codebase-hygiene

A review method for finding different functions that do the same job and for spotting code layers that merely pass work through without adding useful behaviour.

In plain words
What is it for?
Use it to inspect recently changed or high-value code for semantic duplicates and overly thin modules, then propose focused improvements.
Why use it?
These patterns can make a codebase harder to change by duplicating rules or spreading complexity across shallow wrappers.

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/romiluz13/cc10x/codebase-hygiene
Any agent
npx skills add romiluz13/cc10x --skill codebase-hygiene
Clone the repo
git clone --depth 1 https://github.com/romiluz13/cc10x

Made for: Claude Code, Codex.

Per session 67 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,330 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 $0.00067 $0.01330
Opus 5 $0.00034 $0.00665
Sonnet 5 $0.00013 $0.00266
Haiku 4.5 $0.00007 $0.00133

Measured 2d ago against content hash ad3bb93ba656, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

codebase-hygiene 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.

plugins/cc10x/skills/codebase-hygiene/SKILL.md · 99 lines

How it starts

The opening of the file, as written. The whole thing — 99 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Codebase Hygiene (Duplicate Detection + Module Deepening)

Advisory and read-heavy. Diagnoses and proposes; does not refactor. Any actual change goes through BUILD with full gates.

Mode: DUPLICATE DETECTION

Semantic duplicates: functions serving the same purpose but implemented independently under different names. Copy-paste detectors catch syntactic duplicates; this finds "same intent, different implementation."

Method

  1. Scope before you scan — take the user's named target; else git log --oneline for hot spots and weight recently-changed code — deepening pays off in proportion to future change.
  2. Extract catalog — Grep/Glob for exported functions. Record name | file:line | signature.
  3. Categorize by domain (cheap tier) — validation, formatting, path manipulation, HTTP shaping, date handling. Mechanical bucketing to shrink comparison space.
  4. Drop categories with <3 functions — can't hide a meaningful duplication pattern.
  5. Detect duplicates per category (capable tier) — read implementations, decide which share intent. Never use cheap tier for detection — it anchors on names and rubber-stamps "these look different."
  6. Emit findings — group by confidence, highest first. Each finding: what is duplicated, why it matters, the fix, file:line evidence. Route through code-reviewer finding contract.

High-Risk Zones

Zone Why it duplicates
utils/, helpers/, lib/ Catch-all dumping grounds
Validation code "Is this a valid email/id/url" rewritten per feature
Error formatting Every module invents its own Error → string
Path manipulation Join/normalize/relativize reimplemented
String formatting Truncate, slugify, titlecase, pad re-rolled
Date formatting Parse/format/diff scattered
API response shaping Envelope/pagination/error-body copied per endpoint

Consolidation Discipline

Never delete a duplicate until all three hold:

  1. Survivor has tests — pick the implementation with real coverage. If neither has tests, write the test against the chosen survivor first.
  2. All callers updated — Grep to enumerate callers. Missing one is a silent break.
  3. Re-run after consolidation — test suite + build/typecheck pass. Green tests on the survivor license the deletion.

Read the full file on GitHub · 99 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 · 99 lines · 67 tokens per session scan A ad3bb93ba656

Subscribe to this mod's changes

codebase-hygiene is a skill published in the GitHub repository romiluz13/cc10x (164 stars, last pushed 29d ago), licensed MIT. It adds 67 tokens to every session and 1,330 once invoked, about $0.0003 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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