v1.0.0 - Initial release

Initial release of Duplicate Code Cross-Check.

What it does

Detects duplicate code on pull requests using two complementary engines:

• PMD CPD - deep language awareness for Java, Kotlin, C++, Python, Go, and more
• jscpd - language-agnostic token matching as a second perspective

Runs both on the PR branch and the base branch, compares the results, and posts a single unified PR comment with the delta. Fails the build if either engine reports a regression.

Features

• Single combined PR comment with side-by-side engine results
• Base-vs-PR comparison - shows what the PR introduced, not just total duplication
• Inline PR review comments on specific lines of new duplication
• Content-hash matching of clones so refactors that shift line numbers don't cause false positives
• Per-engine configurable thresholds (absolute ceiling + increase-vs-base)
• Emoji reactions on deltas based on magnitude

Why

Agentic programming makes duplicate code a much bigger problem. LLM-based agents tend to copy patterns they've already seen in the codebase rather than refactor to reuse them. Nothing in the GitHub Marketplace does base-vs-PR comparison for duplicate detection, so we built it.

See the README for full usage docs and comparison with related tools.

Usage

- uses: astubbs/duplicate-code-cross-check@v1
  with:
    github-token: ${{ secrets.GITHUB_TOKEN }}
    directories: src