feat: add wa_user_created PostHog event on successful sign-up

Fire a `wa_user_created` telemetry event in the NextAuth `onCreateUser`
handler so we can track successful sign-ups in PostHog, closing a gap
in the visitor-to-sign-up conversion funnel.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: msukkari

CHANGELOG.md

@@ -11,6 +11,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Added PostHog events for chat UI interactions (details card expand/collapse, copy answer, table of contents toggle) and repo tracking in `wa_chat_message_sent`. [#922](https://github.com/sourcebot-dev/sourcebot/pull/922)
 - Added Bitbucket Cloud OAuth identity provider support (`provider: "bitbucket-cloud"`) for SSO and account-linked permission syncing. [#924](https://github.com/sourcebot-dev/sourcebot/pull/924)
 - Added permission syncing support for Bitbucket Cloud. [#925](https://github.com/sourcebot-dev/sourcebot/pull/925)
+- Added `wa_user_created` PostHog event fired on successful user sign-up. [#933](https://github.com/sourcebot-dev/sourcebot/pull/933)
 
 ### Changed
 - Hide version upgrade toast for askgithub deployment (`EXPERIMENT_ASK_GH_ENABLED`). [#931](https://github.com/sourcebot-dev/sourcebot/pull/931)

packages/web/src/lib/authUtils.ts

@@ -107,7 +107,7 @@ export const onCreateUser = async ({ user }: { user: AuthJsUser }) => {
                 type: "org"
             }
         });
-    } else if (!defaultOrg.memberApprovalRequired) { 
+    } else if (!defaultOrg.memberApprovalRequired) {
         const hasAvailability = await orgHasAvailability(defaultOrg.domain);
         if (!hasAvailability) {
             logger.warn(`onCreateUser: org ${SINGLE_TENANT_ORG_ID} has reached max capacity. User ${user.id} was not added to the org.`);
@@ -123,6 +123,10 @@ export const onCreateUser = async ({ user }: { user: AuthJsUser }) => {
         });
     }
 
+    // Dynamic import to avoid circular dependency:
+    // authUtils -> posthog -> auth -> authUtils
+    const { captureEvent } = await import("@/lib/posthog");
+    await captureEvent('wa_user_created', { userId: user.id });
 };
 
 

packages/web/src/lib/posthogEvents.ts

@@ -227,6 +227,9 @@ export type PosthogEventMap = {
         chatId: string,
         isExpanded: boolean,
     },
+    wa_user_created: {
+        userId: string,
+    },
     //////////////////////////////////////////////////////////////////
     wa_demo_docs_link_pressed: {},
     wa_demo_search_example_card_pressed: {