Set user-agent for webhook response

src/RequestWrapper.ts

@@ -17,6 +17,7 @@ import {
   RetryConfig,
 } from './types.js';
 import { handleResponse } from './coreCommon.js';
+import { setWebhookUserAgent } from './resources/webhook/response.js';
 import { Buffer } from 'node:buffer';
 
 export class RequestWrapper {
@@ -128,6 +129,7 @@ export class RequestWrapper {
         : 'application/x-www-form-urlencoded; charset=utf-8';
 
       const userAgent = `Chargebee-NodeJs-Client ${env.clientVersion}${env.userAgentSuffix ? ';' + env.userAgentSuffix : ''}`;
+      setWebhookUserAgent(userAgent);
 
       extend(true, requestHeaders, {
         Authorization:

src/resources/webhook/handler.ts

@@ -8,6 +8,7 @@ import {
   WebhookPayloadValidationError,
   WebhookPayloadParseError,
 } from './errors.js';
+import { setResponseHeader, webhookUserAgent } from './response.js';
 
 export { WebhookEventType, WebhookContentType };
 export {
@@ -511,6 +512,15 @@ export class WebhookHandler<
         );
       }
 
+      try {
+        setResponseHeader(response as any, 'User-Agent', webhookUserAgent);
+      } catch (err) {
+        console.warn(
+          '[chargebee] Warning: Failed to set webhook user agent:',
+          err instanceof Error ? err.message : String(err),
+        );
+      }
+
       const context: WebhookContext<ReqT, ResT> = {
         event,
         request,

src/resources/webhook/response.ts

@@ -0,0 +1,85 @@
+type NodeLike = {
+  setHeader(name: string, value: string | readonly string[]): unknown;
+};
+
+type ReplyLike = {
+  header?(name: string, value: string): unknown; // e.g. fastify/hono-style
+  set?(name: string, value: string): unknown;    // e.g. koa ctx.set
+};
+
+type WebHeaderTarget =
+  | Headers
+  | { headers: Headers }
+  | Response;
+
+type HeaderTarget = WebHeaderTarget | NodeLike | ReplyLike;
+
+export let webhookUserAgent: string = "Chargebee-NodeJs-Client; Webhook";
+
+export function setWebhookUserAgent(userAgent: string) {
+  webhookUserAgent = userAgent;
+}
+
+/**
+ * Set headers on the response object
+ * - Works with:
+ *   - Web: Response, Headers, { headers: Headers }
+ *   - Node/Bun http-like: { setHeader(name, value): any }
+ *   - Some libs (optional): { header(name, value): any } or { set(name, value): any }
+ *
+ * No dependency on express/fastify/hono/etc types existing.
+ */
+export function setResponseHeader<T extends HeaderTarget>(
+  response: T,
+  name: string,
+  value: string
+): T {
+  if (!response) {
+    return response;
+  }
+
+  // instance of Headers
+  if (isHeaders(response)) {
+    response.set(name, value);
+    return response;
+  }
+
+  // Object with .headers (Request-like/Response-like wrappers)
+  if (hasHeaders(response)) {
+    response.headers.set(name, value);
+    return response;
+  }
+
+  // Node/Bun http-like response: setHeader(name, value)
+  if (hasSetHeader(response)) {
+    response.setHeader(name, value);
+    return response;
+  }
+
+  // Object with .header(name, value)
+  if (typeof (response as any).header === "function") {
+    (response as any).header(name, value);
+    return response;
+  }
+  // Context-like object with .set(name, value)
+  if (typeof (response as any).set === "function") {
+    (response as any).set(name, value);
+    return response;
+  }
+
+  return response;
+}
+
+function isHeaders(x: unknown): x is Headers {
+  return typeof x === "object" && x !== null && typeof (x as any).set === "function"
+    && typeof (x as any).append === "function"
+    && typeof (x as any).get === "function";
+}
+
+function hasHeaders(x: unknown): x is { headers: Headers } {
+  return typeof x === "object" && x !== null && isHeaders((x as any).headers);
+}
+
+function hasSetHeader(x: unknown): x is NodeLike {
+  return typeof x === "object" && x !== null && typeof (x as any).setHeader === "function";
+}

test/webhook.test.ts

@@ -2,6 +2,7 @@ import { expect } from 'chai';
 import { WebhookHandler, createDefaultHandler } from '../src/resources/webhook/handler.js';
 import { basicAuthValidator } from '../src/resources/webhook/auth.js';
 import { CreateChargebee } from '../src/createChargebee.js';
+import { setResponseHeader, setWebhookUserAgent, webhookUserAgent } from '../src/resources/webhook/response.js';
 
 // Mock HTTP client for Chargebee instance
 const mockHttpClient = {
@@ -828,3 +829,70 @@ describe('Webhook Auth Warnings', () => {
     expect(eventProcessed).to.be.true;
   });
 });
+
+describe('Webhook User Agent', () => {
+  it('should set the webhook user agent', () => {
+    setWebhookUserAgent('Custom-User-Agent');
+    expect(webhookUserAgent).to.equal('Custom-User-Agent');
+  });
+
+  it('should set webhook user agent for Response object', async () => {
+    const response = new Response('{}');
+    setWebhookUserAgent('Custom-User-Agent');
+    setResponseHeader(response, 'User-Agent', webhookUserAgent);
+
+    expect(response.headers.get('User-Agent')).to.equal('Custom-User-Agent');
+  });
+
+  it('should set webhook user agent for Headers  object', async () => {
+    const headers = new Headers([['Content-Type', 'application/json']]);
+    setWebhookUserAgent('Custom-User-Agent');
+    setResponseHeader(headers, 'User-Agent', webhookUserAgent);
+
+    expect(headers.get('Content-Type')).to.equal('application/json');
+    expect(headers.get('User-Agent')).to.equal('Custom-User-Agent');
+  });
+
+  it('should set webhook user agent for { headers: Headers } object', async () => {
+    const headers = { headers: new Headers([['Content-Type', 'application/json']]) };
+    setWebhookUserAgent('Custom-User-Agent');
+    setResponseHeader(headers, 'User-Agent', webhookUserAgent);
+
+    expect(headers.headers.get('Content-Type')).to.equal('application/json');
+    expect(headers.headers.get('User-Agent')).to.equal('Custom-User-Agent');
+  });
+
+  it('should set webhook user agent for Node/Bun http-like response object', async () => {
+    const response = { setHeader: (name: string, value: string) => {
+      expect(name).to.equal('User-Agent');
+      expect(value).to.equal('Custom-User-Agent');
+    } };
+    setWebhookUserAgent('Custom-User-Agent');
+    setResponseHeader(response, 'User-Agent', webhookUserAgent);
+  });
+
+  it('should set webhook user agent for Context-like object', async () => {
+    const context = { set: (name: string, value: string) => {
+      expect(name).to.equal('User-Agent');
+      expect(value).to.equal('Custom-User-Agent');
+    } };
+    setWebhookUserAgent('Custom-User-Agent');
+    setResponseHeader(context, 'User-Agent', webhookUserAgent);
+  });
+
+  it('should set webhook user agent for Reply-like object', async () => {
+    const reply = { header: (name: string, value: string) => {
+      expect(name).to.equal('User-Agent');
+      expect(value).to.equal('Custom-User-Agent');
+    } };
+    setWebhookUserAgent('Custom-User-Agent');
+    setResponseHeader(reply, 'User-Agent', webhookUserAgent);
+  });
+
+  it('should not throw error for unknown object', async () => {
+    const response: any = null;
+    setWebhookUserAgent('Custom-User-Agent');
+    setResponseHeader(response, 'User-Agent', webhookUserAgent);    
+    expect(response).to.be.null;
+  });
+});