FrenoCorp/FRE-4510-IMPLEMENTATION.md

FRE-4510: Feature Flag Implementation for Spam Classification

Summary

Implemented a centralized feature flag management system for the SpamShield service, enabling runtime control over spam detection features without code deployment.

Changes Made

1. Feature Flag System (apps/api/src/services/spamshield/feature-flags.ts)

New File - Created a complete feature flag management system with:

• FeatureFlagResolver Class: Centralized flag resolution with priority order:

  1. Environment variables (allows runtime updates via FLAG_<KEY> variables)
  2. Resolution cache
  3. Default values

• Pre-defined Flags: 15 flags across three categories:

  SpamShield Flags (8):

  • spamshield.enable.number.reputation - Number reputation checking
  • spamshield.enable.content.classification - SMS content classification
  • spamshield.enable.behavioral.analysis - Call behavioral analysis
  • spamshield.enable.community.intelligence - Community intelligence sharing
  • spamshield.enable.real.time.blocking - Real-time spam blocking
  • spamshield.enable.multiple.sources - Multiple reputation source aggregation
  • spamshield.enable.ml.classifier - ML-based spam classification

  VoicePrint Flags (5):

  • voiceprint.enable.ml.service - ML service integration
  • voiceprint.enable.faiss.index - FAISS index for voice matching
  • voiceprint.enable.batch.analysis - Batch voice analysis
  • voiceprint.enable.realtime.analysis - Real-time voice analysis
  • voiceprint.enable.mock.model - Mock model for development

  Platform Flags (2):

  • platform.enable.audit.logs - Comprehensive audit logging
  • platform.enable.kpi.tracking - KPI snapshot tracking

2. Updated SpamShield Config (apps/api/src/services/spamshield/spamshield.config.ts)

Modified - Integrated feature flag system:

import { checkFlag } from './feature-flags';

export const spamFeatureFlags = {
  enableNumberReputation: checkFlag('spamshield.enable.number.reputation', true),
  enableContentClassification: checkFlag('spamshield.enable.content.classification', true),
  enableBehavioralAnalysis: checkFlag('spamshield.enable.behavioral.analysis', true),
  enableCommunityIntelligence: checkFlag('spamshield.enable.community.intelligence', true),
  enableRealTimeBlocking: checkFlag('spamshield.enable.real.time.blocking', true),
  enableMultipleSources: checkFlag('spamshield.enable.multiple.sources', false),
  enableMLClassifier: checkFlag('spamshield.enable.ml.classifier', false),
};

3. Updated SpamShield Service (apps/api/src/services/spamshield/spamshield.service.ts)

Modified - Added feature flag checks to all major services:

• NumberReputationService.checkReputation(): Returns early with zero values when flag is disabled
• NumberReputationService.checkMultiSource(): Disables multi-source aggregation when flag is off
• SMSClassifierService.classify(): Falls back to feature-based classification when ML flag disabled
• CallAnalysisService.analyzeCall(): Skips behavioral analysis when flag disabled
• SpamFeedbackService.recordFeedback(): Returns mock data when community intelligence disabled

4. Updated Index Exports

Modified both index files to export feature flag utilities:

// apps/api/src/services/spamshield/index.ts
export { checkFlag, isFeatureEnabled } from './spamshield.config';
export * from './feature-flags';

Usage

Environment Variable Configuration

Set feature flags via environment variables:

# Enable number reputation checking
export FLAG_SPAMSHIELD_ENABLE_NUMBER_REPUTATION=true

# Disable ML classifier
export FLAG_SPAMSHIELD_ENABLE_ML_CLASSIFIER=false

# Enable multiple sources
export FLAG_SPAMSHIELD_ENABLE_MULTIPLE_SOURCES=true

Programmatic Access

import { checkFlag, isFeatureEnabled, featureFlags } from './spamshield';

// Check if a flag is enabled
if (isFeatureEnabled('spamshield.enable.number.reputation', true)) {
  // Perform number reputation check
}

// Get flag value with fallback
const isEnabled = checkFlag('spamshield.enable.ml.classifier', false);

// List all flags
console.log(featureFlags);

Runtime Flag Updates

Flags can be updated at runtime by setting environment variables:

# In production, restart the service with new env vars
FLAG_SPAMSHIELD_ENABLE_ML_CLASSIFIER=false npm run start

Testing Recommendations

1. Unit Tests: Test each service method with flags disabled
2. Integration Tests: Verify feature gating works end-to-end
3. E2E Tests: Test fallback behavior when ML/classification features disabled

Next Steps

1. Add unit tests for feature flag system
2. Document flag definitions in README
3. Set up CI/CD pipeline to validate flag configurations
4. Create admin UI for flag management (future enhancement)

Verification

✓ TypeScript compilation successful ✓ All imports resolved correctly ✓ Feature flags exported and accessible ✓ Backward compatible with existing code