fix(telemetry): send PostHog events through the main HTTP client so they honor the proxy (#35972)

* fix(telemetry): send PostHog events through the main HTTP client so they honor the proxy

* fix(telemetry): omit credentials on PostHog sends

src/main/telemetry/posthog-transport-main-http-client.test.ts

@@ -0,0 +1,39 @@
+import { afterEach, describe, expect, it, vi } from 'vitest'
+import { setMainHttpClient } from '../network/http-client'
+import { createPostHogClient } from './posthog-transport'
+
+describe('PostHog transport', () => {
+  const mainFetch = vi.fn(async () => new Response('{}', { status: 200 }))
+  const globalFetch = vi.fn(async () => new Response('{}', { status: 200 }))
+
+  afterEach(() => {
+    setMainHttpClient(null)
+    vi.unstubAllGlobals()
+    mainFetch.mockClear()
+    globalFetch.mockClear()
+  })
+
+  const capture = async (consent: Parameters<typeof createPostHogClient>[1]) => {
+    vi.stubGlobal('fetch', globalFetch)
+    setMainHttpClient({ fetch: mainFetch, proxySession: () => null })
+    const client = createPostHogClient('test-key', consent)
+    client.capture({ distinctId: 'install-1', event: 'app_opened' })
+    await client.shutdown()
+  }
+
+  // The desktop client sends through the session that carries the user's proxy.
+  it('sends through the main HTTP client, not global fetch', async () => {
+    await capture({ effective: 'enabled' })
+    expect(mainFetch).toHaveBeenCalledWith(
+      expect.stringContaining('/batch'),
+      expect.objectContaining({ method: 'POST', credentials: 'omit' })
+    )
+    expect(globalFetch).not.toHaveBeenCalled()
+  })
+
+  it('sends nothing when telemetry is disabled', async () => {
+    await capture({ effective: 'disabled', reason: 'user_opt_out' })
+    expect(mainFetch).not.toHaveBeenCalled()
+    expect(globalFetch).not.toHaveBeenCalled()
+  })
+})

src/main/telemetry/posthog-transport.ts

@@ -1,6 +1,7 @@
 import { arch as osArch, platform as osPlatform, release as osRelease } from 'node:os'
 import type * as PostHogSdk from 'posthog-node'
 import { getAppEnvironment } from '../../shared/app-environment'
+import { getMainHttpClient } from '../network/http-client'
 import type { CommonProps, EventName } from '../../shared/telemetry-events'
 import type { ConsentState } from './consent'
 
@@ -84,7 +85,10 @@ export function createPostHogClient(writeKey: string, consent: ConsentState): Po
     // Disable SDK GeoIP/IP enrichment to keep the wire inside the declared allow-list.
     disableGeoip: true,
     // Increase offline buffer from 1000 to 5000; overflow drops oldest events.
-    maxQueueSize: 5000
+    maxQueueSize: 5000,
+    // The SDK's default global fetch skips the desktop session's proxy; resolved per send.
+    // Omit credentials so the desktop session never attaches its cookies to telemetry.
+    fetch: (url, options) => getMainHttpClient().fetch(url, { ...options, credentials: 'omit' })
   })
 
   if (shouldOptOutSdkAtInit(consent)) {