## 15. Monitoring & Observability

**Recommendation**: Comprehensive observability from day one.

### Metrics to Track

**Business Metrics** (Daily/Monthly Dashboard):
- **Active businesses**: 500+ (Year 1), 2,000+ (Year 2), 5,000+ (Year 3)
- **Sites & resource flows**: 85% data completion rate target
- **Match rate**: 60% conversion from suggested to implemented matches
- **Average savings**: €25,000 per implemented connection
- **Platform adoption**: 15-20% free-to-paid conversion rate

**Technical Metrics** (Real-time Monitoring):
- **API response times**: p50 <500ms, p95 <2s, p99 <5s
- **Graph query performance**: <1s for 95% of queries
- **Match computation latency**: <30s for complex optimizations
- **Error rates**: <1% API errors, <0.1% critical errors
- **Database connection pool**: 70-90% utilization target
- **Cache hit rates**: >85% Redis hit rate, >95% application cache
- **Uptime**: >99.5% availability target

**Domain-Specific Metrics**:
- **Matching accuracy**: >90% user satisfaction with match quality
- **Economic calculation precision**: ±€100 accuracy on savings estimates
- **Geospatial accuracy**: <100m error on location-based matching
- **Real-time updates**: <5s delay for new resource notifications

### Alerting

**Critical Alerts**:
- API error rate > 1%
- Database connection failures
- Match computation failures
- Cache unavailable

**Warning Alerts**:
- High latency (p95 > 2s)
- Low cache hit rate (< 70%)
- Disk space low

**Tools**:
- **Prometheus**: Metrics collection
- **Grafana**: Visualization and dashboards
- **AlertManager**: Alert routing and notification
- **Loki or ELK**: Logging (Elasticsearch, Logstash, Kibana)
- **Jaeger or Zipkin**: Distributed tracing
- **Sentry**: Error tracking

### Observability Tools

- **Metrics**: Prometheus + Grafana
- **Logging**: Loki or ELK stack
- **Tracing**: Jaeger or Zipkin for distributed tracing
- **APM**: Sentry for error tracking
- **OpenTelemetry**: `go.opentelemetry.io/otel` for instrumentation

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