactors or architectural rewrites

Read the full file on GitHub · 97 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. 11d ago First seen · 97 lines · 17 tokens per session scan A 50d6f93023bf

Subscribe to this mod's changes

rein-cleanup is a skill published in the GitHub repository jstxn/rein (12 stars, last pushed 4mo ago), licensed MIT. It adds 17 tokens to every session and 860 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.