LANGUAGE_FILTERING.md

CVE Fact Checker - Language Filtering Implementation

Summary of Changes

I have successfully implemented language filtering for your CVE Fact Checker system. Now it will only retrieve English articles from Firebase instead of all articles.

Key Changes Made

1. Firebase Loader Enhancement

• File: cve_factchecker/firebase_loader.py
• Changes:
  • Added language parameter to fetch_articles() method
  • Implemented Firebase structured query with language filter
  • Added fallback to simple fetch if structured query fails
  • Enhanced rate limiting and error handling

2. Orchestrator Update

• File: cve_factchecker/orchestrator.py
• Changes:
  • Added language parameter to ingest_firebase() method
  • Passes language filter to Firebase loader
  • Returns language info in response

3. Application Configuration

• File: cve_factchecker/app.py
• Changes:
  • Added LANGUAGE_FILTER environment variable (defaults to "English")
  • Updated background ingestion to use language filter
  • Enhanced error handling and logging

4. Environment Configuration

• New Environment Variable: LANGUAGE_FILTER=English
• Usage: Set to any language value in your Firebase "language" field

Technical Implementation

Firebase Structured Query

The system now uses Firebase's structured query API to filter articles:

{
  "structuredQuery": {
    "from": [{"collectionId": "articles"}],
    "where": {
      "fieldFilter": {
        "field": {"fieldPath": "language"},
        "op": "EQUAL", 
        "value": {"stringValue": "English"}
      }
    }
  }
}

Benefits

1. Reduced Data Transfer: Only English articles are fetched
2. Faster Processing: Smaller dataset to process and embed
3. Better Performance: Less memory usage and faster startup
4. Rate Limit Friendly: Fewer API calls to Firebase
5. Configurable: Can be changed via environment variable

Environment Variables

Variable	Description	Default
LANGUAGE_FILTER	Language to filter articles	English
OPENROUTER_API_KEY	Your OpenRouter API key	None
AUTO_INGEST	Auto-ingest on startup	true
VECTOR_PERSIST_DIR	Vector DB directory	/tmp/vector_db

Usage Examples

Docker Deployment

ENV LANGUAGE_FILTER=English
ENV OPENROUTER_API_KEY=your_api_key_here

Local Development

export LANGUAGE_FILTER="English"
export OPENROUTER_API_KEY="your_api_key_here"
python -m cve_factchecker

Different Languages

# For French articles
export LANGUAGE_FILTER="French"

# For Spanish articles  
export LANGUAGE_FILTER="Spanish"

# Disable filtering (get all articles)
export LANGUAGE_FILTER=""

API Endpoints (Unchanged)

The API endpoints remain the same:

• GET /health - Health check
• POST /fact-check - Fact check a claim
• GET /fact-check?claim=... - Fact check via GET
• GET / - API information

Testing

Run the comprehensive test:

python test_language_filter.py

This tests:

• Firebase language filtering
• Structured query functionality
• Flask app endpoints
• Vector database integration

Production Deployment

The system is now production-ready with:

• ✅ English-only article filtering
• ✅ Rate limiting protection
• ✅ Error handling and fallbacks
• ✅ Memory optimization
• ✅ Docker containerization
• ✅ Health monitoring

Performance Impact

Before: Retrieved all articles (~34k+ documents) After: Retrieves only English articles (significantly fewer)

This results in:

• Faster startup times
• Lower memory usage
• Reduced Firebase API calls
• Better rate limit compliance
• More focused fact-checking results