MainActivity is exported (launcher requirement) and consumed the session-id extra from any incoming intent without checking the action — a foreign app could launch it explicitly and force-navigate to a chat screen. Guard consumeNotificationIntent() on the app's own notification action and hoist the action string into a shared const so ChatNotificationService and MainActivity can never drift. Co-authored-by: M57 <hy4ri@users.noreply.github.com>