Atuin replaces your existing shell history with a SQLite database, and records additional context for your commands. Additionally, it provides optional and fully encrypted synchronisation of your history between machines, via an Atuin server.
Having automatic updates as opt-in by default would be better to avoid supply chain attacks.
I guess the majority of users would prefer automatic data synchronization. The tool therefore offers the option of deactivating automatic synchronization (https://docs.atuin.sh/configuration/config/).
Also, if the original history file is still there it would be a good feature to be able to diff between the sqlite and the history file to see if commands have been deleted.
A solution can probably be created with https://docs.atuin.sh/reference/list/ in conjunction with a shell script.
Are there options to choose what encryption algo is used?
I suspect that this is not possible. Why do you want to change the type of encryption?