[duplicate-code] Duplicate Code Pattern: `--guards-mode` Flag Validation in CLI Commands

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Part of duplicate code analysis: #4376

Summary

The --guards-mode flag validation block (3 lines, identical error message) is copy-pasted verbatim in both internal/cmd/root.go and internal/cmd/proxy.go. While minor in isolation, it is a clear exact-copy pattern.

Duplication Details

Pattern: ParseEnforcementMode CLI validation

• Severity: Low
• Occurrences: 2 (identical code, same error string)
• Locations:
  • internal/cmd/root.go (line 194)
  • internal/cmd/proxy.go (line 144)

Code Sample (identical in both files):

if _, err := difc.ParseEnforcementMode(difcMode); err != nil {
    return fmt.Errorf("invalid --guards-mode flag: %w", err)
}

The same pattern also appears as a comment/reference in internal/cmd/flags_difc.go (getDefaultDIFCMode), showing this validation logic is spread across three locations in the cmd package.

Impact Analysis

• Maintainability: If the error message or validation logic changes (e.g., to include valid values in the error), it must be updated in two places
• Bug Risk: Low — the current duplication is stable
• Code Bloat: Minimal, but the pattern could spread as more server modes are added

Refactoring Recommendations

1. Extract validateDIFCModeFlag helper in the cmd package
   • Location: internal/cmd/flags_difc.go (near getDefaultDIFCMode)
   • Signature: func validateDIFCModeFlag(mode string) error
   • Implementation:

     func validateDIFCModeFlag(mode string) error {
         if _, err := difc.ParseEnforcementMode(mode); err != nil {
             return fmt.Errorf("invalid --guards-mode flag: %w", err)
         }
         return nil
     }

   • Both root.go and proxy.go call validateDIFCModeFlag(difcMode) instead
   • Estimated effort: 30 minutes
   • Benefits: single place to update the error message or add valid-values hint

Implementation Checklist

• Review duplication findings
• Add validateDIFCModeFlag helper to internal/cmd/flags_difc.go
• Replace duplicated 3-line block in root.go and proxy.go
• Run make lint and make test to verify no regressions

Parent Issue

See parent analysis report: #4376
Related to #4376

Generated by Duplicate Code Detector · ● 4.8M · ◷

• expires on Apr 30, 2026, 6:17 AM UTC