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Duplicate Code Detector
Detect exact and near-duplicate code clones across any codebase with normalization and CI gate support.
$9.99
Duplicate Code Detector
Example session with this skill installed
Scan the src/ directory for any code clones longer than 8 lines, including cases where variables were renamed. Report the duplication percentage.
- Read your context and instructions
- Compiled the duplicate code detector
- Generated the document
I have completed a deep scan of the src/ directory. By normalizing identifiers and ignoring whitespace, I identified 4 distinct clone groups. The overall duplication rate for this directory is 8.4%.
Duplicate Code Analysis Report
| Clone Group | Occurrences | Avg. Lines | Similarity Type | Locations |
|---|---|---|---|---|
| GROUP_001 | 3 | 12 | Type-2 (Renamed) | src/auth/service.py:45, src/users/service.py:112 |
| GROUP_002 | 2 | 10 | Type-1 (Exact) | src/ui/buttons.tsx:12, src/ui/inputs.tsx:84 |
| GROUP_003 | 2 | 9 | Type-2 (Renamed) | src/api/v1/handlers.go:204, src/api/v2/handlers.go:198 |
| GROUP_004 | 4 | 8 | Type-1 (Exact) | src/db/migrations/001_init.sql, src/db/migrations/002_add_logs.sql |
Refactoring Recommendations
Group 001: The logic for validate_session_token is repeated with different variable names in Auth and User services. Recommend extracting to src/common/security.py.
- Group 002: Exact CSS-in-JS object detected in two UI components. Move to a shared
theme.tsconstant.
Group 003: API response wrapping logic is duplicated across versions. Wrap in a middleware or a shared response utility.
Next steps
- Extract the
validate_session_tokenlogic to a shared service. - Run the scanner with
--fail --max-percent 5in your CI config to prevent future regressions. - Consolidate the UI styling constants into the design system.
buttons.tsx
PDF · document
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About this skill
Duplicate code blocks often bypass standard linters and static analysis, leading to high maintenance debt and hidden bugs. This skill scans your codebase to identify identical (Type-1) and renamed (Type-2) clones that simple grep commands miss.
What it does
- Normalization scanning ignores whitespace, comments, and literals to find logical duplicates.
- Identifier abstraction detects code blocks where variables or functions were renamed.
- Clone grouping merges overlapping matches into logical groups for refactoring.
- Duplication metrics calculates percentage of duplicate lines per file and across the project.
- CI enforcement provides exit codes to fail builds if duplication exceeds a set threshold.
How it works
- Run the detector on a target directory or file glob.
- Specify the minimum line count to filter out trivial repetitions.
- Toggle identifier ignoring to catch near-duplicate logic.
- Review the report of clone groups and their specific locations.
Frameworks & tools
This tool uses a Python-based implementation compatible with any language. It supports standard CLI integration for use in local environments or CI/CD pipelines.
Why this beats prompting it yourself
Manual prompting often fails to track rolling hashes or maintain state across large file trees. This skill handles the heavy lifting of normalization and percentage calculation that LLMs struggle to do accurately at scale.
Use cases
- Identify refactoring opportunities for shared utility modules.
- Audit a legacy codebase to quantify technical debt.
- Prevent copy-paste growth during large-scale migrations.
- Set a hard quality gate in CI pipelines for team projects.
Known limitations
Requires Python 3 environment. Large codebases may require specific file exclusions to maintain performance.
How to use
Skills on Agensi run inside your AI agent. Copy the prompt, paste it into your agent, and it connects to Agensi and installs this skill for you. If a payment is needed, your agent shows it to you first.
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