Real-time updates mode (e.g. like Google docs)

[keyserj]

Is your feature request related to a problem? Please describe.
Right now, if I'm working on a topic with other people, I have to present my screen, or they need to refresh their screen whenever I make a change to my topic and I need to refresh my screen whenever they score something.

It would be nice if we didn't have to refresh to see the changes that others are making.

Note: this issue is not suggesting that privileges should change to allow other users to edit topic data besides scores - just that changes within current privileges (scores for non-creators, scores + diagram parts for creators) should reflect real-time for other users viewing the topic (#303 and #11 are related to changing privileges).

Describe the solution you'd like

• Maybe a button in the toolbar to enter "real-time mode" (because real-time doesn't seem necessary as a default)
• If I'm the creator of a topic, I should be able to see when another user scores it, without refreshing the page. If I'm not the creator, I should be able to see when the creator makes a new node, without refreshing the page.

Describe alternatives you've considered

• Frequent re-polling for data. The API requests would add up, and it'd be too much data transfer unless we track changes on the back end since time x. Seems not worth

Additional context

Technical ideas

• CRDTs are probably the way, yjs seems like a solid implementation
• Third party websocket infrastructure is probably the way to go, since we don't have our own server for nextjs; something like Pusher (vercel guide) or Ably (netlify guide)?

[keyserj]

There's a lot of info that could be real-time. If it's a lot of work for making each piece real-time, potentially a shorter-term solution could be to just have a real-time notification bubble that shows that something has changed, and that you can refresh your page to get the updates.