[duplicate-code] Duplicate Code Pattern: DIFC Component Initialization Sequence

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Part of duplicate code analysis: #4458

Summary

The four-step DIFC component initialization sequence (ParseEnforcementMode → NewAgentRegistryWithDefaults → NewCapabilities → NewEvaluatorWithMode) is repeated in both the server and proxy packages, making it a refactoring opportunity.

Duplication Details

Pattern: DIFC component init sequence

• Severity: Medium
• Occurrences: 2 (constructor sites)
• Locations:
  • internal/server/unified.go lines ~143–168 (NewUnified)
  • internal/proxy/proxy.go lines ~103–124 (New)

internal/server/unified.go:

difcMode, err := difc.ParseEnforcementMode(cfg.DIFCMode)
if err != nil {
    difcMode = difc.EnforcementStrict // default for server
}
// ... struct literal includes:
agentRegistry: difc.NewAgentRegistryWithDefaults(nil, nil),
capabilities:  difc.NewCapabilities(),
evaluator:     difc.NewEvaluatorWithMode(difcMode),

internal/proxy/proxy.go:

difcMode, err := difc.ParseEnforcementMode(cfg.DIFCMode)
if err != nil {
    difcMode = difc.EnforcementFilter // default for proxy
}
// ... struct literal includes:
evaluator:     difc.NewEvaluatorWithMode(difcMode),
agentRegistry: difc.NewAgentRegistryWithDefaults(nil, nil),
capabilities:  difc.NewCapabilities(),

The two variants differ only in the fallback enforcement mode (EnforcementStrict vs EnforcementFilter) and an extra warning log in the proxy.

Impact Analysis

• Maintainability: If the DIFC initialization logic changes (e.g., new components added), both sites must be updated
• Bug Risk: The two sites already use different default modes silently — this could cause unexpected behavioral differences
• Code Bloat: ~8–10 lines duplicated

Refactoring Recommendations

1. Add a difc.NewComponents(modeStr string, defaultMode EnforcementMode) DIFCComponents constructor

   type DIFCComponents struct {
       Mode          EnforcementMode
       AgentRegistry *AgentRegistry
       Capabilities  *Capabilities
       Evaluator     *Evaluator
   }
   func NewComponents(modeStr string, defaultMode EnforcementMode) DIFCComponents { ... }

2. Both server and proxy pass their chosen defaultMode (EnforcementStrict / EnforcementFilter)
3. Estimated effort: 1–2 hours

Implementation Checklist

• Add DIFCComponents struct and NewComponents constructor to internal/difc
• Update internal/server/unified.go:NewUnified to use difc.NewComponents
• Update internal/proxy/proxy.go:New to use difc.NewComponents
• Run make test-all to verify no regressions

Parent Issue

See parent analysis report: #4458
Related to #4458

Generated by Duplicate Code Detector · ● 3M · ◷

• expires on May 1, 2026, 6:15 AM UTC