Feature request: selective undo

[notusknot]

A simple but very nice to have feature would be selective undo, as found in Emacs. A user can choose to only undo the selected area, which saves a lot of time and energy. I don’t know much about the Helix internals, but if someone could point out where the undo is located, I’d be happy to give this feature a shot myself.

[A-Walrus]

This seems like a very useful feature! Undo related code: helix-core/src/history.rs and helix-core/src/transaction.rs also some in helix-view/src/document.rs. Commands, such as undo/redo are located in helix-term/src/commands.rs and that's where you would add the selective undo/redo commands (with most of the logic sitting outside of commands.rs).