A client loses its connection after sending a payment command but before receiving an ack…

A client loses its connection after sending a payment command but before receiving an acknowledgement. What is the safest conclusion?

1. The server definitely did not receive the command.
2. The server definitely committed the payment.
3. The outcome is unknown; query it or retry with a stable idempotency key under the application protocol.
4. Close code 1006 proves that replay is safe.