Backup interruption handling

Are interruptions correctly handled? For example, my laptop uploads 1/2 of a backup then he's powered down/lid closed for three days. When it's opened, will it resume the daily backup or start a new one? Same question with unreliable network, like a wifi that reconnects every 5 minutes.
It would be good to have a section about this in the README, it helps in deciding if your software correspond to the needs.

Review the existing backup documentation and verify behavior for a half-uploaded backup after power or lid interruption and for repeated Wi-Fi reconnections. Document whether backups resume or restart, and include the resulting guidance in the README.

Written by the indexing model from the issue text.