fix(web): scrub invite tokens before analytics

apps/web/app/PostHogPageView.test.ts

@@ -1,5 +1,6 @@
 import { readFile } from 'node:fs/promises'
 import { describe, expect, it } from 'vitest'
+import { redactInvitePaths } from './providers'
 
 const pageViewPath = new URL('./PostHogPageView.tsx', import.meta.url)
 const providerPath = new URL('./providers.tsx', import.meta.url)
@@ -18,7 +19,28 @@ describe('PostHog invite privacy boundary', () => {
     expect(source).toContain('capture_pageview: false')
     expect(source).toContain('capture_pageleave: false')
     expect(source).toContain('get_current_url: redactInviteUrl')
+    expect(source).toContain('before_send: redactInvitePathsBeforeSend')
     expect(source).toContain("url.pathname.startsWith('/join/')")
     expect(source).toContain('/join/[invite]')
   })
+
+  it('removes an invite code from every serialized URL or path property', () => {
+    const inviteCode = 'A4K9BT2Q'
+    const event = {
+      event: 'join_page_viewed',
+      properties: {
+        $current_url: `https://sauci.app/join/${inviteCode}`,
+        $pathname: `/join/${inviteCode}`,
+        $referrer: `https://sauci.app/join/${inviteCode}?source=message`,
+        $session_entry_url: `https://sauci.app/join/${inviteCode}`,
+        nested: { previous_path: `/join/${inviteCode}` },
+      },
+    }
+
+    const serialized = JSON.stringify(redactInvitePaths(event))
+
+    expect(serialized).not.toContain(inviteCode)
+    expect(serialized).toContain('/join/[invite]')
+    expect(serialized).toContain('join_page_viewed')
+  })
 })

apps/web/app/providers.tsx

@@ -1,9 +1,12 @@
 'use client'
 
-import posthog from 'posthog-js'
+import posthog from 'posthog-js'
-import { PostHogProvider as PHProvider } from 'posthog-js/react'
+import { PostHogProvider as PHProvider } from 'posthog-js/react'
+import type { CaptureResult } from 'posthog-js'
 import { useEffect } from 'react'
 
+const INVITE_PATH_PATTERN = /\/join\/[^/?#\s]+/g
+
 function redactInviteUrl(defaultUrl: string): string {
   const url = new URL(defaultUrl)
 
@@ -14,6 +17,26 @@ function redactInviteUrl(defaultUrl: string): string {
   return defaultUrl
 }
 
+export function redactInvitePaths<T>(value: T): T {
+  if (typeof value === 'string') {
+    return value.replace(INVITE_PATH_PATTERN, '/join/[invite]') as T
+  }
+
+  if (Array.isArray(value)) {
+    return value.map(redactInvitePaths) as T
+  }
+
+  if (value && typeof value === 'object' && (Object.getPrototypeOf(value) === Object.prototype || Object.getPrototypeOf(value) === null)) {
+    return Object.fromEntries(Object.entries(value).map(([key, entry]) => [key, redactInvitePaths(entry)])) as T
+  }
+
+  return value
+}
+
+export function redactInvitePathsBeforeSend(event: CaptureResult | null): CaptureResult | null {
+  return event ? redactInvitePaths(event) : null
+}
+
 export function PostHogProvider({ children }: { children: React.ReactNode }) {
   useEffect(() => {
     if (typeof window !== 'undefined' && process.env.NEXT_PUBLIC_POSTHOG_KEY) {
@@ -23,6 +46,7 @@ export function PostHogProvider({ children }: { children: React.ReactNode }) {
         capture_pageview: false,
         capture_pageleave: false,
         get_current_url: redactInviteUrl,
+        before_send: redactInvitePathsBeforeSend,
       })
     }
   }, [])