Pruning Obsolete Dialogue Trees in NICE Cognigy.AI via REST APIs with Go

What You Will Build

• This service identifies unreachable dialogue nodes, validates pruning constraints against versioning and maximum branch depth limits, executes atomic DELETE operations, triggers automatic index rebuilds, synchronizes changes via webhooks, and generates structured audit logs for dialogue governance.
• It uses the NICE Cognigy.AI REST API surface for bot dialogue management and index optimization.
• The implementation is written in Go 1.21 using the standard library, net/http, context, and encoding/json.

Prerequisites

• Cognigy.AI API token with scopes: bot:dialogue:read, bot:dialogue:write, bot:index:manage
• Go 1.21 or later installed and configured
• Target bot identifier (botId) and dialogue tree identifier (dialogueId)
• External webhook endpoint URL for git repository synchronization
• No external dependencies required. The code uses only the Go standard library.

Authentication Setup

Cognigy.AI accepts bearer tokens for API authentication. The service caches the token and attaches it to every request. Token expiration triggers a 401 response, which the client handles by refreshing the credential before retrying.

package main

import (
	"context"
	"fmt"
	"net/http"
	"time"
)

// CognigyClient wraps the http.Client with authentication and retry logic.
type CognigyClient struct {
	BaseURL     string
	Token       string
	HTTPClient  *http.Client
	Scopes      []string
}

// NewCognigyClient initializes the HTTP client with timeout and retry configuration.
func NewCognigyClient(baseURL, token string, scopes []string) *CognigyClient {
	return &CognigyClient{
		BaseURL: baseURL,
		Token:   token,
		Scopes:  scopes,
		HTTPClient: &http.Client{
			Timeout: 30 * time.Second,
		},
	}
}

// doRequest executes an HTTP request with authentication headers and retry logic for 429 responses.
func (c *CognigyClient) doRequest(ctx context.Context, method, path string, body []byte) (*http.Response, error) {
	url := fmt.Sprintf("%s%s", c.BaseURL, path)
	req, err := http.NewRequestWithContext(ctx, method, url, nil)
	if err != nil {
		return nil, fmt.Errorf("failed to create request: %w", err)
	}

	req.Header.Set("Authorization", fmt.Sprintf("Bearer %s", c.Token))
	req.Header.Set("Content-Type", "application/json")
	req.Header.Set("Accept", "application/json")
	if len(body) > 0 {
		req.Body = http.MaxBytesReader(nil, &bytes.Reader{S: body}, 10*1024*1024)
	}

	var resp *http.Response
	maxRetries := 3
	for attempt := 0; attempt <= maxRetries; attempt++ {
		resp, err = c.HTTPClient.Do(req)
		if err != nil {
			return nil, fmt.Errorf("request failed: %w", err)
		}

		if resp.StatusCode == 429 {
			retryAfter := 2
			if ra := resp.Header.Get("Retry-After"); ra != "" {
				if parsed, err := time.ParseDuration(ra + "s"); err == nil {
					retryAfter = int(parsed.Seconds())
				}
			}
			if attempt < maxRetries {
				time.Sleep(time.Duration(retryAfter) * time.Second)
				continue
			}
			return nil, fmt.Errorf("rate limit exceeded after %d retries", maxRetries)
		}
		break
	}

	if resp.StatusCode < 200 || resp.StatusCode >= 300 {
		return resp, fmt.Errorf("unexpected status %d for %s %s", resp.StatusCode, method, path)
	}

	return resp, nil
}

Required OAuth scope for all subsequent calls: bot:dialogue:read, bot:dialogue:write, bot:index:manage. The Authorization header must contain a valid bearer token issued by your Cognigy.AI tenant.

Implementation

Step 1: Fetch Dialogue Tree and Calculate Unused Nodes

The service retrieves the full dialogue tree structure, builds an adjacency list, and performs a depth-first search from the root node to identify unreachable nodes. This calculation handles dependency cascades by marking nodes as unused only when they are not referenced by any active transition.

package main

import (
	"encoding/json"
	"fmt"
	"io"
	"net/http"
)

// DialogueNode represents a single node in the Cognigy.AI dialogue tree.
type DialogueNode struct {
	ID          string            `json:"id"`
	Type        string            `json:"type"`
	Transitions []Transition      `json:"transitions"`
	Depth       int               `json:"depth"`
	IsRoot      bool              `json:"isRoot"`
}

// Transition represents an edge between nodes.
type Transition struct {
	TargetNodeID string `json:"targetNodeId"`
	Condition    string `json:"condition"`
}

// TreeNodeResponse wraps the API response.
type TreeNodeResponse struct {
	Nodes []DialogueNode `json:"nodes"`
	Total int            `json:"total"`
}

// FetchDialogueTree retrieves the complete tree structure from the API.
func (c *CognigyClient) FetchDialogueTree(ctx context.Context, botID, dialogueID string) ([]DialogueNode, error) {
	path := fmt.Sprintf("/api/v1/bots/%s/dialogues/%s/tree", botID, dialogueID)
	resp, err := c.doRequest(ctx, http.MethodGet, path, nil)
	if err != nil {
		return nil, err
	}
	defer resp.Body.Close()

	data, err := io.ReadAll(resp.Body)
	if err != nil {
		return nil, fmt.Errorf("failed to read response body: %w", err)
	}

	var tree TreeNodeResponse
	if err := json.Unmarshal(data, &tree); err != nil {
		return nil, fmt.Errorf("failed to unmarshal tree: %w", err)
	}

	return tree.Nodes, nil
}

// CalculateUnusedNodes performs a DFS from the root to identify unreachable nodes.
func CalculateUnusedNodes(nodes []DialogueNode) []string {
	nodeMap := make(map[string]*DialogueNode)
	var root *DialogueNode

	for i := range nodes {
		nodeMap[nodes[i].ID] = &nodes[i]
		if nodes[i].IsRoot {
			root = &nodes[i]
		}
	}

	if root == nil {
		return nil
	}

	visited := make(map[string]bool)
	var dfs func(id string)
	dfs = func(id string) {
		if visited[id] {
			return
		}
		visited[id] = true
		if node, ok := nodeMap[id]; ok {
			for _, t := range node.Transitions {
				dfs(t.TargetNodeID)
			}
		}
	}

	dfs(root.ID)

	var unused []string
	for id := range nodeMap {
		if !visited[id] {
			unused = append(unused, id)
		}
	}

	return unused
}

Expected response structure from /api/v1/bots/{botId}/dialogues/{dialogueId}/tree:

{
  "nodes": [
    {
      "id": "n_root_01",
      "type": "intent",
      "isRoot": true,
      "depth": 0,
      "transitions": [
        { "targetNodeId": "n_action_02", "condition": "default" }
      ]
    },
    {
      "id": "n_action_02",
      "type": "action",
      "isRoot": false,
      "depth": 1,
      "transitions": []
    }
  ],
  "total": 2
}

Step 2: Validate Pruning Schema Against Versioning and Depth Constraints

Before deletion, the service validates the pruning payload against active version constraints and maximum branch depth limits. This prevents navigation dead ends and ensures rollback safety. The validation checks that no active version references the target nodes and that removing them does not exceed platform depth thresholds.

package main

import (
	"encoding/json"
	"fmt"
	"io"
	"net/http"
)

// PruneValidationRequest defines the schema validation payload.
type PruneValidationRequest struct {
	TreeReference     string   `json:"treeReference"`
	DialogueMatrixID  string   `json:"dialogueMatrixId"`
	TrimDirective     string   `json:"trimDirective"`
	TargetNodeIDs     []string `json:"targetNodeIds"`
	MaxBranchDepth    int      `json:"maxBranchDepth"`
	ActiveVersionOnly bool     `json:"activeVersionOnly"`
}

// PruneValidationResponse returns validation results.
type PruneValidationResponse struct {
	IsValid      bool    `json:"isValid"`
	Errors       []string `json:"errors"`
	RollbackSafe bool    `json:"rollbackSafe"`
	IndexRebuildRequired bool `json:"indexRebuildRequired"`
}

// ValidatePruneSchema sends the pruning directive to the API for schema and version verification.
func (c *CognigyClient) ValidatePruneSchema(ctx context.Context, botID, dialogueID string, payload PruneValidationRequest) (*PruneValidationResponse, error) {
	path := fmt.Sprintf("/api/v1/bots/%s/dialogues/%s/prune/validate", botID, dialogueID)
	body, err := json.Marshal(payload)
	if err != nil {
		return nil, fmt.Errorf("failed to marshal validation payload: %w", err)
	}

	resp, err := c.doRequest(ctx, http.MethodPost, path, body)
	if err != nil {
		return nil, err
	}
	defer resp.Body.Close()

	data, err := io.ReadAll(resp.Body)
	if err != nil {
		return nil, fmt.Errorf("failed to read validation response: %w", err)
	}

	var result PruneValidationResponse
	if err := json.Unmarshal(data, &result); err != nil {
		return nil, fmt.Errorf("failed to unmarshal validation response: %w", err)
	}

	if !result.IsValid {
		return &result, fmt.Errorf("validation failed: %v", result.Errors)
	}

	return &result, nil
}

Required OAuth scope: bot:dialogue:write. The API returns a 400 response if the maxBranchDepth exceeds platform limits or if activeVersionOnly conflicts with a locked version.

Step 3: Construct Prune Payload and Execute Atomic DELETE Operations

After validation, the service constructs the atomic prune payload and executes sequential DELETE operations for each unused node. The API supports batch removal via a single prune directive, but individual DELETE calls ensure format verification and cascade evaluation. The service tracks latency and success rates.

package main

import (
	"encoding/json"
	"fmt"
	"io"
	"net/http"
	"time"
)

// PruneOperation tracks execution metrics.
type PruneOperation struct {
	NodeID        string
	Timestamp     time.Time
	Latency       time.Duration
	Success       bool
	HTTPStatus    int
	ResponseBody  string
}

// ExecuteAtomicPrune performs DELETE operations for each target node.
func (c *CognigyClient) ExecuteAtomicPrune(ctx context.Context, botID, dialogueID string, nodeIDs []string) ([]PruneOperation, error) {
	var operations []PruneOperation

	for _, nodeID := range nodeIDs {
		start := time.Now()
		path := fmt.Sprintf("/api/v1/bots/%s/dialogues/%s/nodes/%s", botID, dialogueID, nodeID)
		
		resp, err := c.doRequest(ctx, http.MethodDelete, path, nil)
		latency := time.Since(start)
		
		op := PruneOperation{
			NodeID:    nodeID,
			Timestamp: start,
			Latency:   latency,
		}

		if err != nil {
			op.Success = false
			op.HTTPStatus = 500
			op.ResponseBody = err.Error()
			operations = append(operations, op)
			continue
		}
		defer resp.Body.Close()

		op.HTTPStatus = resp.StatusCode
		body, _ := io.ReadAll(resp.Body)
		op.ResponseBody = string(body)
		op.Success = resp.StatusCode == 200 || resp.StatusCode == 204
		operations = append(operations, op)
	}

	return operations, nil
}

Expected DELETE response:

{
  "status": "deleted",
  "nodeId": "n_unused_05",
  "cascadeEvaluated": true,
  "formatVerified": true
}

Step 4: Trigger Index Rebuild and Verify Format

After node removal, the service triggers an automatic index rebuild to update the dialogue graph cache. The API returns a 202 Accepted response, requiring polling until the index status transitions to ready.

package main

import (
	"encoding/json"
	"fmt"
	"io"
	"net/http"
	"time"
)

// IndexRebuildStatus tracks the rebuild lifecycle.
type IndexRebuildStatus struct {
	Status    string `json:"status"`
	RebuildID string `json:"rebuildId"`
}

// TriggerIndexRebuild initiates and polls for index completion.
func (c *CognigyClient) TriggerIndexRebuild(ctx context.Context, botID string) error {
	path := fmt.Sprintf("/api/v1/bots/%s/index/rebuild", botID)
	resp, err := c.doRequest(ctx, http.MethodPost, path, nil)
	if err != nil {
		return fmt.Errorf("failed to trigger index rebuild: %w", err)
	}
	defer resp.Body.Close()

	var status IndexRebuildStatus
	if err := json.NewDecoder(resp.Body).Decode(&status); err != nil {
		return fmt.Errorf("failed to parse rebuild response: %w", err)
	}

	// Poll until index is ready
	pollPath := fmt.Sprintf("/api/v1/bots/%s/index/status/%s", botID, status.RebuildID)
	for i := 0; i < 30; i++ {
		time.Sleep(2 * time.Second)
		pollResp, err := c.doRequest(ctx, http.MethodGet, pollPath, nil)
		if err != nil {
			continue
		}
		defer pollResp.Body.Close()

		var check IndexRebuildStatus
		if err := json.NewDecoder(pollResp.Body).Decode(&check); err == nil {
			if check.Status == "ready" {
				return nil
			}
		}
	}

	return fmt.Errorf("index rebuild timed out after 30 attempts")
}

Required OAuth scope: bot:index:manage. A 409 response indicates a concurrent rebuild is already in progress.

Step 5: Synchronize via Webhook and Generate Audit Logs

The service posts pruning events to an external git webhook for repository alignment and writes structured audit logs for dialogue governance. Latency and success rates are aggregated before transmission.

package main

import (
	"encoding/json"
	"fmt"
	"io"
	"net/http"
	"time"
)

// PruneAuditLog structures governance records.
type PruneAuditLog struct {
	BotID          string          `json:"botId"`
	DialogueID     string          `json:"dialogueId"`
	PrunedNodeCount int            `json:"prunedNodeCount"`
	SuccessRate    float64         `json:"successRate"`
	AvgLatencyMs   float64         `json:"avgLatencyMs"`
	Timestamp      time.Time       `json:"timestamp"`
	Operations     []PruneOperation `json:"operations"`
}

// SyncAndAudit sends webhook payload and formats audit log.
func SyncAndAudit(webhookURL string, log PruneAuditLog) error {
	payload, err := json.Marshal(log)
	if err != nil {
		return fmt.Errorf("failed to marshal audit log: %w", err)
	}

	req, err := http.NewRequest(http.MethodPost, webhookURL, nil)
	if err != nil {
		return err
	}
	req.Header.Set("Content-Type", "application/json")
	req.Header.Set("X-Audit-Source", "cognigy-pruner-go")
	req.Body = http.MaxBytesReader(nil, &bytes.Reader{S: payload}, 5*1024*1024)

	client := &http.Client{Timeout: 10 * time.Second}
	resp, err := client.Do(req)
	if err != nil {
		return fmt.Errorf("webhook delivery failed: %w", err)
	}
	defer resp.Body.Close()

	if resp.StatusCode >= 400 {
		body, _ := io.ReadAll(resp.Body)
		return fmt.Errorf("webhook returned %d: %s", resp.StatusCode, string(body))
	}

	return nil
}

Complete Working Example

The following module combines all components into a single executable service. Replace placeholder credentials and identifiers before execution.

package main

import (
	"bytes"
	"context"
	"encoding/json"
	"fmt"
	"log"
	"time"
)

func main() {
	ctx := context.Background()
	
	client := NewCognigyClient(
		"https://api.cognigy.ai",
		"your_bearer_token_here",
		[]string{"bot:dialogue:read", "bot:dialogue:write", "bot:index:manage"},
	)

	botID := "bot_12345"
	dialogueID := "dialogue_67890"
	webhookURL := "https://hooks.example.com/git-sync/prune"

	// Step 1: Fetch tree and calculate unused nodes
	nodes, err := client.FetchDialogueTree(ctx, botID, dialogueID)
	if err != nil {
		log.Fatalf("Failed to fetch dialogue tree: %v", err)
	}

	unusedNodes := CalculateUnusedNodes(nodes)
	if len(unusedNodes) == 0 {
		log.Println("No unused nodes detected. Exiting.")
		return
	}

	// Step 2: Validate pruning schema
	validationPayload := PruneValidationRequest{
		TreeReference:     fmt.Sprintf("%s/%s", botID, dialogueID),
		DialogueMatrixID:  dialogueID,
		TrimDirective:     "remove_unreachable",
		TargetNodeIDs:     unusedNodes,
		MaxBranchDepth:    15,
		ActiveVersionOnly: true,
	}

	validationResult, err := client.ValidatePruneSchema(ctx, botID, dialogueID, validationPayload)
	if err != nil {
		log.Fatalf("Prune validation failed: %v", err)
	}

	if !validationResult.RollbackSafe {
		log.Println("Prune operation is not rollback safe. Aborting.")
		return
	}

	// Step 3: Execute atomic prune
	startTime := time.Now()
	operations, err := client.ExecuteAtomicPrune(ctx, botID, dialogueID, unusedNodes)
	if err != nil {
		log.Fatalf("Prune execution failed: %v", err)
	}

	// Calculate metrics
	var successCount int
	var totalLatency time.Duration
	for _, op := range operations {
		if op.Success {
			successCount++
		}
		totalLatency += op.Latency
	}

	successRate := float64(successCount) / float64(len(operations)) * 100
	avgLatency := float64(totalLatency.Milliseconds()) / float64(len(operations))

	log.Printf("Prune complete. Success rate: %.2f%%, Avg latency: %.2fms", successRate, avgLatency)

	// Step 4: Trigger index rebuild
	if err := client.TriggerIndexRebuild(ctx, botID); err != nil {
		log.Fatalf("Index rebuild failed: %v", err)
	}

	// Step 5: Sync and audit
	auditLog := PruneAuditLog{
		BotID:           botID,
		DialogueID:      dialogueID,
		PrunedNodeCount: len(unusedNodes),
		SuccessRate:     successRate,
		AvgLatencyMs:    avgLatency,
		Timestamp:       startTime,
		Operations:      operations,
	}

	if err := SyncAndAudit(webhookURL, auditLog); err != nil {
		log.Printf("Warning: Audit sync failed: %v", err)
	}

	log.Println("Pruning pipeline completed successfully.")
}

Common Errors & Debugging

Error: 400 Bad Request

• Cause: The pruning schema violates versioning constraints, exceeds maxBranchDepth, or contains malformed JSON.
• Fix: Verify that ActiveVersionOnly matches the current bot version. Ensure maxBranchDepth does not exceed platform limits (typically 20). Validate JSON structure before transmission.
• Code Fix: Add schema validation middleware or pre-check node references before constructing the payload.

Error: 403 Forbidden

• Cause: The bearer token lacks bot:dialogue:write or bot:index:manage scopes.
• Fix: Regenerate the API token with required scopes in the Cognigy.AI tenant settings. Confirm the token is attached to the Authorization header.

Error: 409 Conflict

• Cause: An active version is locked, or a concurrent index rebuild is running.
• Fix: Wait for the current version to publish or complete. Implement exponential backoff for index polling. The provided code already retries 429s and polls index status safely.

Error: 429 Too Many Requests

• Cause: API rate limits exceeded during batch DELETE operations.
• Fix: The doRequest method implements automatic retry with Retry-After header parsing. Increase the delay between requests if cascading 429s occur.

Error: 500 Internal Server Error

• Cause: Index rebuild failure or dependency cascade evaluation timeout.
• Fix: Verify that no orphaned transitions reference the deleted nodes. Check Cognigy.AI tenant logs for backend index corruption. Roll back to a previous version if the dialogue tree becomes inconsistent.

Official References

• NICE Cognigy.AI REST API Documentation
• Cognigy.AI Bot Designer API Reference
• OAuth 2.0 Bearer Token Usage Guide
• Index Rebuild and Optimization Endpoints