The webhook branch of dispatch_reminder validates its target with
check_outbound_url before posting; the ntfy branch posted to the
integration's user-configured base_url with no check, so a base_url
pointing at the metadata range (169.254.169.254) was fetched
server-side — with the integration's Authorization header attached —
every time a reminder fired.
Run the same check (and honor the same REMINDER_WEBHOOK_BLOCK_PRIVATE_IPS
knob) before the post, surfacing rejections in ntfy_error exactly like
the webhook branch does. LAN ntfy servers keep working by default,
matching the project's local-first policy.
Fixes#5141
Co-authored-by: Claude Fable 5 <noreply@anthropic.com>
Wes Huber