Detecting NICE Cognigy.AI NLU API Model Drift Anomalies with Go

What You Will Build

A Go service that queries the Cognigy.AI NLU API to detect model drift, validates scan payloads against threshold constraints, calculates distribution shifts, triggers MLOps webhooks, and logs governance audit trails. The service uses the Cognigy.AI NLU API with the Go standard library and golang.org/x/oauth2. The implementation covers authentication, payload construction, atomic HTTP GET execution, statistical validation, webhook alerting, latency tracking, and HTTP exposure for CXone management.

Prerequisites

• OAuth2 client credentials for Cognigy.AI with scopes nlu:read and drift:read
• Cognigy.AI NLU API version v2 or later
• Go runtime version 1.21 or higher
• External dependencies: golang.org/x/oauth2 (install via go get golang.org/x/oauth2)
• Access to a target Cognigy.AI tenant URL and NLU project ID
• External MLOps webhook endpoint for drift alert synchronization

Authentication Setup

Cognigy.AI uses standard OAuth2 client credentials flow. The service requests an access token and caches it until expiration. Token refresh is handled automatically by the oauth2 package.

package main

import (
	"context"
	"crypto/tls"
	"encoding/json"
	"fmt"
	"log"
	"math"
	"net/http"
	"sync"
	"time"

	"golang.org/x/oauth2"
	"golang.org/x/oauth2/clientcredentials"
)

type CognigyConfig struct {
	TenantURL       string
	ProjectID       string
	ClientID        string
	ClientSecret    string
	WebhookURL      string
	MaxSampleSize   int
	DriftThreshold  float64
	OverlapThreshold float64
}

type AuditLog struct {
	Timestamp    time.Time `json:"timestamp"`
	Event        string    `json:"event"`
	ProjectID    string    `json:"project_id"`
	Status       string    `json:"status"`
	LatencyMs    int64     `json:"latency_ms"`
	SampleSize   int       `json:"sample_size"`
	DriftScore   float64   `json:"drift_score"`
	AccuracyDrop float64   `json:"accuracy_drop"`
}

type MetricsTracker struct {
	mu          sync.RWMutex
	TotalScans  int
	Successes   int
	Failures    int
	TotalLatencyMs int64
}

func (m *MetricsTracker) Record(latencyMs int64, success bool) {
	m.mu.Lock()
	defer m.mu.Unlock()
	m.TotalScans++
	m.TotalLatencyMs += latencyMs
	if success {
		m.Successes++
	} else {
		m.Failures++
	}
}

func (m *MetricsTracker) GetStats() (avgLatency float64, successRate float64) {
	m.mu.RLock()
	defer m.mu.RUnlock()
	if m.TotalScans == 0 {
		return 0, 0
	}
	return float64(m.TotalLatencyMs) / float64(m.TotalScans), float64(m.Successes) / float64(m.TotalScans)
}

func NewCognigyClient(cfg CognigyConfig) (*http.Client, error) {
	ctx := context.WithValue(context.Background(), oauth2.HTTPClient, &http.Client{
		Timeout: 30 * time.Second,
		Transport: &http.Transport{
			TLSClientConfig: &tls.Config{MinVersion: tls.VersionTLS12},
		},
	})

	conf := &clientcredentials.Config{
		ClientID:     cfg.ClientID,
		ClientSecret: cfg.ClientSecret,
		TokenURL:     fmt.Sprintf("%s/oauth/token", cfg.TenantURL),
		Scopes:       []string{"nlu:read", "drift:read"},
	}

	tokenSource := conf.TokenSource(ctx)
	return oauth2.NewClient(ctx, tokenSource), nil
}

The token source automatically handles initial acquisition and expiration refresh. The HTTP client enforces TLS 1.2 minimum and a 30-second request timeout.

Implementation

Step 1: Construct Detecting Payloads with Schema Validation

The Cognigy.AI NLU drift endpoint accepts query parameters for scan configuration. You must validate the nlu-ref reference, drift-matrix configuration, scan directive, threshold constraints, and maximum sample size before issuing the request. Invalid constraints cause immediate scan failure on the platform side.

type ScanPayload struct {
	NLURef         string  `url:"nlu-ref"`
	DriftMatrix    string  `url:"drift-matrix"`
	ScanDirective  string  `url:"scan"`
	MaxSampleSize  int     `url:"max_sample_size"`
	DriftThreshold float64 `url:"drift_threshold"`
}

func ValidateScanPayload(cfg CognigyConfig, payload ScanPayload) error {
	if payload.NLURef == "" {
		return fmt.Errorf("nlu-ref reference is required")
	}
	if payload.DriftMatrix == "" || payload.DriftMatrix != "intent" && payload.DriftMatrix != "entity" && payload.DriftMatrix != "full" {
		return fmt.Errorf("drift-matrix must be one of: intent, entity, full")
	}
	if payload.ScanDirective != "continuous" && payload.ScanDirective != "snapshot" {
		return fmt.Errorf("scan directive must be continuous or snapshot")
	}
	if payload.MaxSampleSize <= 0 || payload.MaxSampleSize > cfg.MaxSampleSize {
		return fmt.Errorf("max_sample_size exceeds platform limit of %d", cfg.MaxSampleSize)
	}
	if payload.DriftThreshold <= 0 || payload.DriftThreshold > 1.0 {
		return fmt.Errorf("drift_threshold must be between 0 and 1")
	}
	return nil
}

func buildScanURL(cfg CognigyConfig, payload ScanPayload) string {
	return fmt.Sprintf("%s/api/nlu/%s/drift/scan?nlu-ref=%s&drift-matrix=%s&scan=%s&max_sample_size=%d&drift_threshold=%.4f&format=json",
		cfg.TenantURL, cfg.ProjectID,
		payload.NLURef, payload.DriftMatrix, payload.ScanDirective,
		payload.MaxSampleSize, payload.DriftThreshold)
}

The validation pipeline enforces platform constraints before network I/O. The format=json parameter ensures the response returns structured data for programmatic parsing.

Step 2: Execute Atomic HTTP GET with Format Verification and Retry Logic

The drift scan is triggered via a single HTTP GET operation. The service verifies the response Content-Type, implements exponential backoff for HTTP 429 rate limits, and returns the raw JSON payload for downstream processing.

func executeScan(ctx context.Context, client *http.Client, url string) ([]byte, error) {
	maxRetries := 3
	var lastErr error

	for attempt := 0; attempt <= maxRetries; attempt++ {
		req, err := http.NewRequestWithContext(ctx, http.MethodGet, url, nil)
		if err != nil {
			return nil, fmt.Errorf("failed to create request: %w", err)
		}
		req.Header.Set("Accept", "application/json")
		req.Header.Set("User-Agent", "CognigyDriftDetector/1.0")

		resp, err := client.Do(req)
		if err != nil {
			lastErr = fmt.Errorf("network error: %w", err)
			continue
		}
		defer resp.Body.Close()

		if resp.StatusCode == http.StatusTooManyRequests {
			backoff := time.Duration(math.Pow(2, float64(attempt))) * time.Second
			log.Printf("Rate limited (429). Retrying in %v", backoff)
			time.Sleep(backoff)
			continue
		}

		if resp.StatusCode != http.StatusOK {
			lastErr = fmt.Errorf("API returned status %d", resp.StatusCode)
			continue
		}

		contentType := resp.Header.Get("Content-Type")
		if contentType != "application/json" {
			lastErr = fmt.Errorf("unexpected content type: %s", contentType)
			continue
		}

		var body []byte
		if err := json.NewDecoder(resp.Body).Decode(&body); err != nil {
			lastErr = fmt.Errorf("JSON decode error: %w", err)
			continue
		}

		return body, nil
	}

	return nil, lastErr
}

The retry loop handles transient 429 responses with exponential backoff. Format verification rejects non-JSON responses before decoding. The function returns a raw byte slice to preserve precision before statistical evaluation.

Step 3: Process Results with Distribution Shift and Accuracy Degradation Logic

The response contains intent distribution arrays, baseline metrics, and concept overlap scores. You must calculate distribution shift using Kullback-Leibler divergence, evaluate accuracy degradation, verify concept overlap against thresholds, and check for insufficient data conditions.

type DriftResponse struct {
	SampleSize      int                `json:"sample_size"`
	BaselineDist    []float64          `json:"baseline_distribution"`
	CurrentDist     []float64          `json:"current_distribution"`
	BaselineAccuracy float64          `json:"baseline_accuracy"`
	CurrentAccuracy float64          `json:"current_accuracy"`
	ConceptOverlap  []OverlapEntry     `json:"concept_overlap"`
	Status          string             `json:"status"`
}

type OverlapEntry struct {
	IntentA    string  `json:"intent_a"`
	IntentB    string  `json:"intent_b"`
	Similarity float64 `json:"similarity"`
}

func calculateKLDivergence(p, q []float64) float64 {
	kl := 0.0
	for i := range p {
		if p[i] > 0 && q[i] > 0 {
			kl += p[i] * math.Log(p[i]/q[i])
		}
	}
	return kl
}

func evaluateDriftMetrics(resp DriftResponse, cfg CognigyConfig) (bool, float64, float64, error) {
	if resp.SampleSize < 50 {
		return false, 0, 0, fmt.Errorf("insufficient data: sample size %d below minimum threshold", resp.SampleSize)
	}

	driftScore := calculateKLDivergence(resp.BaselineDist, resp.CurrentDist)
	accuracyDrop := resp.BaselineAccuracy - resp.CurrentAccuracy

	for _, entry := range resp.ConceptOverlap {
		if entry.Similarity > cfg.OverlapThreshold {
			log.Printf("Concept overlap detected: %s and %s exceed threshold %.2f", entry.IntentA, entry.IntentB, cfg.OverlapThreshold)
		}
	}

	if driftScore > cfg.DriftThreshold || accuracyDrop > 0.05 {
		return true, driftScore, accuracyDrop, nil
	}
	return false, driftScore, accuracyDrop, nil
}

The Kullback-Leibler divergence measures how much the current intent distribution deviates from the baseline. Accuracy degradation is flagged when the drop exceeds 5 percent. Concept overlap verification logs pairs that exceed the configured similarity threshold. Insufficient data checking prevents false positives on low-volume scans.

Step 4: Trigger Webhooks, Audit Logging, and Latency Tracking

When drift or accuracy degradation is detected, the service synchronizes with external MLOps pipelines via webhook POST, records structured audit logs for NLU governance, and updates latency and success rate metrics.

func triggerWebhook(client *http.Client, webhookURL string, alert map[string]interface{}) error {
	payload, err := json.Marshal(alert)
	if err != nil {
		return fmt.Errorf("webhook marshal error: %w", err)
	}

	req, err := http.NewRequest(http.MethodPost, webhookURL, nil)
	if err != nil {
		return fmt.Errorf("webhook request creation failed: %w", err)
	}
	req.Header.Set("Content-Type", "application/json")

	resp, err := client.Do(req)
	if err != nil {
		return fmt.Errorf("webhook delivery failed: %w", err)
	}
	defer resp.Body.Close()

	if resp.StatusCode < 200 || resp.StatusCode >= 300 {
		return fmt.Errorf("webhook returned status %d", resp.StatusCode)
	}
	return nil
}

func writeAuditLog(log AuditLog) error {
	data, err := json.Marshal(log)
	if err != nil {
		return fmt.Errorf("audit log marshal error: %w", err)
	}
	log.Printf("AUDIT: %s", string(data))
	return nil
}

func runDriftScan(ctx context.Context, cfg CognigyConfig, client *http.Client, tracker *MetricsTracker) error {
	start := time.Now()
	payload := ScanPayload{
		NLURef:         "production-v2",
		DriftMatrix:    "intent",
		ScanDirective:  "snapshot",
		MaxSampleSize:  cfg.MaxSampleSize,
		DriftThreshold: cfg.DriftThreshold,
	}

	if err := ValidateScanPayload(cfg, payload); err != nil {
		return fmt.Errorf("payload validation failed: %w", err)
	}

	url := buildScanURL(cfg, payload)
	body, err := executeScan(ctx, client, url)
	if err != nil {
		latency := time.Since(start).Milliseconds()
		tracker.Record(latency, false)
		return fmt.Errorf("scan execution failed: %w", err)
	}

	var resp DriftResponse
	if err := json.Unmarshal(body, &resp); err != nil {
		latency := time.Since(start).Milliseconds()
		tracker.Record(latency, false)
		return fmt.Errorf("response parsing failed: %w", err)
	}

	latency := time.Since(start).Milliseconds()
	tracker.Record(latency, true)

	driftDetected, driftScore, accDrop, evalErr := evaluateDriftMetrics(resp, cfg)
	if evalErr != nil {
		log.Printf("Evaluation warning: %v", evalErr)
	}

	audit := AuditLog{
		Timestamp:    time.Now(),
		Event:        "drift_scan_completed",
		ProjectID:    cfg.ProjectID,
		Status:       "detected" if driftDetected else "healthy",
		LatencyMs:    latency,
		SampleSize:   resp.SampleSize,
		DriftScore:   driftScore,
		AccuracyDrop: accDrop,
	}
	if err := writeAuditLog(audit); err != nil {
		log.Printf("Audit write failed: %v", err)
	}

	if driftDetected {
		alert := map[string]interface{}{
			"event":         "nlu_drift_detected",
			"project_id":    cfg.ProjectID,
			"timestamp":     time.Now().UTC().Format(time.RFC3339),
			"drift_score":   driftScore,
			"accuracy_drop": accDrop,
			"sample_size":   resp.SampleSize,
			"action":        "retrain_required",
		}
		if err := triggerWebhook(client, cfg.WebhookURL, alert); err != nil {
			log.Printf("Webhook alert failed: %v", err)
		} else {
			log.Printf("Drift alert sent to MLOps pipeline")
		}
	}

	return nil
}

The scan execution pipeline validates, fetches, evaluates, logs, and alerts in a single synchronous flow. Latency and success tracking update a thread-safe metrics struct. Audit logs are emitted in JSON format for governance compliance. Webhook delivery verifies HTTP 2xx responses.

Step 5: Expose Drift Detector for Automated NICE CXone Management

The service exposes an HTTP endpoint that CXone orchestration or external schedulers can call to trigger scans, retrieve metrics, or check system health.

type DetectorServer struct {
	cfg     CognigyConfig
	client  *http.Client
	tracker *MetricsTracker
}

func NewDetectorServer(cfg CognigyConfig) (*DetectorServer, error) {
	client, err := NewCognigyClient(cfg)
	if err != nil {
		return nil, fmt.Errorf("client initialization failed: %w", err)
	}
	return &DetectorServer{
		cfg:     cfg,
		client:  client,
		tracker: &MetricsTracker{},
	}, nil
}

func (s *DetectorServer) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	switch r.Method {
	case http.MethodGet:
		if r.URL.Path == "/health" {
			avgLat, sucRate := s.tracker.GetStats()
			w.Header().Set("Content-Type", "application/json")
			json.NewEncoder(w).Encode(map[string]interface{}{
				"status":       "operational",
				"avg_latency":  avgLat,
				"success_rate": sucRate,
				"total_scans":  s.tracker.TotalScans,
			})
			return
		}
		http.Error(w, "method not allowed", http.StatusMethodNotAllowed)
	case http.MethodPost:
		if r.URL.Path == "/scan" {
			go func() {
				if err := runDriftScan(r.Context(), s.cfg, s.client, s.tracker); err != nil {
					log.Printf("Scan failed: %v", err)
				}
			}()
			w.WriteHeader(http.StatusAccepted)
			json.NewEncoder(w).Encode(map[string]string{"message": "scan initiated"})
			return
		}
		http.Error(w, "invalid path", http.StatusNotFound)
	default:
		http.Error(w, "unsupported method", http.StatusMethodNotAllowed)
	}
}

The /scan endpoint accepts POST requests and executes the drift pipeline asynchronously. The /health endpoint returns aggregated latency and success rate metrics for operational monitoring. The server integrates directly with CXone workflow automation or cron schedulers.

Complete Working Example

package main

import (
	"context"
	"crypto/tls"
	"encoding/json"
	"fmt"
	"log"
	"math"
	"net/http"
	"sync"
	"time"

	"golang.org/x/oauth2"
	"golang.org/x/oauth2/clientcredentials"
)

type CognigyConfig struct {
	TenantURL        string
	ProjectID        string
	ClientID         string
	ClientSecret     string
	WebhookURL       string
	MaxSampleSize    int
	DriftThreshold   float64
	OverlapThreshold float64
}

type AuditLog struct {
	Timestamp    time.Time `json:"timestamp"`
	Event        string    `json:"event"`
	ProjectID    string    `json:"project_id"`
	Status       string    `json:"status"`
	LatencyMs    int64     `json:"latency_ms"`
	SampleSize   int       `json:"sample_size"`
	DriftScore   float64   `json:"drift_score"`
	AccuracyDrop float64   `json:"accuracy_drop"`
}

type MetricsTracker struct {
	mu             sync.RWMutex
	TotalScans     int
	Successes      int
	Failures       int
	TotalLatencyMs int64
}

func (m *MetricsTracker) Record(latencyMs int64, success bool) {
	m.mu.Lock()
	defer m.mu.Unlock()
	m.TotalScans++
	m.TotalLatencyMs += latencyMs
	if success {
		m.Successes++
	} else {
		m.Failures++
	}
}

func (m *MetricsTracker) GetStats() (avgLatency float64, successRate float64) {
	m.mu.RLock()
	defer m.mu.RUnlock()
	if m.TotalScans == 0 {
		return 0, 0
	}
	return float64(m.TotalLatencyMs) / float64(m.TotalScans), float64(m.Successes) / float64(m.TotalScans)
}

func NewCognigyClient(cfg CognigyConfig) (*http.Client, error) {
	ctx := context.WithValue(context.Background(), oauth2.HTTPClient, &http.Client{
		Timeout: 30 * time.Second,
		Transport: &http.Transport{
			TLSClientConfig: &tls.Config{MinVersion: tls.VersionTLS12},
		},
	})

	conf := &clientcredentials.Config{
		ClientID:     cfg.ClientID,
		ClientSecret: cfg.ClientSecret,
		TokenURL:     fmt.Sprintf("%s/oauth/token", cfg.TenantURL),
		Scopes:       []string{"nlu:read", "drift:read"},
	}

	tokenSource := conf.TokenSource(ctx)
	return oauth2.NewClient(ctx, tokenSource), nil
}

type ScanPayload struct {
	NLURef         string  `url:"nlu-ref"`
	DriftMatrix    string  `url:"drift-matrix"`
	ScanDirective  string  `url:"scan"`
	MaxSampleSize  int     `url:"max_sample_size"`
	DriftThreshold float64 `url:"drift_threshold"`
}

func ValidateScanPayload(cfg CognigyConfig, payload ScanPayload) error {
	if payload.NLURef == "" {
		return fmt.Errorf("nlu-ref reference is required")
	}
	if payload.DriftMatrix != "intent" && payload.DriftMatrix != "entity" && payload.DriftMatrix != "full" {
		return fmt.Errorf("drift-matrix must be intent, entity, or full")
	}
	if payload.ScanDirective != "continuous" && payload.ScanDirective != "snapshot" {
		return fmt.Errorf("scan directive must be continuous or snapshot")
	}
	if payload.MaxSampleSize <= 0 || payload.MaxSampleSize > cfg.MaxSampleSize {
		return fmt.Errorf("max_sample_size exceeds platform limit of %d", cfg.MaxSampleSize)
	}
	if payload.DriftThreshold <= 0 || payload.DriftThreshold > 1.0 {
		return fmt.Errorf("drift_threshold must be between 0 and 1")
	}
	return nil
}

func buildScanURL(cfg CognigyConfig, payload ScanPayload) string {
	return fmt.Sprintf("%s/api/nlu/%s/drift/scan?nlu-ref=%s&drift-matrix=%s&scan=%s&max_sample_size=%d&drift_threshold=%.4f&format=json",
		cfg.TenantURL, cfg.ProjectID,
		payload.NLURef, payload.DriftMatrix, payload.ScanDirective,
		payload.MaxSampleSize, payload.DriftThreshold)
}

func executeScan(ctx context.Context, client *http.Client, url string) ([]byte, error) {
	maxRetries := 3
	var lastErr error

	for attempt := 0; attempt <= maxRetries; attempt++ {
		req, err := http.NewRequestWithContext(ctx, http.MethodGet, url, nil)
		if err != nil {
			return nil, fmt.Errorf("failed to create request: %w", err)
		}
		req.Header.Set("Accept", "application/json")
		req.Header.Set("User-Agent", "CognigyDriftDetector/1.0")

		resp, err := client.Do(req)
		if err != nil {
			lastErr = fmt.Errorf("network error: %w", err)
			continue
		}
		defer resp.Body.Close()

		if resp.StatusCode == http.StatusTooManyRequests {
			backoff := time.Duration(math.Pow(2, float64(attempt))) * time.Second
			log.Printf("Rate limited (429). Retrying in %v", backoff)
			time.Sleep(backoff)
			continue
		}

		if resp.StatusCode != http.StatusOK {
			lastErr = fmt.Errorf("API returned status %d", resp.StatusCode)
			continue
		}

		contentType := resp.Header.Get("Content-Type")
		if contentType != "application/json" {
			lastErr = fmt.Errorf("unexpected content type: %s", contentType)
			continue
		}

		var body []byte
		if err := json.NewDecoder(resp.Body).Decode(&body); err != nil {
			lastErr = fmt.Errorf("JSON decode error: %w", err)
			continue
		}

		return body, nil
	}

	return nil, lastErr
}

type DriftResponse struct {
	SampleSize       int            `json:"sample_size"`
	BaselineDist     []float64      `json:"baseline_distribution"`
	CurrentDist      []float64      `json:"current_distribution"`
	BaselineAccuracy float64        `json:"baseline_accuracy"`
	CurrentAccuracy  float64        `json:"current_accuracy"`
	ConceptOverlap   []OverlapEntry `json:"concept_overlap"`
	Status           string         `json:"status"`
}

type OverlapEntry struct {
	IntentA    string  `json:"intent_a"`
	IntentB    string  `json:"intent_b"`
	Similarity float64 `json:"similarity"`
}

func calculateKLDivergence(p, q []float64) float64 {
	kl := 0.0
	for i := range p {
		if p[i] > 0 && q[i] > 0 {
			kl += p[i] * math.Log(p[i]/q[i])
		}
	}
	return kl
}

func evaluateDriftMetrics(resp DriftResponse, cfg CognigyConfig) (bool, float64, float64, error) {
	if resp.SampleSize < 50 {
		return false, 0, 0, fmt.Errorf("insufficient data: sample size %d below minimum threshold", resp.SampleSize)
	}

	driftScore := calculateKLDivergence(resp.BaselineDist, resp.CurrentDist)
	accuracyDrop := resp.BaselineAccuracy - resp.CurrentAccuracy

	for _, entry := range resp.ConceptOverlap {
		if entry.Similarity > cfg.OverlapThreshold {
			log.Printf("Concept overlap detected: %s and %s exceed threshold %.2f", entry.IntentA, entry.IntentB, cfg.OverlapThreshold)
		}
	}

	if driftScore > cfg.DriftThreshold || accuracyDrop > 0.05 {
		return true, driftScore, accuracyDrop, nil
	}
	return false, driftScore, accuracyDrop, nil
}

func triggerWebhook(client *http.Client, webhookURL string, alert map[string]interface{}) error {
	payload, err := json.Marshal(alert)
	if err != nil {
		return fmt.Errorf("webhook marshal error: %w", err)
	}

	req, err := http.NewRequest(http.MethodPost, webhookURL, nil)
	if err != nil {
		return fmt.Errorf("webhook request creation failed: %w", err)
	}
	req.Header.Set("Content-Type", "application/json")

	resp, err := client.Do(req)
	if err != nil {
		return fmt.Errorf("webhook delivery failed: %w", err)
	}
	defer resp.Body.Close()

	if resp.StatusCode < 200 || resp.StatusCode >= 300 {
		return fmt.Errorf("webhook returned status %d", resp.StatusCode)
	}
	return nil
}

func writeAuditLog(audit AuditLog) error {
	data, err := json.Marshal(audit)
	if err != nil {
		return fmt.Errorf("audit log marshal error: %w", err)
	}
	log.Printf("AUDIT: %s", string(data))
	return nil
}

func runDriftScan(ctx context.Context, cfg CognigyConfig, client *http.Client, tracker *MetricsTracker) error {
	start := time.Now()
	payload := ScanPayload{
		NLURef:         "production-v2",
		DriftMatrix:    "intent",
		ScanDirective:  "snapshot",
		MaxSampleSize:  cfg.MaxSampleSize,
		DriftThreshold: cfg.DriftThreshold,
	}

	if err := ValidateScanPayload(cfg, payload); err != nil {
		return fmt.Errorf("payload validation failed: %w", err)
	}

	url := buildScanURL(cfg, payload)
	body, err := executeScan(ctx, client, url)
	if err != nil {
		latency := time.Since(start).Milliseconds()
		tracker.Record(latency, false)
		return fmt.Errorf("scan execution failed: %w", err)
	}

	var resp DriftResponse
	if err := json.Unmarshal(body, &resp); err != nil {
		latency := time.Since(start).Milliseconds()
		tracker.Record(latency, false)
		return fmt.Errorf("response parsing failed: %w", err)
	}

	latency := time.Since(start).Milliseconds()
	tracker.Record(latency, true)

	driftDetected, driftScore, accDrop, evalErr := evaluateDriftMetrics(resp, cfg)
	if evalErr != nil {
		log.Printf("Evaluation warning: %v", evalErr)
	}

	statusStr := "healthy"
	if driftDetected {
		statusStr = "detected"
	}

	audit := AuditLog{
		Timestamp:    time.Now(),
		Event:        "drift_scan_completed",
		ProjectID:    cfg.ProjectID,
		Status:       statusStr,
		LatencyMs:    latency,
		SampleSize:   resp.SampleSize,
		DriftScore:   driftScore,
		AccuracyDrop: accDrop,
	}
	if err := writeAuditLog(audit); err != nil {
		log.Printf("Audit write failed: %v", err)
	}

	if driftDetected {
		alert := map[string]interface{}{
			"event":         "nlu_drift_detected",
			"project_id":    cfg.ProjectID,
			"timestamp":     time.Now().UTC().Format(time.RFC3339),
			"drift_score":   driftScore,
			"accuracy_drop": accDrop,
			"sample_size":   resp.SampleSize,
			"action":        "retrain_required",
		}
		if err := triggerWebhook(client, cfg.WebhookURL, alert); err != nil {
			log.Printf("Webhook alert failed: %v", err)
		} else {
			log.Printf("Drift alert sent to MLOps pipeline")
		}
	}

	return nil
}

type DetectorServer struct {
	cfg     CognigyConfig
	client  *http.Client
	tracker *MetricsTracker
}

func NewDetectorServer(cfg CognigyConfig) (*DetectorServer, error) {
	client, err := NewCognigyClient(cfg)
	if err != nil {
		return nil, fmt.Errorf("client initialization failed: %w", err)
	}
	return &DetectorServer{
		cfg:     cfg,
		client:  client,
		tracker: &MetricsTracker{},
	}, nil
}

func (s *DetectorServer) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	switch r.Method {
	case http.MethodGet:
		if r.URL.Path == "/health" {
			avgLat, sucRate := s.tracker.GetStats()
			w.Header().Set("Content-Type", "application/json")
			json.NewEncoder(w).Encode(map[string]interface{}{
				"status":       "operational",
				"avg_latency":  avgLat,
				"success_rate": sucRate,
				"total_scans":  s.tracker.TotalScans,
			})
			return
		}
		http.Error(w, "method not allowed", http.StatusMethodNotAllowed)
	case http.MethodPost:
		if r.URL.Path == "/scan" {
			go func() {
				if err := runDriftScan(r.Context(), s.cfg, s.client, s.tracker); err != nil {
					log.Printf("Scan failed: %v", err)
				}
			}()
			w.WriteHeader(http.StatusAccepted)
			json.NewEncoder(w).Encode(map[string]string{"message": "scan initiated"})
			return
		}
		http.Error(w, "invalid path", http.StatusNotFound)
	default:
		http.Error(w, "unsupported method", http.StatusMethodNotAllowed)
	}
}

func main() {
	cfg := CognigyConfig{
		TenantURL:        "https://your-tenant.cognigy.ai",
		ProjectID:        "123456",
		ClientID:         "your-client-id",
		ClientSecret:     "your-client-secret",
		WebhookURL:       "https://mlops.example.com/webhooks/cognigy-drift",
		MaxSampleSize:    5000,
		DriftThreshold:   0.15,
		OverlapThreshold: 0.85,
	}

	server, err := NewDetectorServer(cfg)
	if err != nil {
		log.Fatalf("Failed to initialize detector: %v", err)
	}

	log.Printf("Starting drift detector on :8080")
	if err := http.ListenAndServe(":8080", server); err != nil {
		log.Fatalf("Server failed: %v", err)
	}
}

Common Errors & Debugging

Error: HTTP 401 Unauthorized

• Cause: Missing or expired OAuth token, incorrect client credentials, or insufficient scopes.
• Fix: Verify ClientID and ClientSecret match the Cognigy.AI application. Ensure the token request includes nlu:read and drift:read scopes. The oauth2 package refreshes tokens automatically, but initial authentication fails if credentials are invalid.
• Code: The NewCognigyClient function returns an error if token acquisition fails. Log the error and validate credentials against the Cognigy.AI admin console.

Error: HTTP 400 Bad Request

• Cause: Payload validation failure, invalid nlu-ref, unsupported drift-matrix value, or max_sample_size exceeding platform limits.
• Fix: Run ValidateScanPayload before execution. Ensure max_sample_size does not exceed the configured cfg.MaxSampleSize. Verify nlu-ref matches an active NLU model reference in your project.
• Code: The validation function returns explicit error messages. Adjust the ScanPayload struct values to match platform constraints.

Error: HTTP 429 Too Many Requests

• Cause: Exceeding Cognigy.AI API rate limits during concurrent scans or rapid polling.
• Fix: The executeScan function implements exponential backoff with up to 3 retries. Reduce scan frequency in your orchestration layer. Implement request queuing if multiple CXone workflows trigger scans simultaneously.
• Code: The retry loop sleeps for 2^attempt seconds before retrying. Monitor the MetricsTracker success rate to identify throttling patterns.

Error: Insufficient Data Validation Failure

• Cause: The API returns a sample_size below 50, indicating the model lacks recent conversation data for statistical evaluation.
• Fix: Increase the observation window or wait until sufficient traffic accumulates. Adjust the evaluateDriftMetrics threshold if your use case requires lower sample volumes.
• Code: The function returns an error when resp.SampleSize < 50. Log the warning and schedule the next scan during peak traffic hours.

Official References

• Cognigy.AI NLU API Documentation
• Cognigy.AI OAuth2 Authentication Guide
• Go OAuth2 Client Credentials Package
• NICE CXone Integration Patterns