payment_success / payment_failed / subscription_activated are captured inside
the Stripe webhook handler and activateSubscription — short requests that return
immediately. posthog-node's fire-and-forget flush was abandoned before the send
completed, so these events were written to the DB but never reached PostHog
(DB had 4 completed Stripe payments in 30d; PostHog had 1 payment_success and 0
payment_failed). payment_initiated, fired in a normal user request, landed fine —
which is what isolated the cause to the webhook/short-request context.
Add PostHogService.flush() and await it at the end of handleWebhook and after the
subscription_activated capture in activateSubscription (the shared Stripe+EFT
chokepoint). Restores server-side paid-conversion visibility so trial→paid ROI is
measurable in PostHog instead of only the DB.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Semih Yesilyurt
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