Systematic Code Refactoring
luongnv89/claude-howto
Guides refactoring in phases based on Martin Fowler's method: research, test coverage check, planning and small tested steps, with your approval at each phase.
Analyze codebases to identify reusable code patterns, duplications, and implementation patterns for future development.
Install Code Pattern Extractor
$ npx skills add majiayu000/claude-skill-registry --skill code-pattern-extractor -a claude-codeProject install by default; add -g for ~/.claude/skills/.
$ gh skill install majiayu000/claude-skill-registry code-pattern-extractor --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/majiayu000/claude-skill-registry.git skills-src && mkdir -p .claude/skills && cp -r skills-src/skills/analysis/code-pattern-extractor .claude/skills/code-pattern-extractor && 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 "code-pattern-extractor" agent skill from https://github.com/majiayu000/claude-skill-registry/tree/main/skills/analysis/code-pattern-extractor into .claude/skills/code-pattern-extractor/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "code-pattern-extractor", 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/majiayu000/claude-skill-registry/tree/main/skills/analysis/code-pattern-extractorType 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 majiayu000/claude-skill-registry --skill code-pattern-extractor -a codexProject install goes to .agents/skills/; add -g for ~/.codex/skills/.
$ gh skill install majiayu000/claude-skill-registry code-pattern-extractor --agent codexProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/majiayu000/claude-skill-registry.git skills-src && mkdir -p .agents/skills && cp -r skills-src/skills/analysis/code-pattern-extractor .agents/skills/code-pattern-extractor && rm -rf skills-srcUse ~/.agents/skills/ instead of .agents/skills for a personal install.
Codex skills documentation · loads skills from .agents/skills/
Install the "code-pattern-extractor" agent skill from https://github.com/majiayu000/claude-skill-registry/tree/main/skills/analysis/code-pattern-extractor into .agents/skills/code-pattern-extractor/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "code-pattern-extractor", 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 majiayu000/claude-skill-registry --skill code-pattern-extractor -a cursorProject install goes to .agents/skills/; add -g for ~/.cursor/skills/.
$ gh skill install majiayu000/claude-skill-registry code-pattern-extractor --agent cursorProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/majiayu000/claude-skill-registry.git skills-src && mkdir -p .cursor/skills && cp -r skills-src/skills/analysis/code-pattern-extractor .cursor/skills/code-pattern-extractor && 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 "code-pattern-extractor" agent skill from https://github.com/majiayu000/claude-skill-registry/tree/main/skills/analysis/code-pattern-extractor into .cursor/skills/code-pattern-extractor/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "code-pattern-extractor", 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/majiayu000/claude-skill-registry.git --path skills/analysis/code-pattern-extractor--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 majiayu000/claude-skill-registry --skill code-pattern-extractor -a gemini-cliProject install goes to .agents/skills/; add -g for ~/.gemini/skills/.
$ gh skill install majiayu000/claude-skill-registry code-pattern-extractor --agent gemini-cliProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/majiayu000/claude-skill-registry.git skills-src && mkdir -p .gemini/skills && cp -r skills-src/skills/analysis/code-pattern-extractor .gemini/skills/code-pattern-extractor && 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 "code-pattern-extractor" agent skill from https://github.com/majiayu000/claude-skill-registry/tree/main/skills/analysis/code-pattern-extractor into .gemini/skills/code-pattern-extractor/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "code-pattern-extractor", 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 majiayu000/claude-skill-registry code-pattern-extractorInstalls 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 majiayu000/claude-skill-registry --skill code-pattern-extractor -a github-copilotProject install goes to .agents/skills/; add -g for ~/.copilot/skills/.
$ git clone --depth 1 https://github.com/majiayu000/claude-skill-registry.git skills-src && mkdir -p .github/skills && cp -r skills-src/skills/analysis/code-pattern-extractor .github/skills/code-pattern-extractor && 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 "code-pattern-extractor" agent skill from https://github.com/majiayu000/claude-skill-registry/tree/main/skills/analysis/code-pattern-extractor into .github/skills/code-pattern-extractor/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "code-pattern-extractor", 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 majiayu000/claude-skill-registry --skill code-pattern-extractor -a opencodeOpenCode documents no install command of its own. Project install goes to .agents/skills/; add -g for ~/.config/opencode/skills/.
$ gh skill install majiayu000/claude-skill-registry code-pattern-extractor --agent opencodeProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/majiayu000/claude-skill-registry.git skills-src && mkdir -p .opencode/skills && cp -r skills-src/skills/analysis/code-pattern-extractor .opencode/skills/code-pattern-extractor && 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 "code-pattern-extractor" agent skill from https://github.com/majiayu000/claude-skill-registry/tree/main/skills/analysis/code-pattern-extractor into .opencode/skills/code-pattern-extractor/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "code-pattern-extractor", 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
code-pattern-extractor- GitHub stars
- 666
- Used in
- 1 other repo
- Token cost
- ~1.5k tokens
- SKILL.md length
- 426 words
- Files
- 2
- Skills in repo
- 971
- Repo updated
- First seen
- Licence
- MIT
At a glance
Analyze codebases to identify reusable code patterns, duplications, and implementation patterns for future development.
- Works in 7 steps: Define Analysis Scope → Scan for Code Duplication → Identify Implementation Patterns → …
- Refactoring code
- SKILL.md covers Overview, Workflow, Output Structure and Pattern Detection Heuristics, plus 1 more section
- Instructions only: no scripts, shell commands, URLs or credentials in SKILL.md
What it does
Code Pattern Extractor is an agent skill from majiayu000/claude-skill-registry. Analyze codebases to identify reusable code patterns, duplications, and implementation patterns for future development. Use when refactoring code, identifying technical debt, finding opportunities for abstraction, or documenting common patterns in a directory or module. Outputs pattern catalogs, refactoring suggestions, and reusable template code.
Its SKILL.md is about 1.5k tokens, which your agent loads only when the skill is triggered. The skill folder holds 1 other file (for example `metadata.json`).
It sits in Development, covering Refactoring and Technical debt. The repository describes itself as: Searchable Claude Code skills catalog with source-linked guides and generated registry artifacts. The licence is MIT.
When your agent uses it
- Refactoring code
- Identifying technical debt
- Finding opportunities for abstraction
- Documenting common patterns in a directory
Example prompts
- “/code-pattern-extractor”
Workflow steps
7 steps, taken from the step headings in SKILL.md.
What it can do on your machine
Read from SKILL.md and the folder at commit 000116a. It shows what the files ask for, not the result of running them.
Tool permissions
Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.
From allowed-tools in the SKILL.md frontmatter.
Runs code
No scripts in the folder and no shell commands in SKILL.md (its code samples are markdown and javascript).
From the folder's file list and the shell code blocks in SKILL.md.
Network
No URLs in SKILL.md.
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
Code Pattern Extractor loads about 1.5k tokens when it runs. Until then it costs about 93 tokens; SKILL.md has 426 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 passed
The automated check found no risky patterns in SKILL.md.
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 majiayu000/claude-skill-registry at commit 000116a, republished under its MIT licence (© majiayu000). 426 words, ~1,544 tokens.
Download SKILL.mdSave it as
.claude/skills/code-pattern-extractor/SKILL.md (or your agent's skills folder). This skill also uses 1 other file; get the full folder from GitHub.- name
- code-pattern-extractor
- description
- Analyze codebases to identify reusable code patterns, duplications, and implementation patterns for future development. Use when refactoring code, identifying technical debt, finding opportunities for abstraction, or documenting common patterns in a directory or module. Outputs pattern catalogs, refactoring suggestions, and reusable template code.
Code Pattern Extractor
Overview
Systematically analyze code in directories or modules to identify recurring patterns, code duplication, and implementation patterns that can be abstracted into reusable components, utilities, or design patterns.
Workflow
1. Define Analysis Scope
Identify the code to analyze:
- Directory/module: Analyze all files in a specific directory
- File set: Analyze a specific set of related files
- Component: Analyze files related to a specific feature or component
Use Glob to find relevant files:
**/*.js, **/*.py, **/*.go, etc.2. Scan for Code Duplication
Identify repeated code blocks that appear multiple times:
Look for:
- Similar function implementations with minor variations
- Repeated code blocks (>5 lines) across files
- Copy-pasted code with slight modifications
- Similar class structures or method patterns
Analysis criteria:
- Similarity threshold: >70% code similarity
- Minimum size: 5+ lines of code
- Frequency: Appears 3+ times
3. Identify Implementation Patterns
Find recurring implementation approaches:
Common patterns:
- API call patterns: Similar fetch/request handling
- Error handling: Repeated try-catch or error checking
- Data validation: Similar input validation logic
- Data transformation: Repeated mapping/filtering operations
- State management: Similar state update patterns
- Configuration: Repeated configuration setup
Example patterns to detect:
// Pattern: API call with error handling
async function fetchX() {
try {
const response = await fetch(url);
if (!response.ok) throw new Error();
return await response.json();
} catch (error) {
console.error(error);
return null;
}
}4. Categorize Patterns
Group identified patterns by type and impact:
Categories:
- High-value: Appears frequently (5+ times), significant code size
- Medium-value: Appears moderately (3-4 times), moderate complexity
- Low-value: Appears rarely (2 times), simple code
Pattern types:
- Utility functions (data processing, formatting, validation)
- API/network patterns (requests, responses, error handling)
- UI patterns (component structures, event handling)
- Business logic patterns (calculations, rules, workflows)
5. Generate Pattern Catalog
Document each identified pattern:
Pattern entry format:
## Pattern: [Descriptive Name]
**Type**: [Utility/API/UI/Business Logic]
**Frequency**: [Number of occurrences]
**Impact**: [High/Medium/Low]
**Description**: [What the pattern does]
**Current implementations**:
- `file1.js:45-60` - [Brief context]
- `file2.js:120-135` - [Brief context]
- `file3.js:89-104` - [Brief context]
**Common variations**:
- [Variation 1 description]
- [Variation 2 description]6. Generate Refactoring Suggestions
For each high-value pattern, provide refactoring recommendations:
Suggestion format:
### Refactoring: Extract [Pattern Name]
**Current state**: Pattern appears in [N] locations with [X]% code duplication
**Proposed solution**: Extract into [utility function/class/hook/module]
**Benefits**:
- Reduce code duplication by ~[N] lines
- Centralize logic for easier maintenance
- Improve testability
**Implementation approach**:
1. Create new file: `utils/[pattern-name].js`
2. Extract common logic with parameters for variations
3. Replace [N] occurrences with function calls
4. Add unit tests
**Estimated effort**: [Small/Medium/Large]Show full SKILL.md (165 more words)Show less
7. Generate Template Code
Create reusable template implementations for high-value patterns:
Template format:
/**
* [Pattern description]
*
* @param {type} param1 - [Description]
* @param {type} param2 - [Description]
* @returns {type} [Description]
*/
function patternTemplate(param1, param2) {
// Extracted common logic
// Parameterized variations
// Return standardized result
}Include:
- Function signature with parameters for variations
- Documentation comments
- Error handling
- Type annotations (if applicable)
- Usage examples
Output Structure
Organize findings into a comprehensive report:
# Code Pattern Analysis: [Directory/Module Name]
## Summary
- Files analyzed: [N]
- Patterns identified: [N]
- High-value patterns: [N]
- Estimated duplication: [N] lines
## Pattern Catalog
[List of all identified patterns with details]
## Refactoring Suggestions
[Prioritized list of refactoring opportunities]
## Template Code
[Reusable implementations for high-value patterns]
## Next Steps
[Recommended actions prioritized by impact]Pattern Detection Heuristics
Code duplication detection:
- Compare function bodies for structural similarity
- Ignore variable names and minor formatting differences
- Focus on logic flow and operations
Implementation pattern detection:
- Look for similar function signatures
- Identify repeated import patterns
- Find similar control flow structures (if-else, loops, try-catch)
- Detect repeated library usage patterns
Abstraction opportunities:
- Multiple functions with similar purpose but different parameters
- Repeated setup/teardown code
- Similar data transformations
- Parallel class hierarchies
Tips
- Start with high-frequency patterns for maximum impact
- Consider language-specific idioms when suggesting abstractions
- Balance DRY principle with code clarity (don't over-abstract)
- Include migration path in refactoring suggestions
- Prioritize patterns that improve maintainability, not just reduce lines
- Consider existing project architecture when suggesting abstractions
- Document trade-offs (flexibility vs. simplicity)
- For large codebases, analyze one module at a time
© majiayu000, MIT. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file
Files
SKILL.md and 1 other file in skills/analysis/code-pattern-extractor of majiayu000/claude-skill-registry.
- SKILL.md
- metadata.json
Open the folder on GitHubat commit 000116a
Used in 1 other repository
We found 1 copy of this SKILL.md (exact, near-identical or edited) in other folders, from 1 other GitHub owner. This page covers the copy in majiayu000/claude-skill-registry, which our catalogue first saw on October 7, 2026.
Compare with similar skills
Code Pattern Extractor 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 |
|---|---|---|---|---|---|---|
| Code Pattern Extractor this skillmajiayu000/claude-skill-registry | 666 | 1 repos | ~1.5k | Automated safety check: Pass | MIT | |
| Systematic Code Refactoringluongnv89/claude-howto | 42k | — | ~3k | Automated safety check: Pass | MIT | |
| Code Simplification for ego-litecitrolabs/ego-lite | 17k | — | ~1.2k | Automated safety check: Pass | MIT | |
| Code Refactoring Workflowluongnv89/claude-howto | 42k | — | ~3.1k | Automated safety check: Pass | MIT | |
| Tech Debt Analyzerailabs-393/ai-labs-claude-skills | 454 | 2 repos | ~3.9k | Automated safety check: Pass | MIT | |
| FIXME Resolvertailcallhq/forgecode | 7.6k | — | ~1.1k | Automated safety check: Pass | Apache-2.0 |
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Code Refactoring Workflow
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Guides systematic, test-backed refactoring in the style of Martin Fowler, moving through research, planning and small incremental changes with your approval at each phase.
Tech Debt Analyzer
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Categories
Questions about Code Pattern Extractor
What does Code Pattern Extractor do?
Analyze codebases to identify reusable code patterns, duplications, and implementation patterns for future development. Code Pattern Extractor is an agent skill from majiayu000/claude-skill-registry. Analyze codebases to identify reusable code patterns, duplications, and implementation patterns for future development.
When should I use Code Pattern Extractor?
Code Pattern Extractor fits situations like: refactoring code; identifying technical debt; finding opportunities for abstraction; documenting common patterns in a directory.
How do I install Code Pattern Extractor in Claude Code?
Run `npx skills add majiayu000/claude-skill-registry --skill code-pattern-extractor -a claude-code`. Or copy the skill folder (skills/analysis/code-pattern-extractor in majiayu000/claude-skill-registry) into .claude/skills/code-pattern-extractor in your project. Claude Code loads it when a task matches its description.
How do I install Code Pattern Extractor in Codex?
Run `npx skills add majiayu000/claude-skill-registry --skill code-pattern-extractor -a codex`. Or copy the skill folder (skills/analysis/code-pattern-extractor in majiayu000/claude-skill-registry) into .agents/skills/code-pattern-extractor in your project. Codex loads it when a task matches its description.
Can I use Code Pattern Extractor 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 majiayu000/claude-skill-registry --skill code-pattern-extractor -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/code-pattern-extractor, .gemini/skills/code-pattern-extractor, .github/skills/code-pattern-extractor and .opencode/skills/code-pattern-extractor in your project.
What does Code Pattern Extractor need to run?
SKILL.md names no scripts, command-line tools or credentials: Code Pattern Extractor is instructions for the agent only.
Does Code Pattern Extractor access the network?
SKILL.md contains no URLs. Any network use would come from the scripts or tools the agent runs. This is read from the text; nothing was executed.
Is Code Pattern Extractor safe to install?
Our automated static check of SKILL.md found no risky patterns, such as piping downloads into a shell, reading credential files or hidden Unicode. It is not a guarantee. Review the folder before installing.
What licence does Code Pattern Extractor use?
Code Pattern Extractor 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 Code Pattern Extractor use?
About 1.5k tokens (SKILL.md is roughly 6.2k 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 Code Pattern Extractor?
Skills that share tags, products or a category with Code Pattern Extractor: Systematic Code Refactoring (luongnv89/claude-howto, 42k stars), Code Simplification for ego-lite (citrolabs/ego-lite, 17k stars), Code Refactoring Workflow (luongnv89/claude-howto, 42k stars) and Tech Debt Analyzer (ailabs-393/ai-labs-claude-skills, 454 stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.
Who maintains Code Pattern Extractor?
majiayu000 (a GitHub user) maintains it in majiayu000/claude-skill-registry, which has 666 GitHub stars. The repository holds 971 skills in this directory. The repository was last updated on October 7, 2026.
Source: majiayu000/claude-skill-registry on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.