Add cell comments

[basilenouvellet]

Issue fix #261

Demo

https://user-images.githubusercontent.com/24209524/162003937-4b392926-7e7c-4cde-bba4-9a4a37b30c16.mp4

Left to do

• [ ] Ability to edit & delete comments
• [ ] Fix autofocus issue on the comment text input
• [ ] Persist comments in *.livemd ~& *.exs~ files

[basilenouvellet]

@josevalim @jonatanklosko even if the PR is still a draft, feel free to comment & provide feedback

[josevalim]

This is looking great @BasileNouvellet! Just one note: we don't need to have comments on the .exs file. Just .livemd ones.

@jonatanklosko do you think it is worth a sidebar item that lists all comments? Not as part of this PR, of course, but something to consider.

[jonatanklosko]

do you think it is worth a sidebar item that lists all comments?

It depends on how prominent we make comments on cells. However, we could list all comments by timestamp, rather than grouped, this way it's easy to check if there's a new comment somewhere.

[jonatanklosko]

In terms of UI mechanics, by default we shouldn't be showing much, my suggestion would be

• when a cell has no comments, we show nothing, and when the cell is focused we show a comment icon, clicking on it opens the discussion
• when a cell has comments, we show the comment icon and comment count next to it, clicking on it opens the discussion

[jonatanklosko]

@BasileNouvellet thanks for the updates! I've just edited the comment above, don't worry about other UI details for now, we will reiterate on it once we have the full design :)

[basilenouvellet]

Hey, just to let you know that I'm off currently, and that I will be able to resume work on this feature next week. In the meantime, did you get the chance to iterate on the final UI design?

[jonatanklosko]

@basilenouvellet thanks for the update, just so you know there is no rush! We are still awaiting the design, as there were several other design-related things we prioritized :)

[josevalim]

Thank you so much for the work here @basilenouvellet, but unfortunately we are postponing this feature for now.

Livebook is moving to an architecture where developers run notebooks on their machine. So while we will definitely want comments in the future, comments are not helpful unless we have a central architecture where comments and collaboration happen on the fly, and that will likely come just later.

[basilenouvellet]

I understand, thank you for the explanation @josevalim. Happy to work on it later when needed!