- mismatched submitted key (BH123) → 400, no VAPID_PRIVATE_KEY leak - absent app_config.vapid_public_key row → 400 - happy path seeds matching app_config row
- mismatched submitted key (BH123) → 400, no VAPID_PRIVATE_KEY leak - absent app_config.vapid_public_key row → 400 - happy path seeds matching app_config row