Finding Duplicate Functions
obra/superpowers-lab
A skill your agent uses when auditing a codebase for semantic duplication - functions that do the same thing but have different names or implementations.
Two-mode skill: (1) find semantic duplicates — functions doing the same thing under different names, invisible to copy-paste detectors; (2) deepen shallow modules — thin wrappers and pass-through…
MITAuto-check: notes
Install Codebase Hygiene
$ npx skills add romiluz13/cc10x --skill codebase-hygiene -a claude-codeProject install by default; add -g for ~/.claude/skills/.
$ gh skill install romiluz13/cc10x codebase-hygiene --agent claude-codeProject scope by default; add --scope user for a personal install. Needs GitHub CLI 2.90.0 or later (public preview).
$ git clone --depth 1 https://github.com/romiluz13/cc10x.git skills-src && mkdir -p .claude/skills && cp -r skills-src/plugins/cc10x/skills/codebase-hygiene .claude/skills/codebase-hygiene && rm -rf skills-srcUse ~/.claude/skills/ instead of .claude/skills for a personal install. The folder must contain SKILL.md.
Claude Code skills documentation · loads skills from .claude/skills/
Install the "codebase-hygiene" agent skill from https://github.com/romiluz13/cc10x/tree/main/plugins/cc10x/skills/codebase-hygiene into .claude/skills/codebase-hygiene/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "codebase-hygiene", then confirm the skill loads.Claude Code copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$skill-installer install https://github.com/romiluz13/cc10x/tree/main/plugins/cc10x/skills/codebase-hygieneType this inside Codex. $skill-installer <name> installs a curated skill from openai/skills. The installer writes to $CODEX_HOME/skills (default ~/.codex/skills). Restart Codex if the skill does not show up.
$ npx skills add romiluz13/cc10x --skill codebase-hygiene -a codexProject install goes to .agents/skills/; add -g for ~/.codex/skills/.
$ gh skill install romiluz13/cc10x codebase-hygiene --agent codexProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/romiluz13/cc10x.git skills-src && mkdir -p .agents/skills && cp -r skills-src/plugins/cc10x/skills/codebase-hygiene .agents/skills/codebase-hygiene && rm -rf skills-srcUse ~/.agents/skills/ instead of .agents/skills for a personal install.
Codex skills documentation · loads skills from .agents/skills/
Install the "codebase-hygiene" agent skill from https://github.com/romiluz13/cc10x/tree/main/plugins/cc10x/skills/codebase-hygiene into .agents/skills/codebase-hygiene/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "codebase-hygiene", then confirm the skill loads.Codex copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$ npx skills add romiluz13/cc10x --skill codebase-hygiene -a cursorProject install goes to .agents/skills/; add -g for ~/.cursor/skills/.
$ gh skill install romiluz13/cc10x codebase-hygiene --agent cursorProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/romiluz13/cc10x.git skills-src && mkdir -p .cursor/skills && cp -r skills-src/plugins/cc10x/skills/codebase-hygiene .cursor/skills/codebase-hygiene && rm -rf skills-srcUse ~/.cursor/skills/ instead of .cursor/skills for a personal install.
Cursor skills documentation · loads skills from .cursor/skills/, .agents/skills/, .claude/skills/, .codex/skills/
Install the "codebase-hygiene" agent skill from https://github.com/romiluz13/cc10x/tree/main/plugins/cc10x/skills/codebase-hygiene into .cursor/skills/codebase-hygiene/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "codebase-hygiene", then confirm the skill loads.Cursor copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$ gemini skills install https://github.com/romiluz13/cc10x.git --path plugins/cc10x/skills/codebase-hygiene--scope user (default) or --scope workspace; --path is the subfolder of the repo that holds the skill; --consent skips the security confirmation prompt.
$ npx skills add romiluz13/cc10x --skill codebase-hygiene -a gemini-cliProject install goes to .agents/skills/; add -g for ~/.gemini/skills/.
$ gh skill install romiluz13/cc10x codebase-hygiene --agent gemini-cliProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/romiluz13/cc10x.git skills-src && mkdir -p .gemini/skills && cp -r skills-src/plugins/cc10x/skills/codebase-hygiene .gemini/skills/codebase-hygiene && rm -rf skills-srcUse ~/.gemini/skills/ instead of .gemini/skills for a personal install, then run /skills reload.
Gemini CLI skills documentation · loads skills from .gemini/skills/, .agents/skills/
Install the "codebase-hygiene" agent skill from https://github.com/romiluz13/cc10x/tree/main/plugins/cc10x/skills/codebase-hygiene into .gemini/skills/codebase-hygiene/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "codebase-hygiene", then confirm the skill loads.Gemini CLI copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$ gh skill install romiluz13/cc10x codebase-hygieneInstalls for Copilot at project scope by default; add --scope user for a personal install. Preview a skill first with gh skill preview. Needs GitHub CLI 2.90.0 or later (public preview).
$ npx skills add romiluz13/cc10x --skill codebase-hygiene -a github-copilotProject install goes to .agents/skills/; add -g for ~/.copilot/skills/.
$ git clone --depth 1 https://github.com/romiluz13/cc10x.git skills-src && mkdir -p .github/skills && cp -r skills-src/plugins/cc10x/skills/codebase-hygiene .github/skills/codebase-hygiene && rm -rf skills-srcUse ~/.copilot/skills/ instead of .github/skills for a personal install. Commit .github/skills so cloud agent and code review can use it.
GitHub Copilot skills documentation · loads skills from .github/skills/, .claude/skills/, .agents/skills/
Install the "codebase-hygiene" agent skill from https://github.com/romiluz13/cc10x/tree/main/plugins/cc10x/skills/codebase-hygiene into .github/skills/codebase-hygiene/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "codebase-hygiene", then confirm the skill loads.GitHub Copilot copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$ npx skills add romiluz13/cc10x --skill codebase-hygiene -a opencodeOpenCode documents no install command of its own. Project install goes to .agents/skills/; add -g for ~/.config/opencode/skills/.
$ gh skill install romiluz13/cc10x codebase-hygiene --agent opencodeProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/romiluz13/cc10x.git skills-src && mkdir -p .opencode/skills && cp -r skills-src/plugins/cc10x/skills/codebase-hygiene .opencode/skills/codebase-hygiene && rm -rf skills-srcUse ~/.config/opencode/skills/ instead of .opencode/skills for a personal install.
OpenCode skills documentation · loads skills from .opencode/skills/, .claude/skills/, .agents/skills/
Install the "codebase-hygiene" agent skill from https://github.com/romiluz13/cc10x/tree/main/plugins/cc10x/skills/codebase-hygiene into .opencode/skills/codebase-hygiene/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "codebase-hygiene", then confirm the skill loads.OpenCode copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
Facts
- Skill name
codebase-hygiene- GitHub stars
- 164
- Token cost
- ~1.5k tokens
- SKILL.md length
- 741 words
- Files
- 1
- Skills in repo
- 22
- Repo updated
- First seen
- Licence
- MIT
At a glance
Two-mode skill: (1) find semantic duplicates — functions doing the same thing under different names, invisible to copy-paste detectors; (2) deepen shallow modules — thin wrappers and pass-through…
- Works in 6 steps: Scope before you scan — take the user's… → Extract catalog — Grep/Glob for exported… → Categorize by domain (cheap tier) —… → …
- SKILL.md covers Mode: DUPLICATE DETECTION and Mode: MODULE DEEPENING
- Calls git
What it does
Codebase Hygiene is an agent skill from romiluz13/cc10x. Two-mode skill: (1) find semantic duplicates — functions doing the same thing under different names, invisible to copy-paste detectors; (2) deepen shallow modules — thin wrappers and pass-through layers that spread complexity. Advisory and read-only; changes route through BUILD with full gates.
Its SKILL.md is about 1.5k tokens, which your agent loads only when the skill is triggered. It is a single SKILL.md file with no bundled scripts.
The repository describes itself as: The Loop Engine for Claude Code — engineer the loop, not the prompt. 1 router · 9 agents · 16 skills · 4 workflows. Fail-closed gates, test honesty, anti-anchored review. The licence is MIT.
Example prompts
- “/codebase-hygiene”
Requirements
- Pre-approved tools (allowed-tools): Read, Grep, Glob, Bash
Workflow steps
6 steps, taken from the first numbered list in SKILL.md.
- Scope before you scan — take the user's named target; else git log --oneline for hot spots and weight recently-changed code — deepening…
- Extract catalog — Grep/Glob for exported functions. Record name | file:line | signature.
- Categorize by domain (cheap tier) — validation, formatting, path manipulation, HTTP shaping, date handling. Mechanical bucketing to shrink…
- Drop categories with <3 functions — can't hide a meaningful duplication pattern.
- Detect duplicates per category (capable tier) — read implementations, decide which share intent. Never use cheap tier for detection — it…
- Emit findings — group by confidence, highest first. Each finding: what is duplicated, why it matters, the fix, file:line evidence. Route…
What it can do on your machine
Read from SKILL.md and the folder at commit 891acf0. It shows what the files ask for, not the result of running them.
Tool permissions
Pre-approves these tools, so the agent can use them without asking each time:
ReadGrepGlobBash
From allowed-tools in the SKILL.md frontmatter.
Runs code
Shell commands in SKILL.md call:
git
From the folder's file list and the shell code blocks in SKILL.md.
Network
No URLs in SKILL.md. Its commands use git, which can reach the network depending on how they are called.
From URLs in SKILL.md, links to its own repository left out.
Credentials
Names no API keys, tokens, secrets or passwords.
From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.
Context cost
Codebase Hygiene loads about 1.5k tokens when it runs. Until then it costs about 78 tokens; SKILL.md has 741 words of instructions outside code blocks.
Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.
Safety
Auto-check: notes
The automated check noted patterns worth knowing about, such as sudo or a known installer.
- NotePre-approves every shell command (allowed-tools: Bash)SKILL.md
allowed-tools: Read, Grep, Glob, Bash
Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.
SKILL.md
The full file from romiluz13/cc10x at commit 891acf0, republished under its MIT licence (© romiluz13). 741 words, ~1,511 tokens.
Download SKILL.mdSave it as
.claude/skills/codebase-hygiene/SKILL.md (or your agent's skills folder).- name
- codebase-hygiene
- description
- Two-mode skill: (1) find semantic duplicates — functions doing the same thing under different names, invisible to copy-paste detectors; (2) deepen shallow modules — thin wrappers and pass-through layers that spread complexity. Advisory and read-only; changes route through BUILD with full gates.
- allowed-tools
- Read, Grep, Glob, Bash
- user-invocable
- false
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
- Scope before you scan — take the user's named target; else
git log --onelinefor hot spots and weight recently-changed code — deepening pays off in proportion to future change. - Extract catalog — Grep/Glob for exported functions. Record
name | file:line | signature. - Categorize by domain (cheap tier) — validation, formatting, path manipulation, HTTP shaping, date handling. Mechanical bucketing to shrink comparison space.
- Drop categories with <3 functions — can't hide a meaningful duplication pattern.
- 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."
- Emit findings — group by confidence, highest first. Each finding: what is duplicated, why it matters, the fix,
file:lineevidence. 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:
- Survivor has tests — pick the implementation with real coverage. If neither has tests, write the test against the chosen survivor first.
- All callers updated — Grep to enumerate callers. Missing one is a silent break.
- Re-run after consolidation — test suite + build/typecheck pass. Green tests on the survivor license the deletion.
Mode: MODULE DEEPENING
Existing code works; the problem is shape, not features. LLM-grown codebases accrete shallow modules — thin wrappers, pass-through layers, near-duplicate helpers. Each looks harmless; together they spread complexity across every caller.
Deep module: hides a lot of behavior behind a small interface. Shallow module: interface is almost as complex as its implementation — callers learn a thing without getting much.
The Deletion Test
For each candidate: If I deleted this module and inlined its code at every call site, where does the complexity go?
- Complexity vanishes → the module was a pass-through / shallow. It adds indirection without hiding complexity. Deepening candidate (delete it or deepen its interface).
- Complexity reappears across N call sites → the module is deep. It earns its existence by hiding complexity that would otherwise be duplicated. Leave it alone.
This verdict agrees with cc10x:codebase-design (canonical) and cc10x:architecture. Depth is leverage at the interface — not a lines-ratio.
| Smell | Usually |
|---|---|
Thin wrapper (doX(a){ return lib.doX(a) }) | Shallow |
| Pass-through layer (service maps 1:1 to repo) | Shallow |
| Near-duplicate helper (same intent, different name) | Shallow — consolidate first |
| Config/leverage module (small interface, branching/retry/state inside) | Deep — keep |
Show full SKILL.md (267 more words)Show less
Diagnosis Flow (READ-ONLY)
- Enumerate exported surface (
name | file:line | signature) - Flag shallow shapes
- Cross-reference near-duplicates (run duplicate detection mode first — consolidate before deepening)
- Run deletion test on each survivor
- Output: candidate list, not a refactor
Present Candidates Before Proposing Interfaces
Badge each candidate: Strong (unambiguous), Worth-exploring (real cost/risk), Speculative (hunch, low confidence).
For each: before/after sketch (current shallow interface vs proposed deeper one) with deletion test result. Then stop and ask which to pursue. Do not design interfaces for candidates the user hasn't chosen.
Two-Adapters Rule for Seam Placement
When designing the deeper interface, a port (an injected external dependency seam) needs two concrete adapters — e.g. a production transport and a test stand-in. An ordinary caller or a test exercising a public interface is NOT an adapter; the two-adapter rule is about ports, not every seam.
For a non-port seam (the common case for module deepening): the test must be able to reach the interface. If only production code crosses the seam and no test can reach it → the seam is a guess. Put the interface where a test can reach it, or don't introduce it. This aligns with cc10x:codebase-design — "one adapter means a hypothetical seam" applies to ports; internal seams need reachability, not a second adapter.
Handoff to BUILD
This skill ends at: chosen candidate + deeper-interface proposal + named seam. It does NOT edit code. The refactor routes through planner → BUILD workflow (builder → reviewer → verifier → doc-sync → memory). The deepening is verified: survivor interface has tests at its seam, every caller is repointed, suite + typecheck pass after merge.
Proposing is read-only; changing is gated.
© romiluz13, MIT. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file
Files
Just SKILL.md in plugins/cc10x/skills/codebase-hygiene of romiluz13/cc10x.
Open the folder on GitHubat commit 891acf0
Compare with similar skills
Codebase Hygiene next to the 5 skills that share the most tags, products or categories with it. Stars are the repository's; “used in” counts other GitHub owners with a copy.
| Skill | Stars | Used in | Tokens | Auto-check | Licence | Repo updated |
|---|---|---|---|---|---|---|
| Codebase Hygiene this skillromiluz13/cc10x | 164 | — | ~1.5k | Automated safety check: Notes | MIT | |
| Finding Duplicate Functionsobra/superpowers-lab | 429 | 2 repos | ~1.2k | Automated safety check: Pass | MIT | |
| Semantic Liststhedaviddias/Front-End-Checklist | 74k | — | ~504 | Automated safety check: Pass | MIT | |
| Duplicate JSthedaviddias/Front-End-Checklist | 74k | — | ~423 | Automated safety check: Pass | MIT | |
| Azure Functionsdavila7/claude-code-templates | 32k | 1 repos | ~344 | Automated safety check: Pass | MIT | |
| Semantic Versioningsickn33/agentic-awesome-skills | 47k | 1 repos | ~2.6k | Automated safety check: Pass | MIT |
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Questions about Codebase Hygiene
What does Codebase Hygiene do?
Two-mode skill: (1) find semantic duplicates — functions doing the same thing under different names, invisible to copy-paste detectors; (2) deepen shallow modules — thin wrappers and pass-through…. Codebase Hygiene is an agent skill from romiluz13/cc10x. Two-mode skill: (1) find semantic duplicates — functions doing the same thing under different names, invisible to copy-paste detectors; (2) deepen shallow modules — thin wrappers and pass-through layers that spread complexity.
How do I install Codebase Hygiene in Claude Code?
Run `npx skills add romiluz13/cc10x --skill codebase-hygiene -a claude-code`. Or copy the skill folder (plugins/cc10x/skills/codebase-hygiene in romiluz13/cc10x) into .claude/skills/codebase-hygiene in your project. Claude Code loads it when a task matches its description.
How do I install Codebase Hygiene in Codex?
Run `npx skills add romiluz13/cc10x --skill codebase-hygiene -a codex`. Or copy the skill folder (plugins/cc10x/skills/codebase-hygiene in romiluz13/cc10x) into .agents/skills/codebase-hygiene in your project. Codex loads it when a task matches its description.
Can I use Codebase Hygiene in Cursor, Gemini CLI or GitHub Copilot?
Cursor, Gemini CLI, GitHub Copilot and OpenCode also load SKILL.md folders. With the skills CLI, run `npx skills add romiluz13/cc10x --skill codebase-hygiene -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/codebase-hygiene, .gemini/skills/codebase-hygiene, .github/skills/codebase-hygiene and .opencode/skills/codebase-hygiene in your project.
What does Codebase Hygiene need to run?
Going by SKILL.md and its folder, Codebase Hygiene needs the command-line tools its instructions call (git). Its frontmatter pre-approves these tools: Read, Grep, Glob, Bash.
Does Codebase Hygiene access the network?
SKILL.md contains no URLs. Its commands use git, which can reach the network depending on how they are called. This is read from the text; nothing was executed.
Is Codebase Hygiene safe to install?
Our automated static check of SKILL.md found notes only (pre-approves every shell command (allowed-tools: bash)), nothing it rates as a warning. It is not a guarantee. Review the folder before installing.
What licence does Codebase Hygiene use?
Codebase Hygiene is published under the MIT licence (the repository's licence). It allows redistribution, so the full SKILL.md is shown on this page.
How many tokens does Codebase Hygiene use?
About 1.5k tokens (SKILL.md is roughly 6k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full.
What are the alternatives to Codebase Hygiene?
Skills that share tags, products or a category with Codebase Hygiene: Finding Duplicate Functions (obra/superpowers-lab, 429 stars), Semantic Lists (thedaviddias/Front-End-Checklist, 74k stars), Duplicate JS (thedaviddias/Front-End-Checklist, 74k stars) and Azure Functions (davila7/claude-code-templates, 32k stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.
Who maintains Codebase Hygiene?
romiluz13 (a GitHub user) maintains it in romiluz13/cc10x, which has 164 GitHub stars. The repository holds 22 skills in this directory. The repository was last updated on September 30, 2026.
Source: romiluz13/cc10x on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.