Duplicate Code: package filtering logic duplicated across build-cli and build-infrastructure

Analysis of commit 928277dfed7029d7ddc344e2c6389582ba762a2b

Assignee: @copilot

Summary

The package filtering logic is duplicated (near-exact copy/paste) between build-cli and build-infrastructure. The functions are identical (or trivially identical) and exceed the duplication threshold, increasing the risk of divergent behavior when one copy is updated without the other.

Duplication Details

Pattern: filterPackages (+ helper scopesToPrefix) duplicated across packages

• Severity: Medium

• Occurrences: 2 (exact duplicates)

• Locations:

  • build-tools/packages/build-cli/src/filter.ts (lines 248–285, helper at 336–338)
  • build-tools/packages/build-infrastructure/src/filter.ts (lines 297–334, helper at 287–289)

• Code Sample (from build-tools/packages/build-cli/src/filter.ts):

  export async function filterPackages(T extends FilterablePackage)(
  	packages: T[],
  	filters: PackageFilterOptions,
  ): Promise(T[]) {
  	const filtered = packages.filter((pkg) => {
  		if (filters === undefined) {
  			return true;
  		}
  
  		const isPrivate: boolean = pkg.private ?? false;
  		if (filters.private !== undefined && filters.private !== isPrivate) {
  			return false;
  		}
  
  		const scopeIn = scopesToPrefix(filters?.scope);
  		const scopeOut = scopesToPrefix(filters?.skipScope);
  
  		if (scopeIn !== undefined) {
  			let found = false;
  			for (const scope of scopeIn) {
  				found ||= pkg.name.startsWith(scope);
  			}
  			if (!found) {
  				return false;
  			}
  		}
  		if (scopeOut !== undefined) {
  			for (const scope of scopeOut) {
  				if (pkg.name.startsWith(scope) === true) {
  					return false;
  				}
  			}
  		}
  		return true;
  	});
  
  	return filtered;
  }
  
  function scopesToPrefix(scopes: string[] | undefined): string[] | undefined {
  	return scopes === undefined ? undefined : scopes.map((s) => `\$\{s}/`);
  }
  

Impact Analysis

• Maintainability: Any future change (e.g., adding new filter criteria, changing scope semantics) must be replicated and kept in sync across both packages.
• Bug Risk: High chance of inconsistent fixes when only one copy is updated.
• Code Bloat: Two copies of non-trivial filtering logic.

Refactoring Recommendations

1. Extract shared filtering utility

   • Extract filterPackages + scopesToPrefix into a shared module (suggestion):
     • build-tools/packages/build-tools/src/common/packageFilters.ts (or similar)
   • Update both build-cli and build-infrastructure to import the shared implementation.
   • Estimated effort: Low–Medium (1–3 hours, mostly wiring/exports).

2. Define a single source of truth and re-export

   • If the dependency direction allows, keep implementation in one package and re-export from the other.
   • This is less ideal than a true shared utility but still removes duplication.

Implementation Checklist

• Confirm both copies are intended to have identical semantics
• Choose a shared home package/module for the implementation
• Move code and update imports
• Run existing package/unit tests for both affected packages
• Ensure no API surface regressions

Analysis Metadata

• Detection Method: Serena semantic symbol comparison (find_symbol on filterPackages and scopesToPrefix)
• Analyzed Files (focused set): build-cli + build-infrastructure filter modules
• Commit: 928277dfed7029d7ddc344e2c6389582ba762a2b
• Analysis Date: 2026-03-20

Generated by Duplicate Code Detector · ◷

To install this agentic workflow, run

gh aw add github/gh-aw/.github/workflows/duplicate-code-detector.md@94662b1dee8ce96c876ba9f33b3ab8be32de82a4

Start by comparing filterPackages and scopesToPrefix in build-tools/packages/build-cli/src/filter.ts and build-tools/packages/build-infrastructure/src/filter.ts, then inspect the suggested shared package location and dependency direction. Choose a shared home, update both packages to use it, and run the existing package/unit tests for both affected packages to verify behavior and API compatibility.