Just to confirm behavior at interrupted backup

I run restic as a daily task for baking up to local repository and an offsite repository.

What happens if the task get interrupted?

• Overall, will restic start over "completely" or continue from where it left off next time it's running?
• On file level: What happens to partially uploaded files - will they be appended or will restic start over with such a file?

Just to understand how damaging an interruption is to the process.

Thanks!