fix(telemetry): pass PostHog distinct_id in identify request (#41322)

packages/api-types/types/platform.d.ts

@@ -9218,6 +9218,8 @@ export interface components {
       reset_project?: boolean
     }
     TelemetryIdentifyBodyV2: {
+      /** PostHog JS SDK's distinct_id - used for aliasing anonymous → authenticated users */
+      anonymous_id?: string
       organization_slug?: string
       project_ref?: string
       user_id: string

packages/common/posthog-client.ts

@@ -11,6 +11,9 @@ interface PostHogClientConfig {
 }
 
 class PostHogClient {
+  /** True after posthog.init() is called (prevents double-init) */
+  private initStarted = false
+  /** True after the `loaded` callback fires, meaning PostHog has fully bootstrapped */
   private initialized = false
   private pendingGroups: Record<string, string> = {}
   private pendingIdentification: { userId: string; properties?: Record<string, any> } | null = null
@@ -27,7 +30,7 @@ class PostHogClient {
   }
 
   init(hasConsent: boolean = true) {
-    if (this.initialized || typeof window === 'undefined' || !hasConsent) return
+    if (this.initStarted || typeof window === 'undefined' || !hasConsent) return
 
     if (!this.config.apiKey) {
       console.warn('PostHog API key not found. Skipping initialization.')
@@ -72,11 +75,13 @@ class PostHogClient {
           }
         })
         this.pendingEvents = []
+
+        this.initialized = true
       },
     }
 
+    this.initStarted = true
     posthog.init(this.config.apiKey, config)
-    this.initialized = true
   }
 
   capturePageView(properties: Record<string, any>, hasConsent: boolean = true) {
@@ -148,7 +153,7 @@ class PostHogClient {
     this.pendingGroups = {}
     this.pendingEvents = []
 
-    if (!this.initialized) return
+    if (!this.initStarted) return
 
     try {
       posthog.reset()
@@ -156,6 +161,21 @@ class PostHogClient {
       console.error('PostHog reset failed:', error)
     }
   }
+
+  /**
+   * Returns PostHog's distinct_id, which holds first-touch attribution data.
+   * Returns undefined until PostHog's `loaded` callback fires.
+   */
+  getDistinctId(): string | undefined {
+    if (!this.initialized) return undefined
+
+    try {
+      return posthog.get_distinct_id()
+    } catch (error) {
+      console.error('PostHog getDistinctId failed:', error)
+      return undefined
+    }
+  }
 }
 
 export const posthogClient = new PostHogClient()

packages/common/telemetry.tsx

@@ -320,12 +320,13 @@ export function useTelemetryIdentify(API_URL: string) {
 
   useEffect(() => {
     if (user?.id) {
-      // Send to backend
+      const anonymousId = posthogClient.getDistinctId()
+
       sendTelemetryIdentify(API_URL, {
         user_id: user.id,
+        ...(anonymousId && { anonymous_id: anonymousId }),
       })
 
-      // Also identify in PostHog client-side
       posthogClient.identify(user.id)
     }
   }, [API_URL, user?.id])