Production AI: 6 thang deploy chatbot cho 100K users

## Stats

- 100K daily users - 500K messages/day - 99.9% uptime

## Lessons Learned

### 1. Caching

Giam 60% API calls

### 2. Rate Limiting

Tranh bill shock

### 3. Fallback

```python try: gemini() except: claude() # backup ```

### 4. Monitoring

Prometheus + Grafana

## Cost: $3,600/month