let metrics = PrismMetrics()
await server.use(PrismMetricsMiddleware(metrics: metrics))
// GET /metrics → JSON metrics snapshot

{
    "requestCount": 15234,
    "errorCount": 42,
    "activeRequests": 3,
    "averageLatencyMs": 12.5,
    "statusCounts": {
        "200": 14800,
        "404": 350,
        "500": 42,
        "201": 42
    },
    "topPaths": {
        "/api/users": 5000,
        "/api/products": 3200,
        "/health": 2100
    }
}

await server.use(PrismMetricsMiddleware(metrics: metrics, path: "/api/metrics"))

let snapshot = await metrics.snapshot()

print("Total requests: \(snapshot.requestCount)")
print("Error rate: \(Double(snapshot.errorCount) / Double(snapshot.requestCount) * 100)%")
print("Average latency: \(Double(snapshot.averageLatencyNanos) / 1_000_000)ms")

if snapshot.activeRequests > 100 {
    print("Warning: high concurrent load")
}

await metrics.requestStarted()
let clock = ContinuousClock()
let start = clock.now

// ... do work ...

let duration = clock.now - start
await metrics.recordRequest(path: "/background-job", statusCode: 200, duration: duration)
await metrics.requestEnded()

await metrics.reset()
// All counters back to zero — useful for testing or periodic snapshots

let health = PrismHealthMonitor()

await health.register(PrismHealthCheck(name: "error-rate") {
    let snapshot = await metrics.snapshot()
    guard snapshot.requestCount > 100 else {
        return PrismHealthCheckResult(name: "error-rate", status: .healthy, message: "Insufficient data")
    }
    let errorRate = Double(snapshot.errorCount) / Double(snapshot.requestCount)
    if errorRate > 0.1 {
        return PrismHealthCheckResult(name: "error-rate", status: .unhealthy, message: "Error rate: \(Int(errorRate * 100))%")
    } else if errorRate > 0.05 {
        return PrismHealthCheckResult(name: "error-rate", status: .degraded, message: "Error rate: \(Int(errorRate * 100))%")
    }
    return PrismHealthCheckResult(name: "error-rate", status: .healthy)
})