feat: add a comment feature for whiteboards

[benjaminfrueh]

Description

Adds a comment feature for collaborative feedback on whiteboards. This is a first basic implementation and supports simple comment threads.

Features

• Comment pins draggable, with user avatar and reply count
• Comment threads with reply, edit, and delete
• Hover preview for quick comment viewing
• Comment sidebar for thread overview, navigation and delete
• Read-only support (no editing and no dragging)

Future enhancements

• add more e2e tests
• resolve/unresolve comment threads
• comment reactions with emoji
• @ mention users in comments
• comment search in sidebar

Screenshots

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Comment thread and reply

Hover comment preview

[marcoambrosini]

Hi Benjamin, really nice!

a few comments:

• Both comments and smart picker buttons should look like the other buttons in the toolbar, both in hover and active state. Currently they look like this

• The input field for comments should auto wrap and grow in height when a new line is required instead of becoming a scroll container

• The comment popover should be movable even if a comment has not been submitted yet. Currently:

Screen.Recording.2025-12-08.at.12.02.40.mov

• When clicking on a thread in the sidebar, the thread itself should be centered in the content. The following screenshot shows what I see after click:

• I would flip the comment hover preview so that the avatar is top aligned with the username

• The send button has dark text in light theme

[benjaminfrueh]

Hi @marcoambrosini - thanks for the good feedback! The changes have been implemented now.

As we discussed, I didn't flip the comment hover preview for now, so the avatar remains in place and the pin tail remains at comment XY. Also the button background styling in the toolbar should be addressed in a separate polishing PR, as it's a general UI change not specific to this feature.

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