Update confirmed calls on team calendars and post alert

You get text confirmations, but events stay unflagged and teams lack context. It flags the event as confirmed and posts a team alert so closers see changes same day.

Overview

Unflagged confirmations create prep friction and wasted rep time; this flow marks text-confirmed calls on the closer's calendar and broadcasts a team alert. The change puts confirmed status in front of closers and schedulers within minutes, removing last-minute surprises.